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Daniel Zaksas, Nicholas P. LaMendola, Tatiana Pasternak; Direction selective activity in prefrontal cortex during a working memory for motion task. Journal of Vision 2005;5(8):495. doi: https://doi.org/10.1167/5.8.495.
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© ARVO (1962-2015); The Authors (2016-present)
While it is known that many neurons in prefrontal cortex (PFC) respond to stimulus shapes and have activity related to working memory, responses of these neurons during tasks involving visual motion has not been explored. We recorded from a region in PFC that is interconnected with motion processing area MT, during a task in which monkeys compared the direction of motion in two sequential stimuli, sample and test, separated by a memory delay. Most neurons with task-related activity clearly responded to the visual stimuli, and more than 70% did so with some degree of direction selectivity. Responses were also modulated by the coherence level of the motion stimuli. The nature of these signals suggests that they may arrive from area MT. Activity during the memory delay was highly dynamic and task dependent. At all times during the delay, at least 20% of neurons had activity selective for the remembered direction, and this number increased to 40% just prior to test onset. Selective delay activity was behaviorally relevant since on error trials these signals were substantially weaker, especially late in the delay. Directional signals carried by individual neurons were relatively transient and occurred at different times for different neurons, suggesting a temporally dynamic mechanism for maintaining information through time. The presence of behaviorally relevant motion signals throughout the task supports the idea of an active role for PFC neurons in working memory for visual motion.
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