No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Hemispheric differences in neural systems for face working memory: A PET‐rCBF study
Human Brain Mapping
Abstract
Neural systems that participate in working memory for faces were investigated in an experiment designed to distinguish face perception areas from working memory areas. Regional cerebral blood flow (rCBF) was measured using positron emission tomography (PET) while subjects performed a sensorimotor control task, a face perception control task, and five working memory tasks with parametrically varied retention intervals, ranging from 1 to 21 sec. Striate and ventral occipitotemporal extrastriate areas demonstrated a simple negative correlation between rCBF and retention delay, indicating that these areas participate principally in perceptual operations performed during visual stimulation. By contrast, right and left frontal areas demonstrated rCBF increases that were significantly more sustained across delays than were increases in ventral extrastriate areas, but the relation between rCBF and retention interval differed significantly by hemisphere. Whereas right frontal rCBF showed a nonsignificant tendency to diminish at longer delays, left inferior frontal, middle frontal, and anterior cingulate cortex, as well as left parietal and inferior temporal cortex, demonstrated their largest rCBF increases at the longest delays. These results indicate that right frontal and left frontal, parietal, and temporal areas all participate in face working memory, but that left hemisphere areas are associated with a more durable working memory representation or strategy that subjects rely on increasingly with longer retention intervals. One possible explanation for this hemispheric difference is that left hemisphere activity is associated with a face representation that embodies the result of more analysis and elaboration, whereas right frontal activity is associated with a simpler, icon-like image of a face that is harder to maintain in working memory. © 1995 Wiley-Liss, Inc.
... 1. We identified Talairach coordinates (Talairach and Tournoux, 1988) for each of the modules in the LSNM visual model (see Table 1) in the visual experimental literature, primarily from Haxby et al. (1995). 2. We used those hypothesized Talairach coordinates to find the closest connectome node (also shown in Table 1) to each Note that the locations of FS, D1, D2, and FR are not explicitly known (see text) and were chosen only to demonstrate validity of the method. ...
... To illustrate the integrated synaptic activity and fMRI signal for each one of the modules of the combined LSNM / TVB model separately, we have assigned a different spatial location to each one of the four PFC sub-modules. We have used the Talairach coordinates of the prefrontal cortex, based on Haxby et al. (1995), for the submodule D1 and have designated spatial locations in Frontiers in Neuroinformatics | www.frontiersin.org adjacent regions of interest for the rest of the submodules (see Table 1). ...
... There are likely to be a number of ways to decide which neural modeling node corresponds to which connectome node. In this paper, we used Talairach coordinates (Talairach and Tournoux, 1988) obtained from experimental task data (Haxby et al., 1995) for assigning topographic locations to the computational modules. The one area where this method did not work was in the PFC. ...
A number of recent efforts have used large-scale, biologically realistic, neural models to help understand the neural basis for the patterns of activity observed in both resting state and task-related functional neural imaging data. An example of the former is The Virtual Brain (TVB) software platform, which allows one to apply large-scale neural modeling in a whole brain framework. TVB provides a set of structural connectomes of the human cerebral cortex, a collection of neural processing units for each connectome node, and various forward models that can convert simulated neural activity into a variety of functional brain imaging signals. In this paper, we demonstrate how to embed a previously or newly constructed task-based large-scale neural model into the TVB platform. We tested our method on a previously constructed large-scale neural model (LSNM) of visual object processing that consisted of interconnected neural populations that represent, primary and secondary visual, inferotemporal , and prefrontal cortex. Some neural elements in the original model were 'non task-specific' (NS) neurons that served as noise generators to 'task-specific' neurons that processed shapes during a delayed match-to-sample (DMS) task. We replaced the NS neurons with an anatomical TVB connectome model of the cerebral cortex comprising 998 regions of interest interconnected by white matter fiber tract weights. We embedded our LSNM of visual object processing into corresponding nodes within the TVB connectome. Reciprocal connections between TVB nodes and our task-based modules were included in this framework. We ran visual object processing simulations and showed that the TVB simulator successfully replaced the noise generation originally provided by NS neurons; i.e., the DMS tasks performed with the hybrid LSNM/TVB simulator generated equivalent neural and fMRI activity to that of the original task-based models. Additionally, we found partial agreement between the functional connectivities using the hybrid LSNM/TVB model and the original LSNM. Our framework thus presents a way to embed task-based neural models into the TVB platform, enabling a better comparison between empirical and computational data, which in turn can lead to a better understanding of how interacting neural populations give rise to human cognitive behaviors.
... While there exists considerable overlap between the activation patterns during reading of English and Chinese language, research has shown unique activation for Chinese character processing in the left lateral middle frontal cortex [12,27,28]. Not surprisingly, this region has been associated with visuo-spatial processing and visual working memory [29,30]. Importantly areas associated with memory for visuo-spatial information such as the right frontal pole (BA10/11), frontal operculum (BA 47/45), dorsolateral frontal gyrus (BA 9/44), and the superior and inferior parietal lobules (BAs 7, 40/39) ( [12], p. 841) are all strongly implicated in Chinese, but not in English reading [12]. ...
... Behavioral research indicating a preference for selecting visually similar characters in a comparison task [9], as well as correlational research suggesting that spatial ability reliably predicts reading ability [19,20], point to the importance of visuo-spatial processing in Chinese character representation. Neuroscience research bolsters this claim, showing processing of Chinese characters is related to activation in brain regions typically associated with visuo-spatial processing and visual working memory [12,[28][29][30]. Because of the visuo-spatial nature of Chinese character representations, it is not surprising that our study showed greater interference overall from a visuo-spatial than a phonological distracting task. ...
... It is clear that language is an important contributor to the organization of one's memory. Several studies have shown that Chinese and English processing activate diverging neural networks [24][25][26][27][28][29][30][31], and our findings suggest that this directly affects the way a memory trace is encoded. People are not typically in situations where they can focus their attention entirely on one task, as there are constant multi-sensory distractions in everyday life. ...
We used the dual-task paradigm to infer how linguistic information is represented in the brain by indexing its susceptibility to retrieval interference. We measured recognition memory, in bilingual Chinese-English, and monolingual English speakers. Participants were visually presented with simplified Chinese characters under full attention, and later asked to recognize them while simultaneously engaging in distracting tasks that required either phonological or visuo-spatial processing of auditorily presented letters. Chinese speakers showed significantly greater memory interference from the visuo-spatial than phonological distracting task, a pattern that was not present in the English group. Such a pattern suggests that retrieval of simplified Chinese characters differentially requires visuo-spatial processing resources in Chinese speakers; these are compromised under dual-task conditions when such resources are otherwise engaged in a distracting task. In a secondary analysis, we showed the complementary pattern in a group of English speakers, whose memory for English words was disrupted to a greater degree from the phonological than visuo-spatial distracting task. Together, these results suggest the mode of representation of linguistic information can be indexed behaviorally by susceptibility to retrieval interference that occurs when representations overlap with resources required in a competing task.
... Studies of both humans and non-human primates report face-selective neural activity in the lateral prefrontal cortex (Haxby et al. 1995;Haxby et al. 1996;Scalaidhe et al. 1997;Ishai et al. 2002;Tsao et al. 2008;Chan and Downing 2011;Shepherd and Freiwald 2018) but how the lateral prefrontal cortex interacts with face-selective areas in the occipitotemporal cortex remains unclear. In the current study we compared the neural response to faces in the lateral prefrontal cortex with that observed in the more commonly studied face-selective areas in the occipitotemporal cortex. ...
... Facial working memory, in which a representation of a face is maintained after it has been removed from view, activates prefrontal regions (Courtney et al. 1996(Courtney et al. , 1997. It has been proposed that right frontal activity may be associated with the maintenance of a simple, icon-like image of the face, whereas the left frontal activity represents a more elaborate face representation that is created after longer retention delays and is more easily maintained (Haxby et al. 1995). Regions in the frontal gyrus were found to be activated during visual imagery of faces but not during face perception (Ishai et al. 2002). ...
Neuroimaging studies identify multiple face-selective areas in the human brain. In the current study we compared the functional response of the face area in the lateral prefrontal cortex to that of other face-selective areas. In Experiment 1 participants (n = 32) were scanned viewing videos containing faces, bodies, scenes, objects, and scrambled objects. We identified a face-selective area in the right inferior frontal gyrus (rIFG). In Experiment 2 participants (n = 24) viewed the same videos or static images. Results showed that the rIFG, right posterior superior temporal sulcus (rpSTS) and right occipital face area (rOFA) exhibited a greater response to moving than static faces. In Experiment 3 participants (n = 18) viewed face videos in the contralateral and ipsilateral visual fields. Results showed that the rIFG and rpSTS showed no visual field bias, while the rOFA and right fusiform face area (rFFA) showed a contralateral bias. These experiments suggest two conclusions; firstly, in all three experiments the face area in the IFG was not as reliably identified as face areas in the occipitotemporal cortex. Secondly, the similarity of the response profiles in the IFG and pSTS suggests the areas may perform similar cognitive functions, a conclusion consistent with prior neuroanatomical and functional connectivity evidence.
... A face-responsive area in the inferior frontal cortex was first reported in humans using functional brain imaging and monkeys using single unit recording (13)(14)(15)(16)(17)(18). Further reports of this area followed in fMRI studies in humans (12,(19)(20)(21)(22) and monkeys (20,23). ...
... Further reports of this area followed in fMRI studies in humans (12,(19)(20)(21)(22) and monkeys (20,23). The human neuroimaging studies have found this area to be face-responsive using perceptual matching of different views of the same identity (13), face working memory (14,15,17), retrieval from long-term memory (16), imagery from long-term memory (19), repetition-suppression (24), release from adaptation (26), and functional localizers with dynamic face stimuli (21,22). The existence of face selective neurons in the inferior frontal cortex also was shown in a human patient with implanted electrodes who reported face-related hallucinations after direct stimulation in prefrontal cortex (27). ...
Neural models of a distributed system for face perception implicate a network of regions in the ventral visual stream for recognition of identity. Here, we report an fMRI neural decoding study in humans that shows that this pathway culminates in a right inferior frontal cortex face area (rIFFA) with a representation of individual identities that has been disentangled from variable visual features in different images of the same person. At earlier stages in the pathway, processing begins in early visual cortex and the occipital face area (OFA) with representations of head view that are invariant across identities, and proceeds to an intermediate level of representation in the fusiform face area (FFA) in which identity is emerging but still entangled with head view. Three-dimensional, view-invariant representation of identities in the rIFFA may be the critical link to the extended system for face perception, affording activation of person knowledge and emotional responses to familiar faces.
Significance Statement
In this fMRI decoding experiment, we address how face images are processed in successive stages to disentangle the view-invariant representation of identity from variable visual features. Representations in early visual cortex and the occipital face area distinguish head views, invariant across identities. An intermediate level of representation in the fusiform face area distinguishes identities but still is entangled with head view. The face-processing pathway culminates in the right inferior frontal area with representation of view-independent identity. This paper clarifies the homologies between the human and macaque face processing systems. The findings show further, however, the importance of the inferior frontal cortex in decoding face identity, a result that has not yet been reported in the monkey literature.
... Using working memory paradigms and functional brain imaging techniques, it has been suggested that the left hemisphere might be more involved in verbal and analytical processing while the right hemisphere is involved in more image-based rehearsal strategies (Courtney, Petit, Haxby, & Ungerleider, 1998;Haxby, Ungerleider, Horwitz, Rapoport, & Grady, 1995;Rämä, Sala, Gillen, Pekar, & Courtney, 2001). Thus, it is possible that children with different vocabulary skills used different rehearsal strategies in their task performance, that is, children with higher vocabulary skills were more engaged to verbal while children with lower vocabulary skills more to image-based strategies resulting in different hemispheric distribution in two language groups. ...
... Results of this study showed that children with higher vocabulary skills exhibited a N400 effect over the left frontal sites whereas in the group of children with lower vocabulary skills the N400 effect was observed over the right hemisphere. Previously, it has been suggested that the left hemisphere might be more involved in verbal and analytical processing while the right hemisphere is involved in more image-based rehearsal strategies (Courtney, Petit, Haxby, & Ungerleider, 1998;Haxby, Ungerleider, Horwitz, Rapoport, & Grady, 1995;Rämä, Sala, Gillen, Pekar, & Courtney, 2001). Thus, it is possible that children with higher vocabulary skills were more likely to be engaged to verbal processing (naming) while children with lower vocabulary skills were more engaged to image-based strategies. ...
This dissertation investigated developmental mechanism underlying scene exploration. The results showed that ambient and focal attention strategies emerge by 12 months of age. Saliency guided eye movements more in children younger than 6 years compared with older children. Additionally, objects that were semantically inconsistent with the scene context equally attracted the gaze in young children and adults. Children were, however, attracted faster to high salient than to low salient objects. High-producers looked longer to consistent objects than low-producers while both groups looked equally long to inconsistent objects. The N400 ERP component was more pronounced for inconsistent than for consistent scene-word pairs. Low-producers exhibited a later N400 effect over the right frontal recording sites while in high-producers the N400 effect was observed earlier over the left frontal sites. Our results suggest that eye movement control during scene viewing mature from infancy to childhood. Even though ambient and focal modes are present in early infancy, scene exploration is dominated by focal mode. Additionally, young children use scene context, similarly to adults, in guidance of their visual attention. However, during early stages of development saliency has a stronger effect on gaze allocation compared with adults. Visual attention was also influenced by linguistic skills in young children.
