Putting Sensory Back into Voluntary Motor Control
Optimal feedback control provides a framework for interpreting why we generate variable, but successful movements. Notable is the importance of sensory feedback for voluntary control. We have explored the sophistication of corrective responses of humans by applying small disturbances to the limb as subjects perform goal-directed actions. We found subjects flexibly modify their corrective responses to consider the size and shape of a behavioural goal, and even avoid obstacles present in the environment. These task-dependent corrective responses elicit changes in muscle activity ~60 ms after the disturbance, implicating the role of a transcortical feedback pathway in the responses. Neurophysiological studies in non-human primates illustrate that neural activity in primary motor cortex responds to mechanical disturbances in as little as 20 ms and is quickly modulated based on the behavioural goal. These studies highlight that feedback processing during voluntary motor action parallels the many sophisticated features associated with motor planning and feed-forward control.
KeywordsVoluntary motor control Optimal feedback control Rapid motor corrections