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Under What Conditions Is Recognition Spared Relative to Recall After Selective Hippocampal Damage in Humans?
Abstract
The claim that recognition memory is spared relative to recall after focal hippocampal damage has been disputed in the literature. We examined this claim by investigating object and object-location recall and recognition memory in a patient, YR, who has adult-onset selective hippocampal damage. Our aim was to identify the conditions under which recognition was spared relative to recall in this patient. She showed unimpaired forced-choice object recognition but clearly impaired recall, even when her control subjects found the object recognition task to be numerically harder than the object recall task. However, on two other recognition tests, YR's performance was not relatively spared. First, she was clearly impaired at an equivalently difficult yes/no object recognition task, but only when targets and foils were very similar. Second, YR was clearly impaired at forced-choice recognition of object-location associations. This impairment was also unrelated to difficulty because this task was no more difficult than the forced-choice object recognition task for control subjects. The clear impairment of yes/no, but not of forced-choice, object recognition after focal hippocampal damage, when targets and foils are very similar, is predicted by the neural network-based Complementary Learning Systems model of recognition. This model postulates that recognition is mediated by hippocampally dependent recollection and cortically dependent familiarity; thus hippocampal damage should not impair item familiarity. The model postulates that familiarity is ineffective when very similar targets and foils are shown one at a time and subjects have to identify which items are old (yes/no recognition). In contrast, familiarity is effective in discriminating which of similar targets and foils, seen together, is old (forced-choice recognition). Independent evidence from the remember/know procedure also indicates that YR's familiarity is normal. The Complementary Learning Systems model can also accommodate the clear impairment of forced-choice object-location recognition memory if it incorporates the view that the most complete convergence of spatial and object information, represented in different cortical regions, occurs in the hippocampus.
... Critically, prior work indicates that rates of false recognition across older and younger adults are reduced considerably in the FC format (Guerin et al., 2012;Migo et al., 2009;Trelle et al., 2017). Existing evidence suggests that this is due, in part, to reduced demands on the hippocampus (Holdstock et al., 2002;Norman, 2010) and PFCdependent recall-based retrieval strategies (e.g., recall-to-reject) when targets and corresponding lures are presented together (Migo et al., 2009;Trelle et al., 2017). Consistent with this possibility, prior work in older adults has demonstrated that the relationship between neuropsychological tests of recall and recognition differs as a function of test format (Migo et al., 2014). ...
... Specifically, we demonstrate age-related decline in Forced Choice performance (replicating work by Trelle et al., 2017), a test format that is known to minimise demands on hippocampalmediated retrieval (e.g. pattern completion; Holdstock et al., 2002;Migo et al., 2009) including strategies such as recall-to-reject (Guerin et al., 2012;Migo et al., 2009;Trelle et al., 2017). Consistent with this idea, executive function was not a significant predictor of FC performance, whereas perceptual discrimination of stimuli with overlapping features explained significant variance. ...
... ability to engage processes that support maintenance and evaluation of these representations), they can also be interpreted in terms of differential contributions of familiarity and recollection processes to performance across test formats. Specifically, prior work suggests that Forced Choice performance, when allowing for direct comparison of targets and corresponding lure, can be supported by cortical familiarity signals, whereas a Yes/No test requires hippocampal-dependent recollection (Holdstock et al., 2002;Migo et al., 2009;Norman, 2010;Trelle et al., 2017). As we did not collect data regarding response strategies during retrieval, we cannot draw strong conclusions regarding the strategies employed across test formats in the present study. ...
Mnemonic discrimination deficits, or impaired ability to discriminate between similar events in memory, is a hallmark of cognitive aging, characterised by a stark age-related increase in false recognition. While individual differences in mnemonic discrimination have gained attention due to potential relevance for early detection of Alzheimer's disease, our understanding of the component processes that contribute to variability in task performance across older adults remains limited. The present investigation explores the roles of representational quality, indexed by perceptual discrimination of objects and scenes with overlapping features, and strategic retrieval ability, indexed by standardised tests of executive function, to mnemonic discrimination in a large cohort of older adults (N=124). We took an individual differences approach and characterised the contributions of these factors to performance under Forced Choice (FC) and Yes/No (YN) recognition memory formats, which place different demands on strategic retrieval. Performance in both test formats declined with age. Accounting for age, individual differences in FC memory performance were best explained by perceptual discrimination score, whereas YN memory performance was best explained by executive functions. A linear mixed model and dominance analyses confirmed the relatively greater importance of perceptual discrimination over executive functioning for FC performance, while the opposite was true for YN. These findings highlight parallels between perceptual and mnemonic discrimination in aging, the importance of considering demands on executive functions in the context of mnemonic discrimination, and the relevance of test format for modulating the impact of these factors on performance in older adults.
... This approach has the additional benefit of being atheoretical and directly testable, and ensures that cognitive theory is linked to biology. As such, memory for items without additional contextual information, which can be remembered by amnesic patients (with hippocampal damage) in item-recognition tests (e.g., Holdstock, Mayes, Gong, Roberts, & Kapur, 2005;Holdstock et al., 2002;Mayes, Holdstock, Isaac, Hunkin, & Roberts, 2002), would not qualify as a sufficient test of episodic memory. This view is congruent with Tulving (2002), and corrects an overgeneralisation made by Tulving (1972). ...
... Providing strong support for the distinction between recollection and familiarity, patients with hippocampal damage show selective impairments to recollection and associative processing (e.g., Aggleton et al., 2005;Brandt, Gardiner, Vargha-Khadem, Baddeley, & Mishkin, 2009;Giovanello, Verfaellie, & Keane, 2003;Holdstock et al., 2002;Mayes et al., 2004;Turriziani, Fadda, Caltagirone, & Carlesimo, 2004;Vann et al., 2009;Verfaellie, Koseff, & Alexander, 2000;Yonelinas, 2001 (2016) reported on experiments with patient M.R., who had an entorhinal cortex lesion that resulted in impaired familiarity, but intact recollection. Despite this compelling evidence, it is also important to acknowledge that lesions to other brain regions, such as in the case of semantic dementia, can also have influences on recollection and familiarity (e.g., Hodges & Graham, 2001). ...
... Not all memory measures are necessarily dependent on episodic memory. As already discussed, old/new recognition can be relatively spared with hippocampal damage (e.g., Holdstock et al., 2005;Holdstock et al., 2002;Mayes et al., 2002). In contrast, performance was highly impaired in recall tests. ...
The definition of episodic memory, as proposed by Tulving, includes a requirement of conscious recall. As we are unable to assess this aspect of memory in nonhuman animals, many researchers have referred to demonstrations of what would otherwise be considered episodic memory as "episodic-like memory." Here the definition of episodic memory is reconsidered based on objective criteria. While the primary focus of this reevaluation is based on work with nonhuman animals, considerations are also drawn from converging evidence from cognitive psychology, neuropsychology, and cognitive neuroscience. Implications of this rethinking are discussed, as well as considerations of familiarity, indirect measures of memory, and generally what should be viewed as necessary for episodic memory. This perspective is intended to begin an iterative process within the field to redefine the meaning of episodic memory and to ultimately establish a consensus view. (PsycInfo Database Record (c) 2020 APA, all rights reserved).
... To gain support for this CLS assumption, Holdstock et al. (2002) tested patient Y.R. who had a selective hippocampal lesion, which impaired recollection but spared familiarity. As predicted, using a picture recognition test involving similar foils, the patient performed within the range of healthy controls when tested in a FC but not in a YN test (Holdstock et al., 2002). ...
... To gain support for this CLS assumption, Holdstock et al. (2002) tested patient Y.R. who had a selective hippocampal lesion, which impaired recollection but spared familiarity. As predicted, using a picture recognition test involving similar foils, the patient performed within the range of healthy controls when tested in a FC but not in a YN test (Holdstock et al., 2002). While other studies showed no benefit from FC tests for hippocampal patients (Bayley et al., 2008;Jeneson et al., 2010), one study with older adults, for whom a disproportional deficit in recollection is assumed, showed an increase in familiarity-based responses in a FC compared to a YN test when recognition memory for similar faces was tested (Bastin and van der Linden, 2003). ...
... Our study is in line with other studies that show an increase in the accuracy of familiarity-based judgments for FCC tests (Bastin and van der Linden, 2003;Holdstock et al., 2002;Migo et al., 2009). Notably, we are aware of only one further study that investigated test format effects in healthy young participants (Migo et al., 2009) in which participants were instructed to exclusively rely on familiarity. ...
Familiarity-based discrimination between studied items and similar foils in yes/no recognition memory tests is relatively poor. The complementary learning systems (CLS) framework explains this with the small difference in familiarity strength between targets and foils. The framework, however, also predicts that familiarity values of targets and corresponding similar foils are directly comparable – as long as they are presented side by side in a forced-choice corresponding (FCC) test. This is because in each trial, targets tend to be more familiar than their corresponding foils. In contrast, when forced-choice displays contain non-corresponding foils (FCNC) which are similar to other studied items, familiarity values are not directly comparable (as in yes/no-tasks). In a recognition memory task with pictures of objects, we found that the putative ERP correlate of familiarity, the mid-frontal old/new effect for targets vs. foils, was significantly larger in FCC compared to FCNC displays. Moreover, single-trial target-foil amplitude differences predicted the accuracy of the recognition judgment. This study supports the assumption of the CLS framework that the test format can influence the diagnostic reliability of familiarity. Moreover, it implies that the mid-frontal old/new effect does not reflect the difference in the familiarity signal between studied and non-studied items but the task-adequate assessment of this signal.
... This approach has the additional benefit of being atheoretical and directly testable, and ensures that cognitive theory is linked to biology. As such, memory for items without additional contextual information, which can be remembered by amnesic patients (with hippocampal damage) in item-recognition tests (e.g., Holdstock, Mayes, Gong, Roberts, & Kapur, 2005;Holdstock et al., 2002;Mayes, Holdstock, Isaac, Hunkin, & Roberts, 2002), would not qualify as a sufficient test of episodic memory. This view is congruent with Tulving (2002), and corrects an overgeneralisation made by Tulving (1972). ...
... Providing strong support for the distinction between recollection and familiarity, patients with hippocampal damage show selective impairments to recollection and associative processing (e.g., Aggleton et al., 2005;Brandt, Gardiner, Vargha-Khadem, Baddeley, & Mishkin, 2009;Giovanello, Verfaellie, & Keane, 2003;Holdstock et al., 2002;Mayes et al., 2004;Turriziani, Fadda, Caltagirone, & Carlesimo, 2004;Vann et al., 2009;Verfaellie, Koseff, & Alexander, 2000;Yonelinas, 2001 (2016) reported on experiments with patient M.R., who had an entorhinal cortex lesion that resulted in impaired familiarity, but intact recollection. Despite this compelling evidence, it is also important to acknowledge that lesions to other brain regions, such as in the case of semantic dementia, can also have influences on recollection and familiarity (e.g., Hodges & Graham, 2001). ...
... Not all memory measures are necessarily dependent on episodic memory. As already discussed, old/new recognition can be relatively spared with hippocampal damage (e.g., Holdstock et al., 2005;Holdstock et al., 2002;Mayes et al., 2002). In contrast, performance was highly impaired in recall tests. ...
The definition of episodic memory, as proposed by Tulving, includes a requirement of conscious recall. As we are unable to assess this aspect of memory in non-human animals, many researchers have referred to demonstrations of what would otherwise be considered episodic memory as “episodic-like memory.” Here the definition of episodic memory is instead re-considered based on objective criteria. While the primary focus of this re-evaluation is based on work with non-human animals, considerations are also made drawing from converging evidence from cognitive psychology, neuropsychology, and cognitive neuroscience. Implications of this rethinking are discussed, as well as considerations of familiarity, indirect measures of memory, and generally what should be viewed as necessary for episodic memory. This perspective is not intended to suddenly redefine the meaning of episodic memory, but rather to advance an open discussion and reconsideration of the consensus view.
... Specifically, the CLS model predicts that the pattern separation mechanisms of the hippocampus allow it to avoid interference between targets and similar lures whereas the distributed representations in the neocortex exhibit interference between targets and similar lures but can support performance for targets and novel foils (i.e., given the low level of similarity between targets and novel foils). Patients with damage to the hippocampus [20,21,22,23], and the dentate gyrus in particular [24], have been shown to exhibit impaired performance on old/new and old/similar/new tests of targets vs. similar lures but intact performance for targets vs. novel foils, thus supporting the predictions of the CLS model. Several neuroscientific studies have supported the prediction that the hippocampus uses pattern separation to reduce the similarity between similar experiences. ...
