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Dissociation of pathways for object and spatial vision: A PET study in humans
Abstract
A positron emission tomography (PET) study was conducted to determine which brain regions are differentially involved in visual object identification and object localization. Subjects engaged in a spatial task in which they matched the location of common objects, and an object task in which they matched the identity of common objects. In both tasks the stimulus arrangements used were of the same kind. Regional cerebral blood flow data showed that a right-sided region in the inferior parietal lobule was more activated during spatial than during object matching. In contrast, bilateral occipitotemporal regions, with the left more predominant, were more activated during object than spatial matching. These results provide support for Ungerleider and Mishkin's dual pathway model of vision and indicate important patterns of lateralization in the human visual system.
(C) Lippincott-Raven Publishers.
... They felt however that the activation was the result of deactivation in the location task rather than activation in the face task. Many other studies of human pattern processing have not reported parahippocampal activation [Baker et al., 1996;Fink et al., 1997;Gulyas et al., 1994Gulyas et al., , 1998Heinze et al., 1994;Kö hler et al., 1995;Nystrom et al., 2000]. The exact role of the parahippocampus in the present study is unclear. ...
... Studies of complex patterns (e.g., faces) result in activation areas extending into the fusiform gyrus and other inferior temporal structures in pattern processing [Haxby et al., 1991;Kö hler et al., 1995;Sams et al., 1997;Sergent et al., 1992;Ishai et al., 1999]. Such fields have been less prominent but nonetheless present in studies requiring simple pattern processing [Corbetta et al., 1991;Gulyas et al., 1994Gulyas et al., , 1998]. ...
... Studies on patients who have had portions of their cerebellum removed for surgical treatment of carcinoma suggest that the cerebellum may have a role in changing the focus of attention from one component of a target to another Courchesne, 1992, 1994]. In recent years it has been noted that the cerebellum has been activated in object identification tasks [Akshoomoff and Courchesne, 1992;Gulyas et al., 1998;Kö hler et al., 1995;Raichle et al., 1994]. In the present study the activation is not merely caused by motor output because the same motor output was required in all tasks. ...
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... It remains to be explained how actions appropriate for an object can be inferred from its visual appearance, if this has not been re cogn ized or retrieved from memory. Although visual object recognition is associated with ventral structures in the brain (Mishkin et al., 1983;Kohler et al., 1995), evidence suggests that dorsal structures have some capacity for object recognition and that these structures are particularly involved in the computations underlying action towards objects (Milner & Goodale, 1995). Information concerning the nature of an object might be mediated by these structures even if the object's visual identity cannot be retrieved. ...
... -21 -As would be expected from models where structural knowledge and semantic knowledge are thought to be stored in functionally independent systems, there were clear effects of task type. The categorization tasks generally caused increased activation in areas believed to be involved in semantic processing (the left inferior temporal gyrus) (Vandenberghe et al., 1996) whereas the object decision tasks generally caused increased activation in areas believed to be involved in structural process ing ( the righ t inferi or temporal gyrus and both fusiform gyri) (Kohler et al., 1995). ...
1999 Cover figure Stimuli used during object decision tasks. The level of difficulty was graded by using chimeric images of nonobjects, composed from single parts of known objects, and completely unknown novel nonobjects. The main activation effect of increased task difficulty was located in the posterior section of the right inferior temporal gyrus shown rendered on a structural MRI scan.
... Consequently, this region was previously more associated with sensory processing than with explicit recognition (Kanwisher et al., 1996; Malach et al., 1995; Rosier et al., 1997). Nevertheless, some studies showed that activity there was also modulated by recognition success (object processing contrasted to word processing (Kohler, Kapur, Moscovitch, Winocur, & Houle, 1995), as a direct function of recognition success (Bar et al., 2001), although to a smaller extent as in the medial part of the anterior fusiform region. This increased activity was also found by Vandenberghe et al. (1996) in both associative (matching task on picture meaning) and visual (matching on real life size) semantic tasks. ...
... Although some studies report bilateral changes in occipito-temporal areas when comparing object identification with a fixation condition (Grill-Spector et al., 1998a,b; Kanwisher et al., 1996; Kohler et al., 1995; Koustaal et al., 2001; Okada et al., 2000), others find strongly lateralized (left hemisphere) activations (Damasio, Grabowski, Tranel, Hichwa, & Damasio, 1996; Kosslyn et al., 1994; Moore & Price, 1999a; Perani et al., 1995 Perani et al., , 1999 Sergent et al., 1992). These findings have suggested that different cortical sites are involved in different aspects of object recognition. ...
Previous data (Boucart & al., 1995, J. of Exp. Psychol.: HPP, 21:584; Boucart & Humphreys, 1997, Perception, 26:1197) have suggested that there is automatic access to object identity when observers attend to a physical property of the form of an object (requiring processing of the global configuration ; e.g., the orientation of the main axis) and no semantic processing when subjects attend to a surface property of an object (requiring only a local processing ; e.g., colour, luminance...). We examined this automatic access to object identity in an fMRI study. We evaluated whether, in addition to neural areas associated with decisions to specific perceptual properties, areas associated with access to semantic information were activated when tasks demanded processing of global configuration. Two perceptual matching tasks were used. In an orientation-matching task, subjects had to match the reference and target stimuli on the basis of their global orientation (vertical versus horizontal). In a colour-matching task, subjects had to match the reference and target stimuli on the basis of their outline colour (blue versus green). These two tasks were compared with control tasks (boxcar paradigm) in which pictures were replaced by oriented (or coloured) rectangles. Results showed activation of areas 18-19 for both colour and orientation, with a predominance of the left hemisphere for colour and the right for orientation. More importantly, activation of the temporal area 37, involved in overt semantic judgements (Buchel & al., 1998, Nature, 394:274) occurred in the orientation decision task and not in the colour decision task. This result suggests that automatic access to object identity, in a task that does not require semantic processing, activates the same brain area as overt processing of semantic information.
... The hypothesis of the left movements being a less automated process than the right, dominant one is also supported by changes in FC between the right BA9 and BA39, both involved in intentional executive control of behaviour in general and movement in particular 36 . Moreover, the right BA39 is also involved in the visuospatial processing, which allows object localization 37 . Left (non-dominant) movement is associated with a complex and widespread contralateral cortical fronto-temporo-parieto-occipital network with probably a top-down control process involving executive functions. ...
Reach&grasp requires highly coordinated activation of different brain areas. We investigated whether reach&grasp kinematics is associated to EEG-based networks changes. We enrolled 10 healthy subjects. We analyzed the reach&grasp kinematics of 15 reach&grasp movements performed with each upper limb. Simultaneously, we obtained a 64-channel EEG, synchronized with the reach&grasp movement time points. We elaborated EEG signals with EEGLAB 12 in order to obtain event related synchronization/desynchronization (ERS/ERD) and lagged linear coherence between Brodmann areas. Finally, we evaluated network topology via sLORETA software, measuring network local and global efficiency (clustering and path length) and the overall balance (small-worldness). We observed a widespread ERD in α and β bands during reach&grasp, especially in the centro-parietal regions of the hemisphere contralateral to the movement. Regarding functional connectivity, we observed an α lagged linear coherence reduction among Brodmann areas contralateral to the arm involved in the reach&grasp movement. Interestingly, left arm movement determined widespread changes of α lagged linear coherence, specifically among right occipital regions, insular cortex and somatosensory cortex, while the right arm movement exerted a restricted contralateral sensory-motor cortex modulation. Finally, no change between rest and movement was found for clustering, path length and small-worldness. Through a synchronized acquisition, we explored the cortical correlates of the reach&grasp movement. Despite EEG perturbations, suggesting that the non-dominant reach&grasp network has a complex architecture probably linked to the necessity of a higher visual control, the pivotal topological measures of network local and global efficiency remained unaffected.
... 42 Therefore, it is possible that the volume of the temporal lobe was maintained in older adults who drove because they were more often engaged in identifying visual objects, such as other vehicles and road signs. 42 The cingulate cortex contains many important neural circuits, including the center of the reward system, amygdala, lateral prefrontal cortex, parietal cortex, motor areas, spinal cord, hippocampus, and limbic regions. 43 The dorsal anterior cingulate cortex projects directly to the spinal cord and the motor and limbic cortices. ...
