Abstract
Reaching movements are known to have large condition-independent neural activity and cyclic neural dynamics. A new precision center-out task was performed by rhesus macaques to test the hypothesis that cyclic, condition-independent neural activity in the primary motor cortex (M1) occurs not only during initial reaching movements but also during subsequent corrective movements. Corrective movements were observed to be discrete with time courses and bell-shaped speed profiles similar to the initial movements. Condition-independent cyclic neural trajectories were similar and repeated for initial and each additional corrective submovement. The phase of the cyclic condition-independent neural activity predicted the time of peak movement speed more accurately than regression of instantaneous firing rate, 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 Statement During 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, such that the phase of this cyclic activity predicts the time of peak speeds—both initial and corrective. These submovements accompanied by cyclic neural activity offer important clues into how we successfully execute precise, corrective reaching movements and may have implications for optimizing control of brain-computer interfaces.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
Conflict of Interest: The authors declare no competing financial interests.
The manuscript has been revised to more clearly describe the difference between condition-independent and condition-dependent neural activity.