... 4,7). Previous PET studies have consistently shown face activation of this region Haxby et al., 1994Haxby et al., , 1995. Activation was more extensive in the right hemisphere (Fig. 4), particularly when faces alternated with letterstrings (Fig. 6B). ...
... Activation was more extensive in the right hemisphere (Fig. 4), particularly when faces alternated with letterstrings (Fig. 6B). These results are consistent with the neuropsychology literature (for review, see Rhodes, 1993) demonstrating a right hemisphere advantage for face recognition and with previous PET (Horwitz et al., 1992;Haxby et al., 1995) and scalp-recorded evoked potential (Bentin et al., 1996) studies. Malach et al. (1995) compared the fMRI activation produced by objects (including faces) with the activation produced by textures. ...
Twelve normal subjects viewed alternating sequences of unfamiliar faces, unpronounceable nonword letterstrings, and textures while echoplanar functional magnetic resonance images were acquired in seven slices extending from the posterior margin of the splenium to near the occipital pole. These stimuli were chosen to elicit initial category-specific processing in extrastriate cortex while minimizing semantic processing. Overall, faces evoked more activation than did letterstrings. Comparing hemispheres, faces evoked greater activation in the right than the left hemisphere, whereas letterstrings evoked greater activation in the left than the right hemisphere. Faces primarily activated the fusiform gyrus bilaterally, and also activated the right occipitotemporal and inferior occipital sulci and a region of lateral cortex centered in the middle temporal gyrus. Letterstrings primarily activated the left occipitotemporal and inferior occipital sulci. Textures primarily activated portions of the collateral sulcus. In the left hemisphere, 9 of the 12 subjects showed a characteristic pattern in which faces activated a discrete region of the lateral fusiform gyrus, whereas letterstrings activated a nearby region of cortex within the occipitotemporal and inferior occipital sulci. These results suggest that different regions of ventral extrastriate cortex are specialized for processing the perceptual features of faces and letterstrings, and that these regions are intermediate between earlier processing in striate and peristriate cortex, and later lexical, semantic, and associative processing in downstream cortical regions.
... A large number of nonhuman primate studies using single-neuron recordings (Miller, Erickson, & Desimone, 1996;Funahashi, Bruce, & Goldman-Rakic, 1989;Fuster, Bauer, & Jervey, 1982) and lesions (Levy & Goldman-Rakic, 1999) have supported the involvement of pFC in working-memory-related processes. Human brain imaging studies (Riley & Constantinidis, 2015;Husain, Tagamets, Fromm, Braun, & Horwitz, 2004;Courtney, Petit, Maisog, Ungerleider, & Haxby, 1998;D'Esposito et al., 1995;Haxby, Ungerleider, Horwitz, Rapoport, & Grady, 1995), using PET and fMRI, have also revealed the crucial role that pFC plays in both object and spatial working memory. ...
... The Talairach coordinates (Talairach & Tournoux, 1988) and the closest node in Hagmann's connectome for each of the LSNM modules discussed above were identified (see Table 1), based on visual experimental findings (Haxby et al., 1991). As to the prefrontal module, which contains four submodules (FS, D1, D2, and R), we used the Talairach coordinates of pFC in Haxby et al. (1995) for the D1 submodule and assigned the locations of adjacent nodes for the rest of the submodules (FS, D2, R; see Table 1). This arrangement is due to the fact, as mentioned above, that the four types of neuronal populations were based on the experimental findings in monkey pFC during a delayed response task (Funahashi et al., 1990). ...
Many cognitive and computational models have been proposed to help understand working memory. In this article, we present a simulation study of cortical processing of visual objects during several working memory tasks using an extended version of a previously constructed large-scale neural model [Tagamets, M. A., & Horwitz, B. Integrating electrophysiological and anatomical experimental data to create a large-scale model that simulates a delayed match-to-sample human brain imaging study. Cerebral Cortex, 8, 310-320, 1998]. The original model consisted of arrays of Wilson-Cowan type of neuronal populations representing primary and secondary visual cortices, inferotemporal (IT) cortex, and pFC. We added a module representing entorhinal cortex, which functions as a gating module. We successfully implemented multiple working memory tasks using the same model and produced neuronal patterns in visual cortex, IT cortex, and pFC that match experimental findings. These working memory tasks can include distractor stimuli or can require that multiple items be retained in mind during a delay period (Sternberg's task). Besides electrophysiology data and behavioral data, we also generated fMRI BOLD time series from our simulation. Our results support the involvement of IT cortex in working memory maintenance and suggest the cortical architecture underlying the neural mechanisms mediating particular working memory tasks. Furthermore, we noticed that, during simulations of memorizing a list of objects, the first and last items in the sequence were recalled best, which may implicate the neural mechanism behind this important psychological effect (i.e., the primacy and recency effect).
... A face-responsive area in the inferior frontal cortex was first reported in humans using functional brain imaging and monkeys using single unit recording (Haxby et al. 1994(Haxby et al. , 1995Courtney et al. 1996Courtney et al. , 1997Scalaidhe et al. 1997). Further reports of this area followed in fMRI studies in humans (Ishai et al. 2002;Fox et al. 2009;Rajimehr et al. 2009;Pitcher et al. 2011;Axelrod and Yovel 2015) and monkeys (Tsao et al. 2008a(Tsao et al. , 2008bRajimehr et al. 2009;Dubois et al. 2015). ...
... Further reports of this area followed in fMRI studies in humans (Ishai et al. 2002;Fox et al. 2009;Rajimehr et al. 2009;Pitcher et al. 2011;Axelrod and Yovel 2015) and monkeys (Tsao et al. 2008a(Tsao et al. , 2008bRajimehr et al. 2009;Dubois et al. 2015). The human neuroimaging studies have found this area to be face-responsive using perceptual matching of different views of the same identity (Haxby et al. 1994), face working memory (Haxby et al. 1995;Courtney et al. 1996Courtney et al. , 1997, retrieval from long-term memory , imagery from long-term memory (Ishai et al. 2002), repetition-suppression (Pourtois et al. 2005), release from adaptation (Rotshtein et al. 2005), and functional localizers with dynamic face stimuli (Fox et al. 2009;Pitcher et al. 2011). There also is evidence from patients that support the role of the IFG in face processing. ...
Neural models of a distributed system for face perception implicate a network of regions in the ventral visual stream for recognition of identity. Here, we report a functional magnetic resonance imaging (fMRI) neural decoding study in humans that shows that this pathway culminates in the right inferior frontal cortex face area (rIFFA) with a representation of individual identities that has been disentangled from variable visual features in different images of the same person. At earlier stages in the pathway, processing begins in early visual cortex and the occipital face area with representations of head view that are invariant across identities, and proceeds to an intermediate level of representation in the fusiform face area in which identity is emerging but still entangled with head view. Three-dimensional, view-invariant representation of identities in the rIFFA may be the critical link to the extended system for face perception, affording activation of person knowledge and emotional responses to familiar faces.
... However, the left fusiform gyrus has also been shown to respond during verbal WM retention and letter presentation, but not during imagery or visuospatial maintenance in match to sample WM tasks (Hamamé et al., 2012). The activation of the left fusiform gyrus during the maintenance plus manipulation task may reflect a verbal rehearsal strategy for visuo-spatial stimuli rather than just visualization alone (Haxby et al., 1995). Interestingly though, the majority of participants in this study reported using a visual strategy for rotating the shapes. ...
... The cluster labels correspond to the details reported in Table 3. four of the 16 participants reported using a verbal strategy to rotate the blocks, statistical comparison based on this small group size could not be reliably justified. A more balanced comparison may allow further insight as to whether the LH activation represents categorical WM, while the RH represents more spatial processes, consistent with van der Ham et al. (2009) or may delineate whether the left fusiform gyrus activation reflects a verbal rehearsal process for visuo-spatial stimuli rather than just visualization (Haxby et al., 1995). Participants' strategy type should be taken into consideration for future studies of WM in combination with mental rotation or other forms of stimuli manipulation. ...
Mapping of the underlying neural mechanisms of visuo-spatial working memory (WM) has been shown to consistently elicit activity in right hemisphere dominant fronto-parietal networks. However to date, the bulk of neuroimaging literature has focused largely on the maintenance aspect of visuo-spatial WM, with a scarcity of research into the aspects of WM involving manipulation of information. Thus this study aimed to compare maintenance-only with maintenance and manipulation of visuo-spatial stimuli (3D cube shapes) utilizing a 1-back task while functional magnetic resonance imaging (fMRI) scans were acquired. Sixteen healthy participants (9 women, M= 23.94 years, SD =2.49) were required to perform the 1-back task with or without mentally rotating the shapes 90⁰ on a vertical axis. When no rotation was required (maintenance-only condition), a right hemispheric lateralization was revealed across fronto-parietal areas. However, when the task involved maintaining and manipulating the same stimuli through 90⁰ rotation, activation was primarily seen in the bilateral parietal lobe and left fusiform gyrus. The findings confirm that the well-established right lateralized fronto-parietal networks are likely to underlie simple maintenance of visuo-spatial stimuli. The results also suggest that the added demand of manipulation of information maintained online appears to require further neural recruitment of functionally related areas. In particular mental rotation of visuospatial stimuli required bilateral parietal areas, and the left fusiform gyrus potentially to maintain a categorical or object representation. It can be concluded that WM is a complex neural process involving the interaction of an increasingly large network.
... As Burgess, Simons, Dumontheil, and Gilbert (2005) pointed out, local hemodynamic (e.g., blood flow, blood oxygenation) changes occur in BA 10 during the performance of a very wide variety of cognitive tasks, from the simplest (e.g., conditioning paradigms; Blaxton et al., 1996) to highly complex tests involving memory and judgment (e.g., Burgess, Quayle, & Frith, 2001;Burgess, Scott, & Frith, 2003;Koechlin, Basso, Pietrini, Panzer, & Grafman, 1999) or problem solving (e.g., Christoff et al., 2001). Indeed, one can find activation of the rostral PFC in just about any kind of task-for example, verbal episodic retrieval (Rugg, Fletcher, Frith, Frackowiak, & Dolan, 1996;Tulving, Markowitsch, Criak, Habib, & Houle, 1996), nonverbal episodic retrieval (Haxby et al. 1996;Roland & Gulyas, 1995), semantic memory (Jennings, Mcintosh, Kapur, Tulving, & Houle, 1997;Martin, Haxby, Lalonde,Wiggs, & Ungerleider 1995), language (Bottini et al., 1994;Klein, Milner, Zatorre, Meyer, & Evans, 1995), motor learning (Jenkins, Brooks, Nixon, Frackowiak, & Passingham, 1994), rule learning (Strange, Henson,Friston,&Dolan, 2001), shock/tone conditioning (Hugdahl et al., 1995), nonverbal working memory (Gold, Berman, Randolph, Goldberg, & Weinberger, 1996;Haxby, Ungerleider, Horwitz, Rapoport, & Grady, 1995), verbal working memory (Petrides, Alivisatos, Meyer, & Evans, 1993), spatial memory (Burgess, Maguire, Spiers, & O'Keefe, 2001), auditory perception (Zatorre, Halpern, Perry, Meyer, & Evans, 1996), object processing (Kosslyn et al., 1994;, the Tower of London Test (Baker et al., 1996), the Wisconsin Card Sorting Test (Berman et al., 1995), reasoning tasks (Goel, Gold, Kapur, & Houle, 1997), and intelligence tests such as Raven's Progressive Matrices (Christoff et al., 2001;Prabhakaran, Smith, Desmond, Glover, & Gabrieli, 1997). ...
... As Burgess, Simons, Dumontheil, and Gilbert (2005) pointed out, local hemodynamic (e.g., blood flow, blood oxygenation) changes occur in BA 10 during the performance of a very wide variety of cognitive tasks, from the simplest (e.g., conditioning paradigms; Blaxton et al., 1996) to highly complex tests involving memory and judgment (e.g., Burgess, Quayle, & Frith, 2001;Burgess, Scott, & Frith, 2003;Koechlin, Basso, Pietrini, Panzer, & Grafman, 1999) or problem solving (e.g., Christoff et al., 2001). Indeed, one can find activation of the rostral PFC in just about any kind of task-for example, verbal episodic retrieval (Rugg, Fletcher, Frith, Frackowiak, & Dolan, 1996;Tulving, Markowitsch, Criak, Habib, & Houle, 1996), nonverbal episodic retrieval (Haxby et al. 1996;Roland & Gulyas, 1995), semantic memory (Jennings, Mcintosh, Kapur, Tulving, & Houle, 1997;Martin, Haxby, Lalonde,Wiggs, & Ungerleider 1995), language (Bottini et al., 1994;Klein, Milner, Zatorre, Meyer, & Evans, 1995), motor learning (Jenkins, Brooks, Nixon, Frackowiak, & Passingham, 1994), rule learning (Strange, Henson,Friston,&Dolan, 2001), shock/tone conditioning (Hugdahl et al., 1995), nonverbal working memory (Gold, Berman, Randolph, Goldberg, & Weinberger, 1996;Haxby, Ungerleider, Horwitz, Rapoport, & Grady, 1995), verbal working memory (Petrides, Alivisatos, Meyer, & Evans, 1993), spatial memory (Burgess, Maguire, Spiers, & O'Keefe, 2001), auditory perception (Zatorre, Halpern, Perry, Meyer, & Evans, 1996), object processing (Kosslyn et al., 1994;, the Tower of London Test (Baker et al., 1996), the Wisconsin Card Sorting Test (Berman et al., 1995), reasoning tasks (Goel, Gold, Kapur, & Houle, 1997), and intelligence tests such as Raven's Progressive Matrices (Christoff et al., 2001;Prabhakaran, Smith, Desmond, Glover, & Gabrieli, 1997). ...
