The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform
Michael Petrides - One of the best experts on this subject based on the ideXlab platform.
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sulcal organization in the medial Frontal Cortex provides insights into primate brain evolution
Nature Communications, 2019Co-Authors: Celine Amiez, Jerome Sallet, Fadila Hadjbouziane, Ben S Hamed, Emmanuel Procyk, Adrien Meguerditchian, William D. Hopkins, Michael PetridesAbstract:Although the relative expansion of the Frontal Cortex in primate evolution is generally accepted, the nature of the human uniqueness, if any, and between-species anatomo-functional comparisons of the Frontal areas remain controversial. To provide a novel interpretation of the evolution of primate brains, sulcal morphological variability of the medial Frontal Cortex was assessed in Old World monkeys (macaque/baboon) and Hominoidea (chimpanzee/human). We show that both Hominoidea possess a paracingulate sulcus, which was previously thought to be unique to the human brain and linked to higher cognitive functions, such as mentalizing. Also, we show systematic sulcal morphological organization of the medial Frontal Cortex that can be traced from Old World monkeys to Hominoidea species, demonstrating an evolutionarily conserved organizational principle. These data provide a new framework to compare sulcal morphology, cytoarchitectonic areal distribution, connectivity, and function across the primate order, leading to clear predictions about how other primate brains might be anatomo-functionally organized. The Frontal Cortex has expanded over primate evolution. Here, the authors use neuroimaging data from the brains of humans, chimpanzees, baboons, and macaques, to reveal shared and distinct sulcal morphology of the medial Frontal Cortex.
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Specialized systems for the processing of mnemonic information within the primate Frontal Cortex.
Philosophical transactions of the Royal Society of London. Series B Biological sciences, 1996Co-Authors: Michael Petrides, Alan D. BaddeleyAbstract:The lateral Frontal Cortex is involved in various aspects of executive processing within short- and long-term memory. It is argued that the different parts of the lateral Frontal Cortex make distinct contributions to memory that differ in terms of the level of executive processing that is carried out in interaction with posterior cortical systems. According to this hypothesis, the mid-dorsolateral Frontal Cortex (areas 46 and 9) is a specialized system for the monitoring and manipulation of information within working memory, whereas the mid-ventrolateral Frontal Cortex (areas 47/12 and 45) is involved in the active retrieval of information from the posterior cortical association areas. Data are presented which support this two-level hypothesis that posits two distinct levels of interaction of the lateral Frontal Cortex with posterior cortical association areas. Functional activation studies with normal human subjects have demonstrated specific activity within the mid-dorsolateral region of the Frontal Cortex during the performance of tasks requiring monitoring of self-generated and externally generated sequences of responses. In the monkey, lesions restricted to this region of the Frontal Cortex yield a severe impairment in performance of the above tasks, this impairment appearing against a background of normal performance on several basic mnemonic tasks. By contrast, a more severe impairment follows damage to the mid-ventrolateral Frontal region and functional activation studies have demonstrated specific changes in activity in this region in relation to the active retrieval of information from memory.
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dissociation of human mid dorsolateral from posterior dorsolateral Frontal Cortex in memory processing
Proceedings of the National Academy of Sciences of the United States of America, 1993Co-Authors: Michael Petrides, Bessie Alivisatos, Alan C Evans, Ernst MeyerAbstract:Work with non-human primates had previously demonstrated that the mid-dorsolateral Frontal Cortex, which comprises cytoarchitectonic areas 46 and 9, plays a critical role in the performance of non-spatial self-ordered working memory tasks, whereas the immediately adjacent posterior dorsolateral Frontal Cortex (area 8) is critical for the learning and performance of visual conditional associative tasks. The present study used positron emission tomography with magnetic resonance imaging to demonstrate the existence, within the human brain, of these two functionally distinct subdivisions of the lateral Frontal Cortex. These findings provide direct evidence that, just as the monkey brain, the human lateral Frontal Cortex is functionally heterogeneous and that comparable anatomical areas underlie similar functions in the two species.
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Functional specialization within the dorsolateral Frontal Cortex for serial order memory.
Proceedings. Biological sciences, 1991Co-Authors: Michael PetridesAbstract:Monkeys with lesions restricted to two anatomically distinct regions of the dorsolateral Frontal Cortex were tested on a novel task that was developed to assess memory for the order of occurrence of stimuli. Monkeys with bilateral lesions of the mid-dorsolateral Frontal Cortex (cytoarchitectonic areas 46 and 9) were severely impaired, whereas monkeys with lesions of the posterior region of the dorsolateral Frontal Cortex (area 8 and rostral area 6) performed as well as the normal control animals. These results show that the primate mid-dorsolateral Frontal Cortex is a critical component of a neural circuit underlying the monitoring of the serial order of stimuli.