... In contrast to the findings for the old/new test formats, the support for the predictions of selective impairments on the forced-choice formats has been equivocal. A case study of a single patient suggested that damage to the hippocampus specifically impaired performance in discriminating between targets and similar lures in the old/new test format with intact performance on the A-A' test format [20] (for similar findings in patients with amnestic mild cognitive impairment see: [55]). However, other studies with a larger sample of patients suggest that hippocampal damage impairs performance on both the old/new and the A-A' test formats [21,22]. ...
Episodic memory is a core function that allows us to remember the events of our lives. Given that many events in our life contain overlapping elements (e.g., similar people and places), it is critical to understand how well we can remember the specific events of our lives vs. how susceptible we are to interference between similar memories. Several prominent theories converged on the notion that pattern separation in the hippocampus causes it to play a greater role in processes such as recollection, associative memory, and memory for specific details, while distributed representations in the neocortex cause it to play a more prominent role in domain-specific memory. We propose that studying human memory performance on tasks with targets and similar lures provides a critical testbed for comparing the competing predictions of the role of hippocampal pattern separation vs. more distributed representations in supporting human episodic memory. We generated predictions from competing computational models and then tested these predictions in a large sample of human participants. We found that the comparison between simulated neural responses in an object-processing region of the brain (area IT) and human memory performance exhibited a linear relationship. We also observed strong effects of test format on performance and consistent relationships between test formats. Altogether, our results were better accounted for by distributed memory models than the pattern-separated representations of the hippocampus. Therefore, our results provide an important challenge to prominent theories of human memory and provide an important alternative mechanism for explaining human memory performance.
... As opposed to functional imaging studies, which can only show correlation between regional brain activity and performance of a behavioral task, neuropsychological studies of the behavioral consequences of brain lesions enable the determination of necessity and causality in structure-function relationships, thus complementing and aiding the interpretation of regional activations in fMRI/PET studies (Siddiqi et al., 2022;Rosenbaum, Gilboa, & Moscovitch, 2014). Unfortunately, the handful of neuropsychological studies related to this issue generally included only a few patients; they did not apply quantitative voxel-wise analyses that provide high spatial resolution; and furthermore, they were limited by a hypothesis-driven focus on predefined regions-of-interest (ROIs), leaving the involvement of other potentially relevant brain regions unassessed (Pigott & Milner, 1993;Holdstock et al., 2002Holdstock et al., , 2005Crane & Milner 2005;Stepankova et al., 2004). Furthermore, to the best of our knowledge, with the exception of Memel et al. (2020), no studies have attempted to assess the contribution of white matter integrity to mnemonic performance for the various aspects of episodic experience elements. ...
... It thus more greatly represents binding of location information with the other features. Lesion studies have also shown that right hippocampal lesions cause deficits in various tasks of object-location and spatial memory (Kopelman, Stanhope & Kingsley, 1997;Pigott & Milner, 1993;Smith & Milner, 1981, 1984Holdstock et al., 2002Holdstock et al., , 2005Crane & Milner 2005;Nunn, Graydon, Polkey & Morris, 1999;Stepankova et al., 2004;van Asselen et al., 2009). Patients with hippocampal pathology due to perinatal anoxia (Vargha-Khadem et al., 1997) show impaired object-location memory. ...
Brain networks supporting visual memory include extrastriate and other cortical regions associated with visual perception, which manifest domain-specific processing of "where," "how," and various aspects of "what" information. However, whether and how such specialization affects memory for these types of information is still a matter of debate. Functional neuroimaging studies point to dissociable as well as common network components supporting the perception and memory of different aspects of visual information. In the current neuropsychological study, we assess the impact of stroke lesion topography on recall of identity, location, and action of event participants, as assessed by the WMS-III Family Pictures subtest. We used voxel-based lesion-behavior mapping (VLBM) to identify brain lesions specifically implicated in memory deficits for each dimension. Behavioral analysis disclosed impaired performance by both right- and left-hemisphere damage patients, with lesions on each side yielding distinct effects. VLBM analysis revealed a bi-hemispheric network supporting these various aspects of visual memory. In the right hemisphere, the network includes frontal, parietal, and temporal cortical regions and the basal ganglia. In the left hemisphere, the network is more restricted, including visual association areas and medial temporal lobe regions. We further observed that a subset of these regions - those included in the ventral ("what") stream, and in the putative core recollection network - is implicated in multiple aspects of visual memory, whereas other areas are specifically implicated in memory for specific aspects of the visual scene.
... Similarly, semantic or orthographic similarity between targets and lures leads to compromised performance in item recognition tests (Heathcote, 2003). Amnesic patients perform poorly on recognition tests when the targets and lures are similar (Bayley et al., 2008;Westerberg et al., 2006;Holdstock et al., 2002), but do about as well as controls when targets are distinct (Mayes, Holdstock, Isaac, Hunkin, & Roberts, 2002;Turriziani, Fadda, Caltagirone, & Carlesimo, 2004;Vargha-Khadem et al., 1997). Furthermore, higher interstimulus similarity seems to affect recognition performance, giving rise to small list length and list strength effects (Osth, Dennis, & Kinnell, 2014;Kinnell & Dennis, 2012). ...
... This is due to the fact that the difference between similar items lies in small details in the input space; therefore, if a memory system can retrieve the representations with high precision, the fidelity of the representations would still allow to distinguish the fine details and to relate the items to each other. We thus predict that people with compromised hippocampus will be impaired both in recognizing the similarity between the items (Olsen et al., 2015) and distinguishing them (Görler, Wiskott, & Cheng, 2020;Bayley et al., 2008;Westerberg et al., 2006;Holdstock et al., 2002). The models by Norman and O'Reilly (2003) and Greve et al. (2010) also account for the decreased discrimination in hippocampal patients; however, they implement different architectures and/or different retrieval processes for different brain regions. ...
Receiver operating characteristic (ROC) analysis is the standard tool for studying recognition memory. In particular, the curvilinearity and the y-offset of recognition ROC curves have been interpreted as indicative of either memory strength (single-process models) or different memory processes (dual-process model). The distinction between familiarity and recollection has been widely studied in cognitive neuroscience in a variety of conditions, including lesions of different brain regions. We develop a computational model that explicitly shows how performance in recognition memory is affected by a complex and, as yet, underappreciated interplay of various factors, such as stimulus statistics, memory processing, and decision-making. We demonstrate that (1) the factors in the model affect recognition ROC curves in unexpected ways, (2) fitting R and F parameters according to the dual-process model is not particularly useful for understanding the underlying processes, and (3) the variability of recognition ROC curves and the controversies they have caused might be due to the uncontrolled variability in the contributing factors. Although our model is abstract, its functional components can be mapped onto brain regions, which are involved in corresponding functions. This enables us to reproduce and interpret in a coherent framework the diverse effects on recognition memory that have been reported in patients with frontal and hippocampal lesions. To conclude, our work highlights the importance of the rich interplay of a variety of factors in driving recognition memory performance, which has to be taken into account when interpreting recognition ROC curves.
... Moreover, evidence suggests that it is the hippocampus that is important for distinguishing highly correlated items. In the Westerberg et al. (2006) paradigm, patients with selective hippocampal lesions rejected highly related lures less frequently than healthy controls (Bayley et al. 2008;Holdstock et al. 2002), whereas recognition performance with unrelated lures is often preserved. In agreement with these findings, theoretical work concludes that representational overlap in cortex is higher than in the hippocampus (Greve et al. 2010;Norman & O'Reilly 2003). ...
... We can only agree that the hippocampus might contribute somewhat to entity pattern discrimination. However, we also note that, in these studies, most patients actually do manage to perform the task well above chance (Bayley et al. 2008;Holdstock et al. 2002), suggesting that they do have some ability to discriminate highly similar lures. Therefore, the hippocampus could contribute, while not being necessary, to entity pattern separation. ...
Despite highlighting the role of the attribution system and proposing a coherent large-scale architecture of declarative memory, the integrative memory model would be more “integrative” if the temporal dynamics of the interactions between its components was clarified. This is necessary to make predictions in patients with brain injury and hypothesize dissociations.
... Moreover, evidence suggests that it is the hippocampus that is important for distinguishing highly correlated items. In the Westerberg et al. (2006) paradigm, patients with selective hippocampal lesions rejected highly related lures less frequently than healthy controls (Bayley et al. 2008;Holdstock et al. 2002), whereas recognition performance with unrelated lures is often preserved. In agreement with these findings, theoretical work concludes that representational overlap in cortex is higher than in the hippocampus (Greve et al. 2010;Norman & O'Reilly 2003). ...
... We can only agree that the hippocampus might contribute somewhat to entity pattern discrimination. However, we also note that, in these studies, most patients actually do manage to perform the task well above chance (Bayley et al. 2008;Holdstock et al. 2002), suggesting that they do have some ability to discriminate highly similar lures. Therefore, the hippocampus could contribute, while not being necessary, to entity pattern separation. ...
The integrative memory model formalizes a new conceptualization of memory in which interactions between representations and cognitive operations within large-scale cerebral networks generate subjective memory feelings. Such interactions allow to explain the complexity of memory expressions, such as the existence of multiples sources for familiarity and recollection feelings and the fact that expectations determine how one recognizes previously encountered information.
... Moreover, evidence suggests that it is the hippocampus that is important for distinguishing highly correlated items. In the Westerberg et al. (2006) paradigm, patients with selective hippocampal lesions rejected highly related lures less frequently than healthy controls (Bayley et al. 2008;Holdstock et al. 2002), whereas recognition performance with unrelated lures is often preserved. In agreement with these findings, theoretical work concludes that representational overlap in cortex is higher than in the hippocampus (Greve et al. 2010;Norman & O'Reilly 2003). ...
... We can only agree that the hippocampus might contribute somewhat to entity pattern discrimination. However, we also note that, in these studies, most patients actually do manage to perform the task well above chance (Bayley et al. 2008;Holdstock et al. 2002), suggesting that they do have some ability to discriminate highly similar lures. Therefore, the hippocampus could contribute, while not being necessary, to entity pattern separation. ...
The ventral lateral parietal cortex (VLPC) shows robust activation during episodic retrieval, and is involved in content representation, as well as in the evaluation of memory traces. This suggests that the VLPC has a crucial contribution to the quality of recollection and the subjective experience of remembering, and situates it at the intersection of the core and attribution systems.
... Moreover, evidence suggests that it is the hippocampus that is important for distinguishing highly correlated items. In the Westerberg et al. (2006) paradigm, patients with selective hippocampal lesions rejected highly related lures less frequently than healthy controls (Bayley et al. 2008;Holdstock et al. 2002), whereas recognition performance with unrelated lures is often preserved. In agreement with these findings, theoretical work concludes that representational overlap in cortex is higher than in the hippocampus (Greve et al. 2010;Norman & O'Reilly 2003). ...
... We can only agree that the hippocampus might contribute somewhat to entity pattern discrimination. However, we also note that, in these studies, most patients actually do manage to perform the task well above chance (Bayley et al. 2008;Holdstock et al. 2002), suggesting that they do have some ability to discriminate highly similar lures. Therefore, the hippocampus could contribute, while not being necessary, to entity pattern separation. ...
The syndrome of semantic dementia represents the “other side of the coin” to Alzheimer's disease, offering convergent evidence to help refine Bastin et al.’s integrative memory model. By considering the integrative memory model through the lens of semantic dementia, we propose a number of important extensions to the framework, to help clarify the complex neurocognitive mechanisms underlying recollection and familiarity.
... In line with this CLS assumption, patient Y.R., who had a selective hippocampal lesion, which impaired recollection but spared familiarity, performed within the range of healthy controls in a picture recognition test involving similar foils when tested in a FC but not in a YN test (Holdstock et al., 2002). While other studies showed no benefit from FC tests for hippocampal patients (Bayley, Wixted, Hopkins, & Squire, 2008;Jeneson, Kirwan, Hopkins, Wixted, & Squire, 2010), one study with older adults, for whom a disproportional deficit in recollection is assumed, showed . ...
... Our study is in line with other studies that show an increase in the accuracy of familiarity-based judgments for FCC tests (Bastin & van der Linden, 2003;Holdstock et al., 2002;Migo et al., 2009). Notably, in the only other study that investigated test format effects in healthy young . ...