Objective: To examine the association between driving and structural brain volume in older individuals.
Methods: In this cross-sectional study, high-resolution magnetic resonance imaging was performed in 1063 older adults. We examined global brain measures, including gray and white matter volumes and subcortical volume, using the FreeSurfer program. Participants were divided into non-drivers, those who drove < 7 days a week, and every day drivers. They were further classified into a non-driving group, an active group (drove 10 km at least once a week), and a less-active group (drove 10 km less than once a week).
Results: Drivers had a larger hippocampal volume than non-drivers (p = 0.048). Low-frequency drivers had a larger occipital cortex volume than non-drivers and high-frequency drivers (p = 0.007). Active drivers had larger temporal cortex volumes than non-active drivers (p = 0.020), larger cingulate cortex volumes than non-drivers and less-active drivers (p = 0.002), and larger hippocampus volumes than non-drivers (p = 0.019). A post-hoc analysis revealed no significant between-group differences in the amygdala.
Conclusions: Driving was associated with diminished hippocampal brain atrophy in older adults. Active drivers with a larger life space exhibited less brain atrophy in several regions, including the temporal and cingulate cortices.
... Although activation patterns were similar for overall encoding and encoding of correct trials, the connectivity patterns varied between the two encoding contrasts, especially in the head and tail regions of the hippocampus. The encoding activation pattern produced by the Face-Place encoding task involved regions along the occipitotemporal visual pathway that are associated with visual memory processes in both primates and humans (Haxby et al. 1991;Kohler et al. 1995;Ungerleider and Mishkin 1982). These regions included visual association cortices in the occipital lobe, and lingual, fusiform, parahippocampal, perirhinal and entorhinal cortices. ...
The hippocampus and underlying cortices are highly susceptible to pathologic change with increasing age. Using an associative face-scene (Face-Place) encoding task designed to target these regions, we investigated activation and connectivity patterns in cognitively normal older adults. Functional MRI scans were collected in 210 older participants (mean age = 76.4 yrs) in the Baltimore Longitudinal Study of Aging (BLSA). Brain activation patterns were examined during encoding of novel Face-Place pairs. Functional connectivity of the hippocampus was also examined during encoding, with seed regions placed along the longitudinal axis in the head, body and tail of the structure. In the temporal lobe, task activation patterns included coverage of the hippocampus and underlying ventral temporal cortices. Extensive activation was also seen in frontal, parietal and occipital lobes of the brain. Functional connectivity analyses during overall encoding showed that the head of the hippocampus was connected to frontal and anterior/middle temporal regions, the body with frontal, widespread temporal and occipital regions, and the tail with posterior temporal and occipital cortical regions. Connectivity limited to encoding of subsequently remembered stimuli showed a similar pattern for the hippocampal body, but differing patterns for the head and tail regions. These results show that the Face-Place task produces activation along the occipitotemporal visual pathway including medial temporal areas. The connectivity results also show that patterns of functional connectivity vary throughout the anterior-posterior extent of the hippocampus during memory encoding. As these patterns include regions vulnerable to pathologic change in early stages of Alzheimer’s disease, continued longitudinal assessment of these individuals can provide valuable information regarding changes in brain-behavior relationships that may occur with advancing age and the onset of cognitive decline.
... En un estudio presentado por Kohler (Kohler et al 1995) a cada participante se le presentan dos láminas con tres objetos cada una. En la modalidad posición el participante debía contestar si las imágenes de ambas láminas estaban ubicadas en la misma posición, en la modalidad objeto el participante debía contestar si los tres objetos de las dos láminas eran los mismos o si había diferencias. ...
This thesis deals with some cognition pathologies, seen from the mathematical tools' point of view. The considered pathologies are related to the semantic memory of the patients, and the associated problems are in general centered around some form of degradation of this critical cognitive function. One of the rare tools available for the diagnostic of these illnesses consists in submitting to the patient very specific psychological tests, but there are many limitations related to them. One of the focuses of the thesis is to propose a new test that aims to provide more discrimination in the analysis, and that can lead to better quantifications of the development level of the considered pathology. The thesis also explores other tools coming from close areas in langage processing, for instance, or in machine learning, with the long term global goal of contributing to the understanding of the cognition problems and the possible paths to improve their clinical treatment.
... , , [46] . , BA18 [47,48] . ...
... The brain and eye analyze the visual perception of brightness, movement, shape, and color of objects [1,2] even the mental imagery of motion and static visual features [3,4]. The three basic color receptors of blue, green, and red have their own photo pigments that react to light to evoke receptor potentials in the visual pathway. ...
Visual cognitive function is important in the construction of executive function in daily life. Perception of visual number form (e.g. Arabic digits) and numerosity (numeric magnitude) is of interest to cognitive neuroscientists. Neural correlates and the functional measurement of number representations are complex events when their semantic categories are assimilated together with concepts of shape and color. Color perception can be processed further to modulate visual cognition. The Ishihara pseudoisochromatic plates are one of the best and most common screening tools for basic red-green color vision testing. However, there has been little study of visual cognitive function assessment using such pseudoisochromatic plates. 25 healthy normal trichromat volunteers were recruited and studied using a 128-sensor net to record event-related electroencephalogram. Subjects were asked to respond by pressing numbered buttons when they saw the number and non-number plates of the Ishihara color vision test. Amplitudes and latencies of N100 and P300 event related potential components were analyzed from 19 electrode sites in the international 10-20 system. A brain topographic map, cortical activation patterns, and Granger causation (effective connectivity) were analyzed from 128 electrode sites. No significant differences between N100 event related potential components for either stimulus indicates early selective attention processing was similar for number and non-number plate stimuli, but non-number plate stimuli evoked significantly higher amplitudes, longer latencies of the P300 event related potential component with a slower reaction time compared to number plate stimuli imply the allocation of attentional load was more in non-number plate processing. A different pattern of the asymmetric scalp voltage map was noticed for P300 components with a higher intensity in the left hemisphere for number plate tasks and higher intensity in the right hemisphere for non-number plate tasks. Asymmetric cortical activation and connectivity patterns revealed that number recognition occurred in the occipital and left frontal areas where as the consequence was limited to the occipital area during the non-number plate processing. Finally, results demonstrated that the visual recognition of numbers dissociates from the recognition of non-numbers at the level of defined neural networks. Number recognition was not only a process of visual perception and attention, but was also related to a higher level of cognitive function, that of language.
... BA46 is known to be involved in executive functions, cognitive flexibility and abstract reasoning (Bembich et al. 2014). BA39 is demonstrated to be involved in sequence and visuospatial processing (Crozier et al. 1999;Köhler et al. 1995). More activation in BA39 during linear thinking might suggest that engineering students took more cognitive effort to perform visuospatial and sequence processing to move forward with their list. ...
Sustainability is a systems problem with interconnected socio-economic-ecological factors. To advance sustainable infrastructure, engineers are expected to more quickly think in systems from individual components to relationships between them. Until recently, understanding of cognition for sustainability was limited to investigating behavior and its outcomes. However, the emergence of neuroimaging techniques enables the collection of objective physiological data in the brain. By measuring the cognitive activation, we can construct a more detailed understanding of the mental processes during systems and linear thinking tasks related to engineering sustainability. Wearing a functional near infrared spectroscopy system, which measures changes in hemodynamic response, engineering students (n = 17) developed both lists and concept maps related to sustainability topics. The results show that systems thinking leads to more concepts generated and requires more cognitive activation in Brodmann area (BA) 46 (BA46 is associated with cognitive flexibility) while less activation in BA39 (associated with sequence and visuospatial processing). Moreover, the brain network analysis indicates the cognitive barriers for engineering students to think in systems for sustainability with lower global efficiency to cognitively integrate information and lower clustering coefficient to separately deal with information in the brain compared to linear thinking. This study is the first step in constructing a better cognition model and brain networks of systems thinking for sustainability. The next step can be how education training cognitively improves systems thinking among engineering students.
... These results are consistent with the results observed in right perisylvian areas by Yousem et al. (1999) investigating olfaction in a smaller sample (N = 5). The significant cluster reported in our study included BA 39, which participates in executive control (Kübler et al. 2006), visuospatial processing (Köhler et al. 1995), visual search (Ellison et al. 2004;Gharabaghi et al. 2006), and lexico-semantic processing (Ischebeck et al. 2004). Additionally, sex-related effects were observed in the inferior frontal gyrus (BA 47). ...
