The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Shintaro Funahashi - One of the best experts on this subject based on the ideXlab platform.
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Working Memory in the Prefrontal Cortex
Brain Sciences, 2017Co-Authors: Shintaro FunahashiAbstract:The Prefrontal Cortex participates in a variety of higher cognitive functions. The concept of working memory is now widely used to understand Prefrontal functions. Neurophysiological studies have revealed that stimulus-selective delay-period activity is a neural correlate of the mechanism for temporarily maintaining information in working memory processes. The central executive, which is the master component of Baddeley’s working memory model and is thought to be a function of the Prefrontal Cortex, controls the performance of other components by allocating a limited capacity of memory resource to each component based on its demand. Recent neurophysiological studies have attempted to reveal how Prefrontal neurons achieve the functions of the central executive. For example, the neural mechanisms of memory control have been examined using the interference effect in a dual-task paradigm. It has been shown that this interference effect is caused by the competitive and overloaded recruitment of overlapping neural populations in the Prefrontal Cortex by two concurrent tasks and that the information-processing capacity of a single neuron is limited to a fixed level, can be flexibly allocated or reallocated between two concurrent tasks based on their needs, and enhances behavioral performance when its allocation to one task is increased. Further, a metamemory task requiring spatial information has been used to understand the neural mechanism for monitoring its own operations, and it has been shown that monitoring the quality of spatial information represented by Prefrontal activity is an important factor in the subject's choice and that the strength of spatially selective delay-period activity reflects confidence in decision-making. Although further studies are needed to elucidate how the Prefrontal Cortex controls memory resource and supervises other systems, some important mechanisms related to the central executive have been identified.
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Prefrontal Cortex and neural mechanisms of executive function
Journal of Physiology-paris, 2013Co-Authors: Shintaro Funahashi, Jorge Mario AndreauAbstract:Executive function is a product of the coordinated operation of multiple neural systems and an essential prerequisite for a variety of cognitive functions. The Prefrontal Cortex is known to be a key structure for the performance of executive functions. To accomplish the coordinated operations of multiple neural systems, the Prefrontal Cortex must monitor the activities in other cortical and subcortical structures and control and supervise their operations by sending command signals, which is called top-down signaling. Although neurophysiological and neuroimaging studies have provided evidence that the Prefrontal Cortex sends top-down signals to the posterior cortices to control information processing, the neural correlate of these top-down signals is not yet known. Through use of the paired association task, it has been demonstrated that top-down signals are used to retrieve specific information stored in long-term memory. Therefore, we used a paired association task to examine the neural correlates of top-down signals in the Prefrontal Cortex. The preliminary results indicate that 32% of visual neurons exhibit pair-selectivity, which is similar to the characteristics of pair-coding activities in temporal neurons. The latency of visual responses in Prefrontal neurons was longer than bottom-up signals but faster than top-down signals in inferior temporal neurons. These results suggest that pair-selective visual responses may be top-down signals that the Prefrontal Cortex provides to the temporal Cortex, although further studies are needed to elucidate the neural correlates of top-down signals and their characteristics to understand the neural mechanism of executive control by the Prefrontal Cortex.
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Space representation in the Prefrontal Cortex
Progress in Neurobiology, 2012Co-Authors: Shintaro FunahashiAbstract:The representation of space and its function in the Prefrontal Cortex have been examined using a variety of behavioral tasks. Among them, since the delayed-response task requires the temporary maintenance of spatial information, this task has been used to examine the mechanisms of spatial representation. In addition, the concept of working memory to explain Prefrontal functions has helped us to understand the nature and functions of space representation in the Prefrontal Cortex. The detailed analysis of delay-period activity observed in spatial working memory tasks has provided important information for understanding space representation in the Prefrontal Cortex. Directional delay-period activity has been shown to be a neural correlate of the mechanism for temporarily maintaining information and represent spatial information for the visual cue and the saccade. In addition, many task-related Prefrontal neurons exhibit spatially selective activities. These neurons are also important components of spatial information processing. In fact, information flow from sensory-related neurons to motor-related neurons has been demonstrated, along with a change in spatial representation as the trial progresses. The dynamic functional interactions among neurons exhibiting different task-related activities and representing different aspects of information could play an essential role in information processing. In addition, information provided from other cortical or subcortical areas might also be necessary for the representation of space in the Prefrontal Cortex. To better understand the representation of space and its function in the Prefrontal Cortex, we need to understand the nature of functional interactions between the Prefrontal Cortex and other cortical and subcortical areas.
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Prefrontal Cortex and working memory processes.
Neuroscience, 2005Co-Authors: Shintaro FunahashiAbstract:Working memory is a mechanism for short-term active maintenance of information as well as for processing maintained information. The dorsolateral Prefrontal Cortex has been known to participate in working memory. The analysis of task-related dorsolateral Prefrontal Cortex activity while monkeys performed a variety of working memory tasks revealed that delay-period activity is a neural correlate of a mechanism for temporary active maintenance of information, because this activity persisted throughout the delay period, showed selectivity to a particular visual feature, and was related to correct behavioral performances. Information processing can be considered as a change of the information represented by a population of neural activities during the progress of the trial. Using population vectors calculated by a population of task-related dorsolateral Prefrontal Cortex activities, we demonstrated the temporal change of information represented by a population of dorsolateral Prefrontal Cortex activities during performances of spatial working memory tasks. Cross-correlation analysis using spike firings of simultaneously isolated pairs of neurons reveals widespread functional interactions among neighboring neurons, especially neurons having delay-period activity, and their dynamic modulation depending on the context of the trial. Functional interactions among neurons and their dynamic modulation could be a mechanism of information processing in the dorsolateral Prefrontal Cortex.
