Neuronal population dynamics during motor plan cancellation in nonhuman primates

Area of Science:

• Neuroscience
• Motor Control
• Computational Neuroscience

Background:

• Understanding cortical neuronal dynamics is crucial for comprehending movement generation and control.
• Most research has focused on movement execution, neglecting the critical role of active movement inhibition.
• Inhibition is fundamental for selecting actions and maintaining posture, representing a primary control mechanism.

Purpose of the Study:

• To investigate the cortical neuronal dynamics underlying active movement inhibition.
• To explore how neuronal activity in the dorsal premotor cortex (PMd) differs during movement execution versus inhibition.
• To elucidate the neural mechanisms that differentiate planned movements from cancelled movements.

Main Methods:

• Recording neuronal activity using multielectrode arrays in the dorsal premotor cortex (PMd) of monkeys.
• Utilizing a countermanding reaching task that incorporates trials requiring movement cancellation.
• Analyzing neuronal activity within a state-space framework to identify distinct subspaces related to task conditions.

Main Results:

• A specific subspace within the PMd neuronal state space was identified where temporal information is conveyed during active inhibition and position holding.
• Movement execution was associated with neuronal activity escaping this subspace towards an orthogonal subspace.
• A threshold related to motor plan maturation was observed to be necessary for movement initiation.

Conclusions:

• Neuronal computations confined within an 'output-null' subspace are not associated with movement production.
• The findings provide detailed insights into the neural dynamics governing movement control, particularly highlighting the role of inhibition.
• This study extends the understanding of how the brain actively controls and inhibits movements, offering a more comprehensive model of motor control.