The study of rostral prefrontal cortex (PFC) must count now as perhaps the fastest-growing new area of cognitive neuroscience. Until approximately 10 years ago, virtually nothing was known about this huge brain region (actually the largest architectonic subregion of the PFC). Now we have evidence that stretches across neuroanatomy, anthropology, brain development, cognitive neuroscience, neuropsychology, neuropsychiatry (adults and children), and, most recently, even behavioral neuroscience (Tsujimoto, Genovesio, & Wise, 2011). The purpose of this chapter is to lay out, in as straightforward a way as possible, the current state of our knowledge about this fascinating brain region. We will conclude by suggesting that perhaps the best description for the overall function of this brain region in humans would be that it is a hub formetacognition.
... Thus, although in SDRST, participants were required to remember the spatial location of the stimuli, they may have made use of intern mechanisms of verbalization in order to complete the task [80,81]. This strategy produces associations between stimulus characteristics, which make its maintenance in working memory more efficient [82]. Higher theta activation on the left parietal region had already been shown [75] in a task where participants had to indicate whether the item had or had not been presented beforehand. ...
... Older adults showed a higher activation for faces in the left frontotemporal region. This is in line with a previous study [82] in which the authors obtained greater activation for working memory tasks with facial stimuli on the left frontal region and a higher activation for the same task with non-facial stimuli on the right one. In another research [76], alpha band activation in tasks where subjects had to remember a face identity was related to focusing attention in a certain part of the task and inhibiting not important parts. ...
Emotion, importantly displayed by facial expressions, is one of the most significant memory modulators. The interaction between memory and the different emotional valences change across lifespan, while young adults (YA) are expected to better recall negative events (Negativity Bias Hypothesis), older adults (OA) tend to focus on positive stimuli (Positivity Effect Hypothesis). This research work aims at verifying whether cortical electrical activity of these two age groups would also be differently influenced by emotional valences in a visuo-spatial working memory task. 27 YA (13 males) and 25 OA (14 males), all healthy volunteers, underwent electroencephalographic recordings (21 scalp electrodes montage), while performing the Spatial Delayed Recognition Span Task using a touch screen with different stimuli categories: neutral, positive and negative faces and geometric pictures. YA obtained higher scores than OA, and showed higher activation of theta and alpha bands in the frontal and midline regions, besides a more evident right-hemispheric asymmetry on alpha band when compared to OA. For both age groups, performance in the task was worse for positive faces than to negative and to neutral faces. Facial stimuli induced a better performance and higher alpha activation on the pre-frontal region for YA, and on the midline, occipital and left temporal regions for OA when compared to geometric figures. The superior performance of YA was expected due to the natural cognitive deficits connected to ageing, as was a better performance with facial stimuli due to the evolutionary importance of faces. These results were related to cortical activity on areas of importance for action-planning, decision making and sustained attention. Taken together, they are in accordance with the Negativity Bias but do not support the Positivity Effect. The methodology used was able to identify age-related differences in cortical activity during emotional mnemonic processing and may be interesting to future investigations.
... . This area shows larger increases in activity for faces than for other kinds of stimuli (Haxby et al., 1999;Kanwisher et al., 1997;Kanwisher, Stanley, & Harris, 1999) and is an important part of the face perception network (Horwitz et al., 1992;McIntosh et al., 1994). The participation of additional brain areas, such as prefrontal and temporal cortices as well as the hippocampus, becomes increasingly more prominent as the delay between the initial presentation of a face and subsequent presentations lengthens, that is, as the demands on memory increase (Courtney et al., 1997;Haxby et al., 1996;Haxby, Ungerleider, Horwitz, Rapoport, & Grady, 1995). From these experiments, it seems clear that a variety of brain areas, along with the fusiform gyrus, can be engaged in tasks involving face processing, depending on the specific task demands. ...
Age-related differences in brain activity mediating face recognition were examined using positron emission tomography. Participants encoded faces using a pleasant–unpleasant judgment, a right–left orientation task, and intentional learning. Scans also were obtained during recognition. Both young and old groups showed signficant effects of encoding task on recognition accuracy, but older adults showed reduced accuracy overall. Increased brain activity in older adults was similar to that seen in young adults during conditions associated with deeper processing, but was reduced during the shallow encoding and recognition conditions. Left prefrontal activity was less in older adults during encoding, but greater during recognition. Differential correlations of brain activity and behavior were found that suggest older adults use unique neural systems to facilitate face memory.
... Lettvin et al. [91] proposed the term "grandmother cell" to describe individual neurons that respond best to hypercomplex stimuli, such as faces [92]. EEG responses of 3-month-old infants differ between familiar and unfamiliar faces at different sites on the scalp, corresponding topographically to what has been observed in adults [93,94]. It could be that the interhemispheric connectivity and communication demonstrated in this study are specific to face visual stimuli. ...
Little is known empirically about connectivity and communication between the two hemispheres of the brain in the first year of life, and what theoretical opinion exists appears to be at variance with the meager extant anatomical evidence. To shed initial light on the question of interhemispheric connectivity and communication, this study investigated brain correlates of interhemispheric transmission of information in young human infants. We analyzed EEG data from 12 4-month-olds undergoing a face-related oddball ERP protocol. The activity in the contralateral hemisphere differed between odd-same and odd-difference trials, with the odd-different response being weaker than the response during odd-same trials. The infants’ contralateral hemisphere “recognized” the odd familiar stimulus and “discriminated” the odd-different one. These findings demonstrate connectivity and communication between the two hemispheres of the brain in the first year of life and lead to a better understanding of the functional integrity of the developing human infant brain.
... The brain area that is activated by spatial memory appears to be variable, and it depends on the length of the memory interval. Shorter intervals will activate the left prefrontal lobe and longer intervals will activate the right prefrontal lobe [62]. The dorsolateral area is a key area for spatial attention, the maintenance of information (memory), and scene memory [63]. ...
Objective:
To investigate the intervention effect of orienteering exercises on the spatial memory ability of college students of different genders and its underlying mechanism.
Methods:
Forty-eight college students were randomly screened into experimental and control groups, 12 each of male and female, by SBSOD scale. The effects of 12 weeks of orienteering exercises on the behavioral performance and brain activation patterns during the spatial memory tasks of college students of different genders were explored by behavioral tests and the fNIRS technique.
Results:
After the orienteering exercise intervention in the experimental group, the male students had significantly greater correct rates and significantly lower reaction times than the female students; left and right dorsolateral prefrontal activation was significantly reduced in the experimental group, and the male students had a significantly greater reduction in the left dorsolateral prefrontal than the female students. The degree of activation in the left and right dorsolateral prefrontals of the male students and the right dorsolateral prefrontals of the female students correlated significantly with behavioral performance, and the functional coupling between the brain regions showed an enhanced performance.
Discussion:
Orienteering exercises improve the spatial memory ability of college students, more significantly in male students. The degree of activation of different brain regions correlated with behavioral performance and showed some gender differences.
... The Talairach coordinates (Talairach and Tournoux, 1988) and the closest node in Hagmann's connectome (Hagmann et al., 2008) for each of the modules discussed above (as well as for the visual model) were identified (see Table 1) based on experimental findings. As to the PFC module, which contains four submodules (FS, D1, D2, R), we used the Talairach coordinates of the prefrontal cortex in Haxby et al. (1995) for the D1 submodule in the visual model and assigned the locations of adjacent nodes for the other submodules (FS, D2, R) (see Table 1); similarly, for the PFC module in the auditory model, we used the Talairach coordinates from Husain et al. (2004) for the auditory model D1 units. This arrangement is due to the fact, as mentioned above, that the four types of neuronal populations were based on the experimental findings in monkey PFC during a visual delayed response task (Funahashi et al., 1990) and we assume that auditory working memory possesses the analogous mechanism as visual working memory. ...
The spatiotemporal dynamics of the neural mechanisms underlying endogenous (top-down) and exogenous (bottom-up) attention, and how attention is controlled or allocated in intersensory perception are not fully understood. We investigated these issues using a biologically realistic large-scale neural network model of visual-auditory object processing of short-term memory. We modeled and incorporated into our visual-auditory object-processing model the temporally changing neuronal mechanisms for the control of endogenous and exogenous attention. The model successfully performed various bimodal working memory tasks, and produced simulated behavioral and neural results that are consistent with experimental findings. Simulated fMRI data were generated that constitute predictions that human experiments could test. Furthermore, in our visual-auditory bimodality simulations, we found that increased working memory load in one modality would reduce the distraction from the other modality, and a possible network mediating this effect is proposed based on our model.
... One such particular example was the patient H.M., who could remember a number for 15 minutes by constantly rehearsing it, forgetting that he had even been given a number to remember the moment the examiner switched subjects of talk [21]. Our results are also consistent with neuroimaging studies reporting hippocampal or MTL activity in WM tasks [9,[22][23][24][25] and in delayed-match-to-sample tasks [26,27]. For example, Elliott and Dolan [23] reported that a long delay was associated with more hippocampal activity than a short delay in a delayed-match-to-sample task and that this result could be explained as the longer delay increasing the chances of functional discontiguity occurring. ...
Theoretical assessment of the function of the hippocampus has suggested that given certain physiological constraints at both the neuronal and cortical level, the hippocampus is best suited to associate discontiguous items that occur in different temporal or spatial positions. Conceptually, “discontiguous” refers to events that are to be associated with one another but do not temporally or spatially overlap. However, given that humans can actively maintain information “online” by rehearsing it, even when the information is no longer being presented to the sensory system, the right way to experimentally define “discontiguity” is still a question. Does it refer to a “gap” in the presentation of information (temporal discontiguity) or to an “interruption” of the active maintenance of working memory (WM) information (functional discontiguity)? To assess this, participants were imaged by functional magnetic resonance imaging (fMRI) when making judgments on whether two words were semantically related or not. In contrast with recognition memory that can be carried out through perceptual familiarity heuristics, judgments on semantic relatedness can only be accomplished through associative processing. To assess this experimentally, two words are either (1) presented at the same time (Event AB) or (2) one after the other with an unfilled, cross-viewing delay (Event A_B) (the uninterrupted discontiguity) or (3) presented one after the other, between which participants are required to perform a calculation task (Event A#B) (the interrupted discontiguity). Results of event-related fMRI analysis revealed that relative to Event AB, Event A_B was not associated with more hippocampal activity, whereas Event A#B was. The direct contrast of Event A#B relative to Event A_B also revealed significant hippocampal and parahippocampal activity. This result implied that functional discontiguity (the interruption of online maintenance of the inputted information) could be more apt at engaging the function of the hippocampus.
1. Introduction
The hippocampus has been recognized as the important cortical region for episodic memory. Its key feature has been proposed to be the representation of event sequences [1–3]. Theories have pointed to the role of the hippocampus in associating events across time [4]. Correspondingly, computational models also demonstrated how “local context” neurons (i.e., hippocampal cells that represent events in relation to the preceding and following events) could link discontiguous events to create a network of related episodic memories [2]. In addition, study also found the “time cells” in the hippocampus that mediated the bridging of temporal gap in memory for discontiguous events [5–7]. Conceptually, this “discontiguity” refers to the events that are to be associated with one another but do not temporally or spatially overlap [2]. However, the working memory (WM) system, especially that of humans, can actively maintain information “online” even when the stimulus is no longer being presented to the sensory system. For example, one can hold a piece of verbal information online by rehearsing it, meaning that the information that is not perceptually available may not necessarily be “discontiguous.” This raises the question of how to experimentally define this concept of “discontiguity.” Does it simply refer to a “gap” in the presentation of information (temporal discontiguity) or an “interruption” of the active maintenance of information stored in WM (functional discontiguity)?
To assess this, we asked participants to perform a semantic relatedness judgment task during neuroimaging scanning. Participants were required to judge whether two words were semantically related or not. The two words were presented either (1) at the same time (the AB trials) or (2) one after the other separated by a cross-viewing delay (the A_B trials) or (3) one after the other, between which participants performed a calculation task (the A#B trials) (Figure 1). AB trials served as a baseline, whereas the other two conditions contained the association of the two items that did not temporally overlap with one another. In the A_B trials, the first word could be actively maintained in WM by rehearsing it during the cross-viewing delay between the display of the two words. For this reason, the first word could also be maintained “online” at the moment of associative processing elicited by the presentation of the second word. However, in the A#B trials, participants were asked to engage in a distracting calculation task between the presentation of the two words, thereby interrupting the active maintenance of the first word. In this case, the first word could be “offline” at the moment of associative processing.
... At a first glance, these results might seem somewhat unexpected. However, enhanced activity to non-nameable stimuli such as pseudowords has been previously observed (Park et al., 2014;Park, Hebrank, et al., 2012;Vinckier et al., 2007) over regions of the right hemisphere (Beason-Held et al., 1998;Haxby et al., 1995). ...