Introduction
Olfactory dysfunction is an early marker of neurological disease and a common symptom in psychotic disorders. Previous anatomical and functional research suggests that sex effects may be crucial in the assessment of the olfactory system. Nonetheless, the neural mechanisms through which the factor sex impacts olfactory perception are still not well understood. In this context, we use fMRI to investigate sex differences in the passive processing of chemical stimuli, in order to obtain new neuroscientific data that may help improve the assessment of odor perception.
Methods
Thirty healthy subjects (17 women) were stimulated with mint and butanol (event-related design) in a 3.0-T MRI scanner. A one-sample t test analysis was performed in order to observe olfactory-related activations. Intergroup differences (women vs. men) and the influence of each aroma were analyzed using a 2 × 2 ANOVA and post hoc contrasts.
Results
Men and women showed differential activity (males > females) in right superior/middle temporal areas, the right inferior frontal cortex, and the hypothalamus. Both groups showed a predominance of the right hemisphere for the processing of odors.
Conclusion
Functional differences between women and men in olfaction are not restricted to specific sensory areas and reflect a more general sex-dependent effect in multisensory integration processes.
Implications
Considering sex differences is essential in order to develop more specific and efficient strategies for the assessment and rehabilitation of the olfactory system and for the interpretation of the olfactory loss as an early biomarker of neurological and psychiatric diseases.
... The angular gyrus (BA 39) and inferior parietal lobule (BA 40), which showed greater activation for the ASD group than the control group, have been reported to be connected to somatosensory spatial discrimination 31) and visuospatial processing. 32) The relative activation of the left insula (BA 13) in the ASD group is also important. Cognitive processing occurs in the left insula to assess appropriate context using affect regarding emotional experiences. ...
Objectives: The purpose of this study was to investigate whether the neural activity of autism spectrum disorder (ASD) patients is different from that of normal individuals when performing aesthetic judgments.
Methods: We recruited typical ASD patients without savant skills (n=17, ASD group) and healthy controls (n=19, HC group) for an fMRI study. All subjects were scanned while performing aesthetic judgment tasks on two kinds of artwork (magnificent landscape images and fractal images). Differences in brain activation between the two groups were assessed by contrasting neural activity during the tasks.
Results: The aesthetic judgment score for all images was significantly lower in the ASD group than in the HC group. During the aesthetic judgment tasks, the ASD group showed less activation than the HC group in the anterior region of the superior frontal gyrus, and more activation in the temporoparietal area and insula , regardless of the type of images being judged. In addition, during the aesthetic judgment task for the fractal images, the ASD group exhibited greater neural activity in the amygdala and the posterior region of the middle/inferior temporal gyrus (BA 37) than the HC group.
Conclusion: The results of this study suggest that the brain activation patterns associated with aesthetic experiences in ASD patients may differ from those of normal individuals.
... The brain and eye communicate with each other to analyse the visual perception of brightness, movement, shape and colour of objects (DeYoe and Van Essen [18]; Köhler et al. [40]) even in the mental imagery of motion and static visual features (Chang and Pearson [10]; Roldan [64]). The three basic colour receptors of blue, green and red have their own photo pigments that react to light to evoke the receptor potentials in the visual pathway. ...
Visual cognitive function is important to build up executive function in daily life. Perception of visual Number form (e.g., Arabic digit) and numerosity (magnitude of the Number) is of interest to cognitive neuroscientists. Neural correlates and the functional measurement of Number representations are complex occurrences when their semantic categories are assimilated with other concepts of shape and colour. Colour perception can be processed further to modulate visual cognition. The Ishihara pseudoisochromatic plates are one of the best and most common screening tools for basic red-green colour vision testing. However, there is a lack of study of visual cognitive function assessment using these pseudoisochromatic plates. We recruited 25 healthy normal trichromat volunteers and extended these studies using a 128-sensor net to record event-related EEG. Subjects were asked to respond by pressing Numbered buttons when they saw the Number and Non-number plates of the Ishihara colour vision test. Amplitudes and latencies of N100 and P300 event related potential (ERP) components were analysed from 19 electrode sites in the international 10-20 system. A brain topographic map, cortical activation patterns and Granger causation (effective connectivity) were analysed from 128 electrode sites. No major significant differences between N100 ERP components in either stimulus indicate early selective attention processing was similar for Number and Non-number plate stimuli, but Non-number plate stimuli evoked significantly higher amplitudes, longer latencies of the P300 ERP component with a slower reaction time compared to Number plate stimuli imply the allocation of attentional load was more in Non-number plate processing. A different pattern of asymmetric scalp voltage map was noticed for P300 components with a higher intensity in the left hemisphere for Number plate tasks and higher intensity in the right hemisphere for Non-number plate tasks. Asymmetric cortical activation and connectivity patterns revealed that Number recognition occurred in the occipital and left frontal areas where as the consequence was limited to the occipital area during the Non-number plate processing. Finally, the results displayed that the visual recognition of Numbers dissociates from the recognition of Non-numbers at the level of defined neural networks. Number recognition was not only a process of visual perception and attention, but it was also related to a higher level of cognitive function, that of language.
... Their model envisages a separation of visual processing into two distinct cortical streams: a dorsal stream, from V1 into the inferior parietal cortex, which deals with the spatial relationships of objects (the "where" stream), and a ventral stream, extending from V1 into the inferior temporal cortex, dealing with the shape and identity of objects (the "what" stream) (e.g. Desimone & Ungerleider, 1989;Haxby et al., 1991Haxby et al., , 1993Köhler et al., 1995). Attention and Performance XIX Where in this dichotomy do the cells described here fit? ...
We review the properties of cells in the temporal cortex of the macaque monkey, which are sensitive to visual cues arising from the face and body and their movements. We speculate that the responses of populations of cells in the cortex of the anterior superior temporal sulcus (STSa) support an understanding of the behaviour of others. Actions of an agent including whole body movements (e.g. walking) and articulations (of the limbs and torso) made during the redirecting of attention and reaching are coded by STSa cells in a way which: (1) allows generalization over different views and orientations of the agent with respect to the observer, (2) utilises information about the agent's current and (3) imagined position while occluded from sight and (4) is sensitive to sequences of the agent's movements. The selectivity of cells is described from the perspective of hierarchical processing, which presumes that early processing establishes sensitivity to simple body cues and later coding combines these cues to specify progressively more subtle and abstract aspects of behaviour. The action coding of STSa cells is discussed in terms of dorsal and ventral cortical systems, the binding problem and the functional architecture, which allows hierarchical information processing.
... The spatiotemporal parameters that capture this distinction are its place in space for a stationary object or its trajectory of motion for a moving object. Neuroscientists have shown that the location of objects in space and their trajectories of motion can be established by perceptual processing (Haxby et al., 1991;Kohler, Kapur, Moscovitch, Winocur, & Houle, 1995;Watamaniuk, McKee, & Grzywacz, 1995). ...
This chapter proposes an identity development (ID) account of object permanence that locates the origins and development of permanence in infants' notions of how to determine and trace numerical identity. The arguments and evidence generated from this approach suggest a number of conclusions: (a) object permanence understanding is not an all-or-none attainment; (b) permanence is understood for some disappearance transforms but not others; (c) the development of infants' spatiotemporal criteria for numerical identity provide the form and ordering of the disappearance transforms over which they understand permanence; (d) apparent violations of permanence can cause negative emotion; and (e) taking seriously the conceptual distinctions between representation, identity, and permanence offers considerable theoretical power. The chapter presents a mechanism of change to account for the transition from having no concept of permanence to having permanence.
... L"un est donc impliqué dans le langage, l"autre dans le visuel. De plus, en accord avec les études précédentes (Haxby et Al., 1994 ;Kohler et Al., 1995), l"encodage de l"information spatiale d"un événement (le où) montre une augmentation de l"activité du lobe pariétal droit. L"encodage de l"information temporelle (le quand) montre, en revanche, une augmentation de la région du gyrus fusiforme gauche. ...