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Monitoring of Selections of Visual Stimuli and the Primate Frontal Cortex
Proceedings. Biological sciences, 1991Co-Authors: Michael PetridesAbstract:This investigation shows that lesions confined to the middle sector of the dorsolateral Frontal Cortex, i.e. cytoarchitectonic areas 46 and 9, cause a striking impairment in the ability of non-human primates to recall which one from a set of stimuli they chose, without in any way affecting their ability to recognize that they had previously seen those stimuli. By contrast, lesions placed within the adjacent posterior dorsolateral Frontal Cortex affect neither recognition of visual stimuli nor recall of prior choices. These findings delineate the mid-dorsolateral Frontal Cortex as a critical component of a neural system mediating the monitoring of self-generated responses.
Gabriel Kreiman - One of the best experts on this subject based on the ideXlab platform.
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Cascade of neural processing orchestrates cognitive control in human Frontal Cortex
eLife, 2016Co-Authors: Hanlin Tang, Chien-chen Chou, Nathan E. Crone, Joseph R. Madsen, William S. Anderson, Gabriel KreimanAbstract:Rapid and flexible interpretation of conflicting sensory inputs in the context of current goals is a critical component of cognitive control that is orchestrated by Frontal Cortex. The relative roles of distinct subregions within Frontal Cortex are poorly understood. To examine the dynamics underlying cognitive control across Frontal regions, we took advantage of the spatiotemporal resolution of intracranial recordings in epilepsy patients while subjects resolved color-word conflict. We observed differential activity preceding the behavioral responses to conflict trials throughout Frontal Cortex; this activity was correlated with behavioral reaction times. These signals emerged first in anterior cingulate Cortex (ACC) before dorsolateral preFrontal Cortex (dlPFC), followed by medial Frontal Cortex (mFC) and then by orbitoFrontal Cortex (OFC). These results disassociate the Frontal subregions based on their dynamics, and suggest a temporal hierarchy for cognitive control in human Cortex.
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cascade of neural processing orchestrates cognitive control in human Frontal Cortex
eLife, 2016Co-Authors: Hanlin Tang, Chien-chen Chou, Nathan E. Crone, Joseph R. Madsen, William S. Anderson, Hsiang Yu Yu, Gabriel KreimanAbstract:The brain adapts to control our behavior in different ways depending on the specific situation, which is particularly useful when deciding how to interpret conflicting sets of information. The 'Stroop task' is a classic demonstration of this process. In this task, individuals are shown words where the color and the meaning of the text conflict – for example, the word 'green' is written in blue. When asked what the color of the text is, individuals must suppress the instinct to read the word. This causes them to make more mistakes and take longer to decide on an answer than when they perform the same task using words that have no conflict (for example, when “red” is written in red). Previous work has suggested that several regions within part of the brain called the Frontal Cortex play a role in this cognitive control process. However, the relative contributions of each of these regions, and the order in which they are activated, remain unclear. This is in part due to the fact that accurately measuring the electrical activity of the Frontal Cortex requires implanting electrodes into the brain. Tang et al. took advantage of a rare opportunity to record this activity from a group of patients who had electrodes implanted in their Frontal Cortex to treat epilepsy. The electrical signals recorded by these electrodes as the subjects performed the Stroop task revealed that four regions in the Frontal Cortex altered their activity during trials where the color and the meaning of a word conflicted. These responses corresponded with the subject’s reaction time, changed depending on the exact nature of the task, and even reflected the subjects’ errors. These responses arose at different times in different regions, allowing Tang et al. to suggest how signals flow through the Frontal Cortex during cognitive control. In the future it will be important to further understand how the regions of the Frontal Cortex identified by Tang et al. interact with each other and to establish their roles in cognitive control. These observations could then be used to produce a theoretical framework that describes how the brain adapts behavior to different circumstances.
Hanlin Tang - One of the best experts on this subject based on the ideXlab platform.
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Cascade of neural processing orchestrates cognitive control in human Frontal Cortex
eLife, 2016Co-Authors: Hanlin Tang, Chien-chen Chou, Nathan E. Crone, Joseph R. Madsen, William S. Anderson, Gabriel KreimanAbstract:Rapid and flexible interpretation of conflicting sensory inputs in the context of current goals is a critical component of cognitive control that is orchestrated by Frontal Cortex. The relative roles of distinct subregions within Frontal Cortex are poorly understood. To examine the dynamics underlying cognitive control across Frontal regions, we took advantage of the spatiotemporal resolution of intracranial recordings in epilepsy patients while subjects resolved color-word conflict. We observed differential activity preceding the behavioral responses to conflict trials throughout Frontal Cortex; this activity was correlated with behavioral reaction times. These signals emerged first in anterior cingulate Cortex (ACC) before dorsolateral preFrontal Cortex (dlPFC), followed by medial Frontal Cortex (mFC) and then by orbitoFrontal Cortex (OFC). These results disassociate the Frontal subregions based on their dynamics, and suggest a temporal hierarchy for cognitive control in human Cortex.