Familiarity-based discrimination between studied target items and similar foils in yes/no recognition memory tests is relatively poor. According to the complementary learning systems (CLS) framework this is due do a relatively small difference in familiarity strength between these two item classes. The model, however, also predicts that when targets and corresponding similar foils are presented next to each other in a forced-choice corresponding (FCC) test format, familiarity values for targets and foils can be directly compared because in each trial, targets are reliably more familiar than their corresponding foils. In contrast, when forced-choice displays contain non-corresponding foils (FCNC) which are similar to other studied items (but not the target), familiarity should not be diagnostic because familiarity values are not directly comparable (as in yes/no-tasks). We compared ERP old/new effects (ERPs of targets vs. foils) when participants were tested with FCC vs. FCNC displays after having intentionally encoded pictures of objects. As predicted, the mid-frontal old/new effect which is associated with familiarity was significantly larger in FCC compared to FCNC displays. Moreover, the target-foil amplitude difference predicted the accuracy of the recognition judgment in a given trial. This is one of the very few studies which support the assumption of the CLS framework that the test format can influence the diagnosticity of familiarity. Moreover, it implies that the mid-frontal old/new effect does not reflect the mean difference in the familiarity signal itself between studied and non-studied items but reflects the task-adequate assessment of the familiarity signal.
... When target and distractor items are not very similar to each other, both recollection and familiarity may adequately support recognition in yes-no tasks as well as in forced-choice tasks (Norman & O'Reilly, 2001). Such an interaction between the test format and the similarity between targets and distractors has been reported in a study by Holdstock et al. (2002). In this study, yes-no and forced-choice recognition memory for pictures were examined in a hippocampal patient. ...
Whether the format of a recognition memory task influences the contribution of recollection and familiarity to performance is a matter of debate. The authors investigated this issue by comparing the performance of 64 young (mean age = 21.7 years; mean education = 14.5 years) and 62 older participants (mean age = 64.4 years; mean education = 14.2 years) on a yes-no and a forced-choice recognition task for unfamiliar faces using the remember-know-guess procedure. Familiarity contributed more to forced-choice than to yes-no performance. Moreover, older participants, who showed a decrease in recollection together with an increase in familiarity, performed better on the forced-choice task than on the yes-no task, whereas younger participants showed the opposite pattern.
... Prior work has demonstrated that neocortex is capable of computing a scalar familiarity signal that discriminates between previously-encountered and novel stimuli (Yonelinas, 2002;Norman and O'Reilly, 2003;Holdstock et al., 2002); likewise, signals can be extracted from models of the hippocampus that discriminate between novel and familiar stimuli (e.g., Hasselmo and Wyble, 1997;see Norman, 2010 for a comparison of the properties of these neocortical and hippocampal signals). In this section, we study how familiarity signals can support episodic retrieval policy. ...
Recent human behavioral and neuroimaging results suggest that people are selective in when they encode and retrieve episodic memories. To explain these findings, we trained a memory-augmented neural network to use its episodic memory to support prediction of upcoming states in an environment where past situations sometimes reoccur. We found that the network learned to retrieve selectively as a function of several factors, including its uncertainty about the upcoming state. Additionally, we found that selectively encoding episodic memories at the end of an event (but not mid-event) led to better subsequent prediction performance. In all of these cases, the benefits of selective retrieval and encoding can be explained in terms of reducing the risk of retrieving irrelevant memories. Overall, these modeling results provide a resource-rational account of why episodic retrieval and encoding should be selective and lead to several testable predictions.
... Some studies propose that participants tend to use the recall-to-reject strategy for successful lure discrimination in the traditional form of the MST (e.g., Kirwan & Stark, 2007), however, some recent findings suggest that the feeling of familiarity also contributes to lure discrimination performance (Kim & Yassa, 2013;Szőllősi, Bencze, & Racsmány, 2020). Other studies examined lure discrimination in a recognition task involving multiple similar lures presented together with their corresponding target item in the same task (see : Holdstock, Mayes, Roberts, Cezayirli, Isaac, O'Reilly, & Norman, 2002). Holdstock and colleagues (2002) found that lure discrimination in a yes/no recognition task was impaired in a patient with selective hippocampal damage, and it was reported that healthy individuals mainly use recall-to-reject strategy in the same task (Migo, Montaldi, Norman, Quamme, & Mayes, 2009). ...
Pattern separation is a computational mechanism performed by the hippocampus allowing the reduction of overlap between sensory inputs with similar perceptual features. Our first aim was to develop a new paradigm sensitive to the behavioural consequences of pattern separation (mnemonic discrimination). For this purpose, we constructed morphed face stimuli with parametrically changing levels of similarity. After encoding participants saw studied items and similar lure faces. Perceptual similarity affected false recognition and there was a gradual reduction in discrimination accuracy with the increment of similarity between the stimuli. However, confidence ratings were sensitive to smaller changes (Experiment 1) than the other test type with “old”/“similar”/“new” response options (Experiment 2). Mnemonic discrimination relies strongly on retrieving details of the original stimulus. Therefore, we investigated whether pattern separation can be tuned by retrieval in the form of a discrimination task (Experiment 3). Our findings suggest that repeatedly encountering the stimuli within a two-alternative forced-choice task (in comparison with the repeated presentation of the material) increased both the correct identification and the false recognition of similar stimuli two days after encoding. We conclude that basic computational mechanisms of the hippocampus can be tuned by a task that requires discrimination between studied and new stimuli.
... Prior work has demonstrated that cortex is capable of computing a familiarity signal on its own (i.e., without hippocampus) that discriminates between previously encountered and novel stimuli (Holdstock et al., 2002;Norman, 2010;Norman & O'Reilly, 2003;Yonelinas, 2002). In this section, we study how this cortical familiarity signal can support episodic recall policy. ...
When should episodic memories be stored and retrieved to support event understanding? Traditional list-learning memory experiments make it obvious when to store and retrieve memories, but it is less obvious when to do this in naturalistic settings. To address this question, we trained a memory-augmented neural network to predict upcoming events, in an environment where situations (sets of parameters governing transitions between events) sometimes reoccurred. The model was allowed to learn a policy for when to consult episodic memory, and we explored how this learned policy varied as a function of the task environment. We found that the learned retrieval policy is shaped by internal uncertainty about upcoming events, the level of penalty associated with incorrect predictions, the confusability of stored memories, the presence of a "familiarity signal" indicating the availability of relevant memories, and the presence of statistical regularities (prototypical events). With regard to encoding policy, we found that selectively storing episodic memories at the end of an event (but not mid-event) leads to better subsequent event prediction performance and less incorrect recall. Additionally, we found that the model can integrate information over long timescales even without the hippocampus; it can link information over many event segments via episodic memory; and it shows classic schema-consistent memory effects when the upcoming time point has a prototypical event. Overall, these modeling results provide a normative explanation of several existing behavioral and neuroimaging findings regarding the use of episodic memory in naturalistic settings, and lead to a wide range of testable predictions.
... Further investigations into aphantasia will also provide critical insight to the nature of imagery, and how it compares to different forms of memory. While aphantasic participants show an impairment during recall performance, no evidence has shown impairments in visual recognition, supporting converging evidence towards a neural dissociation in the processes of quick, automatic visual recognition and slower, elaborative visual recall (Bainbridge et al., 2019;Barbeau, Pariente, Felician, & Puel, 2011;Holdstock et al., 2002;Jacoby, 1991;Staresina & Davachi, 2006). That being said, the recognition task in the current experiment had low difficulty, testing foil images of the same semantic category, but without other matched detail (e.g., identities of objects). ...
Congenital aphantasia is a recently characterized variation of experience defined by the inability to form voluntary visual imagery, in individuals who are otherwise high performing. Because of this specific deficit to visual imagery, individuals with aphantasia serve as an ideal group for probing the nature of representations in visual memory, particularly the interplay of object, spatial, and symbolic information. Here, we conducted a large-scale online study of aphantasia and revealed a dissociation in object and spatial content in their memory representations. Sixty-one individuals with aphantasia and matched controls with typical imagery studied real-world scene images, and were asked to draw them from memory, and then later copy them during a matched perceptual condition. Drawings were objectively quantified by 2,795 online scorers for object and spatial details. Aphantasic participants recalled significantly fewer objects than controls, with less color in their drawings, and an increased reliance on verbal scaffolding. However, aphantasic participants showed high spatial accuracy equivalent to controls, and made significantly fewer memory errors. These differences between groups only manifested during recall, with no differences between groups during the matched perceptual condition. This object-specific memory impairment in individuals with aphantasia provides evidence for separate systems in memory that support object versus spatial information. The study also provides an important experimental validation for the existence of aphantasia as a variation in human imagery experience.
... Asterisks represent significant differences (*P < 0.05). and recall memory tasks, where recall might be more challenging (24) and involves more hippocampal activity (25), that might also have an influence on our findings. To further explore the effect of ON-tDCS on memory, we conduct a follow-up experiment using a recall memory task (Fig. 3, F and G) to investigate the long-term effects of ON-tDCS. ...
An ongoing debate surrounding transcranial direct current stimulation (tDCS) of the scalp is whether it modulates brain activity both directly and in a regionally constrained manner enough to positively affect symptoms in patients with neurological disorders. One alternative explanation is that direct current stimulation affects neural circuits mainly indirectly, i.e., via peripheral nerves. Here, we report that noninvasive direct current stimulation indirectly affects neural circuits via peripheral nerves. In a series of studies, we show that direct current stimulation can cause activation of the greater occipital nerve (ON-tDCS) and augments memory via the ascending fibers of the occipital nerve to the locus coeruleus, promoting noradrenaline release. This noradrenergic pathway plays a key role in driving hippocampal activity by modifying functional connectivity supporting the consolidation of a memory event.
... Item memory, on the other hand, may be processed in other medial temporal lobe structures (e.g., perirhinal cortex) (McClelland et al. 1995;Eichenbaum et al. 2007), but see also (Squire and Zola-Morgan 1991). Although the use of an old/new recognition paradigm with similar foils may require the hippocampus for recollection of small details rather than familiarity (Holdstock et al. 2002), it does not require pattern separation at encoding and so does not directly address the formation of separated representations for storage to avoid interference during recall. ...
An essential feature of episodic memory is the ability to recall the multiple elements relating to one event from the multitude of elements relating to other, potentially similar events. Hippocampal pattern separation is thought to play a fundamental role in this process, by orthogonalizing the representations of overlapping events during encoding, to reduce interference between them during the process of pattern completion by which one or other is recalled. We introduce a new paradigm to test the hypothesis that similar memories, but not unrelated memories, are actively separated at encoding. Participants memorized events which were either unique or shared a common element with another event (paired "overlapping" events). We used a measure of dependency, originally devised to measure pattern completion, to quantify how much the probability of successfully retrieving associations from one event depends on successful retrieval of associations from the same event, an unrelated event or the overlapping event. In two experiments, we saw that within event retrievals were highly dependent, indicating pattern completion; retrievals from unrelated events were independent; and retrievals from overlapping events were antidependent (i.e., less than independent), indicating pattern separation. This suggests that representations of similar (overlapping) memories are actively separated, resulting in lowered dependency of retrieval performance between them, as would be predicted by the pattern separation account.
... Higher functioning individuals with ASD perform well on standard cued recall and paired-association learning (Boucher and Warrington, 1976;Minshew and Goldstein, 2001;Williams et al., 2006) and recall tasks involving non-social items, such as buildings and leaves, but have been found to perform poorly on face memory tasks (Blair et al., 2002). Neurobiologically, specific memory deficits like these are unlikely to be due to changes in the hippocampus, as patients with hippocampal lesions show broad memory deficiencies (Winocur and Weiskrantz, 1976;Shimamura and Squire, 1988;Holdstock et al., 2002). Instead, these specific deficits are better attributed to memory recall functions in the posterior parietal cortex (Hadjikhani et al., 2004), which, when lesioned, produce subtle and selective memory deficits resembling episodic memory impairments (Boucher and Mayes, 2012). ...
Restricted interests (RIs) in autism spectrum disorder (ASD) are clinically impairing interests of unusual focus or intensity. They are a subtype of restricted and repetitive behaviors which are one of two diagnostic criteria for the disorder. Despite the near ubiquity of RIs in ASD, the neural basis for their development is not well understood. However, recent cognitive neuroscience findings from nonclinical samples and from individuals with ASD shed light on neural mechanisms that may explain the emergence of RIs. We propose the nexus model of RIs in ASD, a novel conceptualization of this symptom domain that suggests that RIs may reflect a co-opting of brain systems that typically serve to integrate complex attention, memory, semantic, and social communication functions during development. The nexus model of RIs hypothesizes that when social communicative development is compromised, brain functions typically located within the lateral surface of cortex may expand into social processing brain systems and alter cortical representations of various cognitive functions during development. These changes, in turn, promote the development of RIs as an alternative process mediated by these brain networks. The nexus model of RIs makes testable predictions about reciprocal relations between the impaired development of social communication and the emergence of RIs in ASD and suggests novel avenues for treatment development.