Numbers and letters are culturally created symbols which are learned through repeated training. This experience leads to a functional specialization of the perceptual system of our brain. Recent evidence suggests a neural dissociation between these two symbols. While previous literature has shown that letters elicit a left lateralized neural response, new studies suggest that numbers elicit preferentially a bilateral or right lateralized response. However, the time course of the neural patterns that characterize this dissociation is still underspecified. In the present study, we investigated with magnetoencephalography (MEG) the spatio-temporal dynamics of the neural response generated by numbers, letters and perceptually matched false fonts presented visually. Twenty-five healthy adults were recorded while participants performed a dot detection task. By including two experiments, we were able to study the effects of single characters as well as those of strings of characters. The signal analysis was focused on the event related fields (ERF) of the MEG signal in the sensors and in the source space. The main results of our study showed an early (<200 ms) preferential dissociation between single numbers and single letters on occipito-temporal sensors. When comparing strings of numbers and pseudowords, they differed also over prefrontal regions of the brain. These data offer a new example of acquired category-specific responses in the human brain.
... In working memory, a functionally connected cognitive control network involves the frontal and parietal regions (Cabeza and Nyberg, 1997). One study has found that when the retention interval is short, the occipital, and right frontal regions are significantly activated; however, when there is a longer retention interval, the involvement of parietal and left frontal regions is prominent (Haxby et al., 1995). Regarding task novelty, the frontal lobe contributes its executive functions to the early learning stage (Duncan and Owen, 2000), which has also been proved by a lesion study (Rogers et al., 1998). ...
The multiple-demand (MD) system has proven to be associated with creating structured mental programs in comprehensive behaviors, but the functional mechanisms of this system have not been clarified in the musical domain. In this study, we explored the hypothesis that the MD system is involved in a comprehensive music-related behavior known as musical improvisation. Under a functional magnetic resonance imaging (fMRI) paradigm, 29 composers were recruited to improvise melodies through visual imagery tasks according to familiar and unfamiliar cues. We found that the main regions of the MD system were significantly activated during both musical improvisation conditions. However, only a greater involvement of the intraparietal sulcus (IPS) within the MD system was shown when improvising with unfamiliar cues. Our results revealed that the MD system strongly participated in musical improvisation through processing the novelty of melodies, working memory, and attention. In particular, improvising with unfamiliar cues required more musical transposition manipulations. Moreover, both functional and structural analyses indicated evidence of neuroplasticity in MD regions that could be associated with musical improvisation training. These findings can help unveil the functional mechanisms of the MD system in musical cognition, as well as improve our understanding of musical improvisation.
... In contrast, in our study the preview of a scene was followed by a short break before the spoken word was delivered involving a higher requirement of working memory. Using working memory paradigms and functional brain imaging techniques, it has been suggested that the left hemisphere might be more involved in verbal and analytical processing while the right hemisphere is involved in more image-based rehearsal strategies (Courtney, Petit, Haxby, & Ungerleider, 1998;Haxby, Ungerleider, Horwitz, Rapoport, & Grady, 1995;Rämä, Sala, Gillen, Pekar, & Courtney, 2001). In addition, an earlier eye-tracking study showed that even though the gaze of two-years-old high and low producers were equally attracted to inconsistent objects, the high producers looked longer to consistent objects than the low producers (Helo et al., 2017). ...
Semantic priming has been demonstrated in object or word contexts in toddlers. However, less is known about semantic priming in scene context. In this study, 24-month-olds with high and low vocabulary skills were presented with visual scenes (e.g., kitchen) followed by semantically consistent (e.g., spoon) or inconsistent (e.g., bed) spoken words. Inconsistent scene-word pairs evoked a larger N400 component over the frontal areas. Low-producers presented a larger N400 over the right while high-producers over the left frontal areas. Our results suggest that contextual information facilitates word processing in young children. Additionally, children with different linguistic skills activate different neural structures.
... conditioning paradigms;Blaxton et al. 1996) to highly complex tests involving memory and judgment (e.g.Burgess, Quayle, & Frith, 2001;Burgess, Scott, & Frith, 2003;Koechlin, Basso, Pietrini, Panzer, & Grafman, 1999) or problem-solving (e.g.Christoff et al. 2001). Indeed, one can find activation of the rostral PFC in just about any kind of task, for example, verbal episodic retrieval (Rugg, Fletcher, Frith, Frackowiak, & Dolan, 1996;Tulving, Markowitsch, Criak, Habib, & Houle, 1996); nonverbal episodic retrieval (Haxby et al. 1996;Roland & Gulyas, 1995); semantic memory (Jennings, McIntosh, Kapur, Tulving, & Houle, 1997;Martin,Haxby, Lalonde,Wigges, & Ungerleider 1995); language (Bottini et al. 1994;Klein, Milner, Zatorre, Meyer, & Evans, 1995); motor learning (Jenkins, Brooks, Nixon, Frackowiak, & Passingham, 1994); rule learning (Strange, Henson, Friston, & Dolan, 2001); shock/ tone conditioning (Hugdahl et al. 1995); nonverbal working memory (Gold, Berman, Randolph, Goldberg, & Weinberger, 1996;Haxby,Ungerleider, Horwitz, Rapoport, & Grady, 1995); verbal working memory (Petrides, Alivisatos,Meyer, & Evans, 1993); spatial memory (Burgess,Maguire, Spiers, & O'Keefe, 2001); auditory perception (Zatorre, Halpern, Perry,Meyer, & Evans, 1996); object processing (Kosslyn et al. 1994;; Tower of London Test (Baker et al. 1996);Wisconsin Card Sorting Test (Berman et al. 1995); reasoning tasks (Goel, Gold, Kapur, & Houle, 1997); intelligence tests such as Raven's Progressive Matrices (Christoff et al. 2001;Prabhakaran, Smith, Desmond, Glover, & Gabrieli, 1997). Indeed, it might be more of a challenge to find a task which does not activate some sub-region of rostral PFC at least some of the time. ...
The study of rostral prefrontal cortex (PFC) must count now as perhaps the fastest-growing new area of cognitive neuroscience. Until approximately 10 years ago, virtually nothing was known about this huge brain region (actually the largest architectonic subregion of the PFC). Now we have evidence that stretches across neuroanatomy, anthropology, brain development, cognitive neuroscience, neuropsychology, neuropsychiatry (adults and children), and, most recently, even behavioral neuroscience (Tsujimoto, Genovesio, & Wise, 2011). The purpose of this chapter is to lay out, in as straightforward a way as possible, the current state of our knowledge about this fascinating brain region. We will conclude by suggesting that perhaps the best description for the overall function of this brain region in humans would be that it is a hub for metacognition.
... Christoff et al. 2001). Indeed, one can find activation of the rostral PFC in just about any kind of task, for example, verbal episodic retrieval (Rugg, Fletcher, Frith, Frackowiak, & Dolan, 1996;Tulving, Markowitsch, Criak, Habib, & Houle, 1996); nonverbal episodic retrieval (Haxby et al. 1996;Roland & Gulyas, 1995); semantic memory (Jennings, McIntosh, Kapur, Tulving, & Houle, 1997;Martin, Haxby, Lalonde, Wigges, & Ungerleider 1995); language (Bottini et al. 1994;Klein, Milner, Zatorre, Meyer, & Evans, 1995); motor learning (Jenkins, Brooks, Nixon, Frackowiak, & Passingham, 1994); rule learning (Strange, Henson, Friston, & Dolan, 2001); shock/ tone conditioning (Hugdahl et al. 1995); nonverbal working memory (Gold, Berman, Randolph, Goldberg, & Weinberger, 1996;Haxby, Ungerleider, Horwitz, Rapoport, & Grady, 1995); verbal working memory (Petrides, Alivisatos, Meyer, & Evans, 1993); spatial memory (Burgess, Maguire, Spiers, & O'Keefe, 2001); auditory perception (Zatorre, Halpern, Perry, Meyer, & Evans, 1996); object processing (Kosslyn et al. 1994;Kosslyn, Alpert, & Thompson, 1995); Tower of London Test (Baker et al. 1996); Wisconsin Card Sorting Test (Berman et al. 1995); reasoning tasks (Goel, Gold, Kapur, & Houle, 1997); intelligence tests such as Raven's Progressive Matrices (Christoff et al. 2001;Prabhakaran, Smith, Desmond, Glover, & Gabrieli, 1997). ...
... In a study that examined material-dependent prefrontal lateralization, Binder and Urbanik (2006) demonstrated that the LH dominance with verbal stimuli was similar to that of visual patterns. Within the PFC, a lateralization effect for words, drawings, and spatial stimuli has been observed (Baker, Frith, Frackowiak, & Dolan, 1996;Courtney, Petit, Maisog, Ungerleider, & Haxby, 1998;Haxby, Ungerleider, Horwitz, Rapoport, & Grady, 1995;Smith et al., 1995). The current findings also showed high activation in the RH with words and syllables, possibly due to involvement of the pitch component in the verbal sounds (Bänziger & Scherer, 2005;Mozziconacci & Hermes, 1997). ...
Different working memory (WM) mechanisms that underlie words, tones, and timbres have been proposed in previous studies. In this regard, the present study developed a WM test with nonverbal sounds and compared it to the conventional verbal WM test. A total of twenty-five, non-music major, right-handed college students were presented with four different types of sounds (words, syllables, pitches, timbres) that varied from two to eight digits in length. Both accuracy and oxygenated hemoglobin (oxyHb) were measured. The results showed significant effects of number of targets on accuracy and sound type on oxyHb. A further analysis showed prefrontal asymmetry with pitch being processed by the right hemisphere (RH) and timbre by the left hemisphere (LH). These findings suggest a potential for employing musical sounds (i.e., pitch and timbre) as a complementary stimuli for conventional nonverbal WM tests, which can additionally examine its asymmetrical roles in the prefrontal regions.
... For example, several neuroimaging studies of normal readers have shown activation in the left middle frontal gyrus (MFG; BA 9) during Chinese reading, which was thought to be specialized for orthography-to-phonology transformation in Chinese processing (Tan et al., 2005;Siok et al., 2008), while in alphabetic-language reading, the left posterior temporal lobe was recruited to perform the conversion of written symbols (letters) into phonological units of speech (phonemes) (Booth et al., 2002). The right parietal and inferior occipital cortices were thought to be engaged in visuospatial analysis in processing Chinese characters (Tan et al., 2001;Chen et al., 2002), while the right superior frontal gyrus, right parietal regions and bilateral cuneus were known to be critical for visuospatial processes in processing alphabetic words (Haxby et al., 1995;Lepage et al., 2000). Thus, there is a discrepancy of the neural basis between Chinese and alphabetic languages processing. ...
The cerebellar deficit hypothesis for developmental dyslexia claims that cerebellar dysfunction causes the failures in the acquisition of visuomotor skills and automatic reading and writing skills. In people with dyslexia in the alphabetic languages, the abnormal activation and structure of the right or bilateral cerebellar lobes have been identified. Using a typical implicit motor learning task, however, one neuroimaging study demonstrated the left cerebellar dysfunction in Chinese children with dyslexia. In the present study, using voxel-based morphometry, we found decreased gray matter volume in the left cerebellum in Chinese children with dyslexia relative to age-matched controls. The positive correlation between reading performance and regional gray matter volume suggests that the abnormal structure in the left cerebellum is responsible for reading disability in Chinese children with dyslexia.
... Christoff et al. 2001). Indeed, one can find activation of the rostral PFC in just about any kind of task, for example, verbal episodic retrieval (Rugg, Fletcher, Frith, Frackowiak, & Dolan, 1996;Tulving, Markowitsch, Criak, Habib, & Houle, 1996); nonverbal episodic retrieval (Haxby et al. 1996;Roland & Gulyas, 1995); semantic memory (Jennings, McIntosh, Kapur, Tulving, & Houle, 1997;Martin, Haxby, Lalonde, Wigges, & Ungerleider 1995); language (Bottini et al. 1994;Klein, Milner, Zatorre, Meyer, & Evans, 1995); motor learning (Jenkins, Brooks, Nixon, Frackowiak, & Passingham, 1994); rule learning (Strange, Henson, Friston, & Dolan, 2001); shock/ tone conditioning (Hugdahl et al. 1995); nonverbal working memory (Gold, Berman, Randolph, Goldberg, & Weinberger, 1996;Haxby, Ungerleider, Horwitz, Rapoport, & Grady, 1995); verbal working memory (Petrides, Alivisatos, Meyer, & Evans, 1993); spatial memory (Burgess, Maguire, Spiers, & O'Keefe, 2001); auditory perception (Zatorre, Halpern, Perry, Meyer, & Evans, 1996); object processing (Kosslyn et al. 1994;Kosslyn, Alpert, & Thompson, 1995); Tower of London Test (Baker et al. 1996); Wisconsin Card Sorting Test (Berman et al. 1995); reasoning tasks (Goel, Gold, Kapur, & Houle, 1997); intelligence tests such as Raven's Progressive Matrices (Christoff et al. 2001;Prabhakaran, Smith, Desmond, Glover, & Gabrieli, 1997). ...