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cascade of neural processing orchestrates cognitive control in human Frontal Cortex
eLife, 2016Co-Authors: Hanlin Tang, Chien-chen Chou, Nathan E. Crone, Joseph R. Madsen, William S. Anderson, Hsiang Yu Yu, Gabriel KreimanAbstract:The brain adapts to control our behavior in different ways depending on the specific situation, which is particularly useful when deciding how to interpret conflicting sets of information. The 'Stroop task' is a classic demonstration of this process. In this task, individuals are shown words where the color and the meaning of the text conflict – for example, the word 'green' is written in blue. When asked what the color of the text is, individuals must suppress the instinct to read the word. This causes them to make more mistakes and take longer to decide on an answer than when they perform the same task using words that have no conflict (for example, when “red” is written in red). Previous work has suggested that several regions within part of the brain called the Frontal Cortex play a role in this cognitive control process. However, the relative contributions of each of these regions, and the order in which they are activated, remain unclear. This is in part due to the fact that accurately measuring the electrical activity of the Frontal Cortex requires implanting electrodes into the brain. Tang et al. took advantage of a rare opportunity to record this activity from a group of patients who had electrodes implanted in their Frontal Cortex to treat epilepsy. The electrical signals recorded by these electrodes as the subjects performed the Stroop task revealed that four regions in the Frontal Cortex altered their activity during trials where the color and the meaning of a word conflicted. These responses corresponded with the subject’s reaction time, changed depending on the exact nature of the task, and even reflected the subjects’ errors. These responses arose at different times in different regions, allowing Tang et al. to suggest how signals flow through the Frontal Cortex during cognitive control. In the future it will be important to further understand how the regions of the Frontal Cortex identified by Tang et al. interact with each other and to establish their roles in cognitive control. These observations could then be used to produce a theoretical framework that describes how the brain adapts behavior to different circumstances.
K. Ranga Rama Krishnan - One of the best experts on this subject based on the ideXlab platform.
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Reduction of orbital Frontal Cortex volume in geriatric depression.
Biological psychiatry, 2000Co-Authors: Te-jen Lai, Martha E. Payne, Christopher E. Byrum, David C. Steffens, K. Ranga Rama KrishnanAbstract:Abstract Background: Postmortem studies have documented abnormalities in the medial orbital Frontal Cortex in depressed patients. In this study we evaluated whether atrophy of this region can be identified in older depressed patients using magnetic resonance imaging. Methods: Twenty elderly patients meeting DSM-IV criteria for major depression and 20 matched control subjects were studied. The orbital Frontal Cortex was measured in both hemispheres using magnetic resonance imaging. Results: Depressive patients had reduced volume in the total orbital Frontal Cortex, right orbital Frontal Cortex, and left orbital Frontal Cortex. Conclusions: Our finding of a reduction in orbital Frontal Cortex volume in both sides of the brain suggests that this region of the brain may have a critical role in the development of depression and raises questions about the etiology of the changes.
R J R Blair - One of the best experts on this subject based on the ideXlab platform.
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the roles of orbital Frontal Cortex in the modulation of antisocial behavior
Brain and Cognition, 2004Co-Authors: R J R BlairAbstract:This article considers potential roles of orbital Frontal Cortex in the modulation of antisocial behavior. Two forms of aggression are distinguished: reactive aggression elicited in response to frustration/threat and goal directed, instrumental aggression. It is suggested that orbital Frontal Cortex is directly involved in the modulation of reactive aggression. It is argued that orbital Frontal Cortex does not "inhibit" reactive aggression but rather may both increase or decrease its probability as a function of social cues present in the environment. Early dysfunction in this function of orbital Frontal Cortex may be linked to the development of Borderline Personality Disorder. Instrumental aggression is linked to a fundamental failure in moral socialization. However, the available data suggest that the amygdala, but not orbital Frontal Cortex, is required for functions such as aversive conditioning and passive avoidance learning that are necessary for moral socialization. Psychopathic individuals who present with significant instrumental aggression, are impaired in aversive conditioning and passive avoidance learning and show evidence of amygdala dysfunction. Orbital Frontal Cortex and the amygdala are involved in response reversal where instrumental responses must be reversed following contingency change. Impairments in response reversal are also seen in psychopathic individuals. However, it remains unclear whether impairment in response reversal per se is associated with antisocial behavior.