The aim of this study was to evaluate a possible contextual binding deficit in schizophrenic patients by using a visuo-spatial task and to test the construction of a cognitive map of the environment by patients. A navigation task was performed by 20 young schizophrenics patients and 28 controls subjects. Visuo-spatial memory explorations consisted in three different tasks: free recall, recognitions without effect order; recognition with effect order. Schizophrenics patients performed significantly less actions, identified less landmarks and made more errors in orientation changes than control subjects. For task with order effect schizophrenic patients made more errors than controls. Schizophrenic patients were impaired in cognitive map construction as well as during recognition of chronological landmarks. These results are compatible with the hypothesis of hippocampal and prefrontal cortex abnormalities in schizophrenia.
... These object processing functions have been extensively investigated through both functional imaging and ERP studies, and object processing in humans has been specifically associated with neuronal activation in a cluster of brain regions in the ventral visual stream known as the lateral occipital complex (LOC; e.g. Kohler et al., 1995;Malach et al., 1995;Puce et al., 1996Puce et al., , 1999Kanwisher et al., 1997;Allison et al., 1999;Haxby et al., 1999;Ishai et al., 1999;Doniger et al., 2000Doniger et al., , 2001Doniger et al., , 2002James et al., 2002a;Lerner et al., 2002;Murray et al., 2002). An ERP signature of the processing of the features of visual objects in the ventral visual stream may be found in the N1 component of the visual evoked potential (or one or more subcomponents of the N1 complex). ...
Multisensory object-recognition processes were investigated by examining the combined influence of visual and auditory inputs upon object identification — in this case, pictures and vocalizations of animals. Behaviorally, subjects were significantly faster and more accurate at identifying targets when the picture and vocalization were matched (i.e. from the same animal), than when the target was represented in only one sensory modality. This behavioral enhancement was accompanied by a modulation of the evoked potential in the latency range and general topographic region of the visual evoked N1 component, which is associated with early feature processing in the ventral visual stream. High-density topographic mapping and dipole modeling of this multisensory effect were consistent with generators in lateral occipito-temporal cortices, suggesting that auditory inputs were modulating processing in regions of the lateral occipital cortices. Both the timing and scalp topography of this modulation suggests that there are multisensory effects during what is considered to be a relatively early stage of visual object-recognition processes, and that this modulation occurs in regions of the visual system that have traditionally been held to be unisensory processing areas. Multisensory inputs also modulated the visual ‘selection-negativity’, an attention dependent component of the evoked potential this is usually evoked when subjects selectively attend to a particular feature of a visual stimulus.
... It should be however considered that further previous findings indicate the presence of some advantages for both the left and the right side. In fact, while music processing in musicians is principally LH biased (Bever and Chiarello, 1974), as pointed out above, music sight-reading is at least in part based on the activity of the dorsal pathway, which has been shown to be strongly RH biased (Köhler et al., 1995). ...
... Nagahama et al. [10] also found a predominance of left occipital involvement. This lateralization suggests that impairment of visual perception is crucial in VHs, for which the dominant pathway is the left occipitotemporal cortex, whereas visuospatial function preferentially follows the right occipitoparietal pathway [30,31]. ...
The aim of this study was to investigate the association between visual hallucinations in dementia with Lewy bodies (DLB) and brain perfusion using single-photon emission computed tomography.
We retrospectively included 66 patients with DLB, 36 of whom were having visual hallucinations (DLB-hallu) and 30 of whom were not (DLB-c). We assessed visual hallucination severity on a 3-point scale of increasing severity: illusions, simple visual hallucinations and complex visual hallucinations. We performed voxel-level comparisons between the two groups and assessed correlations between perfusion and visual hallucinations severity.
We found a significant decrease in perfusion in the left anterior cingulate cortex, the left orbitofrontal cortex and the left cuneus in the DLB-hallu group compared with the DLB-c group. We also found a significant correlation between decreased bilateral anterior cingulate cortex, left orbitofrontal cortex, right parahippocampal gyrus, right inferior temporal cortex and left cuneus perfusion with the severity of hallucinations.
Visual hallucinations seem to be associated with the impairment of anterior and posterior regions (secondary visual areas, orbitofrontal cortex and anterior cingulate cortex) involved in a top-down and bottom-up mechanism, respectively. Furthermore, involvement of the bilateral anterior cingulate cortex and right parahippocampal gyrus seems to lead to more complex hallucinations.
... A dissociation between object and spatial pathways was attempted by Haxby and colleagues (1991) and others Kohler et al., 1995), using PET methods. These investigators compared regional cerebral blood flow (rCBF) responses when subjects were engaged in a face-matching task (object processing) versus a dot-location matching task (spatial processing). ...
Numerous magnetoencephalographic (MEG) investigations of the functional organization of the human visual system have been conducted since 1968. MEG can provide sensitive temporal information about sensory and cognitive functions, on the order of milliseconds, and can provide good spatial resolution as well. Early MEG investigations of the visual system attempted to corroborate findings between noninvasive MEG measures and invasive studies in monkeys, because much of the knowledge of the visual system had been gained from these anatomical, lesional, and electrophysiological studies. Invasive studies reveal a number of different areas in the monkey brain that contain different representations of the visual field and which process information in slightly different ways. The MEG studies reviewed in this chapter represent the steps toward the general goal of a noninvasive delineation of visual information-processing pathways in the human brain. Despite reliable reports of gamma band activation in cats and monkeys, it has been more difficult to visualize this activity in humans using MEG. Mental imagery draws on much of the same neural machinery as perception in the same modality, and can engage mechanisms in memory, emotion, and motor control.
... see Démonet, Wise, & Frackowiak, 1993;Petersen & Fiez, 1993), perception (e.g., Köhler, S. Kapur, Moscovitch, Winocur & Houle, 1995;Kosslyn et al., 1994;Sergent, Ohta, & Macdonald, 1992), attention (for a review, see Petersen, Corbetta, Miezin, & Shulman, 1994), and memory (for a review, see Buckner & Tulving, 1995). Memory has become the most intensively investigated cognitive function, with studies concerning working memory (e.g., Jonides et al., 1993;Paulesu, Frith, & Frackowiak, 1993;Petrides, Alivisatos, Evans, & Meyer, 1993;Petrides, Alivisatos, Meyer, & Evans, 1993), episodic memory (e.g., Andreasen, O'Leary, et al., 1995a, 1995bCabeza, S. Kapur et al., in press;Fletcher et al., 1995;Grasby et al., 1993;Nyberg et al., 1995;Schacter et al., 1995;Squire et al., 1992;Tulving, S. Kapur, Markovitsch, et al., 1994), semantic memory (e.g., Démonet et al., 1992;Frith, Friston, Liddle, & Frackowiak, 1991a;S. ...
We review positron emission tomography (PET) studies whose results converge on the hemispheric encoding/retrieval asymmetry (HERA) model of the involvement of prefrontal cortical regions in the processes of human memory. The model holds that the left prefrontal cortex is differentially more involved in retrieval of information from semantic memory, and in simultaneously encoding novel aspects of the retrieved information into episodic memory, than is the right prefrontal cortex. The right prefrontal cortex, on the other hand, is differentially more involved in episodic memory retrieval than is the left prefrontal cortex. This general pattern holds for different kinds of information (e.g., verbal materials, pictures, faces) and a variety of conditions of encoding and retrieval.
... Four recent functional imaging papers have addressed the brain locus of visual object recognition or related processes. In one using PM: Kohler, Kapur, Moscovitch, Winocur, and Houle (1995) showed subjects pairs of two sequentially-presented displays each containing three objects and asked them to judge in one condition whether the three locations were the same, and in another condition whether the three objects were the same. Areas that were significantly more active in the identity task than the location task included the inferior temporal cortex in the region of the fusiform gyrus (Brodmann areas 19 and 37) in the left hemisphere, extending posteriorly into the lingual gyrus (Brodmann areas 18 and 17), and in the ventral occipital cortex of the right hemisphere in the region of the fusiform gyrus. ...
Positron emission tomography (PET) was used to locate an area in human extrastriate cortex that subserves a specific component process of visual object recognition. Regional blood flow increased in a bilateral extrastriate area on the inferolateral surface of the brain near the border between the occipital and temporal lobes (and a smaller area in the right fusiform gyms) when subjects viewed line drawings of 3-dimensional objects compared to viewing scrambled drawings with no clear shape interpretation. Responses were Seen for both novel and familiar objects, implicating this area in the bottom-up (i.e., memory-independent) analysis of visual shape.