The rostral prefrontal cortex (or Area 10) is a sizeable brain region that is especially large in humans compared with other animals, yet very little is known about what role it plays in cognition. This chapter contains three sections. The first reviews the existing empirical and theoretical evidence. The second presents a new theoretical account of its function that synthesises this evidence. The third section describes a recent series of experiments that demonstrate the plausibility of the theory. Rostral prefrontal cortex (rostral PFC) is identified as subserving a system that biases the relative influence of stimulus-oriented and stimulus-independent thought. This cognitive control function is used in a wide range of situations critical to competent human behaviour in everyday life, ranging from straightforward 'watchfulness' to complex activities such as remembering to carry out intended actions after a delay, multitasking, and aspects of recollection.
... In two nonspatial studies known dominant role of this hemisphere in the processing that employed face stimuli, ventrolateral activation foci of verbal information (Milner, 1971). Phonological pro-were reported rather more anteriorly at y coordinates of cesseswithnospecificrelationshiptomemorypersemay between 33 and 40 rom (Courtney et aI., 1996; be recruited during many working memory tasks in order Ungerleider, Horwitz, Rapoport, & Grady, 1995). In the to facilitate normal memory function, through mecha-present verbal working memory study, the ventrolateral nisms such as verbal rehearsal. ...
There is now converging evidence that suggests that working memory processes within the dorsolateral and ventrolateral frontal cortices are organized according to the type of processing required, rather than according to the nature (i.e., domain) of the information being processed, as has been widely assumed. For example, recent positron emission tomography (PET) studies have demonstrated that either, or both, of these two lateral frontal areas can be activated in spatial working memory tasks, depending on the precise executive processes that are called upon by the task being performed. Moreover, in a recent study using functional magnetic resonance imaging, performances of visual spatial and visual nonspatial working memory tasks were shown to involve identical regions of the lateral prefrontal cortex when all the factors unrelated to the type of stimulus domain were appropriately controlled. These results concur fully with recent reviews of the imaging literature, which have demonstrated that spatial and nonspatial working memory studies, in general, have produced a widely distributed pattern of overlapping activation foci within these lateral frontal regions. In this study, the effects of varying the executive requirements of a simple verbal working memory task (forward vs. backward digit span) were explored in 8 subjects, using PET, in order to establish whether this model generalizes to the verbal domain. As was expected, during forward digit span, significant activation was observed within the midventrolateral frontal cortex, but not within the middorsolateral frontal cortex. In contrast, during backward digit span, significant activation was observed in both regions. The results provide further evidence that the middorsolateral and midventrolateral frontal cortical areas make distinct functional contributions to memory and that this corresponds, in psychological terms, to a fractionation of working memory processes.
... They found that words lateralize to the dominant hemisphere, patterns to the nondominant hemisphere, and faces and nature scenes with variably symmetrical activation. Haxby et al 93 showed that positron emission tomography of relative cerebral blood flow dominates in the left prefrontal area with longer exposure to faces (16-21 seconds) but on the right with shorter exposure (1-6 seconds), which suggests that longer exposure may allow for the recruitment of verbal encoding. ...
A foundational framework for understanding functional and dysfunctional imaging of episodic memory emerges from the last 3 decades of human and animal research. This comprehensive review is presented from the vantage point of the fornix, a white matter bridge that occupies a central position in this functional network. Salient insights are identified, spanning topics such as hippocampal efferent and afferent networks, input and processing streams, hemispheric specialization, dysfunctional effects of pathologic and surgical injury, optimization of functional magnetic resonance imaging design and neuropsychological tests, and rehabilitation strategies. Far-reaching implications are considered for radiologists, whose clinical effect stretches beyond imaging and interfaces with neurosurgeons, neuropsychologists, and other neurospecialists.
Copyright © 2015 Elsevier Inc. All rights reserved.
... Toward the Where and What of Consciousness in the Brain over increasing delay periods, as compared with the frontal sites with an increase of rCBF signal. The conclusion from this and related studies (Haxby et al., 1995) was (Ungerleider et al., 1998), "Thus, prefrontal regions likely play a more important role in the maintenance of a representation during working memory." ...
We consider here how new results arising especially from brain imaging but also from other areas of brain science (single cell analysis, deficits) are modifying our understanding of the neural representations involved in consciousness. The problem is discussed in terms of the two basic questions: where are the crucial sites for the creation of consciousness in the brain, and what is the appropriate representation involved? A framework is first developed and criteria thereby deduced for a neural site to be regarded as essential for the creation of consciousness. Various sites in the brain are considered, but only few are found to satisfy all the criteria. Past models of consciousness are considered as guides to developing an answer to the 'what' question. The notion of the central representation is then created, regarded as composed of information intrinsic to awareness; this representation is suggested as being in the parietal lobes. The manner in which the central representation can contain the complexity of consciousness is then analysed in terms of the three-stage model of awareness, for which brain imaging support is also presented. This model is then related to the higher-order thought approach. The paper concludes with a summary.
... Studies of the neurology underlying WM show how different areas of the prefrontal cortex are active when presented with visual input. Specifically, processing of visual inDut has been linked to the Dosterial Darietal areas and the prefrontal right hemisphere (e.g., Haxby, Ungerleider, Honvitz, Rapoport, & Grady, 1995;Smith, Jonides, & Koeppe, 1996). Additionally, evidence suggest that components of the visuo-spatial sketchpad themselves are dissociable. ...
Human factors research has long included discussions of the importance of mental models when understanding human-human interaction and human-system interaction. Additionally, a small number of researchers in the field have included theories of working memory and related constructs in their research approaches. Nonetheless, little if any research has acknowledged the connection between these two very important constructs arising out of the cognitive sciences. In this paper we discuss recent theoretical and empirical developments on working memory from cognitive psychology and cognitive neuroscience and relate these to our understanding of mental models. We show how the connection between these two concepts can facilitate a deeper understanding of issues associated with cognitive engineering and decision making research.
... This variability has been most frequently attributed to differences in strategy use or selection, primarily the degree to which a task allows for linguistic or symbolic encoding or rehearsal (Fletcher & Henson, 2001;Smith & Jonides, 1995;Ungerleider et al., 1998;Zarahn, Aguirre, & D'Esposito, 1999). Some support for this hypothesis was provided by a positron emission tomography (PET) study, in which the retention delay was systematically varied in an effort to examine the temporal dynamics of working memory for face stimuli (Haxby, Ungerleider, Horwitz, Rapoport, & Grady, 1995). The increase in regional cerebral blood flow (rCBF) to right prefrontal regions was reported to be smaller at longer delays, whereas the greatest activity in left prefrontal areas was noted during the longer delays. ...
... The significance of the left-lateralized nature of bilateral amygdala-prefrontal cortical functional connectivity across groups is unclear. The VLPFC has a specific role in supporting reversal learning and set shifting (Rygula et al. 2010) and the left hemisphere is involved in activities requiring attention to distinctive features and judgment (Haxby et al. 1995). Thus, recruitment of the left VLPFC during this task may be required to allow redirection of attention away from facial features during facial emotion processing to facilitate task performance. ...
Neuroimaging measures of behavioral and emotional dysregulation can yield biomarkers denoting developmental trajectories of psychiatric pathology in youth. We aimed to identify functional abnormalities in emotion regulation (ER) neural circuitry associated with different behavioral and emotional dysregulation trajectories using latent class growth analysis (LCGA) and neuroimaging.
A total of 61 youth (9-17 years) from the Longitudinal Assessment of Manic Symptoms study, and 24 healthy control youth, completed an emotional face n-back ER task during scanning. LCGA was performed on 12 biannual reports completed over 5 years of the Parent General Behavior Inventory 10-Item Mania Scale (PGBI-10M), a parental report of the child's difficulty regulating positive mood and energy.
There were two latent classes of PGBI-10M trajectories: high and decreasing (HighD; n = 22) and low and decreasing (LowD; n = 39) course of behavioral and emotional dysregulation over the 12 time points. Task performance was >89% in all youth, but more accurate in healthy controls and LowD versus HighD (p < 0.001). During ER, LowD had greater activity than HighD and healthy controls in the dorsolateral prefrontal cortex, a key ER region, and greater functional connectivity than HighD between the amygdala and ventrolateral prefrontal cortex (p's < 0.001, corrected).
Patterns of function in lateral prefrontal cortical-amygdala circuitry in youth denote the severity of the developmental trajectory of behavioral and emotional dysregulation over time, and may be biological targets to guide differential treatment and novel treatment development for different levels of behavioral and emotional dysregulation in youth.
... For fMRI, the integrated synaptic activities were calculated for a time period of about 50 ms (the time needed to acquire a single MRI slice), convolved with a function representing the hemodynamic response, and then downsampled each TR (e.g., TR = 2 s) to represent simulated BOLD-fMRI (Horwitz and Tagamets, 1999). Good agreement was obtained between the simulated PET data and the experimental PET data of Haxby et al. (1995) (see Tagamets and Horwitz, 1998 for details). This model was later modified by Husain et al. (2004) to produce a simulation model for auditory object processing. ...
Recently, there have been a large number of studies using resting state fMRI to characterize abnormal brain connectivity in patients with a variety of neurological, psychiatric, and developmental disorders. However, interpreting what the differences in resting state fMRI functional connectivity (rsfMRI-FC) actually reflect in terms of the underlying neural pathology has proved to be elusive because of the complexity of brain anatomical connectivity. The same is the case for task-based fMRI studies. In the last few years, several groups have used large-scale neural modeling to help provide some insight into the relationship between brain anatomical connectivity and the corresponding patterns of fMRI-FC. In this paper we review several efforts at using large-scale neural modeling to investigate the relationship between structural connectivity and functional/effective connectivity to determine how alterations in structural connectivity are manifested in altered patterns of functional/effective connectivity. Because the alterations made in the anatomical connectivity between specific brain regions in the model are known in detail, one can use the results of these simulations to determine the corresponding alterations in rsfMRI-FC. Many of these simulation studies found that structural connectivity changes do not necessarily result in matching changes in functional/effective connectivity in the areas of structural modification. Often, it was observed that increases in functional/effective connectivity in the altered brain did not necessarily correspond to increases in the strength of the anatomical connection weights. Note that increases in rsfMRI-FC in patients have been interpreted in some cases as resulting from neural plasticity. These results suggest that this interpretation can be mistaken. The relevance of these simulation findings to the use of functional/effective fMRI connectivity as biomarkers for brain disorders is also discussed.
... While lesions that produce prosopagnosia are often bilateral, lesions limited to the right occipitotemporal region can also produce prosopagnosia (Whiteley & Warrington, 1977;Damasio et al., 1990;De Renzi, Perani, Carlesimo, Silveri, & Fazio, 1994). PET@orwitz et al., 1992;Haxby, Ungerleider, Horwitz, Rapoport, & Grady, 1995), fMRI (Puce et al., 1995;Puce, Allison, Asgari, Gore, & McCarthy, 1996;Kanwisher, McDermott, & Chun, 1996;Kanwisher, Chun, McDermott, & Hamilton, 1996), and scalp-recorded evoked potential (Bentin, Allison, Puce, Perez, & McCarthy, 1996) studies reveal greater activation by faces in the right than the left occipito-temporal region. In this study, the volume of cortex activated by faces among nonobjects was approximately twice as large in the right than in the left hemisphere. ...
The perception of faces is sometimes regarded as a specialized task involving discrete brain regions. In an attempt to identi$ face-specific cortex, we used functional magnetic resonance imaging (fMRI) to measure activation evoked by faces presented in a continuously changing montage of common objects or in a similar montage of nonobjects. Bilateral regions of the posterior fusiform gyrus were activated by faces viewed among nonobjects, but when viewed among objects, faces activated only a focal right fusiform region. To determine whether this focal activation would occur for another category of familiar stimuli, subjects viewed flowers presented among nonobjects and objects. While flowers among nonobjects evoked bilateral fusiform activation, flowers among objects evoked no activation. These results demonstrate that both faces and flowers activate large and partially overlapping regions of inferior extrastriate cortex. A smaller region, located primarily in the right lateral fusiform gyrus, is activated specifically by faces.
... The infrequent occurrence of hippocampal activation may reflect the sparse nature of neural coding in this region (Stern and Hasselmo, 1999). Nonetheless, several groups have reported anterior hippocampal activity associated with working memory (Haxby et al., 1995;Eliot and Dolan, 1999;Curtis et al., 2000;Ranganath and D'Esposito, 2001;Stern et al., 2001). Furthermore, when complex, trial-unique stimuli were used, anterior hippocampal activation was consistently observed across three studies (Eliot and Dolan, 1999;Ranganath and D'Esposito, 2001;Stern et al., 2001). ...
Recent research in cognitive neuroscience has supported the idea that active rehearsal of information over short delays, or working memory maintenance, is accomplished by activating long-term memory representations. Nonetheless, it is widely assumed that although the human hippocampus and related medial temporal lobe structures may be critical for the formation of long-term memories, they are not involved in working memory maintenance. Here, we reconsider this issue and review evidence suggesting that humans and nonhuman primates with large medial temporal lobe lesions have difficulty retaining complex, novel information even across short delays. These results suggest that perirhinal and entorhinal regions, and under some circumstances, even the hippocampus, may be necessary for some forms of working memory as well as long-term memory. Moreover, neurophysiological and neuroimaging evidence suggests that all of these medial temporal regions exhibit activity associated with the active maintenance of novel information. Finally, we review a neurally plausible computational model of cortico- hippocampal interactions that points to a special role of the hippocampus in the representation of relational codes in memory. Our analyses suggest that the hippocampus plays this special role not only in episodic long-term memory, but also in working memory maintenance. Collectively, these results are consistent with the hypothesis that the active maintenance of complex, novel information is accomplished through the sustained activation of long-term memory representations bound together by the hippocampus and medial temporal cortical regions.