... Previous studies have indicated that generally AD patients are also impaired in recognition as well as recall since sensory processing also seems to be affected in AD [21]. Indeed, the previous study showed that recognition was impaired in a patient with hippocampal lesion [22]. However, there is a possibility that object recognition impairments could not be obviously observed at mild AD stage [23], which is line with the result of this study. ...
To date, it is unclear whether cognitive intervention on episodic memory (EM) is effective in improving all or a subset of EM components in Alzheimer's disease (AD). Therefore, this study investigated effects of EM training on the elderly aged over 65 with AD. For this study, 13 AD patients and 16 healthy older adults were recruited. The pre- and post-test for components of EM was a memory task designed to test memory for object identity ("what"), spatial location ("where"), and temporal order ("when"). Training in the AD group consisted of 16 sessions of practice remembering temporal sequences of different objects being hidden in various locations. At pre-test, accuracy on the "where" and "when" conditions were impaired in the AD patients compared with the healthy elderly (p < 0.01). At post-test, accuracy on the "where" condition was significantly improved (p < 0.05) whereas, there were no significant improvements on the "what" and "when" conditions (p > 0.05). Interestingly, there were no significant improvements in standard neuropsychological measures. These findings suggest that AD, in its early stages, selectively impaired spatial and temporal memory rather than object memory. Additionally, it was observed that EM training in AD had different effects depending on the components of EM.
... Findings consistent with this viewpoint offer evidence of specific recollection deficits in patients with selective damage to the hippocampal memory system (e.g., Brandt, Gardiner, Vargha-Khadem, Baddeley, & Mishkin, 2009;Holdstock et al., 2002) and/or a double dissociation between recall-and familiarity-based recognition (e.g., Bowles et al., 2010; see also Brandt, Eysenck, Nielsen, & von Oertzen, 2016). However, single-process theorists dispute these functional and structural dissociations, arguing that these apparent dissociations are driven by differences in memory strength, and point to studies that report impairment of both recall and recognition (e.g., Manns et al., 2003), and of both the recollection and familiaritybased recognition (for review see Wixted & Squire, 2010), following bilateral hippocampal damage. ...
Since the publication of Scoville and Milner's (1957) seminal paper, the precise functional role played by the hippocampus in support of human memory has been fiercely debated. For instance, the single question of whether the hippocampus plays a time‐limited or an indelible role in the recollection of personal memories led to a deep and tenacious schism within the field. Similar polarizations arose between those who debated the precise nature of the role played by the hippocampus in support of semantic relative to episodic memories and in recall/recollection relative to familiarity‐based recognition. At the epicenter of these divisions lies conflicting neuropsychological findings. These differences likely arise due to the consistent use of heterogeneous patient populations to adjudicate between these positions. Here we utilized traditional neuropsychological measures in a homogenous patient population with a highly discrete hippocampal lesion (i.e., VGKCC‐Ab related autoimmune limbic encephalitis patients). We observed consistent impairment of recent episodic memories, a present but less striking impairment of remote episodic memories, preservation of personal semantic memory, and recall but not recognition memory deficits. We conclude that this increasingly well‐characterized patient group may represent an important homogeneous population in which the functional role played by the hippocampus may be more precisely delineated.
... For instance, the patient from Warrington and McCarthy (1988) showed normal memory for the meaning of premorbid and postmorbid words. The same result occurred with a group of non-Korsakoff amnesic patients studied by Verfaellie and colleagues (1995), as well as with Holdstock et al.'s (2002) patient, who was able to recognize postmorbid celebrities and famous events. However, perhaps the strongest piece of evidence in support of the claim that semantic facts can be learned independently of the hippocampus comes from well-documented cases of developmental amnesia. ...
A longstanding tradition in philosophy distinguishes between knowthatand know-how. This traditional “anti-intellectualist” view is soentrenched in folk psychology that it is often invoked in supportof an allegedly equivalent distinction between explicit and implicitmemory, derived from the so-called “standard model of memory.”In the last two decades, the received philosophical view has beenchallenged by an “intellectualist” view of know-how. Surprisingly, defenders of the anti-intellectualist view have turned to the cognitivescience of memory, and to the standard model in particular, todefend their view. Here, I argue that this strategy is a mistake. As it turns out, upon closer scrutiny, the evidence from cognitivepsychology and neuroscience of memory does not support theanti-intellectualist approach, mainly because the standard modelof memory is likely wrong. However, this need not be interpretedas good news for the intellectualist, for it is not clear that theempirical evidence necessarily supports their view either. I arguethat, currently, the philosophical debate is couched in terms thatdo not correspond to categories in psychological science. As aresult, the debate has to either be re-interpreted in a vocabularythat is amenable to experimental scrutiny, or it cannot be settledempirically.
... Findings consistent with this viewpoint offer evidence of specific recollection deficits in patients with selective damage to the hippocampal memory system (e.g. Brandt, Gardiner, Vargha-Khadem, Baddeley, & Mishkin, 2009;Holdstock et al., 2002) and/or a double dissociation between recall-and familiarity-based recognition (e.g. Bowles et al., 2010; see also Brandt, Eysenck, Nielsen, & von Oertzen, 2016). ...
Since the publication of Scoville and Milner's (1957) seminal paper, the precise functional role played by the hippocampus in support of human memory has been fiercely debated. For instance, the single question of whether the hippocampus plays a time-limited or an indelible role in the recollection of personal memories led to a deep and tenacious schism within the field. Similar polarisations arose between those who debated the precise nature of the role played by the hippocampus in support of semantic relative to episodic memories and in recall/recollection relative to familiarity-based recognition. At the epicentre of these divisions lies conflicting neuropsychological findings. These differences likely arise due to the consistent use of heterogeneous patient populations to adjudicate between these positions. Here we utilised traditional neuropsychological measures in a homogenous patient population with a highly discrete hippocampal lesion (i.e. patients with voltage-gated potassium channel complex antibody associated limbic encephalitis (VGKC-LE)). We observed impairment of recent but not remote episodic memory, a preservation of semantic memory, and recall but not recognition memory deficits. We conclude that this increasingly well-characterised group of patients may represent an important homogeneous population in which the functional role played by the hippocampus may be more precisely delineated.
The Cambridge Handbook of Consciousness is the first of its kind in the field, and its appearance marks a unique time in the history of intellectual inquiry on the topic. After decades during which consciousness was considered beyond the scope of legitimate scientific investigation, consciousness re-emerged as a popular focus of research towards the end of the last century, and it has remained so for nearly 20 years. There are now so many different lines of investigation on consciousness that the time has come when the field may finally benefit from a book that pulls them together and, by juxtaposing them, provides a comprehensive survey of this exciting field. An authoritative desk reference, which will also be suitable as an advanced textbook.
The Cambridge Handbook of Consciousness is the first of its kind in the field, and its appearance marks a unique time in the history of intellectual inquiry on the topic. After decades during which consciousness was considered beyond the scope of legitimate scientific investigation, consciousness re-emerged as a popular focus of research towards the end of the last century, and it has remained so for nearly 20 years. There are now so many different lines of investigation on consciousness that the time has come when the field may finally benefit from a book that pulls them together and, by juxtaposing them, provides a comprehensive survey of this exciting field. An authoritative desk reference, which will also be suitable as an advanced textbook.
The Cambridge Handbook of Consciousness is the first of its kind in the field, and its appearance marks a unique time in the history of intellectual inquiry on the topic. After decades during which consciousness was considered beyond the scope of legitimate scientific investigation, consciousness re-emerged as a popular focus of research towards the end of the last century, and it has remained so for nearly 20 years. There are now so many different lines of investigation on consciousness that the time has come when the field may finally benefit from a book that pulls them together and, by juxtaposing them, provides a comprehensive survey of this exciting field. An authoritative desk reference, which will also be suitable as an advanced textbook.
The Cambridge Handbook of Consciousness is the first of its kind in the field, and its appearance marks a unique time in the history of intellectual inquiry on the topic. After decades during which consciousness was considered beyond the scope of legitimate scientific investigation, consciousness re-emerged as a popular focus of research towards the end of the last century, and it has remained so for nearly 20 years. There are now so many different lines of investigation on consciousness that the time has come when the field may finally benefit from a book that pulls them together and, by juxtaposing them, provides a comprehensive survey of this exciting field. An authoritative desk reference, which will also be suitable as an advanced textbook.
The Cambridge Handbook of Consciousness is the first of its kind in the field, and its appearance marks a unique time in the history of intellectual inquiry on the topic. After decades during which consciousness was considered beyond the scope of legitimate scientific investigation, consciousness re-emerged as a popular focus of research towards the end of the last century, and it has remained so for nearly 20 years. There are now so many different lines of investigation on consciousness that the time has come when the field may finally benefit from a book that pulls them together and, by juxtaposing them, provides a comprehensive survey of this exciting field. An authoritative desk reference, which will also be suitable as an advanced textbook.
Alzheimer’s disease (AD) is the most common type of dementia, characterized by early memory impairments and gradual worsening of daily functions. AD-related pathology, such as amyloid-beta (Aβ) plaques, begins to accumulate many years before the onset of clinical symptoms. Predicting risk for AD via related pathology is critical as the preclinical stage could serve as a therapeutic time window, allowing for early management of the disease and reducing health and economic costs. Current methods for detecting AD pathology, however, are often expensive and invasive, limiting wide and easy access to a clinical setting. A non-invasive, cost-efficient platform, such as computerized cognitive tests, could be potentially useful to identify at-risk individuals as early as possible. In this study, we examined the diagnostic value of an episodic memory task, the mnemonic discrimination task (MDT), for predicting risk of cognitive impairment or Aβ burden. We constructed a random forest classification algorithm, utilizing MDT performance metrics and various neuropsychological test scores as input features, and assessed model performance using area under the curve (AUC). Models based on MDT performance metrics achieved classification results with an AUC of 0.83 for cognitive status and an AUC of 0.64 for Aβ status. Our findings suggest that mnemonic discrimination function may be a useful predictor of progression to prodromal AD or increased risk of Aβ load, which could be a cost-efficient, noninvasive cognitive testing solution for potentially wide-scale assessment of AD pathological and cognitive risk.
This book is a definitive reference source for the growing, increasingly more important, and interdisciplinary field of computational cognitive modeling, that is, computational psychology. It combines breadth of coverage with definitive statements by leading scientists in this field. Research in computational cognitive modeling explores the essence of cognition and various cognitive functionalities through developing detailed, process-based understanding by specifying computational mechanisms, structures, and processes. Given the complexity of the human mind and its manifestation in behavioral flexibility, process-based computational models may be necessary to explicate and elucidate the intricate details of the mind. The key to understanding cognitive processes is often in fine details. Computational models provide algorithmic specificity: detailed, exactly specified, and carefully thought-out steps, arranged in precise yet flexible sequences. These models provide both conceptual clarity and precision at the same time. This book substantiates this approach through overviews and many examples.
This book is a definitive reference source for the growing, increasingly more important, and interdisciplinary field of computational cognitive modeling, that is, computational psychology. It combines breadth of coverage with definitive statements by leading scientists in this field. Research in computational cognitive modeling explores the essence of cognition and various cognitive functionalities through developing detailed, process-based understanding by specifying computational mechanisms, structures, and processes. Given the complexity of the human mind and its manifestation in behavioral flexibility, process-based computational models may be necessary to explicate and elucidate the intricate details of the mind. The key to understanding cognitive processes is often in fine details. Computational models provide algorithmic specificity: detailed, exactly specified, and carefully thought-out steps, arranged in precise yet flexible sequences. These models provide both conceptual clarity and precision at the same time. This book substantiates this approach through overviews and many examples.
This book is a definitive reference source for the growing, increasingly more important, and interdisciplinary field of computational cognitive modeling, that is, computational psychology. It combines breadth of coverage with definitive statements by leading scientists in this field. Research in computational cognitive modeling explores the essence of cognition and various cognitive functionalities through developing detailed, process-based understanding by specifying computational mechanisms, structures, and processes. Given the complexity of the human mind and its manifestation in behavioral flexibility, process-based computational models may be necessary to explicate and elucidate the intricate details of the mind. The key to understanding cognitive processes is often in fine details. Computational models provide algorithmic specificity: detailed, exactly specified, and carefully thought-out steps, arranged in precise yet flexible sequences. These models provide both conceptual clarity and precision at the same time. This book substantiates this approach through overviews and many examples.