... Positron emission tomography (PET) and fMRI demonstrate that regions of occipito-temporal cortex are activated by a variety of face-processing tasks (Sergent, Ohta, & MacDonald, 1992;Haxby et al., 1994;Clark et al., 1995;Puce, AUison, Gore, & McCarthy, 1995). However, these regions are also activated by objects (Malach et al., 1995;Schacter et al., 1995;Kohler, Kapur, Moscovitch, Winocur, & Houle, 1995;Kanwisher, Woods, Iacoboni, & Mazziotta, 1997); hence activation by faces may simply reflect gen-0 1997 Massachusetts Institute of Technology 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. ...
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.
... In accord with the behavioral data, the results of the grand averaged ERPs, the topographic maps of as a reflection of the episodic retrieval process (Heun, Freymann, Erb, et al., 2007). BA18 is the primary visual cortex, and it is likely to be involved in identification of visual items (Kohler, 1995). It is believed that the reactivation of the processing to events or objects during the retrieval includes BA18 (Schacter & Norman et al., 1998). ...
An event-related potential study was conducted to make clear that how picture-word delayed matching encoding affects upon episodic retrieval, and to further investigate the relationship between encoding and episodic retrieval by ERP source analysis using the LORATA method (low resolution electromagnetic tomography, via Curry V6.0). The experiment used learning and recognition paradigm. The results showed that the identical matching encoding facilitated episodic retrieval, and there was extra activation of Lingual gyrus in the identical match old condition in ERP source analysis, whereas the categorical matching and non-match conditions showed similar mechanisms. Casting back to the encoding processing, it was shown that in the identical match condition an early P300 component from 350 to 450ms was evoked. Our results suggest that the early P300 component evoked by the picture-word identical matching is the critical factor affecting episodic retrieval.
... Positron emission tomography (PET) and fMRI demonstrate that regions of occipito-temporal cortex are activated by a variety of face-processing tasks (Sergent, Ohta, & MacDonald, 1992;Haxby et al., 1994;Clark et al., 1995;Puce, AUison, Gore, & McCarthy, 1995). However, these regions are also activated by objects (Malach et al., 1995;Schacter et al., 1995;Kohler, Kapur, Moscovitch, Winocur, & Houle, 1995;Kanwisher, Woods, Iacoboni, & Mazziotta, 1997); hence activation by faces may simply reflect gen-0 1997 Massachusetts Institute of Technology 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. ...
Background
Driving cessation is a major negative life event that has been associated with a decline in health conditions including dementia. The increase in activity owing to the expansion of life space is a possible explanation for the positive relationship between driving and brain health. The present study examined the association between driving, life space, and structural brain volume in older individuals.
Methods
High-resolution magnetic resonance imaging was employed to examine the brain volume in 1063 older adults. Participants were classified as non-drivers, those who drove <7 days a week, and everyday drivers. They were further classified into a non-driving group, an active group (drove 10 km at least once a week), and a less-active group (drove 10 km less than once a week).
Results
The hippocampal volume was greater in drivers than in non-drivers. Occipital cortex volume was greater in low-frequency drivers than in non-drivers and high-frequency drivers. Active drivers exhibited larger temporal cortex volumes than less-active drivers, larger cingulate cortex volumes than non-drivers and less-active drivers, and larger hippocampal volumes than non-drivers.
Conclusion
Driving was associated with hippocampal brain atrophy attenuation, with active drivers exhibiting decreased brain atrophy in the temporal and cingulate cortices.
Traffic situations like turning at intersections are destined for safety-critical situations and accidents. Human errors are one of the main reasons for accidents in these situations. A model that recognizes the driver's turning intent could help to reduce accidents by warning the driver or stopping the vehicle before a dangerous turning maneuver. Most models that aim at predicting the probability of a driver's turning intent use only contextual information, such as gap size or waiting time. The objective of this study is to investigate whether the combination of context information and brain activation measurements enhances the recognition of turning intent. We conducted a driving simulator study while simultaneously measuring brain activation using high-density fNIRS. A neural network model for turning intent recognition was trained on the fNIRS and contextual data. The input variables were analyzed using SHAP (SHapley Additive exPlanations) feature importance analysis to show the positive effect of the inclusion of brain activation data. Both the model's evaluation and the feature importance analysis suggest that the combination of context information and brain activation leads to an improved turning intent recognition. The fNIRS results showed increased brain activation differences during the “turn” decision-making phase before turning execution in parts of the left motor cortices, such as the primary motor cortex (PMC; putative BA 4), premotor area (PMA; putative BA 6), and supplementary motor area (SMA; putative BA 8). Furthermore, we also observed increased activation differences in the left prefrontal areas, potentially in the left middle frontal gyrus (putative BA 9), which has been associated with the control of executive functions, such as decision-making and action planning. We hypothesize that brain activation measurements could be a more direct indicator with potentially high specificity for the turning behavior and thus help to increase the recognition model's performance.
Many years ago when Somatics magazine was young, it occurred to me that it would be valuable to collect and publish research article references in Somatics magazine that were relevant to the different somatics disciplines to encourage the development of the field. There were next to no studies devoted to Somatics itself, but there were many studies devoted to the elements of somatic practices. Somatics is a multidisciplinary field. It builds on the research findings from many fields, such as anatomy, physiology, neurophysiology, psychology, dance, biomechanics, and education. The references are selected to be suggestive to the interested researcher and practitioner for their purposes and of the many possible research avenues that are yet to be explored. I have collected these research references for more than four decades. I worked originally with Psychological Abstracts, then PsychInfo, and finally, PubMed. Over that time there has been more research done on the somatic disciplines themselves. The greatest amount of research has been done on yoga (the oldest and largest of the somatic disciplines) and yoga therapy. These studies are examples of the research that can be done with the other somatics disciplines as well. We are in an era that appreciates evidence-based practice and practice-based evidence. This is evidence. These research articles are selected according to the following criteria: The article combines both body and mind either in its research design or theoretical perspective; the research design incorporates convergent measures—that is, it includes physiological, behavioral, and psychological measures; subjective and objective measures; and the research focuses on the whole organism (human) from a somatic perspective—that is, the effect of a body therapy on a psychological state. Topics addressed include biofeedback, body psychotherapy, consciousness states, electrophysiology, kinesiology, mind and body, motor processes, neural basis of motor control, neuroscience, posture and emotion, psychophysiology, and yoga/yoga therapy.
Purpose:
Proprioceptive feedback is crucial for motor control and stabilization of the shoulder joint in everyday life and sports. Shoulder dislocation causes anatomical and proprioceptive feedback damage that contributes to subsequent dislocations. Previous recurrent anterior shoulder instability (RSI) studies did not investigate functional neuroplasticity related to proprioception of the injured shoulder. Thus, we aimed to study the differences in neuroplasticity related to motor control between patients with RSI and healthy individuals, using functional magnetic resonance imaging, and assess the effects of peripheral proprioceptive deficits due to RSI on central nervous system (CNS) activity.
Methods:
Using passive shoulder motion and voluntary shoulder muscles contraction tasks, we compared the CNS correlates of proprioceptive activity between patients having RSI (n = 13) and healthy controls (n = 12) to clarify RSI pathophysiology and the effects of RSI-related peripheral proprioceptive deficits on CNS activity.
Results:
Decreased proprioception-related brain activity indicated a deficient passive proprioception in patients with RSI (P < 0.05 family-wise error, cluster level). Proprioceptive afferent-related right cerebellar activity significantly negatively correlated with the extent of shoulder damage (P = 0.001, r = -0.79). Functional magnetic resonance imaging demonstrated abnormal motor control in the CNS during voluntary shoulder muscles contraction.
Conclusion:
Our integrated analysis of peripheral anatomical information and brain activity during motion tasks can be used to investigate other orthopedic diseases.