В пособии представлены современные фундаментальные и прикладные исследования нейрофизиологических оснований образовательного процесса, результаты которых прямо или косвенно оптимизируют процессы преподавания и обучения. Главы содержат сведения о структурно-функциональной организации головного мозга (на макро- и микроуровнях), о нейрональных механизмах психологических оснований обучения (особенностях воспри- ятия, внимания, памяти, формирования универсальных учебных действий), о нейрофизи- ологических закономерностях овладения письмом, чтением, иностранной речью и матема- тическими умениями.
Книга предназначена для студентов и аспирантов факультетов психологии и педаго- гики, специалистов сферы образования, готовых применять результаты нейропсихологических и нейрофизиологических исследований в методических целях.
Establishing a connection between intrinsic and task-evoked brain activities is critical because it would provide a way to map task-related brain regions in patients unable to comply with such tasks. A crucial question within this realm is to what extent the execution of a cognitive task affects the intrinsic activity of brain regions not involved in the task. Computational models can be useful to answer this question because they allow us to distinguish task from nontask neural elements while giving us the effects of task execution on nontask regions of interest at the neuroimaging level. The quantification of those effects in a computational model would represent a step toward elucidating the intrinsic versus task-evoked connection. In this study we used computational modeling and graph theoretical metrics to quantify changes in intrinsic functional brain connectivity due to task execution. We used our large-scale neural modeling framework to embed a computational model of visual short-term memory into an empirically derived connectome. We simulated a neuroimaging study consisting of 10 subjects performing passive fixation (PF), passive viewing (PV), and delayed match-to-sample (DMS) tasks. We used the simulated blood oxygen level-dependent functional magnetic resonance imaging time series to calculate functional connectivity (FC) matrices and used those matrices to compute several graph theoretical measures. After determining that the simulated graph theoretical measures were largely consistent with experiments, we were able to quantify the differences between the graph metrics of the PF condition and those of the PV and DMS conditions. Thus, we show that we can use graph theoretical methods applied to simulated brain networks to aid in the quantification of changes in intrinsic brain FC during task execution. Our results represent a step toward establishing a connection between intrinsic and task-related brain activities.
The process of learning and retaining information has been a well-researched area, especially regarding cognitive load. One of the recent methods of study is the field of psychophysiology, which relates the mental and physical processes of the human body. Data collected in this area of biometrics can provide measurements beyond simply cognitive load, including behavioral states, stress, emotion, personality, and intelligence. It can be beneficial to combine these techniques to measure data simultaneously in a process known as co-registration, which ensures that multiple systems are synchronized as a means to triangulate findings. This chapter will provide a summary of various psychophysiological techniques and include an example of a study using co-registration of electroencephalography (EEG) and eye tracking to determine the scanpath students follow and the area of the brain activated when given both a familiar and novel biochemical pathway to examine. The collected data from the Tobii X2-30 eye tracker revealed the differences in areas of interest (AOI), fixation, and scanpath between students with and without instruction on reading biochemical pathways. The EEG data provided evidence for usage of different areas of brain activation between students given the representations.
Invasive electrophysiological and neuroanatomical studies in nonhuman mammalian experimental preparations have helped elucidate the lamina (layer) dependence of neural computations and interregional connections. Noninvasive functional neuroimaging can, in principle, resolve cortical laminae (layers), and thus provide insight into human neural computations and interregional connections. However human neuroimaging data are noisy and difficult to interpret; biologically realistic simulations can aid experimental interpretation by relating the neuroimaging data to simulated neural activity. We illustrate the potential of laminar neuroimaging by upgrading an existing large-scale, multiregion neural model that simulates a visual delayed match-to-sample (DMS) task. The new laminar-based neural unit incorporates spiny stellate, pyramidal, and inhibitory neural populations which are divided among supragranular, granular, and infragranular laminae (layers). We simulated neural activity which is translated into local field potential-like data used to simulate conventional and laminar fMRI activity. We implemented the laminar connectivity schemes proposed by Felleman and Van Essen (Cerebral Cortex, 1991) for interregional connections. The hemodynamic model that we employ is a modified version of one due to Heinzle et al. (Neuroimage, 2016) that incorporates the effects of draining veins. We show that the laminar version of the model replicates the findings of the existing model. The laminar model shows the finer structure in fMRI activity and functional connectivity. Laminar differences in the magnitude of neural activities are a prominent finding; these are also visible in the simulated fMRI. We illustrate differences between task and control conditions in the fMRI signal, and demonstrate differences in interregional laminar functional connectivity that reflect the underlying connectivity scheme. These results indicate that multi-layer computational models can aid in interpreting layer-specific fMRI, and suggest that increased use of laminar fMRI could provide unique and fundamental insights to human neuroscience.
Very little is known about the connectivity of the human cerebral cortex. Nonhuman primates often serve as a model, but they are very unsatisfactory when it comes to specifically human functions. Evidence from (human) lesion and activation studies indicates that Broca's and Wernicke's areas play a critical role in language functions, whereas the inferior temporal cortex of the right hemisphere tends to be associated with high-level visual recognition. We describe here monosynaptic interhemispheric input from the right inferior temporal cortex to Wernicke's and Broca's areas. The connections were traced in a brain with a right inferior temporal infarction by means of the Nauta method for anterogradely degenerating axons. Afferents were found both in Broca's and Wernicke's areas, with a higher density in the latter. Three organizational principles emerge from this study. First, the presence of direct connections from the right inferior temporal cortex to the speech areas indicates that human interhemispheric connections can be widely heterotopic. Second, the fact that connections from the inferior temporal cortex terminate in both Wernicke's and Broca's areas speaks in favor of parallel pathways in visuo-verbal processing. And third, the patchy distribution of visual interhemispheric afferents in Wernicke's area hints at a possible functional compartmentalization within this area. Hum. Brain Mapping 5:347–354, 1997.
Face perception is mediated by a distributed brain network comprised of the core system at occipito-temporal areas and the extended system at other relevant brain areas involving bilateral hemispheres. In this study we explored how the brain connectivity changes over the time for face-sensitive processing. We investigated the dynamic functional connectivity in face perception by analyzing time-dependent EEG phase synchronization in four different frequency bands: theta (4–7 Hz), alpha (8–14 Hz), beta (15–24 Hz), and gamma (25–45 Hz) bands in the early stages of face processing from 30 to 300 ms. High-density EEG were recorded from subjects who were passively viewing faces, buildings, and chairs. The dynamic connectivity within the core system and between the extended system were investigated. Significant differences between faces and non-faces mainly appear in theta band connectivity: (1) at the time segment of 90–120 ms between parietal area and occipito-temporal area in the right hemisphere, and (2) at the time segment of 150–180 ms between bilateral occipito-temporal areas. These results indicate (1) the importance of theta-band connectivity in the face-sensitive processing, and (2) that different parts of network are involved for the initial stage of face categorization and the stage of face structural encoding.
The visual cortex in human and nonhuman primates consists of multiple areas that are hierarchically organized into processing pathways. A ventral pathway in the occipitotemporal cortex is critical for the perception of object identity, and a dorsal pathway in the occipitoparietal cortex is critical for the perception of the spatial relations among objects, the perception of movement, and the direction of movements toward objects. The ventral object vision and dorsal spatial vision pathways have projections into different parts of the prefrontal cortex. Functional brain imaging studies of visual working memory for faces and spatial locations reveal activity throughout the ventral object vision and dorsal spatial vision pathways, respectively. Different prefrontal areas are associated with working memory for faces and for locations. Face working memory is selectively associated with regions in the inferior and mid-frontal cortex. Location working memory is selectively associated with a more dorsal and posterior region in the superior frontal sulcus. These prefrontal regions demonstrate sustained activity during working memory delays demonstrating the role these areas play in maintenance of an active representation of a visual working memory. Functional brain imaging studies of long-term episodic memory also demonstrate a mnemonic role for prefrontal areas. Encoding new long-term memories for faces was associated with activity in the right hippocampus and in the left prefrontal and inferior temporal cortex. Recognition of memorized faces, on the other hand, was not associated with hippocampal activity but was associated with increased activity in the right prefrontal and parietal cortex. This research shows that widely distributed neural systems are associated with working and episodic visual memory. Mnemonic functions involve the concerted activity of the multiple regions in the posterior extrastriate and prefrontal cortices.
The cerebral cortex of the human brain can be subdivided by microscopic anatomical criteria into two major parts, isocortex and allocortex. Despite regional variations, the largest part of the adult human isocortex is characterized by its six-layered structure visible in cell body-stained sections. In contrast to the six-layered architecture of the isocortex, the laminar pattern of the allocortex shows a regionally highly variable appearance reaching from a hardly subdivisible single-cell band to a highly differentiated architecture with more than 10 layers. The isocortex contains primary sensory areas, which are main targets of unimodal sensory afferents originating in the ventroposterior nucleus of the thalamus, medial and lateral geniculate bodies, respectively. These primary areas project to a whole set of higher order unimodal sensory areas in a hierarchical and parallel organization. The higher order unimodal sensory cortices border to multimodal association areas. Uni- and multimodal areas send projections to the motor cortex, which is again subdivided into a primary motor area and nonprimary motor areas.
To compare the effect of mentat and Donepezil was on working memory in rats. The rats were trained for conditioned avoidance response by using Cook"s pole climbing apparatus. Rats trained for CAR received scopolamine (hydrobromide) in a dose of 0.5mg/kg by intraperitoneal route before administration of study drugs. This is known to produce amnesia which will be used to evaluate the effect on learning and memory of study drugs. Donepezil was given in a dose of 0.32mg/kg by intraperitoneal route and mentat was given in a dose of 200mg/kg by oral route for eight days in the animals after training for conditioned avoidance response. Data was analysed by the chi-square test. Findings show that administration of single dose of scopolamine 20 minutes before the test run on the apparatus causes transient amnesia daily for resulting in disruption of the retention of CAR. Mentat and donepezil significantly increased the retention of condition avoidance response in comparison to scopolamine. However there was no significant statistical difference in the increase in the retention of CAR in mentat or donepezil given alone, but the combination of the two drugs showed statistically significant increase in the retention of CAR than either of these drugs alone. Results from this study provide good platform to conduct clinical studies to assess the benefit of combining mentat with donepezil when given for a longer period of time.
In the present PET study we explore some functional aspects of the interactionbetween attentional/control processes and learning/memory processes. The network of brainregions supporting recall of abstract designs were studied in a less practiced and in a wellpracticed state. The results indicate that automaticity, i.e., a decreased dependence on attentionaland working memory resources, develops as a consequence of practice. This corresponds to thepractice related decreases of activity in the prefrontal, anterior cingulate, and posterior parietalregions. In addition, the activity of the medial temporal regions decreased as a function ofpractice. This indicates an inverse relation between the strength of encoding and the activation ofthe MTL during retrieval. Furthermore, the pattern of practice related increases in the auditory,posterior insular-opercular extending into perisylvian supramarginal region, and the right midoccipito-temporal region, may reflect a lower degree of inhibitory attentional modulation of taskirrelevant processing and more fully developed representations of the abstract designs,respectively. We also suggest that free recall is dependent on bilateral prefrontal processing, inparticular non-automatic free recall.The present results confirm previous functional neuroimaging studies of memory retrievalindicating that recall is subserved by a network of interacting brain regions. Furthermore, theresults indicate that some components of the neural network subserving free recall may have adynamic role and that there is a functional restructuring of the information processing networksduring the learning process.
The recognition of individuals is a basic cognitive ability of social animals. A prerequisite for individual recognition is distinct characteristics that can be used to distinguish between other conspecific individuals. Studies of birds have shown that visual information, such as colour patterning, is used in individual recognition. However, in the case of monochromatic birds, colour patterning cannot be used to identify individuals. Therefore, we expected that the configuration of facial features, such as the shape of the bills or eyes, may have enough individuality to permit individual recognition in such species. In this study, we aimed to clarify visible individual differences in the facial configuration of large-billed crows (Corvus macrorhynchos). Specifically, we analysed the profile pictures of 16 crows. We measured 26 variables in 20 pictures of each bird and then performed principal component analysis and discriminant function analysis. The results showed that the configuration of the facial profiles was individually distinct, but re-classification by discriminant functions implied that it did not clearly differ between sexes. These results suggest that crows may be able to recognise individuals on the basis of the individuality of facial configuration, even in the absence of any conspicuous colour patterning.
This chapter reviews some of the methods that have been used for the analysis of functional brain imaging data. The chapter describes the neural modeling that can be used to provide the basis for understanding the functional networks mediating specific cognitive tasks in normal subjects and in patients with brain disorders. Two types of neural modeling have been applied to functional brain imaging data: systems-level modeling and large-scale neural modeling. The chapter also reviews the use of structural equation modeling. The chapter discusses how large-scale neural modeling can be used to enhance interpretation of functional imaging data. The chapter describes that large-scale neural modeling can help to elucidate complex interactions, such as those that result from recurrent feedforward/feedback loops that are thought to be operative in the brain. With a large-scale model, explicit hypotheses can be examined in different contexts by varying the effects of parameters that correspond to biological substrates, such as synaptic density or receptor efficacy.