This book is a definitive reference source for the growing, increasingly more important, and interdisciplinary field of computational cognitive modeling, that is, computational psychology. It combines breadth of coverage with definitive statements by leading scientists in this field. Research in computational cognitive modeling explores the essence of cognition and various cognitive functionalities through developing detailed, process-based understanding by specifying computational mechanisms, structures, and processes. Given the complexity of the human mind and its manifestation in behavioral flexibility, process-based computational models may be necessary to explicate and elucidate the intricate details of the mind. The key to understanding cognitive processes is often in fine details. Computational models provide algorithmic specificity: detailed, exactly specified, and carefully thought-out steps, arranged in precise yet flexible sequences. These models provide both conceptual clarity and precision at the same time. This book substantiates this approach through overviews and many examples.
Our brains are capable of discriminating similar inputs (pattern separation) and rapidly generalizing across inputs (statistical learning). Are these two processes dissociable in behavior? Here, we asked whether cognitive aging affects them in a differential or parallel manner. Older and younger adults were tested on their ability to discriminate between similar trisyllabic words and to extract trisyllabic words embedded in a continuous speech stream. Older adults demonstrated intact statistical learning on an implicit, reaction time-based measure and an explicit, familiarity-based measure of learning. However, they performed poorly in discriminating similar items presented in isolation, both for episodically-encoded items and for statistically-learned regularities. These results indicate that pattern separation and statistical learning are dissociable and differentially affected by aging. The acquisition of implicit representations of statistical regularities operates robustly into old age, whereas pattern separation influences the expression of statistical learning with high representational fidelity and is subject to age-related decline.
This book is a definitive reference source for the growing, increasingly more important, and interdisciplinary field of computational cognitive modeling, that is, computational psychology. It combines breadth of coverage with definitive statements by leading scientists in this field. Research in computational cognitive modeling explores the essence of cognition and various cognitive functionalities through developing detailed, process-based understanding by specifying computational mechanisms, structures, and processes. Given the complexity of the human mind and its manifestation in behavioral flexibility, process-based computational models may be necessary to explicate and elucidate the intricate details of the mind. The key to understanding cognitive processes is often in fine details. Computational models provide algorithmic specificity: detailed, exactly specified, and carefully thought-out steps, arranged in precise yet flexible sequences. These models provide both conceptual clarity and precision at the same time. This book substantiates this approach through overviews and many examples.
This book is a definitive reference source for the growing, increasingly more important, and interdisciplinary field of computational cognitive modeling, that is, computational psychology. It combines breadth of coverage with definitive statements by leading scientists in this field. Research in computational cognitive modeling explores the essence of cognition and various cognitive functionalities through developing detailed, process-based understanding by specifying computational mechanisms, structures, and processes. Given the complexity of the human mind and its manifestation in behavioral flexibility, process-based computational models may be necessary to explicate and elucidate the intricate details of the mind. The key to understanding cognitive processes is often in fine details. Computational models provide algorithmic specificity: detailed, exactly specified, and carefully thought-out steps, arranged in precise yet flexible sequences. These models provide both conceptual clarity and precision at the same time. This book substantiates this approach through overviews and many examples.
The Cambridge Handbook of Consciousness is the first of its kind in the field, and its appearance marks a unique time in the history of intellectual inquiry on the topic. After decades during which consciousness was considered beyond the scope of legitimate scientific investigation, consciousness re-emerged as a popular focus of research towards the end of the last century, and it has remained so for nearly 20 years. There are now so many different lines of investigation on consciousness that the time has come when the field may finally benefit from a book that pulls them together and, by juxtaposing them, provides a comprehensive survey of this exciting field. An authoritative desk reference, which will also be suitable as an advanced textbook.
The Cambridge Handbook of Consciousness is the first of its kind in the field, and its appearance marks a unique time in the history of intellectual inquiry on the topic. After decades during which consciousness was considered beyond the scope of legitimate scientific investigation, consciousness re-emerged as a popular focus of research towards the end of the last century, and it has remained so for nearly 20 years. There are now so many different lines of investigation on consciousness that the time has come when the field may finally benefit from a book that pulls them together and, by juxtaposing them, provides a comprehensive survey of this exciting field. An authoritative desk reference, which will also be suitable as an advanced textbook.
Pattern separation, the creation of distinct representations of similar inputs, and statistical learning, the rapid extraction of regularities across multiple inputs, have both been linked to hippocampal processing. It has been proposed that there may be functional differentiation within the hippocampus, such that the trisynaptic pathway (entorhinal cortex > dentate gyrus > CA3 > CA1) supports pattern separation, whereas the monosynaptic pathway (entorhinal cortex > CA1) supports statistical learning. To test this hypothesis, we investigated the behavioral expression of these two processes in B. L., an individual with highly selective bilateral lesions in the dentate gyrus that presumably disrupts the trisynaptic pathway. We tested pattern separation with two novel auditory versions of the continuous mnemonic similarity task, requiring the discrimination of similar environmental sounds and trisyllabic words. For statistical learning, participants were exposed to a continuous speech stream made up of repeating trisyllabic words. They were then tested implicitly through a RT-based task and explicitly through a rating task and a forced-choice recognition task. B. L. showed significant deficits in pattern separation on the mnemonic similarity tasks and on the explicit rating measure of statistical learning. In contrast, B. L. showed intact statistical learning on the implicit measure and the familiarity-based forced-choice recognition measure. Together, these results suggest that dentate gyrus integrity is critical for high-precision discrimination of similar inputs, but not the implicit expression of statistical regularities in behavior. Our findings offer unique new support for the view that pattern separation and statistical learning rely on distinct neural mechanisms.
Cognitive tests sensitive to the integrity of the medial temporal lobe (MTL), such as mnemonic discrimination of perceptually similar stimuli, may be useful early markers of risk for cognitive decline in older populations. Perceptual discrimination of stimuli with overlapping features also relies on MTL, but remains relatively unexplored in this context. We assessed mnemonic discrimination in two test formats (Forced Choice, Yes/No) and perceptual discrimination of objects and scenes in 111 community-dwelling older adults at different risk status for cognitive impairment based on neuropsychological screening. We also investigated associations between performance and MTL subregion volume and thickness. The at-risk group exhibited reduced entorhinal thickness and impaired perceptual and mnemonic discrimination. Perceptual discrimination impairment partially explained group differences in mnemonic discrimination and correlated with entorhinal thickness. Executive dysfunction accounted for Yes/No deficits in at-risk adults, demonstrating the importance of test format for the interpretation of memory decline. These results suggest that perceptual discrimination tasks may be useful tools for detecting incipient cognitive impairment related to reduced MTL integrity in non-clinical populations.
Since the first description of the case of H.M. in the mid-1950s, the debate over the contribution of the mesial temporal lobe (MTL) to human memory functioning has not ceased to stimulate new experimental work and the development of new theoretical models. The early demonstration that despite their devastating memory loss patients with hippocampal damage are still able to learn a number of visuo-motor and visuo-perceptual skills at a normal rate and to be normally primed by verbal and visual material suggested that the term “memory” is actually an umbrella concept that includes very different brain plasticity phenomena and that MTL damage actually impairs only one of these. Subsequent research, which capitalized on a detailed anatomical description of MTL structures and on the close analysis of memory-related phenomena, tried to define the unique role of the MTL structures in brain plasticity and in the government of human behavior. A first hypothesis identified this role in the conscious forms of memory as opposed to implicit ones. In the last two decades, the emphasis has moved to the relational role of the hippocampus in binding together different pieces of unimodal information to provide unitary, multimodal representations of personal experiences.
Whereas both human and animal lesion and human neuroimaging studies have implicated the hippocampus in memory for associations, some studies find preserved associative memory following hippocampal damage. Starting with a classic summed similarity model of item recognition, we can account for associative recognition without assuming a specific hippocampally-mediated associative process. We add one key assumption: that one item can influence activation of another item's features. Feature-strength patterns, evaluated for each probe item individually, are then diagnostic of whether an item was paired with one item versus another. We suggest that feature-level inference, without explicit storage of associations, may play a critical role in associative recognition tasks. (PsycInfo Database Record (c) 2021 APA, all rights reserved).
Five experiments employed event-related potentials (ERPs) to investigate dual-process models of recognition memory. Each experiment consisted of a three phase design in which two lists of words were presented in two temporally segregated study tasks. During the third, 'test', phase, subjects were required to respond on one key to old items from a specified study phase, and to respond on another key both to old items from the alternate study phase and to new items. As recognised items require differential responding depending on their source, it is argued that recollection-based recognition of a studied item allows subjects to respond accurately whereas familiarity-based recognition does not. Four principal patterns of neural activity were observed throughout the course of the five experiments. Items recognised on the basis of familiarity elicited greater positivity than new items at frontal sites between 300-600 msec. Recollected items were associated with a second phase of positivity between 500-800 msec, maximal at parietal sites. The finding that these two patterns of neural activity were qualitatively distinct supports dual-process models of recognition memory which state that recollection and familiarity are independent. Recognised items also elicited greater positivity than new items over right frontal and frontopolar sites from 800 msec until the end of the recording epoch (approximately 1400 msec). It is argued that this ERP effect reflects processes that evaluate and monitor the products of retrieval. Finally, a fourth pattern of neural activity is reported in which ERPs associated with studied items are more negative going than those associated with new items, maximal at mid and right parietal sites between 800-1400 msec. It is suggested that this ERP effect may reflect the response conflict experienced when recognition does not determine the response. The implications of these findings for models of recognition memory are discussed.
Describing what one saw to another person is common in everyday experience, such as spatial navigation and crime investigations. Past studies have examined the effects of recounting on one's own memory, neglecting an important function of memory recall in social communication. Here we report surprisingly low utility of one's verbal descriptions for others, even when visual memory for the stimuli has high capacity. Participants described photographs of common objects they had seen to enable judges to identify the target object from a foil in the same basic-level category. When describing from perception, participants were able to provide useful descriptions, allowing judges to accurately identify the target objects 87% of the time. Judges' accuracy decreased to just 57% when participants provided descriptions from memory acquired minutes ago, and to near chance (51.8%) when the verbal descriptions were based on memory acquired 24 hours ago. Comparison of participants' own identification accuracy with judges' accuracy suggests the presence of a common source of errors. This finding suggests that recall and recognition of visual objects share common memory sources. In addition, the low utility of one's verbal descriptions constrains theories about the extension of one's memory to the external world and has implications for eyewitness identification and laws governing it.
Studies attempting to identify the mechanisms that are responsible for the level of false recognition in the DRM paradigm usually apply a manipulation during encoding. The main aim of the studies reported here was to investigate the within- and between-participant effects of a testing method on memory performance using a standard yes/no recognition test and a 2-alternative forced-choice recognition test (2FC). To allow a direct comparison of the 2 testing methods, a 2FC test containing similar items as a typical yes/no test in the DRM paradigm was elaborated on in the pilot study. Moreover, 2 methods of data calculation were used: comparing rates of hit and false alarms with critical lures and with unstudied and unrelated items between the 2 tests and comparing measures of sensitivity (d') derived from signal detection theory. Both experiments showed a lower false alarm rate to critical lures and higher hit rate in a 2FC test as compared with a yes/no test, depicting a typical mirror effect. A within-participant design (Experiment 1) also showed that this increased accuracy of a 2FC test diminished when memory performance was expressed in terms of a sensitivity measure, which may suggest that similar processes are used during these 2 retrieval methods. A similar analysis performed for a between-participants design (Experiment 2) revealed that a 2FC test was less susceptible to associative memory distortions, but the quality of memory (“remember/know” judgments) remained similar for both tests.
We fully support dissociating the subjective experience from the memory contents in recognition memory, as Bastin et al. posit in the target article. However, having two generic memory modules with qualitatively different functions is not mandatory and is in fact inconsistent with experimental evidence. We propose that quantitative differences in the properties of the memory modules can account for the apparent dissociation of recollection and familiarity along anatomical lines.
Explain the theoretical models underlying recognition memory processes and test their implications in a theory-informed paradigm with a right-sided mediodorsal thalamic lesion subject.
A recent literature survey of results from a widely used recognition memory test raised questions about the extent to which recognition memory impairment ordinarily occurs in human amnesia and, in particular, whether recognition memory is impaired at all after damage limited to the hippocampal region (J. P. Aggleton & C. Shaw, 1996). Experiment 1 examined the performance of 6 amnesic patients on 11 to 25 different recognition memory tests. Three patients had bilateral lesions limited primarily to the hippocampus (G.D.) or the hippocampal formation (W.H. and L.M.), as determined by postmortem, neurohistological analysis (N. Rempel-Clower, S. M. Zola, L. R. Squire, & D. G. Amaral, 1996). All 6 patients exhibited unequivocally impaired recognition memory. In Experiment 2, the 3 patients still available for study were each markedly impaired on a test of object recognition similar to the kind used to test recognition memory in nonhuman primates. Recognition memory impairment is a robust feature of human amnesia, even when damage is limited primarily to the hippocampus.
