The Experts below are selected from a list of 375 Experts worldwide ranked by ideXlab platform
David A Crowe - One of the best experts on this subject based on the ideXlab platform.
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understanding the parietal lobe syndrome from a neurophysiological and evolutionary perspective
European Journal of Neuroscience, 2010Co-Authors: Roberto Caminiti, Matthew V Chafee, Bruno B Averbeck, David A Crowe, Alexandra Battagliamayer, Apostolos P GeorgopoulosAbstract:In human and nonhuman primates parietal cortex is formed by a multiplicity of areas. For those of the superior parietal lobule (SPL) there exists a certain homology between man and macaques. As a consequence, optic ataxia, a disturbed visual control of hand reaching, has similar features in man and monkeys. Establishing such correspondence has proven difficult for the areas of the inferior parietal lobule (IPL). This difficulty depends on many factors. First, no physiological information is available in man on the dynamic properties of cells in the IPL. Second, the number of IPL areas identified in the monkey is paradoxically higher than that so far described in man, although this issue will probably be reconsidered in future years, thanks to comparative imaging studies. Third, the consequences of parietal lesions in monkeys do not always match those observed in humans. This is another paradox if one considers that, in certain cases, the functional properties of neurons in the monkey's IPL would predict the presence of behavioral skills, such as construction capacity, that however do not seem to emerge in the wild. Therefore, Constructional Apraxia, which is well characterized in man, has never been described in monkeys and apes. Finally, only certain aspects, i.e. hand directional hypokinesia and gaze Apraxia (Balint's psychic paralysis of gaze), of the multifaceted syndrome hemispatial neglect have been described in monkeys. These similarities, differences and paradoxes, among many others, make the study of the evolution and function of parietal cortex a challenging case.
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representing spatial relationships in posterior parietal cortex single neurons code object referenced position
Cerebral Cortex, 2007Co-Authors: Matthew V Chafee, Bruno B Averbeck, David A CroweAbstract:The brain computes spatial relationships as necessary to achieve behavioral goals. Loss of this spatial cognitive ability after damage to posterior parietal cortex may contribute to Constructional Apraxia, a syndrome in which a patient's ability to reproduce spatial relationships between the parts of an object is disrupted. To explore neural correlates of object-relative spatial representation, we recorded neural activity in parietal area 7a of monkeys performing an object construction task. We found that neurons were activated as a function of the spatial relationship between a task-critical coordinate and a reference object. Individual neurons exhibited an object-relative spatial preference, such that different neural populations were activated when the spatial coordinate was located to the left or right of the reference object. In each case, the representation was robust to translation of the reference object, and neurons maintained their object-relative preference when the position of the object varied relative to the angle of gaze and viewer-centered frames of reference. This provides evidence that the activity of a subpopulation of parietal neurons active in the construction task represented relative position as referenced to an object and not absolute position with respect to the viewer.
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Representing spatial relationships in posterior parietal cortex: Single neurons code object-referenced position. Cerebral Cortex
2007Co-Authors: Matthew V Chafee, Bruno B Averbeck, David A CroweAbstract:The brain computes spatial relationships as necessary to achieve behavioral goals. Loss of this spatial cognitive ability after damage to posterior parietal cortex may contribute to Constructional Apraxia, a syndrome in which a patient’s ability to reproduce spatial relationships between the parts of an object is disrupted. To explore neural correlates of object-relative spatial representation, we recorded neural activity in parietal area 7a of monkeys performing an object construction task. We found that neurons were activated as a function of the spatial relationship between a task-critical coordinate and a reference object. Individual neurons exhibited an object-relative spatial preference, such that different neural populations were activated when the spatial coordinate was located to the left or right of the reference object. In each case, the representation was robust to translation of the reference object, and neurons maintained their object-relative preference when the position of the object varied relative to the angle of gaze and viewer-centered frames of reference. This provides evidence that the activity of a subpopulation of parietal neurons active in the construction task represented relative position as referenced to an object and not absolute position with respect to the viewer
Matthew V Chafee - One of the best experts on this subject based on the ideXlab platform.
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understanding the parietal lobe syndrome from a neurophysiological and evolutionary perspective
European Journal of Neuroscience, 2010Co-Authors: Roberto Caminiti, Matthew V Chafee, Bruno B Averbeck, David A Crowe, Alexandra Battagliamayer, Apostolos P GeorgopoulosAbstract:In human and nonhuman primates parietal cortex is formed by a multiplicity of areas. For those of the superior parietal lobule (SPL) there exists a certain homology between man and macaques. As a consequence, optic ataxia, a disturbed visual control of hand reaching, has similar features in man and monkeys. Establishing such correspondence has proven difficult for the areas of the inferior parietal lobule (IPL). This difficulty depends on many factors. First, no physiological information is available in man on the dynamic properties of cells in the IPL. Second, the number of IPL areas identified in the monkey is paradoxically higher than that so far described in man, although this issue will probably be reconsidered in future years, thanks to comparative imaging studies. Third, the consequences of parietal lesions in monkeys do not always match those observed in humans. This is another paradox if one considers that, in certain cases, the functional properties of neurons in the monkey's IPL would predict the presence of behavioral skills, such as construction capacity, that however do not seem to emerge in the wild. Therefore, Constructional Apraxia, which is well characterized in man, has never been described in monkeys and apes. Finally, only certain aspects, i.e. hand directional hypokinesia and gaze Apraxia (Balint's psychic paralysis of gaze), of the multifaceted syndrome hemispatial neglect have been described in monkeys. These similarities, differences and paradoxes, among many others, make the study of the evolution and function of parietal cortex a challenging case.