The authors summarize developments in the concept of working memory as a multicomponent system, beginning by contrasting this approach with alternative uses of the term
working memory. According to a 3-component model, working memory comprises a phonological loop for manipulating and storing speech-based information and a visuospatial sketchpad that performs a similar function for visual and spatial information. Both are supervised by a central executive, which functions as an attentional control system. A simple trace-decay model of the phonological loop provides a coherent account of the effects of word length, phonemic similarity, irrelevant speech, and articulatory suppression in verbal short-term memory tasks. This model of the loop has also proved useful in the analysis of neuropsychological, developmental and, cross-cultural data. The notion of the sketchpad is supported by selective interference with imagery in normal adults and by specific neuropsychological impairment. Analysis of the central executive is illustrated by work on deficits in the ability to coordinate subproccesses in Alzheimer's disease (AD). (PsycINFO Database Record (c) 2012 APA, all rights reserved)
SuperLab is a general-purpose psychology testing package for the Macintosh. SuperLab presents static visual and auditory stimuli
in blocks of trials, each trial consisting of a user-specified sequence of stimuli. Responses can be recorded from the keyboard
or from switches connected to an I/O board. Stimuli can be contingent on subjects’ responses, allowing feedback based on response
accuracy. Timing uses Time Manager routines from the Macintosh Toolbox. Data are recorded in a text format with tabs delimiting
fields, allowing analysis and presentation by other Macintosh spreadsheet, statistics, and graph-making applications. SuperLab
has a Macintosh user interface for developing experiments. Psychological tasks can also be designed and modified with any
application that generates a text format file.
The display and analysis of functional brain images often benefit from head rotational correction and centering. An automated method was developed to align brain PET images into a standard three-dimensional orientation. The algorithm performs transverse and coronal rotational correction as well as centering of a brain image set. Optimal rotational correction and centering are determined by maximizing a bilateral hemispheric similarity index, the stochastic sign change criterion. Testing of this algorithm on simulated symmetrical brain image sets showed errors less than 1.0 degree and 0.5 pixels for rotational correction and centering, respectively. With actual PET data, the algorithm results correlated well with those obtained by visual inspection. Testing on asymmetrical brain image sets with simulated lesions indicated that performance of the algorithm is not sensitive to focal asymmetries. This automated method provides objective, reproducible image alignment into a standard orientation and facilitates subsequent data analysis techniques for functional brain images.
Statistical parametric maps (SPMs) are potentially powerful ways of localizing differences in regional cerebral activity. This potential is limited by uncertainties in assessing the significance of these maps. In this report, we describe an approach that may partially resolve this issue. A distinction is made between using SPMs as images of change significance and using them to identify foci of significant change. In the first case, the SPM can be reported nonselectively as a single mathematical object with its omnibus significance. Alternatively, the SPM constitutes a large number of repeated measures over the brain. To reject the null hypothesis, that no change has occurred at a specific location, a threshold adjustment must be made that accounts for the large number of comparisons made. This adjustment is shown to depend on the SPM's smoothness. Smoothness can be determined empirically and be used to calculate a threshold required to identify significant foci. The approach models the SPM as a stationary stochastic process. The theory and applications are illustrated using uniform phantom images and data from a verbal fluency activation study of four normal subjects.
In order to localize cerebral cognitive or sensorimotor function, activation paradigms are being used in conjunction with PET measures of cerebral activity (e.g., rCBF). The changes in local cerebral activity have two components: a global, region independent change and a local or regional change. As the first step in localizing the regional effects of an activation, global variance must be removed by a normalization procedure. A simple normalization procedure is division of regional values by the whole brain mean. This requires the dependence of local activity on global activity to be one of simple proportionality. This is shown not to be the case. Furthermore, a systematic deviation from a proportional relationship across brain regions is demonstrated. Consequently, any normalization must be approached on a pixel-by-pixel basis by measuring the change in local activity and change in global activity. The changes associated with an activation can be partitioned into global and local effects according to two models: one assumes that the increase in local activity depends on global values and the other assumes independence. It is shown that the increase in activity due to a cognitive activation is independent of global activity. This independence of the (activation) condition effect and the confounding linear effect of global activity on observed local activity meet the requirements for an analysis of covariance, with the "nuisance" variable as global activity and the activation condition as the categorical independent variable. These conclusions are based on analysis of data from 24 scans: six conditions over four normal subjects using a verbal fluency paradigm.(ABSTRACT TRUNCATED AT 250 WORDS)
A technique is described for estimating the position of the intercommisural line (AC-PC line) directly from landmarks on positron emission tomographic (PET) images, namely the ventral aspects of the anterior and posterior corpus callosum, the thalamus, and occipital pole. The relationship of this estimate to the true AC-PC line, fitted through the centres of the anterior and posterior commissures, showed minimal vertical and angular displacement when measured on magnetic resonance imaging (MRI) scans. Using regression analysis, the ease and reliability of fitting to these points was found to be high. This directly derived AC-PC line estimate was validated in terms of the assumptions used in the method of Fox et al. The ratio of distance between the AC-PC line and a line passing through the base of the inion (GI line) to total brain height was 0.21, as predicted. The technique has been further validated by localizing focal activation of the sensorimotor cortex. The technique is discussed in terms of absolute limits to localization of structures in the brain using noninvasive tomographic techniques in general and PET in particular.
Although objects in visual mental images may seem to appear all of a piece, when the time to form images is measured this
introspection is revealed to be incorrect; objects in images are constructed a part at a time. Studies with split-brain patients
and normal subjects reveal that two classes of processes are used to form images--ones that activate stored memories of the
appearances of parts and ones that arrange parts into the proper configuration. Some of the processes used to arrange parts
are more effective in the left cerebral hemisphere and some are more effective in the right cerebral hemisphere; the notion
that mental images are the product of right hemisphere activity is an oversimplification.
The functional dissociation of human extrastriate cortical processing streams for the perception of face identity and location was investigated in healthy men by measuring visual task-related changes in regional cerebral blood flow (rCBF) with positron emission tomography (PET) and H2(15)O. Separate scans were obtained while subjects performed face matching, location matching, or sensorimotor control tasks. The matching tasks used identical stimuli for some scans and stimuli of equivalent visual complexity for others. Face matching was associated with selective rCBF increases in the fusiform gyrus in occipital and occipitotemporal cortex bilaterally and in a right prefrontal area in the inferior frontal gyrus. Location matching was associated with selective rCBF increases in dorsal occipital, superior parietal, and intraparietal sulcus cortex bilaterally and in dorsal right premotor cortex. Decreases in rCBF, relative to the sensorimotor control task, were observed for both matching tasks in auditory, auditory association, somatosensory, and midcingulate cortex. These results suggest that, within a sensory modality, selective attention is associated with increased activity in those cortical areas that process the attended information but is not associated with decreased activity in areas that process unattended visual information. Selective attention to one sensory modality, on the other hand, is associated with decreased activity in cortical areas dedicated to processing input from other sensory modalities. Direct comparison of our results with those from other PET-rCBF studies of extrastriate cortex demonstrates agreement in the localization of cortical areas mediating face and location perception and dissociations between these areas and those mediating the perception of color and motion.
This study used positron emission tomography (PET) to investigate the neuroanatomical correlates of remembering previously experienced events. Twelve young healthy adults listened to "old" meaningful sentences which they had studied 24 hr previously. As a control task the subjects listened to comparable "new" sentences that they had never heard before. Regional cerebral blood flow associated with each task was measured by PET scans using 15O-labeled water. Comparison (old-sentence task minus new-sentence task) of the PET images revealed an extended strip of increased blood flow in the right dorsolateral prefrontal cortex (Brodmann's areas 10, 46, and 9) and the anterior portion of area 6. Other principal regions of increased blood flow were situated around the left anterior cingulate sulcus and bilaterally in the parietal lobes (areas 7 and 40). Major decreases in blood flow were situated bilaterally in the temporal lobes (areas 21, 22, 41, and 42). A high proportion of activity changes seemed to be located in the depths of cortical sulci. Increases in blood flow are seen as reflecting the operations of a widely distributed neuronal network involving prefrontal and parietal cortical regions that subserves the conscious recollection of previously experienced events. Decreases in blood flow in the temporal auditory areas are interpreted as reflecting auditory priming. The prevalence of sulcal blood-flow changes may reflect extensive cortical gyrification; it may also indicate that memory-related processes rely on the densely packed neuropil of sulcal regions.
1. Twenty-four patients with electrodes chronically implanted on the surface of extrastriate visual cortex viewed faces, equiluminant scrambled faces, cars, scrambled cars, and butterflies. 2. A surface-negative potential, N200, was evoked by faces but not by the other categories of stimuli. N200 was recorded only from small regions of the left and right fusiform and inferior temporal gyri. Electrical stimulation of the same region frequently produced a temporary inability to name familiar faces. 3. The results suggest that discrete regions of inferior extrastriate visual cortex, varying in location between individuals, are specialized for the recognition of faces. These "face modules" appear to be intercalated among other functionally specific small regions.
Positron emission tomography (PET) was used to identify the neural systems involved in shifting spatial attention to visual stimuli in the left or right visual field along foveofugal or foveocentric directions. Psychophysical evidence indicated that stimuli at validly cued locations were responded to faster than stimuli at invalidly cued locations. Reaction times to invalid probes were faster when they were presented in the same than in the opposite direction of an ongoing attention movement. PET evidence indicated that superior parietal and superior frontal cortex were more active when attention was shifted to peripheral locations than when maintained at the center of gaze. Both regions encoded the visual field and not the direction of an attention shift. In the right superior parietal lobe, two distinct responses were localized for attention to left and right visual field. Finally, the superior parietal region was active when peripheral locations were selected on the basis of cognitive or sensory cues independent of the execution of an overt response. The frontal region was active only when responses were made to stimuli at selected peripheral locations. These findings indicate that parietal and frontal regions control different aspects of spatial selection. The functional asymmetry in superior parietal cortex may be relevant for the pathophysiology of unilateral neglect.
Positron emission tomography measurements of regional cerebral blood flow (rCBF) were performed in normal volunteers during two auditory--verbal memory tasks: a subspan and supraspan task. The difference in rCBF between tasks was used to identify brain areas/systems involved in auditory--verbal long-term memory. Increases in rCBF were observed in the left and right prefrontal cortex, precuneus and the retrosplenial area of the cingulate gyrus. Decreases in blood flow were centred in the superior temporal gyrus bilaterally. Separate comparisons were also made between each span task and a resting state. Brain regions showing increases in rCBF in these comparisons included the thalamus, left anterior cingulate, right parahippocampal gyrus, cerebellum and the superior temporal gyrus. The brain areas identified in these comparison define a number of the neuroanatomical components of a distributed system for signal processing and storage relevant to auditory--verbal memory function.
The concept of working memory is central to theories of human cognition because working memory is essential to such human skills as language comprehension and deductive reasoning. Working memory is thought to be composed of two parts, a set of buffers that temporarily store information in either a phonological or visuospatial form, and a central executive responsible for various computations such as mental arithmetic. Although most data on working memory come from behavioural studies of normal and brain-injured humans, there is evidence about its physiological basis from invasive studies of monkeys. Here we report positron emission tomography (PET) studies of regional cerebral blood flow in normal humans that reveal activation in right-hemisphere prefrontal, occipital, parietal and premotor cortices accompanying spatial working memory processes. These results begin to uncover the circuitry of a working memory system in humans.
This study investigates the hypothesis that, as a consequence of Parkinson's disease, disturbed caudate outflow will lead to deficits in cognitive functions dependent upon the integrity of the prefrontal cortex, the cortical focus of caudatofugal signals. Since Parkinson's disease also involves lesions in extrastriatal midbrain cells which reduce the intrinsic supply of dopamine to this cortical region, such functions are at double risk. Forty nondemented parkinsonian patients were drawn from a pool of 100 consecutive patients and matched with 40 normal control subjects according to age, education, IQ, and sex. All patients were quantitatively rated on neurological indices of disease. Neuropsychological assessment of the patient and normal groups included tests of general intelligence, psychomotor skills, memory, visuospatial and executive functions. No global cognitive decline was observed in the parkinsonian group. Moreover, memory and visuospatial abilities were generally intact. A small cluster of deficits emerged, interpreted as reflecting impairment in the ability to spontaneously generate efficient strategies when relying on self-directed task-specific planning. In addition, several tests thought to be sensitive to frontal lobe function distinguished patients with symptoms strongly lateralized to the right versus left side of the body. Deficits in strategic planning were later investigated in relation to severity of disease and to patient attributes including IQ and age, both of which were relevant to performance on specific tasks. Results were compared with previous investigations in parkinsonian patients and discussed from the perspective of both animal and human studies involving damage to the cerebral cortex and basal ganglia. As the prefrontal cortex is thought to play a crucial role in self-directed behavioural planning, the validity of an outflow model in predicting the consequences of caudate nucleus dysfunction was supported.