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Neuronal mechanisms of executive control by the Prefrontal Cortex.
Neuroscience Research, 2001Co-Authors: Shintaro FunahashiAbstract:Executive function is considered to be a product of the coordinated operation of various processes to accomplish a particular goal in a flexible manner. The mechanism or system responsible for the coordinated operation of various processes is called executive control. Impairments caused by damage to the Prefrontal Cortex are often called dysexecutive syndromes. Therefore, the Prefrontal Cortex is considered to play a significant role in executive control. Prefrontal participation to executive control can be partly explained by working memory that includes mechanisms for temporary active storage of information and processing stored information. For the Prefrontal Cortex to exert executive control, neuronal mechanisms for temporary storage of information and dynamic and flexible interactions among them are necessary. In this article, we present the presence of dynamic and flexible changes in the strength of functional interaction and extensive functional interactions among temporal information-storage processes in the Prefrontal Cortex. In addition, recent imaging studies show dynamic changes in functional connectivity between the Prefrontal Cortex and other cortical and subcortical structures depending upon the characteristics or the temporal context of the task. These observations indicate that the examination of dynamic and flexible modulation in neuronal interaction among Prefrontal neurons as well as between the Prefrontal Cortex and other cortical and subcortical areas is important for explaining how the Prefrontal Cortex exerts executive control. © 2001 Elsevier Science Ireland Ltd and the Japan Neuroscience Society. All rights reserved.
Richard A Andersen - One of the best experts on this subject based on the ideXlab platform.
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spatial selectivity in human ventrolateral Prefrontal Cortex
Nature Neuroscience, 2005Co-Authors: Daniel S Rizzuto, Igor Fineman, William W Sutherling, Adam N Mamelak, Richard A AndersenAbstract:The functional organization of lateral Prefrontal Cortex is not well understood, and there is debate as to whether the dorsal and ventral aspects mediate distinct spatial and non-spatial functions, respectively. We show for the first time that recordings from human ventrolateral Prefrontal Cortex show spatial selectivity, supporting the idea that ventrolateral Prefrontal Cortex is involved in spatial processing. Our results also indicate that Prefrontal Cortex may be a source of control signals for neuroprosthetic applications.
Adam N Mamelak - One of the best experts on this subject based on the ideXlab platform.
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spatial selectivity in human ventrolateral Prefrontal Cortex
Nature Neuroscience, 2005Co-Authors: Daniel S Rizzuto, Igor Fineman, William W Sutherling, Adam N Mamelak, Richard A AndersenAbstract:The functional organization of lateral Prefrontal Cortex is not well understood, and there is debate as to whether the dorsal and ventral aspects mediate distinct spatial and non-spatial functions, respectively. We show for the first time that recordings from human ventrolateral Prefrontal Cortex show spatial selectivity, supporting the idea that ventrolateral Prefrontal Cortex is involved in spatial processing. Our results also indicate that Prefrontal Cortex may be a source of control signals for neuroprosthetic applications.
Igor Fineman - One of the best experts on this subject based on the ideXlab platform.
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spatial selectivity in human ventrolateral Prefrontal Cortex
Nature Neuroscience, 2005Co-Authors: Daniel S Rizzuto, Igor Fineman, William W Sutherling, Adam N Mamelak, Richard A AndersenAbstract:The functional organization of lateral Prefrontal Cortex is not well understood, and there is debate as to whether the dorsal and ventral aspects mediate distinct spatial and non-spatial functions, respectively. We show for the first time that recordings from human ventrolateral Prefrontal Cortex show spatial selectivity, supporting the idea that ventrolateral Prefrontal Cortex is involved in spatial processing. Our results also indicate that Prefrontal Cortex may be a source of control signals for neuroprosthetic applications.
Derek G V Mitchell - One of the best experts on this subject based on the ideXlab platform.
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the contribution of ventrolateral and dorsolateral Prefrontal Cortex to response reversal
Behavioural Brain Research, 2008Co-Authors: Rebecca Rhodes, Derek G V Mitchell, Daniel S Pine, R J R BlairAbstract:Abstract Studies investigating response reversal consistently implicate regions of medial and lateral Prefrontal Cortex when reinforcement contingencies change. However, it is unclear from these studies how these regions give rise to the individual components of response reversal, such as reinforcement value encoding, response inhibition, and response change. Here we report a novel instrumental learning task designed to determine whether regions implicated in processing reversal errors are uniquely involved in this process, or whether they play a more general role in representing response competition, reinforcement value, or punishment value in the absence of demands for response change. In line with previous findings, reversal errors activated orbitofrontal Cortex, dorsomedial Prefrontal Cortex, ventrolateral Prefrontal Cortex, caudate, and dorsolateral Prefrontal Cortex. These regions also showed increased activity to errors in the absence of contingency changes. In addition, ventrolateral PFC, caudate, and dorsolateral PFC each exhibited increased activity following correct reversals. Activity in these regions was not significantly modulated by changes in reinforcement value that were not sufficient to make an alternative response advantageous. These data do not support punishment-processing or prepotent response inhibition accounts of ventrolateral Prefrontal Cortex function. Instead, they support recent conceptualizations of ventrolateral Prefrontal Cortex function that implicate this region in resolving response competition by manipulating the representation of either motor response options, or object features. These data also suggest that dorsolateral Prefrontal Cortex plays a role in reversal learning, probably through top down attentional control of object or reinforcement features when task demands increase.