Three experiments are reported that examine the dissociations in performance on two tests of retention, speeded reading and recognition in young people, home-dwelling and institutionalized elderly people, and people with severe memory disorders. In Experiment 1, subjects read sentences in normal and in geometrically transformed script at initial presentation, 1–2 hr later, and again 4–14 days later. On the latter two occasions, they were required to distinguish old sentences that they had read previously from new ones. In general, the young and elderly subjects could distinguish old from new sentences at the short delay, and all but the institutionalized elderly people could do so at the long delay. Retention as measured by reading speed typically paralleled recognition performance in that those items that were recognized best were read most quickly. The dissociation between these two tests of retention is seen only in people with memory disorders. Although these people could not distinguish old from new items even at short delays (most could not even remember having seen any sentences), their retention as assessed by reading time was similar to that of the other groups. Old sentences were read most quickly, indicating retention of item-specific information, and reading time of new sentences improved, indicating the acquisition and retention of a general skill.
Experiment 2 examined what type of item-specific information was retained. Young, elderly, and memory-disordered subjects studied weakly associated word pairs and sentences. A few minutes later they were tested on both recognition and speeded reading of old, new, and recombined pairs and sentences, the last being those in which words from a studied pair or sentence were recombined with words from other such pairs or sentences. The results of both retention tests indicated that young and elderly people could distinguish old from new and recombined items. People with memory disorders, however, again failed on recognition but performed normally on speeded reading. Like the other two groups, they read old items faster than either recombined or new items. In Experiment 3, similar results were obtained even when the word pairs were constructed using randomly associated items.
The results of all three experiments suggest that on implicit tests of memory, such as speeded reading, people with memory disorders can be shown to have formed and retained new associations despite failing utterly on explicit tests, such as recognition, that require conscious recollection of a previous episode. The dissociation between these two ways of testing memory, or two forms of remembering, in normal young and old people, as well as in patients with memory disorders, is discussed in terms of a task-specific, component-process approach to memory that is contrasted with a multiple-memory-system approach.
Extended the search of associative memory model for recall proposed by J. G. Raaijmakers and R. M. Shiffrin by assuming that a familiarity process is used for recognition. The recall model posits cue-dependent probabilistic sampling and recovery from an associative network. The present recognition model is closely related to the recall model because the total episodic activation due to the context and item cues is used in recall as a basis for sampling and in recognition to make a decision. The model, formalized in a computer simulation program, correctly predicts a number of findings in the literature as well as the results from an experiment on the word-frequency effect in which 80 undergraduates participated. (3½ p ref)
The multiple-trace simulation model, MINERVA 2, was applied to a number of phenomena found in experiments on relative and absolute judgments of frequency, and forced-choice and yes-no recognition memory. How the basic model deals with effects of repetition, forgetting, list length, orientation task, selective retrieval, and similarity and how a slightly modified version accounts for effects of contextual variability on frequency judgments were shown. Two new experiments on similarity and recognition memory were presented, together with appropriate simulations; attempts to modify the model to deal with additional phenomena were also described. Questions related to the representation of frequency are addressed, and the model is evaluated and compared with related models of frequency judgments and recognition memory.
Pattern association memory autoassociation memory competitive networks, including self-organizing maps error-correcting networks - perceptrons, backpropagation of error in multilayer networks, and reinforcement learning algorithms hippocampus and memory pattern association in the brain - amygdala and orbitofrontal cortex cortical networks for invariant pattern recognition motor systems - cerebellum and basal ganglia cerebral neocortex. Appendix 1: introduction to linear algebra for neural networks. Appendix 2: Information theory. Appendix 3: Pattern associators. Appendix 4: Autoassociators. Appendix 5: Recurrent dynamics.
We report the performance on recognition memory tests of Jon, who, despite amnesia from early childhood, has developed normal levels of performance on tests of intelligence, language, and general knowledge. Despite impaired recall, he performed within the normal range on each of six recognition tests, but he appears to lack the recollective phenomenological experience normally associated with episodic memory. His recall of previously unfamiliar newsreel event was impaired, but gained substantially from repetition over a 2-day period. Our results are consistent with the hypothesis that the recollective process of episodic memory is not necessary either for recognition or for the acquisition of semantic knowledge.
The multiple-trace simulation model, {minerva} 2, was applied to a number of phenomena found in experiments on relative and absolute judgments of frequency, and forced-choice and yes–no recognition memory. How the basic model deals with effects of repetition, forgetting, list length, orientation task, selective retrieval, and similarity and how a slightly modified version accounts for effects of contextual variability on frequency judgments were shown. Two new experiments on similarity and recognition memory were presented, together with appropriate simulations; attempts to modify the model to deal with additional phenomena were also described. Questions related to the representation of frequency are addressed, and the model is evaluated and compared with related models of frequency judgments and recognition memory. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Several suggestions for a class of theories of recognition memory have been proposed during the past decade. These models address predictions about judgments of prior occurrence of an event, not the identification of what it is. The history and current status of one of these models is discussed. The model postulates the detection of familiarity and the utilization of retrieval mechanisms as additive and separate processes. The phenomenal experience of familiarity is assigned to intraevent organizational integrative processes; retrieval depends on interevent elaborative processes. Other current theoretical options are described, and relevant supportive data from the literature are reviewed. New tests of the model involving both free recall and word pair paradigms are presented. The dual process model is extended to the word frequency effect and to the recognition difficulties of amnesic patients. (68 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
A new model of recognition memory is reported. This model is placed within, and introduces, a more elaborate theory that is being developed to predict the phenomena of explicit and implicit, and episodic and generic, memory. The recognition model is applied to basic findings, including phenomena that pose problems for extant models: the list-strength effect (e.g., Ratcliff, Clark, & Shiffrin, 1990), the mirror effect (e.g., Glanzer & Adams, 1990), and the normal-ROC slope effect (e.g., Ratcliff, McKoon, & Tindall, 1994). The model assumes storage of separate episodic images for different words, each image consisting of a vector of feature values. Each image is an incomplete and error prone copy of the studied vector. For the simplest case, it is possible to calculate the probability that a test item is "old," and it is assumed that a default "old" response is given if this probability is greater than .5. It is demonstrated that this model and its more complete and realistic versions produce excellent qualitative predictions.
This article considers the role of the hippocampus in memory function. A central thesis is that work with rats, monkeys, and humans--which has sometimes seemed to proceed independently in 3 separate literatures--is now largely in agreement about the function of the hippocampus and related structures. A biological perspective is presented, which proposes multiple memory systems with different functions and distinct anatomical organizations. The hippocampus (together with anatomically related structures) is essential for a specific kind of memory, here termed declarative memory (similar terms include explicit and relational). Declarative memory is contrasted with a heterogeneous collection of nondeclarative (implicit) memory abilities that do not require the hippocampus (skills and habits, simple conditioning, and the phenomenon of priming). The hippocampus is needed temporarily to bind together distributed sites in neocortex that together represent a whole memory.
Examined the dissociations in performance on 2 tests of retention—speeded reading and recognition. In Exp I, 14 undergraduates, 14 community-dwelling elderly people (CDP [mean age 68.2 yrs]), 10 institutionalized elderly people (mean age 78.6 yrs), and 8 people with memory disorders (MDP [mean age 55.3 yrs]) read sentences in normal and in geometrically transformed script at initial presentation, 1–2 hrs later, and 4–24 days later, and were required to distinguish old sentences from new ones on the latter 2 occasions. In Exp II, 12 CDP (mean age 71.4 yrs), 12 undergraduates, and 8 MDP (mean age 50.6 yrs) studied weakly-associated word pairs and sentences and were tested on recognition and speeded reading of old, new, and recombined sentences. In Exp III, 12 normal elderly people (mean age 71.4 yrs), 12 undergraduates, and 12 MDP (mean age 64.25 yrs) studied randomly-paired words and sentences. Overall results suggest that on speeded reading tests, Ss with MDs formed and retained new associations despite failing on recognition tests that required conscious recollection of a previous episode. The dissociation between these 2 ways of testing memory in normal young, elderly, and MD people is discussed in terms of a task-specific, component-process approach to memory that is contrasted with a multiple-memory-system approach. (70 ref)
Extended the search of associative memory model for recall proposed by J. G. Raaijmakers and R. M. Shiffrin (see record 1981-20491-001) by assuming that a familiarity process is used for recognition. The recall model posits cue-dependent probabilistic sampling and recovery from an associative network. The present recognition model is closely related to the recall model because the total episodic activation due to the context and item cues is used in recall as a basis for sampling and in recognition to make a decision. The model, formalized in a computer simulation program, correctly predicts a number of findings in the literature as well as the results from an experiment on the word-frequency effect in which 80 undergraduates participated. (3½ p ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Damage to the hippocampal system disrupts recent memory but leaves remote memory intact. The account presented here suggests that memories are first stored via synaptic changes in the hippocampal system, that these changes support reinstatement of recent memories in the neocortex, that neocortical synapses change a little on each reinstatement, and that remote memory is based on accumulated neocortical changes. Models that learn via changes to connections help explain this organization. These models discover the structure in ensembles of items if learning of each item is gradual and interleaved with learning about other items. This suggests that the neocortex learns slowly to discover the structure in ensembles of experiences. The hippocampal system permits rapid learning of new items without disrupting this structure, and reinstatement of new memories interleaves them with others to integrate them into structured neocortical memory systems.
Items located within an array were presented to alcoholic Korsakoff and nonalcoholic mixed-etiology amnesics and to alcoholic and normal controls. Recognition memory for the locations of items was tested after incidental and intentional encoding. When equated on item recognition, neither Korsakoff amnesics nor alcoholic controls benefited from intentional, relative to incidental, encoding instructions. Furthermore, Korsakoff amnesics showed neither disproportionately impaired incidental nor intentional location recognition memory relative to alcoholic controls. In contrast, mixed-etiology amnesics profited significantly from intentional location acquisition relative to incidental instructions, and were impaired somewhat in incidental, but not intentional, location memory relative to normal controls. We discuss these data in relation to Mayes' (1992) contextual memory deficit hypothesis and Hirst's (1982) automatic encoding deficit account, and propose an alternative framework in which the location memory deficit observed in mixed-etiology amnesics is interpreted as a disruption to the ability to bind item and location information.
Global anterograde amnesia is described in three patients with brain injuries that occurred in one case at birth, in another
by age 4, and in the third at age 9. Magnetic resonance techniques revealed bilateral hippocampal pathology in all three cases.
Remarkably, despite their pronounced amnesia for the episodes of everyday life, all three patients attended mainstream schools
and attained levels of speech and language competence, literacy, and factual knowledge that are within the low average to
average range. The findings provide support for the view that the episodic and semantic components of cognitive memory are
partly dissociable, with only the episodic component being fully dependent on the hippocampus.
Some memories are linked to a specific time and place, allowing one to re-experience the original event, whereas others are accompanied only by a feeling of familiarity. To uncover the distinct neural bases for these two types of memory, we measured brain activity during memory retrieval using event-related functional magnetic resonance imaging. We show that activity in the hippocampus increased only when retrieval was accompanied by conscious recollection of the learning episode. Hippocampal activity did not increase for items recognized based on familiarity or for unrecognized items. These results indicate that the hippocampus selectively supports the retrieval of episodic memories.
This study examines the ability of amnesic patients to recover newly formed associations implicitly after a single study trial. Fifteen amnesic patients with various etiologies studied pairs by forming a sentence containing both words. At test, all participants saw 40 intact pairs, 40 rearranged pairs, and 40 new words. All pairs appeared side by side both at study and at test. For the implicit lexical-decision task, 40 nonwords were intermixed with the other pairs, and participants indicated whether both items were words. For the explicit speeded-recognition test, participants were asked to indicate whether both words had appeared at study. Despite being severely impaired on the explicit test, amnesic patients performed like healthy controls on the implicit test, with faster and more accurate responses to intact pairs than to recombined pairs. Contrary to existing theories, the results suggest that amnesic patients can form and retain new associations.
The authors present a theoretical framework for understanding the roles of the hippocampus and neocortex in learning and memory. This framework incorporates a theme found in many theories of hippocampal function: that the hippocampus is responsible for developing conjunctive representations binding together stimulus elements into a unitary representation that can later be recalled from partial input cues. This idea is contradicted by the fact that hippocampally lesioned rats can learn nonlinear discrimination problems that require conjunctive representations. The authors' framework accommodates this finding by establishing a principled division of labor, where the cortex is responsible for slow learning that integrates over multiple experiences to extract generalities whereas the hippocampus performs rapid learning of the arbitrary contents of individual experiences. This framework suggests that tasks involving rapid, incidental conjunctive learning are better tests of hippocampal function. The authors implement this framework in a computational neural network model and show that it can account for a wide range of data in animal learning.
