Cyclic, condition-independent activity in primary motor cortex predicts corrective movement behavior

Reaching movements have previously been observed to have large condition-independent neural activity and cyclic neural dynamics. A new precision center-out task was used to test whether cyclic neural activity in the primary motor cortex (M1) occurred not only during initial reaching movements but also during subsequent corrective movements. Corrective movements were observed to be discrete with a time course and bell-shaped speed profile similar to the initial movements. Cyclic trajectories identified in the condition-independent neural activity were similar for initial and corrective submovements. The phase of the cyclic condition-independent neural activity predicted when peak movement speeds occurred, even when the subject made multiple corrective movements. Rather than being controlled as continuations of the initial reach, a discrete cycle of motor cortex activity encodes each corrective submovement.Significance StatementDuring a precision center-out task, initial and subsequent corrective movements occur as discrete submovements with bell-shaped speed profiles. A cycle of condition-independent activity in primary motor cortex neuron populations corresponds to each submovement whether initial or corrective, such that the phase of this cyclic activity predicts the time of peak speed. These submovements accompanied by cyclic neural activity offer important clues into how the we successfully execute precise, corrective reaching movements and may have implications for optimizing control of brain-computer interfaces.