Premotor Ramping of Thalamic Neuronal Activity Is Modulated by Nigral Inputs and Contributes to Control the Timing of Action Release
J. Neurosci.. 2021-01-14; 41(9): 1878-1891
DOI: 10.1523/JNEUROSCI.1204-20.2020
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Catanese J(1), Jaeger D(1).
Author information:
(1)Department of Biology, Emory University, Atlanta, Georgia 30322
.
The ventromedial (VM)/ventro-anterior-lateral (VAL) motor thalamus is a key
junction within the brain circuits sustaining normal and pathologic motor control
functions and decision-making. In this area of thalamus, on one hand, the
inhibitory nigro-thalamic pathway provides a main output from the basal ganglia,
and, on the other hand, motor thalamo-cortical loops are involved in the
maintenance of ramping preparatory activity before goal-directed movements. To
better understand the nigral impact on thalamic activity, we recorded
electrophysiological responses from VM/VAL neurons while male and female mice
were performing a delayed right/left decision licking task. Analysis of correct
(corr) and error trials revealed that thalamic ramping activity was stronger for
premature licks (impulsive action) and weaker for trials with no licks [omission
(omi)] compared with correct trials. Suppressing ramping activity through
optogenetic activation of nigral terminals in the motor thalamus during the delay
epoch of the task led to a reduced probability of impulsive action and an
increased amount of omissions trials. We propose a parsimonious model explaining
our data and conclude that a thalamic ramping mechanism contributes to the
control of proper timing of action release and that inhibitory nigral inputs are
sufficient to interrupt this mechanism and modulate the amount of motor
impulsivity in this task.SIGNIFICANCE STATEMENT Coordinated neural activity in
motor circuits is essential for correct movement preparation and execution, and
even slight imbalances in neural processing can lead to failure in behavioral
tasks or motor disorders. Here we focused on how failure to regulate the control
of activity balance in the motor thalamus can be implicated in impulsive action
release or omissions to act, through an activity ramping mechanism that is
required for proper action release. Using optogenetic activation of inhibitory
basal ganglia terminals in motor thalamus we show that basal ganglia input is
well positioned to control this ramping activity and determine the timing of
action initiation.
Copyright © 2021 the authors.