Patients with stroke can experience a drastic change in their body representation (BR), beyond the physical and psychological consequences of stroke itself. Noteworthy, the misperception of BR could affect patients' motor performance even more. Our study aimed at evaluating the usefulness of a robot-aided gait training (RAGT) equipped with augmented visuomotor feedback, expected to target BR (RAGT + VR) in improving lower limb sensorimotor function, gait performance (using Fugl-Meyer Assessment scale for lower extremities, FMA-LE), and BR (using the Body Esteem Scale—BES- and the Body Uneasiness Test—BUT), as compared to RAGT − VR. We also assessed the neurophysiologic basis putatively subtending the BR-based motor function recovery, using EEG recording during RAGT. Forty-five patients with stroke were enrolled in this study and randomized with a 1:2 ratio into either the RAGT + VR (n = 30) or the RAGT − VR (n = 15) group. The former group carried out rehabilitation training with the Lokomat©Pro; whereas, the latter used the Lokomat©Nanos. The rehabilitation protocol consisted of 40 one-hour training sessions. At the end of the training, the RAGT + VR improved in FMA-LE (p < 0.001) and BR (as per BES, (p < 0.001), and BUT, (p < 0.001)) more than the RAGT- did (p < 0.001). These differences in clinical outcomes were paralleled by a greater strengthening of visuomotor connectivity and corticomotor excitability (as detected at the EEG analyses) in the RAGT + VR than in the RAGT − VR (all comparisons p < 0.001), corresponding to an improved motor programming and execution in the former group.
We may argue that BR recovery was important concerning functional motor improvement by its integration with the motor control system. This likely occurred through the activation of the Mirror Neuron System secondary to the visuomotor feedback provision, resembling virtual reality. Last, our data further confirm the important role of visuomotor feedback in post-stroke rehabilitation, which can achieve better patient-tailored improvement in functional gait by means of RAGT + VR targeting BR.
Purpose:
Unicoronal synostosis (UCS) has been associated with reading, language, and social dysfunction. Limited brain function connectivity studies exist for UCS with none devoted to comparing outcomes by side of synostosis (left versus right-sided UCS).
Methods:
Twelve patients with surgically treated UCS, 7 right-sided and 5 left-sided, were age matched to healthy controls. Resting state functional MRI was acquired in a 3T Siemens TIM Trio scanner (Erlangen, Germany). Data was collected with intrinsic connectivity distribution and seed-connectivity analysis using BioImage Suite (Yale School of Medicine). Region of interest analysis was performed based on Brodmann areas related to emotional, executive, language, motor, and visuo-spatial function. Significance was set at P < 0.05.
Results:
Compared to controls, all UCS patients demonstrated decreased connectivity in areas of the parietal and temporal cortices responsible for visuo-motor coordination and language function. Right UCS patients demonstrated decreased intrinsic connectivity in regions related to complex motor movement and proprioception relative to control subjects. Left UCS patients demonstrated decreased seed connectivity between regions of the parietal lobe and occipital lobe related to motor coordination, visual function, and language compared to right UCS patients.
Conclusion:
Unicoronal synostosis had decreased functional connectivity in regions associated with memory, visual information processing, and motor function. Moreover, left-sided UCS had decreased connectivity in circuits for motor coordination and language when compared to right-sided UCS. This study provides data suggestive of long-term sequelae of UCS that varies by sidedness, which may be responsible for neurocognitive impairments found in previous cognitive analyses.
The purpose of this study is to identify brain activations when learning digital learning contents of biology using smartpad by measuring functional Magnetic Resonance Imaging. Twenty male students in a general high school of Chungbuk province were recruited for BOLD fMRI measurement while learning about the structure of biological organism with traditional fixed learning image and digital learning contents, respectively, based on interaction. SPM8 software was applied to analyze the acquired MR images and identify the brain regions which are specific on using digital learning contents compared with fixed learning images and on using fixed learning images compared with digital learning contents, respectivly. During learning with digital learning contents, high brain activations were identified in middle temporal gyrus, inferior temporal gyrus, middle occipital gyrus, cuneus and cerebellar tonsil that are associated with connections between visual image information and lingual information and regulation of the spatial attention. During learning with fixed learning images, precentral gyrus, postcentral gyrus, transverse temporal gyrus, cingulate gyrus and caudate tail that are related with perception of visual word, experience of successful learning and regulation of finger movement were observed active. These results can suggest a possibility to elaborate the development of digital textbook on biology.
Introduction:
With the recent technical advances in brain imaging modalities like MRI, PET, and fMRI, researchers' interests have inclined over the years to study brain functions through the analysis of the variations in the statistical dependence amongst various brain regions. Through its wide use in studying brain connectivity, the low temporal resolution of the fMRI represented by the limited number of samples per second in addition to its dependence on brain slow hemodynamic changes, make it of limited capability in studying the fast underlying neural processes during information exchange between brain regions.
Materials & methods:
In this paper, the high temporal resolution of the electroencephalography (EEG) is utilized to estimate the effective connectivity within the Default Mode Network (DMN). The EEG data is collected from 20 subjects with alcoholism and 25 healthy subjects (controls) and used to obtain the effective connectivity diagram of the DMN using the Partial Directed Coherence (PDC) algorithm.
Results:
The resulting effective connectivity diagram within the DMN shows the unidirectional causal effect of each region on the other. The variations in the causal effects within the DMN between controls and alcoholics, show clear correlation with the symptoms that are usually associated with alcoholism, such as cognitive and memory impairments, executive control, and attention deficiency. The correlation between the exchanged causal effects within the DMN and symptoms related to alcoholism is discussed and properly analysed.
Conclusion:
The establishment of the causal differences between control and alcoholic subjects within the DMN regions, provides valuable insight into the mechanism by which alcohol modulate our cognitive and executive functions and create better possibility for effective treatment of alcohol use disorder (AUD).
Sustainable development is a systems problem that requires a shift in thinking from individual parts to the relationships between them. Enabling those involved in the development process to more quickly think in systems is therefore vital to create more sustainable solutions. However, measuring the ability to think in systems is a challenge because of the limited methods to observe behavior or measure outcomes. Recent advances in neuroimaging offer a radically new approach to measure one's ability to think in systems. The specific technique, called functional near-infrared spectroscopy (fNIRS), captures the change in oxygenated blood in the cortical region of the brain, which is a proxy for elevated cognitive activation. In this study, engineering students (n = 28) performed both concept mapping (i.e., labeling concepts and drawing directional connections between them) and concept listing (i.e., generating a list of concepts without indicating relationships) related to grand challenges for sustainability. fNIRS captured the increase in oxygenated blood along the prefrontal and parietal cortex during both concept mapping and listing tasks. Self-evaluation and concept mapping scores were also captured and compared. Concept mapping led to significantly more concepts compared to concept listing. Concept mapping also required less cognitive resources (i.e., oxygenated blood) to generate more concepts. The region of the brain that received more cognitive resources is also significantly different when participants were using concept listing and mapping. Concept mapping directed more cognitive resources to the regions of the brain associated with cognitive flexibility and decreased cognitive resources in regions associated with visuospatial processing. Self-evaluation of systems thinking was negatively correlated with concept mapping scores, meaning students with high perceived ability produce worse concept maps. Global efficiency of brain networks was positively correlated to concept map scores and more accurately measure performance compared to self-evaluation. This study provides neurocognitive evidence to support the benefits of concept mapping and also demonstrates the added advantages of neuroimaging to study systems thinking.
The observation of walking improves gait ability in chronic stroke survivors. It has also been suggested that activation of the mirror neuron system contributes to this effect. However, activation of the mirror neuron system during gait observation has not yet been assessed in sub-acute stroke patients. The objective of this study was to clarify the activation of mirror neuron system during gait observation in sub-acute stroke patients and healthy persons. In this study, we sequentially enrolled five sub-acute stroke patients who had undergone gait training and nine healthy persons. We used fMRI to detect neuronal activation during gait observation. During the observation period in the stroke group, neural activity in the left inferior parietal lobule, right and left inferior frontal gyrus was significantly higher than during the rest period. In the healthy group, neural activity in the left inferior parietal lobule, left inferior frontal gyrus, left middle frontal gyrus, left superior temporal lobule and right and left middle temporal gyrus was significantly higher than during the rest period. The results indicate that the mirror neuron system was activated during gait observation in sub-acute stroke patients who had undergone gait training and also in healthy persons. Our findings suggest that gait observation treatment may provide a promising therapeutic strategy in sub-acute stroke patients who have experienced gait training.