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representing spatial relationships in posterior parietal cortex single neurons code object referenced position
Cerebral Cortex, 2007Co-Authors: Matthew V Chafee, Bruno B Averbeck, David A CroweAbstract:The brain computes spatial relationships as necessary to achieve behavioral goals. Loss of this spatial cognitive ability after damage to posterior parietal cortex may contribute to Constructional Apraxia, a syndrome in which a patient's ability to reproduce spatial relationships between the parts of an object is disrupted. To explore neural correlates of object-relative spatial representation, we recorded neural activity in parietal area 7a of monkeys performing an object construction task. We found that neurons were activated as a function of the spatial relationship between a task-critical coordinate and a reference object. Individual neurons exhibited an object-relative spatial preference, such that different neural populations were activated when the spatial coordinate was located to the left or right of the reference object. In each case, the representation was robust to translation of the reference object, and neurons maintained their object-relative preference when the position of the object varied relative to the angle of gaze and viewer-centered frames of reference. This provides evidence that the activity of a subpopulation of parietal neurons active in the construction task represented relative position as referenced to an object and not absolute position with respect to the viewer.
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Representing spatial relationships in posterior parietal cortex: Single neurons code object-referenced position. Cerebral Cortex
2007Co-Authors: Matthew V Chafee, Bruno B Averbeck, David A CroweAbstract:The brain computes spatial relationships as necessary to achieve behavioral goals. Loss of this spatial cognitive ability after damage to posterior parietal cortex may contribute to Constructional Apraxia, a syndrome in which a patient’s ability to reproduce spatial relationships between the parts of an object is disrupted. To explore neural correlates of object-relative spatial representation, we recorded neural activity in parietal area 7a of monkeys performing an object construction task. We found that neurons were activated as a function of the spatial relationship between a task-critical coordinate and a reference object. Individual neurons exhibited an object-relative spatial preference, such that different neural populations were activated when the spatial coordinate was located to the left or right of the reference object. In each case, the representation was robust to translation of the reference object, and neurons maintained their object-relative preference when the position of the object varied relative to the angle of gaze and viewer-centered frames of reference. This provides evidence that the activity of a subpopulation of parietal neurons active in the construction task represented relative position as referenced to an object and not absolute position with respect to the viewer
Bruno B Averbeck - One of the best experts on this subject based on the ideXlab platform.
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understanding the parietal lobe syndrome from a neurophysiological and evolutionary perspective
European Journal of Neuroscience, 2010Co-Authors: Roberto Caminiti, Matthew V Chafee, Bruno B Averbeck, David A Crowe, Alexandra Battagliamayer, Apostolos P GeorgopoulosAbstract:In human and nonhuman primates parietal cortex is formed by a multiplicity of areas. For those of the superior parietal lobule (SPL) there exists a certain homology between man and macaques. As a consequence, optic ataxia, a disturbed visual control of hand reaching, has similar features in man and monkeys. Establishing such correspondence has proven difficult for the areas of the inferior parietal lobule (IPL). This difficulty depends on many factors. First, no physiological information is available in man on the dynamic properties of cells in the IPL. Second, the number of IPL areas identified in the monkey is paradoxically higher than that so far described in man, although this issue will probably be reconsidered in future years, thanks to comparative imaging studies. Third, the consequences of parietal lesions in monkeys do not always match those observed in humans. This is another paradox if one considers that, in certain cases, the functional properties of neurons in the monkey's IPL would predict the presence of behavioral skills, such as construction capacity, that however do not seem to emerge in the wild. Therefore, Constructional Apraxia, which is well characterized in man, has never been described in monkeys and apes. Finally, only certain aspects, i.e. hand directional hypokinesia and gaze Apraxia (Balint's psychic paralysis of gaze), of the multifaceted syndrome hemispatial neglect have been described in monkeys. These similarities, differences and paradoxes, among many others, make the study of the evolution and function of parietal cortex a challenging case.