Numerous studies have found a null list strength effect (LSE) for recognition sensitivity: Strengthening memory traces associated with some studied items does not impair recognition of nonstrengthened studied items. In Experiment 1, the author found a LSE using receiver operating characteristic-based measures of recognition sensitivity. To account for the discrepancy between this and prior research, the author (a) argues that a LSE occurs for recollection but not for discrimination based on familiarity, and (b) presents self-report data consistent with this hypothesis. Experiment 2 tested the dual-process hypothesis more directly, using switched-plurality (SP) lures to isolate the contribution of recollection. There was a significant LSE for comparisons involving SP lures; the LSE for discrimination of studied items and nominally unrelated lures (which can be supported by familiarity) was not significant.
The hippocampus and related structures are thought to be capable of: 1) representing cortical activity in a way that minimizes overlap of the representations assigned to different cortical patterns (pattern separation); and 2) modifying synaptic connections so that these representations can later be reinstated from partial or noisy versions of the cortical activity pattern that was present at the time of storage (pattern completion). We point out that there is a tradeoff between pattern separation and completion, and propose that the unique anatomical and physiological properties of the hippocampus might serve to minimize this tradeoff. We use analytical methods to determine quantitative estimates of both separation and completion for specified parameterized models of the hippocampus. These estimates are then used to evaluate the role of various properties and of the hippocampus, such as the activity levels seen in different hippocampal regions, synaptic potentiation and depression, th...
The present study compared the recognition memory deficit in different groups of amnesics using scores from a standard test. The data, taken from a literature search, came from 33 studies reporting the performance of amnesic subjects on the recognition memory test (RMT) [77]. A total of 112 amnesic subjects were grouped according to their pathology. In addition, the analysis included subjects with schizophrenia, amygdala damage, or frontal lobe damage. Of these three nonamnesic groups, only the frontal lobe subjects were impaired on both RMT subtests, while the schizophrenics showed a disproportionate impairment for the recognition of faces. The amygdala subjects were also poor at face recognition. Among the amnesic groups, those subjects likely to have multiple sites of pathology (e.g. Korsakoff amnesics, post-encephalitics) were found to be the most impaired on the RMT. In contrast, those amnesics with more focal, limbic lesions in the hippocampus, fornix, or mamillary body region showed much milder deficits on the RMT task, some performing at normal levels. Despite their apparent sparing of recognition, the overall severity of amnesia in those subjects with limbic lesions appeared comparable to that in the remaining amnesics. These findings indicate that deficits on both subtests of the RMT are a frequent but not inevitable component of anterograde amnesia. They also point to a distinct subgroup of amnesias associated with selective damage in the hippocampus or its diencephalic targets, in which there is a relative sparing of recognition under certain test conditions.
Reports an error in the original article by L. R. Squire (Psychological Review, 1992[Apr], Vol 99[2], 195–231). The caption for Figure 7 was incorrect. The corrected caption is given. (The following abstract of this article originally appeared in record 1992-26428-001.) Considers the role of the hippocampus in memory function. A central thesis involving work with rats, monkeys, and humans (which has sometimes seemed to proceed independently in 3 separate literatures) is now largely in agreement about the function of the hippocampus and related structures. A biological perspective is presented that proposes multiple memory systems with different functions and distinct anatomical organizations. The hippocampus (together with anatomically related structures) is essential for a specific kind of memory, here termed declarative memory (similar terms include explicit and relational). Declarative memory is contrasted with a heterogeneous collection of nondeclarative (implicit) memory abilities that do not require the hippocampus (skills and habits, simple conditioning, and the phenomenon of priming). The hippocampus is needed temporarily to bind together distributed sites in the neocortex that together represent a whole memory. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
,Ther ei sdisagreemen tabou twhethe rselectiv ehippocampal lesion si nhuman scaus eclea rite mrecognitio na swel la srecal ldeficits. Wherea sRee dan dSquir e(Beha vNeurosc i1997;111:667‐775 )foun dthat patient swit hadult-onse trelativel yselectiv ehippocampa llesion sshowed clea rite mrecognitio ndeficits ,Vargha-Khade me tal .(Scienc e1997;277: 376‐380 ,So cNeurosc iAbst r1998;24:1523 )foun dtha t 3patient swho suffere dselectiv ehippocampa ldamag ei nearl ychildhoo dshowe dclear recal ldeficits ,bu tha drelativel ynorma lite mrecognition .Mann san dSquire (Hippocampu s1999;9:495‐499 )argued ,however ,tha tite mrecognition ma yhav ebee nspare di nthes epatient sbecaus eth eearl yonse to ftheir patholog yallowe dcompensator ymechanism st odevelop .Therefore ,t ode- termin ewhethe rearl ylesio nonse ti scritica lfo rth erelativ esparin go fitem recognitio nan dt odetermin ewhethe rit soccurrenc ei sinfluence db ytask factors ,w eextensivel yexamine dite mrecognitio ni npatien tY.R. ,wh ohas patholog yo fadult-onse trestricte dt oth ehippocampus .Lik eth edevelop- menta lcases ,sh eshowe dclea rfre erecal ldeficit so n3 4tests ,bu the ritem recognitio no n4 3test swa srelativel yspared ,an dmarkedl yles sdisrupted tha nhe rrecall .He rite mrecognitio nperformanc erelativ et otha to fher control swa sno tsignificantl yinfluence db ywhethe rtest stappe dvisua lor verba lmaterials ,ha da yes/n oo rforced-choic eformat ,containe dfe wor man yitems ,ha don eo rsevera lfoil spe rtarge titem ,use dshor to rver ylong delays ,o rwer edifficul to reas yfo rnorma lsubjects .Interestingly ,YR’s bilatera lhippocampa ldestructio nwa sgreate rtha na tleas t2 o fth e3 patients o fMann san dSquir e(Hippocampu s1999;9:495‐499) .Th epossibl ereasons wh yite mrecognitio ndiffer sacros spatient swit hrelativel yselectiv ehip-
This study examined whether amnesic patients have preserved implicit memory for new associations between unrelated words, as measured by repetition priming, despite impaired explicit memory for such new associations Prior studies provide conflicting and ambiguous results Amnesic and control participants read aloud visually presented, unrelated word pairs and then attempted to identify old, recombined, and new word pairs shown at threshold durations Amnesic and control groups showed equivalent priming for new associations by identifying old pairs better than recombined pairs Amnesic patients were impaired on a matched explicit test of memory for new associations The preserved priming in amnesia indicates that implicit memory for new associations need not be supported by the mnemonic processes and brain structures that mediate explicit memory for new associations.
Episodic memory and semantic memory are two types of declarative memory. There have been two principal views about how this distinction might be reflected in the organization of memory functions in the brain. One view, that episodic memory and semantic memory are both dependent on the integrity of medial temporal lobe and midline dience- phalic structures, predicts that amnesic patients with medial temporal lobe/diencephalic damage should be proportionately impaired in both episodic and semantic memory. An alternative view is that the capacity for semantic memory is spared, or partially spared, in amnesia relative to episodic memory ability. This article reviews two kinds of relevant data: 1) case studies where amnesia has occurred early in childhood, before much of an individual's semantic knowledge has been acquired, and 2) experi- mental studies with amnesic patients of fact and event learning, remember- ing and knowing, and remote memory. The data provide no compelling support for the view that episodic and semantic memory are affected differently in medial temporal lobe/diencephalic amnesia. However, episodic and semantic memory may be dissociable in those amnesic patients who additionally have severe frontal lobe damage.
This chapter discusses the functions of neuronal networks in the hippocampus and neocortex in memory. It also presents the experimental evidence and theoretical approaches to the function of the hippocampus and of backprojections in the neocortex. The theories are at the level of neuronal networks and are based on evidence on the fine architecture of the networks, on the rules of synaptic modifiability incorporated, and on the systems-level connections. It is suggested that this approach will be useful in the future in linking anatomical evidence on structure to physiological evidence on modifiability. The approach will also be useful in understanding the global properties of the networks and, thus, understanding the role of the networks in brain function and behavior.
A hippocampal patient is described who shows preserved item
recognition and simple recognition-based recollection but impaired
recall and associative recognition. These data and other evidence
suggest that contrary to Aggleton & Brown's target article,
Papez circuit damage impairs only complex item-item-context
recollection. A patient with perirhinal cortex damage and a delayed
global memory deficit, apparently inconsistent with A&B's
framework, is also described.
Early hippocampal injury in humans has been found to result in a limited form of global anterograde amnesia. At issue is whether the limitation is qualitative, with the amnesia reflecting substantially greater impairment in episodic than in semantic memory, or only quantitative, with both episodic and semantic memory being partially and equivalently impaired. Evidence from neuroanatomical and lesion studies in animals suggests that the hippocampus and subhippocampal cortices form a hierarchically organized system, such that the greatest convergence of information (and, by implication, the richest amount of association) takes place within the hippocampus, located at the top of the hierarchy. On the one hand, this evidence is consistent with the view that selective hippocampal damage produces a differential impairment in context-rich episodic memory as compared with context-free semantic memory, because only the latter can be supported by the subhippocampal cortices. On the other hand, given the system's hierarchical form of organization, this dissociation of deficits is difficult to prove, because a quantitatively limited deficit will nearly always be a viable alternative. A final choice between the alternative views is therefore likely to depend less on further evidence gathered in brain-injured patients than on which view accounts for more of the data gathered from converging approaches to the problem. Hippocampus 1998;8:212–216. © 1998 Wiley-Liss, Inc.
In three recognition memory experiments, subjects studied a list of randomly generated geometric shapes, followed by a recognition test in which old items were either size congruent (same size at study and test) or size incongruent. In Experiment 1, the process dissociation procedure (Jacoby, 1991) showed that changing the size of the items led to a decrease in both recollection and familiarity. In Experiment 2, the remember/know procedure (Tulving, 1985) showed that recollection, as indexed by the proportion of "remember" responses, decreased with size incongruence, but familiarity, as indexed by the proportion of "know" responses, increased. The latter effect along with other problems with the remember/know procedure were found to arise because of the procedure′s underlying assumption that recollection and familiarity are mutually exclusive. When an independence assumption was combined with the remember/know data (IRK), results agreed with those of the process dissociation procedure. In Experiment 3, receiver operating characteristics (ROCs) were examined using the remember/know procedure and showed that familiarity was well described by a signal detection process that was independent of recollection.
This paper begins by considering problems that have plagued investigations of automatic or unconscious influences of perception and memory. A process dissociation procedure that provides an escape from those problems is introduced. The process dissociation procedure separates the contributions of different types of processes to performance of a task, rather than equating processes with tasks. Using that procedure, I provide new evidence in favor of a two-factor theory of recognition memory; one factor relies on automatic processes and the other relies on intentional processes. Recollection (an intentional use of memory) is hampered when attention is divided, rather than full, at the time of test. In contrast, the use of familiarity as a basis for recognition memory judgments (an automatic use of memory) is shown to be invariant across full versus divided attention, manipulated at test. Process dissociation procedures provide a general framework for separating automatic from intentional forms of processing in a variety of domains; including perception, memory, and thought.
One kind of between-list and two kinds of within-list temporal order memory were examined in a patient with selective bilateral hippocampal lesions. This damage disrupted memory for all three kinds of temporal order memory, but left item and word pair recognition relatively intact. These findings are inconsistent with claims that (1) hippocampal lesions, like those of the medial temporal lobe (MTL) cortex, disrupt item and word pair recognition, and that (2) hippocampal lesions disrupt temporal order memory and item recognition to the same degree. Not only was word pair recognition intact in the patient, but further evidence indicates that her recognition of other associations between items of the same kind is also spared so retrieval of such associations cannot be sufficient to support within-list temporal order recognition. Rather, as other evidence indicates that the patient is impaired at recognition of associations between different kinds of information, within-list (and possibly between-list) temporal order memory may be impaired by hippocampal lesions because it critically depends on retrieving associations between different kinds of information.
Twenty-four amnesics, including patients with Korsakoff's disease, post-encephalitic amnesia and amnesia caused by rupture of an anterior communicating artery aneurysm (ACoAA), were compared with 24 matched control subjects on a task in which words were presented in any one of four positions on a computer screen and subjects were instructed to remember both the words and their locations. The patients were tested after more learning opportunity, exposure to shorter lists, and after shorter delays than were their controls in order to match the word recognition performance of the two groups. Under these conditions, the amnesics' ability to locate recognized words was significantly worse than that of their controls. Although there was a tendency for the ACoAA patients to show more severe spatial memory deficits than Korsakoff patients, there was no clear evidence that aetiology of amnesia was a critical determinant of whether spatial memory was more impaired than word recognition. It was concluded that amnesics show a disproportionately severe memory deficit for spatial information that is intentionally encoded as well as for that which is incidentally encoded.
