Cerebellar-Recipient Motor Thalamus Drives Behavioral Context-Specific Movement Initiation
41 Pages Posted: 18 Oct 2019 Sneak Peek Status: Review CompleteMore...
To initiate goal-directed behavior, animals must transform sensory cues into motor commands that generate appropriately timed actions. Sensorimotor transformations along the cerebellar-thalamocortical pathway are thought to shape motor cortical output and movement timing, but whether this pathway initiates goal-directed movement remains poorly understood. Here, we recorded and perturbed activity in cerebellar-recipient regions of motor thalamus (dentate / interpositus nucleus-recipient regions, MThDN/IPN) and primary motor cortex (M1) in mice trained to execute a cued forelimb lever push task for reward. MThDN/IPN population responses were dominated by a time-locked increase in activity immediately prior to movement that was temporally uncoupled from cue presentation, providing a fixed latency feedforward motor timing signal to M1FL. Blocking MThDN/IPN output suppressed cued movement initiation. Stimulating the MThDN/IPN thalamocortical pathway in the absence of the cue recapitulated cue-evoked M1 membrane potential dynamics and forelimb behavior in the learned behavioral context, but generated semi-random movements in an altered behavioral context. Thus, cerebellar-recipient motor thalamocortical input to M1 is indispensable for the generation of motor commands that initiate goal-directed movement, refining our understanding of how the cerebellar-thalamocortical pathway contributes to movement timing.
Keywords: Motor behavior, cerebellar thalamocortical pathway, movement initiation, goal-directed, motor timing signal, photostimulation, in vivo patch-clamp electrophysiology, GRIN lens-mediated population calcium imaging, forelimb kinematics, cued forelimb push task
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