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representing spatial relationships in posterior parietal cortex single neurons code object referenced position
Cerebral Cortex, 2007Co-Authors: Matthew V Chafee, Bruno B Averbeck, David A CroweAbstract:The brain computes spatial relationships as necessary to achieve behavioral goals. Loss of this spatial cognitive ability after damage to posterior parietal cortex may contribute to Constructional Apraxia, a syndrome in which a patient's ability to reproduce spatial relationships between the parts of an object is disrupted. To explore neural correlates of object-relative spatial representation, we recorded neural activity in parietal area 7a of monkeys performing an object construction task. We found that neurons were activated as a function of the spatial relationship between a task-critical coordinate and a reference object. Individual neurons exhibited an object-relative spatial preference, such that different neural populations were activated when the spatial coordinate was located to the left or right of the reference object. In each case, the representation was robust to translation of the reference object, and neurons maintained their object-relative preference when the position of the object varied relative to the angle of gaze and viewer-centered frames of reference. This provides evidence that the activity of a subpopulation of parietal neurons active in the construction task represented relative position as referenced to an object and not absolute position with respect to the viewer.
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Representing spatial relationships in posterior parietal cortex: Single neurons code object-referenced position. Cerebral Cortex
2007Co-Authors: Matthew V Chafee, Bruno B Averbeck, David A CroweAbstract:The brain computes spatial relationships as necessary to achieve behavioral goals. Loss of this spatial cognitive ability after damage to posterior parietal cortex may contribute to Constructional Apraxia, a syndrome in which a patient’s ability to reproduce spatial relationships between the parts of an object is disrupted. To explore neural correlates of object-relative spatial representation, we recorded neural activity in parietal area 7a of monkeys performing an object construction task. We found that neurons were activated as a function of the spatial relationship between a task-critical coordinate and a reference object. Individual neurons exhibited an object-relative spatial preference, such that different neural populations were activated when the spatial coordinate was located to the left or right of the reference object. In each case, the representation was robust to translation of the reference object, and neurons maintained their object-relative preference when the position of the object varied relative to the angle of gaze and viewer-centered frames of reference. This provides evidence that the activity of a subpopulation of parietal neurons active in the construction task represented relative position as referenced to an object and not absolute position with respect to the viewer
Zs Nagy - One of the best experts on this subject based on the ideXlab platform.
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Constructional Apraxia in alzheimer s disease association with occipital lobe pathology and accelerated cognitive decline
Dementia and Geriatric Cognitive Disorders, 2001Co-Authors: M Z Smith, L Barnetson, E M F King, Margaret M. Esiri, Zs NagyAbstract:The functional impact and progression of occipital lobe pathology in sporadic late onset Alzheimer’s disease (AD) is barely explored. It is accepted that the primary and association visual areas are a
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Constructional Apraxia in alzheimer s disease association with occipital lobe pathology and accelerated cognitive decline
Dementia and Geriatric Cognitive Disorders, 2001Co-Authors: M Z Smith, L Barnetson, Margaret M. Esiri, Elizabeth King, Zs NagyAbstract:The functional impact and progression of occipital lobe pathology in sporadic late onset Alzheimer's disease (AD) is barely explored. It is accepted that the primary and association visual areas are affected relatively late, in the neocortical stages of AD. We analysed 60 prospectively assessed AD patients in whom global cognitive deterioration and Constructional Apraxia were evaluated longitudinally using the CAMDEX. Radioactive immunohistochemistry was used to assess the amount of AD-related pathology in Brodmann areas 18 and 17. Braak staging of each case was also carried out. This study showed that in AD patients Constructional Apraxia is associated with higher expression of hyperphosphorylated tau. Additionally our findings indicate that early Constructional Apraxia is a predictor of accelerated cognitive decline in AD.
M Z Smith - One of the best experts on this subject based on the ideXlab platform.
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Constructional Apraxia in alzheimer s disease association with occipital lobe pathology and accelerated cognitive decline
Dementia and Geriatric Cognitive Disorders, 2001Co-Authors: M Z Smith, L Barnetson, E M F King, Margaret M. Esiri, Zs NagyAbstract:The functional impact and progression of occipital lobe pathology in sporadic late onset Alzheimer’s disease (AD) is barely explored. It is accepted that the primary and association visual areas are a
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Constructional Apraxia in alzheimer s disease association with occipital lobe pathology and accelerated cognitive decline
Dementia and Geriatric Cognitive Disorders, 2001Co-Authors: M Z Smith, L Barnetson, Margaret M. Esiri, Elizabeth King, Zs NagyAbstract:The functional impact and progression of occipital lobe pathology in sporadic late onset Alzheimer's disease (AD) is barely explored. It is accepted that the primary and association visual areas are affected relatively late, in the neocortical stages of AD. We analysed 60 prospectively assessed AD patients in whom global cognitive deterioration and Constructional Apraxia were evaluated longitudinally using the CAMDEX. Radioactive immunohistochemistry was used to assess the amount of AD-related pathology in Brodmann areas 18 and 17. Braak staging of each case was also carried out. This study showed that in AD patients Constructional Apraxia is associated with higher expression of hyperphosphorylated tau. Additionally our findings indicate that early Constructional Apraxia is a predictor of accelerated cognitive decline in AD.