Patients with unilateral frontal- or temporal-lobe excisions and normal control subjects were tested on the recall of objects and of their location in an array. An incidental-learning situation was used, in which the task was presented as a test of the ability to estimate the prices of the objects. Patients with right frontal-lobe lesions were the only group impaired on price estimation, but a correlation was obtained between error-score in price estimation and lesion-size for the left frontal-lobe group. In contrast to patients with extensive right hippocampal excisions, both frontal-lobe groups were accurate on location-recall when tested immediately and again 24 hr later.
The hippocampus and related structures are thought to be capable of 1) representing cortical activity in a way that minimizes overlap of the representations assigned to different cortical patterns (pattern separation); and 2) modifying synaptic connections so that these representations can later be reinstated from partial or noisy versions of the cortical activity pattern that was present at the time of storage (pattern completion). We point out that there is a trade-off between pattern separation and completion and propose that the unique anatomical and physiological properties of the hippocampus might serve to minimize this trade-off. We use analytical methods to determine quantitative estimates of both separation and completion for specified parameterized models of the hippocampus. These estimates are then used to evaluate the role of various properties and of the hippocampus, such as the activity levels seen in different hippocampal regions, synaptic potentiation and depression, the multi-layer connectivity of the system, and the relatively focused and strong mossy fiber projections. This analysis is focused on the feedforward pathways from the entorhinal cortex (EC) to the dentate gyrus (DG) and region CA3. Among our results are the following: 1) Hebbian synaptic modification (LTP) facilitates completion but reduces separation, unless the strengths of synapses from inactive presynaptic units to active postsynaptic units are reduced (LTD). 2) Multiple layers, as in EC to DG to CA3, allow the compounding of pattern separation, but not pattern completion. 3) The variance of the input signal carried by the mossy fibers is important for separation, not the raw strength, which may explain why the mossy fiber inputs are few and relatively strong, rather than many and relatively weak like the other hippocampal pathways. 4) The EC projects to CA3 both directly and indirectly via the DG, which suggests that the two-stage pathway may dominate during pattern separation and the one-stage pathway may dominate during completion; methods the hippocampus may use to enhance this effect are discussed.
A recent literature survey of results from a widely used recognition memory test raised questions about the extent to which recognition memory impairment ordinarily occurs in human amnesia and, in particular, whether recognition memory is impaired at all after damage limited to the hippocampal region (J. P. Aggleton & C. Shaw, 1996). Experiment 1 examined the performance of 6 amnesic patients on 11 to 25 different recognition memory tests. Three patients had bilateral lesions limited primarily to the hippocampus (G.D.) or the hippocampal formation (W.H. and L.M.), as determined by postmortem, neurohistological analysis (N. Rempel-Clower, S. M. Zola, L. R. Squire, & D. G. Amaral, 1996). All 6 patients exhibited unequivocally impaired recognition memory. In Experiment 2, the 3 patients still available for study were each markedly impaired on a test of object recognition similar to the kind used to test recognition memory in nonhuman primates. Recognition memory impairment is a robust feature of human amnesia, even when damage is limited primarily to the hippocampus.
Cognitive neuroscience has provided strong support for the idea that there are multiple memory systems. Recent evidence suggests that remembering and knowing may be two types of recognition with different neural substrates. The remember/know distinction is not equivalent to the explicit/implicit distinction because both remembering and knowing are impaired after damage to medial temporal lobe structures. A number of converging lines of evidence suggest that the relationship between remembering and knowing is one redundancy, with "knowing" processes also active during remembering. Remembering appears to depend additionally on frontal lobe functioning.
Episodic memory and semantic memory are two types of declarative memory. There have been two principal views about how this distinction might be reflected in the organization of memory functions in the brain. One view, that episodic memory and semantic memory are both dependent on the integrity of medial temporal lobe and midline diencephalic structures, predicts that amnesic patients with medial temporal lobe/diencephalic damage should be proportionately impaired in both episodic and semantic memory. An alternative view is that the capacity for semantic memory is spared, or partially spared, in amnesia relative to episodic memory ability. This article reviews two kinds of relevant data: 1) case studies where amnesia has occurred early in childhood, before much of an individual's semantic knowledge has been acquired, and 2) experimental studies with amnesic patients of fact and event learning, remembering and knowing, and remote memory. The data provide no compelling support for the view that episodic and semantic memory are affected differently in medial temporal lobe/diencephalic amnesia. However, episodic and semantic memory may be dissociable in those amnesic patients who additionally have severe frontal lobe damage.
The role of the hippocampus and adjacent medial temporal lobe structures in memory systems has long been debated. Here we show in humans that these neural structures are important for encoding implicit contextual information from the environment. We used a contextual cuing task in which repeated visual context facilitates visual search for embedded target objects. An important feature of our task is that memory traces for contextual information were not accessible to conscious awareness, and hence could be classified as implicit. Amnesic patients with medial temporal system damage showed normal implicit perceptual/skill learning but were impaired on implicit contextual learning. Our results demonstrate that the human medial temporal memory system is important for learning contextual information, which requires the binding of multiple cues.
There have been conflicting reports about the importance of the hippocampal region for recognition memory. Vargha-Khadem et al. (1997) described three patients who became amnesic early in life as a result of damage apparently limited to the hippocampal region. One of these patients (Jon) performed normally on the recognition portion of the Doors and People Test but was severely impaired in recall. To compare adult-onset amnesia directly with these early-onset cases, we tested six amnesic patients on the Doors and People Test. Three of the patients have damage thought to be limited to the hippocampal region. All six patients were markedly impaired on both the recall and recognition portions of the test. To account for the difference between our adult-onset cases and the early-onset case (Jon), we suggest that some compensation for Jon's injury occurred during development, either due to functional reorganization of cortex adjacent to the hippocampus or as the result of learned strategies.
The spatial memory of a single patient (YR) was investigated. This patient, who had relatively selective bilateral hippocampal damage, showed the pattern of impaired recall but preserved item recognition on standardised memory tests that has been suggested by Aggleton and Shaw [Aggleton JP, Shaw C. Amnesia and recognition memory: a reanalysis of psychometric data. Neuropsychologia 1996;34:51-62] to be a consequence of Papez circuit lesions. YR was tested on three recall tests and one recognition test for visuospatial information. The initial recall test assessed visuospatial memory over very short unfilled delays and YR was not significantly impaired. This test was then modified to test recall of allocentric and egocentric spatial information separately after filled delays of between 5 and 60 s. YR was found to be more impaired at recalling allocentric than egocentric information after a 60 s interval with a tendency for the impairment to increase up to this delay. Recognition of allocentric spatial information was also assessed after delays of 5 and 60 s. YR was impaired after the 60 s delay. The results suggest that the human hippocampus has a greater involvement in allocentric than egocentric spatial memory, and that this most likely concerns the consolidation of allocentric information into long-term memory rather than the initial encoding of allocentric spatial information. The findings also suggest that YR's item recognition/free recall deficit pattern reflects a problem retrieving or storing certain kinds of associative information.
A meta-analysis was conducted on studies of implicit memory for novel and familiar information in organic amnesic patients and healthy controls. Across studies, the amnesics performed equivalently to the controls on indirect memory tests for familiar information. However, the controls performed better than amnesics for indirect memory tests for novel item and novel associative information. This is in accord with memory theories which suggest that medial temporal lobe structures are essential for encoding and storing arbitrary associations between items or events.
Two questions were addressed by the present study. The first was whether the previously reported item recognition deficit which is shown by amnesic patients may be due to a perceptual rather than a memory deficit. To address this question a group of amnesic patients were tested on a 14-choice forced-choice visual item recognition test which included a "simultaneous" condition in which the sample remained visible during the matching decision and a zero second delay. Eacott, Gaffan and Murray (1994) have reported an impairment in simultaneous matching-to-sample following perirhinal damage in monkeys. In our amnesic patients, a deficit was found only after filled delays of 10 seconds or longer and this was also the case for a subgroup of patients whose damage included the perirhinal cortex. The second question, which arose from the model of Aggleton and Brown (1999), was whether performance on the DMS task would remain intact following selective damage to the hippocampus. We tested a patient with bilateral damage to the hippocampus on the 14-choice DMS task and found that her performance was not significantly impaired at delays of up to 30 seconds.
By utilizing new information from both clinical and experimental (lesion, electrophysiological, and gene-activation) studies with animals, the anatomy underlying anterograde amnesia has been reformulated. The distinction between temporal lobe and diencephalic amnesia is of limited value in that a common feature of anterograde amnesia is damage to part of an "extended hippocampal system" comprising the hippocampus, the fornix, the mamillary bodies, and the anterior thalamic nuclei. This view, which can be traced back to Delay and Brion (1969), differs from other recent models in placing critical importance on the efferents from the hippocampus via the fornix to the diencephalon. These are necessary for the encoding and, hence, the effective subsequent recall of episodic memory. An additional feature of this hippocampal-anterior thalamic axis is the presence of projections back from the diencephalon to the temporal cortex and hippocampus that also support episodic memory. In contrast, this hippocampal system is not required for tests of item recognition that primarily tax familiarity judgements. Familiarity judgements reflect an independent process that depends on a distinct system involving the perirhinal cortex of the temporal lobe and the medial dorsal nucleus of the thalamus. In the large majority of amnesic cases both the hippocampal-anterior thalamic and the perirhinal-medial dorsal thalamic systems are compromised, leading to severe deficits in both recall and recognition.
The present study examined the rapid and slow acquisition of new semantic information by two patients with differing brain pathology. A partial double dissociation was found between the patterns of new learning shown by these two patients. Rapid acquisition was impaired in a patient (YR) who had relatively selective hippocampal damage, but it was unimpaired in another patient (JL) who, according to structural MRI, had an intact hippocampus but damage to anterolateral temporal cortex accompanied by epileptic seizures. Slow acquisition was impaired in both patients, but was impaired to a much greater extent in JL. The dissociation suggests that the mechanisms underlying rapid and slow acquisition of new semantic information are at least partially separable. The findings indicate that rapid acquisition of semantic, as well as episodic information, is critically dependent on the hippocampus. However, they suggest that hippocampal processing is less important for the gradual acquisition of semantic information through repeated exposure, although it is probably necessary for normal levels of such learning to be achieved.
There is disagreement about whether selective hippocampal lesions in humans cause clear item recognition as well as recall deficits. Whereas Reed and Squire (Behav Neurosci 1997;111:667-775) found that patients with adult-onset relatively selective hippocampal lesions showed clear item recognition deficits, Vargha-Khadem et al. (Science 1997;277: 376-380, Soc Neurosci Abstr 1998;24:1523) found that 3 patients who suffered selective hippocampal damage in early childhood showed clear recall deficits, but had relatively normal item recognition. Manns and Squire (Hippocampus 1999;9:495-499) argued, however, that item recognition may have been spared in these patients because the early onset of their pathology allowed compensatory mechanisms to develop. Therefore, to determine whether early lesion onset is critical for the relative sparing of item recognition and to determine whether its occurrence is influenced by task factors, we extensively examined item recognition in patient Y.R., who has pathology of adult-onset restricted to the hippocampus. Like the developmental cases, she showed clear free recall deficits on 34 tests, but her item recognition on 43 tests was relatively spared, and markedly less disrupted than her recall. Her item recognition performance relative to that of her controls was not significantly influenced by whether tests tapped visual or verbal materials, had a yes/no or forced-choice format, contained few or many items, had one or several foils per target item, used short or very long delays, or were difficult or easy for normal subjects. Interestingly, YR's bilateral hippocampal destruction was greater than at least 2 of the 3 patients of Manns and Squire (Hippocampus 1999;9:495-499). The possible reasons why item recognition differs across patients with relatively selective hippocampal damage of adult-onset and how the reasons that are truly critical can be best identified are discussed.
Impairedrecognitionmemoryinpatientswith lesions limited to the hippocampal formation
- Reedjm
- Squirelr
ReedJM,SquireLR.1997.Impairedrecognitionmemoryinpatientswith lesions limited to the hippocampal formation. Behav Neurosci 111: 667–675
Preservation ofimplicitmemoryfornewassociationsinglobalamnesia
- Gabrielijde
- Keanemm
- Zarellamm
- Poldrackra
GabrieliJDE,KeaneMM,ZarellaMM,PoldrackRA.1997.Preservation ofimplicitmemoryfornewassociationsinglobalamnesia.PsycholSci 8:326–329