Primate extrastriate visual cortex is organized into an occipitotemporal pathway for object vision and an occipitoparietal pathway for spatial vision. Correlations between normalized regional cerebral blood flow values (regional divided by global flows), obtained using H215O and positron emission tomography, were used to examine functional associations among posterior brain regions for these two pathways in 17 young men during performance of a face matching task and a dot-location matching task. During face matching, there was a significant correlation in the right hemisphere between an extrastriate occipital region that was equally activated during both the face matching and dot-location matching tasks and a region in inferior occipitotemporal cortex that was activated more during the face matching task. The corresponding correlation in the left hemisphere was not significantly different from zero. Significant intrahemispheric correlations among posterior regions were observed more often for the right than for the left hemisphere. During dot-location matching, many significant correlations were found among posterior regions in both hemispheres, but significant correlations between specific regions in occipital and parietal cortex shown to be reliably activated during this spatial vision test were found only in the right cerebral hemisphere. These results suggest that (1) correlational analysis of normalized rCBF can detect functional interactions between components of proposed brain circuits, and (2) face and dot-location matching depend primarily on functional interactions between posterior cortical areas in the right cerebral hemisphere. At the same time, left hemisphere cerebral processing may contribute more to dot-location matching than to face matching.
Current approaches to detecting significantly activated regions of cerebral tissue use statistical parametric maps, which are thresholded to render the probability of one or more activated regions of one voxel, or larger, suitably small (e. g., 0.05). We present an approximate analysis giving the probability that one or more activated regions of a specified volume, or larger, could have occurred by chance. These results mean that detecting significant activations no longer depends on a fixed (and high) threshold, but can be effected at any (lower) threshold, in terms of the spatial extent of the activated region. The substantial improvement in sensitivity that ensues is illustrated using a power analysis and a simulated phantom activation study. © 1994 Wiley-Liss, Inc.
A method is described for the minimization of a function of n variables, which depends on the comparison of function values at the (n + 1) vertices of a general simplex, followed by the replacement of the vertex with the highest value by another point. The
simplex adapts itself to the local landscape, and contracts on to the final minimum. The method is shown to be effective and
computationally compact. A procedure is given for the estimation of the Hessian matrix in the neighbourhood of the minimum,
needed in statistical estimation problems.
Studies of brain-damaged patients have revealed the existence of a selective impairment of face processing, prosopagnosia, resulting from lesions at different loci in the occipital and temporal lobes. The results of such studies have led to the identification of several cortical areas underlying the processing of faces, but it remains unclear what functional aspects of face processing are served by these areas and whether they are uniquely devoted to the processing of faces. The present study addresses these questions in a positron emission tomography (PET) study of regional cerebral blood flow in normal adults, using the 15 oxygen water bolus technique. The subjects participated in six tasks (with gratings, faces and objects), and the resulting level of cerebral activation was mapped on images of the subjects' cerebral structures obtained through magnetic resonance and was compared between tasks using the subtraction method. Compared with a fixation condition, regional cerebral blood flow (rCBF) changes were found in the striate and extrastriate cortex when subjects had to decide on the orientation of sine-wave gratings. A face-gender categorization resulted in activation changes in the right extrastriate cortex, and a face-identity condition produced additional activation of the fusiform gyrus and anterior temporal cortex of both hemispheres, and of the right parahippocampal gyrus and adjacent areas. Cerebral activation during an object-recognition task occurred essentially in the left occipito-temporal cortex and did not involve the right hemisphere regions specifically activated during the face-identity task. The results provide the first empirical evidence from normal subjects regarding the crucial role of the ventro-medial region of the right hemisphere in face recognition, and they offer new information about the dissociation between face and object processing.
Several studies suggest that the abilities to make inferences and interpret events are stronger in the left hemisphere than the right hemisphere (Gazzaniga, M. S., The Social Brain. Basic Books, New York, 1985). Given that inference and interpretation are important aspects of normal memory functioning (Bartlett, F. C., Remembering: A Study in Experimental and Social Psychology, Cambridge University Press, 1932), one would expect this hemispheric difference to extend to mnemonic processing. Two split brain subjects were shown a series of pictures representing a common scene. Their memory for these pictures was later tested with a lateralized Yes-No recognition test where the distractor pictures were either consistent or inconsistent with the scene. The left hemisphere performed below chance on consistent distractor pictures whereas the right hemisphere was above chance on these pictures and performed at the same level of accuracy as the pictures originally presented. These results suggest that recognition performance in the left hemisphere was more strongly influenced by the expectations for actions common to a scene than the right hemisphere and provide evidence that the left hemisphere superiority in interpretation and inference effect memory performance.
A theory and technique are presented that allow nonlinear resampling of positron emission tomography data to remove nonlinear differences in brain shape. The resampling is determined empirically by a function relating the observed image and a desired template. The validity, reliability, and precision of the plastic transformation are compared with linear rescaling alone, within, and between subjects.
Information about the basal ganglia has accumulated at a prodigious pace over the past decade, necessitating major revisions in the authors' concepts of the structural and functional organization of these nuclei. Recent anatomical and physiological findings have further substantiated the concept of segregated basal ganglia-thalamocortical pathways, and reinforced the general principle that basal ganglia influences are transmitted only to restricted portions of the frontal lobe (even though the striatum receives projections from nearly the entire neocortex). Using the 'motor' circuit as a model, the authors have reexamined the available data on other portions of the basal ganglia-thalamocortical pathways and found that the evidence strongly suggests the existence of at least four additional circuits organized in parallel with the 'motor' circuit. In the discussion that follows, they review some of the anatomic and physiologic features of the 'motor circuit,' as well as the data that support the existence of the other proposed parallel circuits, which they have designated the 'oculomotor,' the 'dorsolateral prefrontal,' the 'lateral orbitofrontal,' and the 'anterior cingulate,' respectively. Each of these five basal ganglia-thalamocortical circuits appears to be centered upon a separate part of the frontal lobe. This list of basal ganglia-thalamocortical circuits is not intended to be exhaustive. In fact, if the conclusions suggested in this review are valid, future investigations might be expected to disclose not only further details (or the need for revisions) of these five circuits, but perhaps also the existence of additional parallel circuits whose identification is currently precluded by a paucity of data.
This study investigates the hypothesis that, as a consequence of Parkinson's disease, disturbed caudate outflow will lead to deficits in cognitive functions dependent upon the integrity of the prefrontal cortex, the cortical focus of caudatofugal signals. Since Parkinson's disease also involves lesions in extra-striatal midbrain cells which reduce the extrinsic supply of dopamine to this cortical region, such functions are at double risk. Forty nondemented parkinsonian patients were drawn from a pool of 100 consecutive patients and matched with 40 normal control subjects according to age, education, IQ, and sex. All patients were quantitatively rated on neurological indices of disease. Neuropsychological assessment of the patient and normal groups included tests of general intelligence, psychomotor skills, memory, visuospatial and executive functions. No global cognitive decline was observed in the parkinsonian group. Moreover, memory and visuospatial abilities were generally intact. A small cluster of deficits emerged, interpreted as reflecting impairment in the ability to spontaneously generate efficient strategies when relying on self-directed task-specific planning. In addition, several tests thought to be sensitive to frontal lobe function distinguished patients with symptoms strongly lateralized to the right versus left side of the body. Deficits in strategic planning were later investigated in relation to severity of disease and to patient attributes including IQ and age, both of which were relevant to performance on specific tasks. Results were compared with previous investigations in parkinsonian patients and discussed from the perspective of both animal and human studies involving damage to the cerebral cortex and basal ganglia. As the prefrontal cortex is thought to play a crucial role in self-directed behavioural planning, the validity of an outflow model in predicting the consequences of caudate nucleus dysfunction was supported.
Seventy-nine patients with unilateral frontal- or temporal-lobe excisions and 18 normal control subjects were tested on four self-ordered tasks requiring the organization of a sequence of pointing responses. There were two verbal and two nonverbal tasks. Patients wih excisions from the left frontal lobe exhibited significant impairments on all four tasks, whilst patients with excisions from the right frontal lobe showed deficits only on the two nonverbal tasks. Patients with temporal-love lesions not extending posteriorly, on the medial side, beyond the pes of the hippocampus were unimpaired on all tasks, whereas those with more radical hippocampal excisions exhibited material-specific deficits that varied with the side of the lesion.
It is widely held that conscious recall of past experiences involves a specific system--episodic memory. Patients with amnesia have gross impairments of episodic memory while other kinds of memory remain intact, suggesting that a separable brain system underlies episodic memory. We have used positron emission tomography (PET) to identify components of this system in normal volunteers. A dual-task interference paradigm was used to isolate brain areas associated with acquisition, and a cueing paradigm to isolate the areas concerned with retrieval from verbal episodic memory. Acquisition was associated with activity in the left prefrontal cortex and the retrosplenial area, whereas retrieval was associated with activity in right prefrontal cortex and the precuneus. Our results provide clear evidence that episodic memory involves a network of specific prefrontal and posterior structures which can be fractionated into different component processes.
Areas and pathways subserving object and spatial vision are segregated in the visual system. Experiments show that the primate prefrontal cortex is similarly segregated into object and spatial domains. Neurons that code information related to stimulus identity are dissociable, both by function and region, from those that code information related to stimulus location. These findings indicate that the prefrontal cortex contains separate processing mechanisms for remembering "what" and "where" an object is.
Two cortical visual systems Analysis of Visual Behavior
- Ungerleider Lg
- Mishkin
Ungerleider LG, Mishkin M (1982) Two cortical visual systems. In: Ingle DJ, Goodale MA, Mansfield RJW (eds): Analysis of Visual Behavior. Cambridge: MIT Press, p p 549-586.
Behavioral electrophysiology of the prefrontal cortex of the primate Progress in Brain Re-search
- Van Fuster Jm Uylings Hbm
- De Jpc Eden
- Ma Bruin
- Corner
- Ma
Fuster JM (1990) Behavioral electrophysiology of the prefrontal cortex of the primate. In: Uylings HBM, Van Eden JPC, De Bruin MA, Corner MA, Feenstra MGP (eds): Progress in Brain Re-search. Amsterdam: Elsevier, p p 313-323.
Co-Planar Stereotaxic Atlas of the Human Brain New York Thieme Medical Publishers Frontal lobe dysfunction in Parkinson's disease: The cortical focus of neostriatal outflow
- J Talairach
- Tournoux
Talairach J, Tournoux P (1988): Co-Planar Stereotaxic Atlas of the Human Brain. New York Thieme Medical Publishers, Inc. Taylor AE, Saint-Cyr JA, Lang AE (1986): Frontal lobe dysfunction in Parkinson's disease: The cortical focus of neostriatal outflow. Brain 109:845-883.
Face recognition in human extrastriate cortex Working memory The Psychology of Learning and Motivation
- Allison T H Ginter
- G Mccarthy
- Nobre Ac
- A Puce
- M Luby
- Spencer
- Dd
Allison T, Ginter H, McCarthy G, Nobre AC, Puce A, Luby M, Spencer DD (1994): Face recognition in human extrastriate cortex. J Neurophysiol4:544-554. Baddeley AD, Hitch GJ (1974) Working memory. In: Bower G (eds): The Psychology of Learning and Motivation. San Diego, CA: Academic Press, p p 47-90. Baddeley AD, Hitch GJ (1994): Developments in the concept of working memory. Neuropsychology 8:485493.
SuperLab: General-purpose Macintosh software for human experimental psychology and psychological testing The functional organization of human extrastriate cortex: A PET-rCBF study of selective attention to faces and locations
- Haxby Jv
- R Parasuraman
- F Lalonde
- Abboud
Haxby JV, Parasuraman R, Lalonde F, Abboud H (1993): SuperLab: General-purpose Macintosh software for human experimental psychology and psychological testing. Behav Res Meth lnstr Comp 25:400405. Haxby JV, Horwitz 8, Ungerleider LG, Maisog JM, Pietrini P, Grady CL (1994a): The functional organization of human extrastriate cortex: A PET-rCBF study of selective attention to faces and locations. J Neurosci 14:6336-6353.
Mathematical registration of PET images enhances detection of neural activation foci by subtraction image analysis An automated method for rotational correction and centering of three-dimensional functional brain images
- Lee Ks Berger Kl
- S Mintun Ma Minoshima
- Berger
- Kl
- Ks Lee
- Mintun
- Ma
Lee KS, Berger KL, Mintun MA (1991): Mathematical registration of PET images enhances detection of neural activation foci by subtraction image analysis. J Cereb Blood Flow Metab 11[Suppl Minoshima S, Berger KL, Lee KS, Mintun MA (1992): An automated method for rotational correction and centering of three-dimensional functional brain images. J Nucl Med 33:1579-1585.
Neural systems for encoding and retrieving new longterm visual memories: A PET‐rCBF study
- Haxby JV
Haxby JV, Ungerleider LG, Horwitz B, Maisog JM, Grady CL (1994b): Neural systems for encoding and retrieving new long-term visual memories: A PET-rCBF study. Invest Ophthalmol Vis Sci 35:1813.
Dissociation and interaction of human neural systems for object and spatial visual working memory: A PET‐rCBF study
- Courtney SM
Mathematical registration of PET images enhances detection of neural activation foci by subtraction image analysis
- Lee KS
Dissociation of object and spatial processing domains in primate prefrontal cortex
- Wilson