Rapid online corrections for proprioceptive and visual perturbations recruit similar circuits in primary motor cortex.

An important aspect of motor function is our ability to rapidly generate goal-directed corrections for disturbances to the limb or behavioural goal. Primary motor cortex (M1) is a key region involved in processing feedback for rapid motor corrections, yet we know little about how M1 circuits are recruited by different sources of sensory feedback to make rapid corrections. We trained two male monkeys ( Macaca mulatta ) to make goal-directed reaches and on random trials introduced different sensory errors by either jumping the visual location of the goal (goal jump), jumping the visual location of the hand (cursor jump) or by applying a mechanical load to displace the hand (proprioceptive feedback). Sensory perturbations evoked a broad response in M1 with ∼73% of neurons (n=257) responding to at least one of the sensory perturbations. Feedback responses were also similar as response ranges between the goal and cursor jumps were highly correlated (range of r=[0.91, 0.97]) as were the response ranges between the mechanical loads and the visual perturbations (range of r=[0.68, 0.86]). Lastly, we identified the neural subspace each perturbation response resided in and found a strong overlap between the two visual perturbations (range of overlap index=0.73-0.89) and between the mechanical loads and visual perturbations (range of overlap index=0.36-0.47) indicating each perturbation evoked similar structure of activity at the population-level. Collectively, our results indicate rapid responses to errors from different sensory sources target similar overlapping circuits in M1. Significance Statement Motor actions often require continuously integrating multiple sources of information, such as the locations of a goal and your limb. Primary motor cortex (M1) plays a critical role in correcting for unexpected errors to the goal and limb. How might goal and limb feedback recruit circuits in M1 during a motor correction? We found M1 responded similarly for errors to the visual feedback of the goal and errors to the visual feedback of the limb. Furthermore, errors to the proprioceptive feedback of the limb and visual errors evoked similar patterns of activity in M1. Collectively these results suggest a partial convergence of feedback sources in M1 that supports online control.