Neuronal population dynamics during motor plan cancellation in non-human primates

To understand the cortical neuronal dynamics behind movement generation and control most studies focused on tasks where actions were planned and then executed, using different instances of visuomotor transformations. However, to fully understand the dynamics related to movement control one must also study how movements are actively inhibited. Inhibition, indeed, represents the first level of control both when different alternatives are available and only one solution could be adopted and when is necessary to maintain the current position.We recorded neuronal activity from a multielectrode array in the dorsal premotor (PMd) cortex of monkeys performing a countermanding reaching task that requires, in a subset of trials, to cancel a potentially planned movement before its onset. In the analysis of the neuronal state-spaces of PMd we found a subspace in which activities conveying temporal information were confined during active inhibition and position holding. Movement execution required activities to escape from the plane toward an orthogonal subspace and, furthermore, surpass a threshold associated to the maturation of the motor plan.These results revealed further details in the neuronal dynamics underlying movement control extending the hypothesis that neuronal computation confined in an output-null subspace does not produce movements.