The present study investigates human visual processing of simple two-colour patterns using a delayed match to sample paradigm with positron emission tomography (PET). This study is unique in that we specifically designed the visual stimuli to be the same for both pattern and colour recognition with all patterns being abstract shapes not easily verbally coded composed of two-colour combinations. We did this to explore those brain regions required for both colour and pattern processing and to separate those areas of activation required for one or the other. We found that both tasks activated similar occipital regions, the major difference being more extensive activation in pattern recognition. A right-sided network that involved the inferior parietal lobule, the head of the caudate nucleus, and the pulvinar nucleus of the thalamus was common to both paradigms. Pattern recognition also activated the left temporal pole and right lateral orbital gyrus, whereas colour recognition activated the left fusiform gyrus and several right frontal regions. Hum. Brain Mapping 13:213–225, 2001.
This chapter proposes that not only is bottom-up processing liable to affect cortical maps but top-down processing might also play a role. I will argue that the cognitive and neural mechanisms involved in the perception of human actions are worth investigating from a cognitive neuroscience perspective. I will marshal behavioral studies, physiological recordings in monkeys and positron emission tomography (PET) experiments in humans for a better and integrated understanding of the neural bases of perception of biological motion. I propose that top-down processing may have an effect on brain plasticity. Perception of action is also relevant to a contemporary theory of mind. Therefore, a final section deals with its implications for cognitive neuropsychiatry.
This paper reviews our knowledge concering the neurobiological foundations of hallucinations. It discusses organic visual and auditory hallucinations and focuses specifically on auditory-verbal hallucinations (>>hearing voices<<) in schizophrenia. Relying on evidence from functional neuroimaging studies with SPECT, PET, fMRT and MEG, a model is proposed that assumes that a disorder of internal monitoring of inner speech is crucially involved in the pathogenesis of auditory-verbal-hallucinations.
The majority of older adults live their later years free of neurodegenerative diseases; however, normal aging is associated with perpetual and cognitive changes which impinge on older adults' quality of life. Because of space limitations, the chapter performs a limited review of those functions that have been tested in neuroimaging studies for extensive reviews of cognitive aging. The chapter also describes the results from nonhuman animal studies, neuropsychological studies of patients with brain damage, as well as neuroimaging studies with young adults, which help to elucidate the brain regions that are important for different cognitive functions. The chapter also reviews the functional neuroimaging studies that have been conducted with healthy older adults, and describes the way in which brain activation during memory tasks differ between younger and older adults. It also describes the available aging positron emission tomography data and attempts to identify the brain regions in which activation in the face of a cognitive challenge is continuously altered by aging.
The purpose of the present PET study was (i) to investigate the neural correlates of object recognition, i.e. the matching of visual forms to memory, and (ii) to test the hypothesis that this process is more difficult for natural objects than for artefacts. This was done by using object decision tasks where subjects decided whether pictures represented real objects or non-objects. The object decision tasks differed in their difficulty (the degree of perceptual differentiation needed to perform them) and in the category of the real objects used (natural objects versus artefacts). A clear effect of task difficulty was found in both the behavioural and in the PET data. In the PET data, the increase in task difficulty was associated with increased regional cerebral blood flow in the posterior part of the right inferior temporal gyrus and in the anterior part of the right fusiform gyrus. This may be the neural correlate of matching visual forms to memory, and the amount of activation in these regions may correspond to the degree of perceptual differentiation required for recognition to occur. With respect to behaviour, it took significantly longer to make object decisions on natural objects than on artefacts in the difficult object decision tasks. Natural objects also recruited larger parts of the right inferior temporal and anterior fusiform gyri compared with artefacts as task difficulty increased. Differences in the amount of activation in these regions may reflect the greater perceptual differentiation required for recognizing natural objects. These findings are discussed in relation to category-specific impairments after neural damage.
Background:
Previous use of heterogeneous diagnostic criteria and insensitive cognitive measures has impeded clarification of the extent and type of cognitive impairment specific to late-onset delusional disorder. We examined whether clinical presentations of late-onset delusional disorder are associated with prodromal or established dementia, and whether it might be a discrete clinical syndrome characterized by its own profile of cognitive impairment.
Method:
Nineteen patients with late-onset delusional disorder from a hospital psychiatric service and 20 patients with dementia of the Alzheimer's type (AD) from an outpatient memory clinic were recruited in a consecutive case series. All patients underwent comprehensive neuropsychological assessment that included general intellectual function, executive function, new learning and delayed memory, language, processing speed, and visuo-perceptual skills.
Results:
Late-onset delusional disorder patients showed moderate impairment to conceptual reasoning, visual object recognition, processing speed, and confrontation naming. Severe impairment appeared in visuo-perceptual planning and organization, and divided attention. Compared with the Alzheimer's disease (AD) group, the late-onset delusional disorder group demonstrated significantly poorer visuo-perceptual skills but a significantly better capacity to consolidate information into delayed memory.
Conclusions:
A high rate of marked cognitive impairment occurs in late-onset delusional disorder. There was evidence of a conceptual reasoning deficit, plus the presence of a visuo-perceptual impairment affecting object recognition. This impairment profile can explain the genesis and maintenance of the observed delusions. Understanding late-onset delusional disorder as other than a purely psychiatric phenomenon or a precursor to AD will lead to better assessment and management approaches.
Classical artificial neural networks (ANN) and neurocomputing are reviewed for implementing a real time medical image diagnosis. An algorithm known as the self-reference matched filter that emulates the spatio-temporal integration ability of the human visual system might be utilized for multi-frame processing of medical imaging data. A Cauchy machine, implementing a fast simulated annealing schedule, can determine the degree of abnormality by the degree of orthogonality between the patient imagery and the class of features of healthy persons. An automatic inspection process based on multiple modality image sequences is simulated by incorporating the following new developments: (1) 1-D space-filling Peano curves to preserve the 2-D neighborhood pixels' relationship; (2) fast simulated Cauchy annealing for the global optimization of self-feature extraction; and (3) a mini-max energy function for the intra-inter cluster-segregation respectively useful for top-down ANN designs.
The purpose of this study was to directly compare the brain regions involved in episodic-memory recall and recognition. Changes in regional cerebral blood flow were measured by positron emission tomography while young healthy test persons were either recognizing or recalling previously studied word pairs. Reading of previously nonstudied pairs served as a reference task for subtractive comparisons. Compared to reading, both recall and recognition were associated with higher blood flow (activation) at identical sites in the right prefrontal cortex (areas 47, 45, and 10) and the anterior cingulate. Compared to recognition, recall was associated with higher activation in the anterior cingulate, globus pallidus, thalamus, and cerebellum, suggesting that these components of the cerebello-frontal pathway play a role in recall processes that they do not in recognition. Compared to recall, recognition was associated with higher activation in the right inferior parietal cortex (areas 39, 40, and 19), suggesting a larger perceptual component in recognition than in recall. Contrary to the expectations based on lesion data, the activations of the frontal regions were indistinguishable in recall and recognition. This finding is consistent with the notion that frontal activations in explicit memory tasks are related to the general episodic retrieval mode or retrieval attempt, rather than to specific mechanisms of ecphory (recovery of stored information).
In order to study face recognition in relative isolation from visual processes that may also contribute to object recognition and reading, we investigated CK, a man with normal face recognition but with object agnosia and dyslexia caused by a closed-head injury. We administered recognition tests of up right faces, of family resemblance, of age-transformed faces, of caricatures, of cartoons, of inverted faces, and of face features, of disguised faces, of perceptually degraded faces, of fractured faces, of faces parts, and of faces whose parts were made of objects. We compared CK's performance with that of at least 12 control participants. We found that CK performed as well as controls as long as the face was upright and retained the configurational integrity among the internal facial features, the eyes, nose, and mouth. This held regardless of whether the face was disguised or degraded and whether the face was represented as a photo, a caricature, a cartoon, or a face composed of objects. In the last case, CK perceived the face but, unlike controls, was rarely aware that it was composed of objects. When the face, or just the internal features, were inverted or when the configurational gestalt was broken by fracturing the face or misaligning the top and bottom halves, CK's performance suffered far more than that of controls. We conclude that face recognition normally depends on two systems: (1) a holistic, face-specific system that is dependent on orientationspecific coding of second-order relational features (internal), which is intact in CK and (2) a part-based object-recognition system, which is damaged in CK and which contributes to face recognition when the face stimulus does not satisfy the domain-specific conditions needed to activate the face system.
