NEUROPHYSIOLOGY OF ACTION SELECTION IN THE CEREBRAL CORT

University Of Montreal, Montreal PQ

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Abstract

The purpose of the proposed project is to investigate the cerebral cortical mechanisms involved in the specification and selection of multiple potential motor actions. The motivation for this work lies in a broad theoretical framework based on parallel neural mechanisms of "action specification" (which specify the parameters of potential actions) and mechanisms of "action selection" (which choose between several possible courses of action). In this framework, neural processing of sensory input can lead to the simultaneous specification of several potential motor actions, one of which may be released into execution (selected) depending on the behavioral context. In our experiment, we train a monkey to make reaching movements to spatial targets after an instructed delay period during which two potential targets are presented. During the first half of the instructed delay, the monkey does not know which target will be the correct one. During the second half, a non-spatial cue indicates the correct target. The question is: In how much detail does the monkey prepare the two potential movements while he still does not know which will be the correct one? That is, does he merely remember sensory representations of the targets or does he prepare (specify) both potential movements with the same degree of detail with which a single unambiguous movement can be prepared? Preliminary results favor the latter possibility, supporting the framework of parallel action specification and selection.