20 novembre 2020

HHMI Janelia Research Campus, Howard Hughes Medical Institute

Descending forebrain circuits for action specification

Invité par Nicolas Wanaverbecq

Abstract : Our group is interested in the neural circuit mechanisms that allow animals to execute purposive behaviors. Neocortical and basal ganglia circuits constitute the two major forebrain descending pathways thought to be important for the voluntary control of movement. The influence of cortical output on movement execution arises from two broad classes of projection neurons pyramidal tract neurons (PT), which project directly from forebrain to the hindbrain, brainstem and spinal cord and intratelencephalic neurons (IT), which project within the forebrain including the basal ganglia input nucleus, striatum. Prevailing models suggest that PT pathways constitute the primary source of descending motor commands for coordinated, goal-directed movements. However, simultaneous recording from these identified forebrain projection pathways has been limited to date. In my talk I will discuss our recent work combining large-scale electrophysiological recording and imaging from multiple identified cell types in the motor cortex and striatum of mice. We combined these recordings with open-loop and closed-loop cell-type specific perturbations in the context of two forebrain-dependent motor skills : manipulation of a joystick and reaching to a target. Our data point to a model in which descending forebrain pathways through basal ganglia constitute an essential component of descending motor commands for skilled movement execution. I will then use this insight to articulate a proposed circuit mechanism for how past experience and reinforcement are used to refine and specify continuous parameters of skilled forelimb movements.

Research Field : Voluntary, purposive behavior requires that we extract information about the world, formulate plans for action, and then execute the movements required to bring about desired outcomes. Our lab studies a critical nexus in the mammalian brain where sensory information and motor planning come together to subserve volition - the basal ganglia.

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