We review PET studies of higher-order cognitive processes, including attention (sustained and selective), perception (of objects, faces, and locations), language (word listening, reading, and production), working memory (phonological and visuo-spatial), semantic memory retrieval (intentional and incidental), episodic memory retrieval (verbal and nonverbal), priming, and procedural memory (conditioning and skill learning). For each process, we identify activation patterns including the most consistently involved regions. These regions constitute important components of the network of brain regions that underlie each function.
Objectives: Regional cerebral blood flow (rCBF) was measured by positron emission tomography with bolus injections of 15 O-labeled water in order to learn the normal pattern of response of the occipital rCBF to flicker and video stimulation. Materials and methods: Six normal volunteers and a patient with partial cortical blindness were studied. They underwent quantitative rCBF measurement in the eye closed resting condition, under full-field stimulation with flickering light, and during video movie viewing, which contains form, color, and movement visual information. Stimulation-minus-rest subtraction PET images were overlaid onto the MRI images resliced parallel to the midline. Results: In normal subjects, the rCBF response to flickering stimuli and to the video in the posterior part of primary visual cortex was +30.5 and +34.5% of whole brain mean value, respectively. The rCBF increase in the association visual cortex was more pronounced by the video movie viewing (+27.5% of whole brain mean value) than by the flickering light stimulation (+6.5% of whole brain mean value). Activated areas in the primary visual cortex corresponded well to the stimulated visual field according to retinotopic organization. Poor activation in primary and in association visual cortex were seen in the patient with cortical blindness. Conclusion: Flickering light and video movie induced different activation patterns. More complicated visual stimuli, which require more extensive neuronal integration, caused greater activation of the higher visual cortex.
Visual imagery is the creation of mental representations that share many features with veridical visual percepts. Studies of normal and brain-damaged people reinforce the view that visual imagery and visual perception are mediated by a common neural substrate and activate the same representations. Thus, brain-damaged patients with intact vision who have an impairment in perception should have impaired visual imagery. Here we present evidence to the contrary from a patient with severely impaired object recognition (visual object agnosia) but with normal mental imagery. He draws objects in considerable detail from memory and uses information derived from mental images in a variety of tasks. In contrast, he cannot identify visually presented objects, even those he has drawn himself. He has normal visual acuity and intact perception of equally complex material in other domains. We conclude that rich internal representations can be activated to support visual imagery even when they cannot support visually mediated perception of objects.
The purpose of the present study was to investigate by using positron emission tomography (PET) whether the cortical pathways that are involved in visual perception of spatial location and object identity are also differentially implicated in retrieval of these types of information from episodic long-term memory. Subjects studied a set of displays consisting of three unique representational line drawings arranged in different spatial configurations. Later, while undergoing PET scanning, subjects' memory for spatial location and identity of the objects in the displays was tested and compared to a perceptual baseline task involving the same displays. In comparison to the baseline task, each of the memory tasks activated both the dorsal and the ventral pathways in the right hemisphere but not to an equal extent. There was also activation of the right prefrontal cortex. When PET scans of the memory tasks were compared to each other, areas of activation were very circumscribed and restricted to the right hemisphere: For retrieval of object identity, the area was in the inferior temporal cortex in the region of the fusiform gyrus (area 37), whereas for retrieval of spatial location, it was in the inferior parietal lobule in the region of the supramarginal gyrus (area 40). Thus, our study shows that distinct neural pathways are activated during retrieval of information about spatial location and object identity from long-term memory.
Positron emission tomography scans were acquired when subjects performed three tasks, each in a separate block of trials. They decided whether words named pictures of objects viewed from a canonical perspective, decided whether words named pictures of objects viewed from a non-canonical (unusual) perspective or saw random patterns of lines and pressed a pedal when they heard the word (this was a baseline condition). The dorsolateral prefrontal region was activated when subjects identified objects seen from non-canonical perspectives, as expected if the frontal lobes are involved in top-down perceptual processing. In addition, several areas in the occipital, temporal and parietal lobes were selectively activated when subjects identified objects seen from non-canonical perspectives, as specifically predicted by a recent theory. Overall, the pattern of results supported the view that the human brain identifies objects by using a system of areas similar to that suggested by studies of other primates.
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.
A single case study is reported of a patient with a naming disorder specific to visually presented stimuli. The patient was often able to gesture correctly to objects he could not name, and he showed intact access to structural knowledge of objects.Further examination revealed an impairment in accessing semantic knowledge about objects, which was most marked when the patient had to discriminate between objects which were visually as well as semantically similar. It is suggested that the patient's naming deficit is due to an impairment in accessing semantic information from vision, following intact access to stored structural knowledge. Correct gestures may be contingent on access to the system specifying structural knowledge. The data are interpreted in terms of a model of visual object identification in which access to semantic information, from the system specifying structural knowledge, is held to operate in cascade.
The patterns of co-occurrence among associative agnosia for faces, words and other objects are analysed and found to be consistent with the existence of two, rather than three, underlying visual recognition capacities. Different degrees and combinations of damage to these two capacities can account for the five different combinations of word, face, and object agnosia that are found, as well as for the apparent absence of two particular combinations. A tentative interpretation of the two inferred visual recognition capacities is offered, in terms of the idea of structural representations.
Accumulating neuropsychological, electrophysiological and behavioural evidence suggests that the neural substrates of visual perception may be quite distinct from those underlying the visual control of actions. In other words, the set of object descriptions that permit identification and recognition may be computed independently of the set of descriptions that allow an observer to shape the hand appropriately to pick up an object. We propose that the ventral stream of projections from the striate cortex to the inferotemporal cortex plays the major role in the perceptual identification of objects, while the dorsal stream projecting from the striate cortex to the posterior parietal region mediates the required sensorimotor transformations for visually guided actions directed at such objects.
A detailed neuropsychological evaluation was performed on a patient with an idiopathic cerebellar degenerative disorder. Significant deficits were found in verbal and nonverbal intelligence, verbal associative learning, and visuospatial skills. These deficits were not readily explained by motor control difficulties. In contrast to the patient's moderately impaired language abilities, he was severely impaired on a test of verbal fluency and demonstrated mild naming deficits. Severe cerebellar parenchymal volume loss was demonstrated by magnetic resonance examination. Supratentorial structures showed only minimal posterior parietal and occipital sulcal prominence. On neurological examination, this patient had signs of severe involvement of the cerebellar systems and mild-to-moderate dysfunction of the corticospinal tract. As is characteristic of patients with cerebellar degeneration, there was neurophysiological evidence of subclinical involvement of auditory and somatosensory pathways at the level of the brain stem. Since relatively little cerebral cortical atrophy was noted in this patient, these findings suggest that an intact cerebellum is important for normal cognitive functions.
Tasks of perceptual matching, including three types of visual stimulus (slope of line, position of dot and size of gap in contour) were devised. Seventy-four patients with unilateral cortical lesions were tested. The right parietal group was impaired on the perceptual matching tasks. There was no association between performance on perceptual matching tasks and tachistoscopic threshold measurements or a test of picture recognition. The relationship between perceptual matching and performance on other more complex visual tasks is discussed.
Practice of a novel task leads to improved performance. The brain mechanisms associated with practice-induced improvement in performance are largely unknown. To address this question we have examined the functional anatomy of the human brain with positron emission tomography (PET) during the naive and practiced performance of a simple verbal response selection task (saying an appropriate verb for a visually presented noun). As a control state, subjects were asked to repeat the visually presented nouns. Areas of the brain most active during naive performance (anterior cingulate, left prefrontal and left posterior temporal cortices, and the right cerebellar hemisphere), compared to repeating the visually presented nouns, were all significantly less active during practiced performance. These changes were accompanied by changes in the opposite direction in sylvian-insular cortex bilaterally and left medial extrastriate cortex. In effect, brief practice made the cortical circuitry used for verbal response selection indistinguishable from simple word repetition. Introduction of a novel list of words reversed the learning-related effects. These results indicate that two distinct circuits can be used for verbal response selection and normal subjects can change the brain circuits used during task performance following less than 15 min of practice. One critical factor in determining the circuitry used appears to be the degree to which a task is learned or automatic.