Mechanisms of network interactions for flexible cortico-basal ganglia-mediated action control.

Fischer P

Precisely how the mammalian brain controls and invigorates movement is unclear. Brief synchronization of nerve cell activity in specialized brain networks might be a key mechanism. This article describes in detail how synchronization of brain activity may enable flexible action control.

Scientific Abstract

In humans, finely tuned gamma synchronization (60-90 Hz) rapidly appears at movement onset in a motor control network involving primary motor cortex, the basal ganglia and motor thalamus. Yet the functional consequences of brief movement-related synchronization are still unclear. Distinct synchronization phenomena have also been linked to different forms of motor inhibition, including relaxing antagonist muscles, rapid movement interruption and stabilizing network dynamics for sustained contractions. Here I will introduce detailed hypotheses about how intra- and inter-site synchronization could interact with firing rate changes in different parts of the network to enable flexible action control. The here proposed cause-and-effect relationships shine a spotlight on potential key mechanisms of cortico-basal ganglia-thalamo-cortical communication. Confirming or revising these hypotheses will be critical in understanding the neuronal basis of flexible movement initiation, invigoration and inhibition. Ultimately, the study of more complex cognitive phenomena will also become more tractable once we understand the neuronal mechanisms underlying behavioural readouts.In spite of tremendous progress in describing how neuronal activity unfolds before and during movements, the mechanisms that trigger the switch from movement preparation to execution, regulate movement vigour and enable movement inhibition remain unknown. Brief synchronization of neural activity within and between cortical sites and the basal ganglia may be a key factor in controlling these mechanisms. Here I review the evidence and describe in detail how synchronization may shape firing rates in distinct sites of the cortico-basal ganglia-thalamo-cortical network to enable flexible action control.

A cartoon of brain region interacting during movement initiation and stopping.
The top part shows several brain regions that play a role in motor control and are synchronized, or in other words ‘phase-coupled’, during movement initiation. The bottom part shows the hypothesized changes in network activity during stopping or changing of an ongoing movement: Cortical inputs (preSMA/IFC) to the subthalamic nucleus (STN) shift activity in the basal ganglia such that activity at the level of the thalamus (Thal) is efficiently cancelled. MCtx = primary motor cortex; preSMA = presupplementary motor area. IFC = Inferior frontal cortex; GPi = internal globus pallidus; TRN = thalamic reticular nucleus.
2021. eNeuro, (Apr 19):ENEURO.0009-21.2021.
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