The Emergence of Multiple Movement Units in the Presence of Noise and Feedback Delay

Tangential hand velocity profiles of rapid human arm movements of- ten appear as sequences of several bell-shaped acceleration-deceleration phases called submovements or movement units. This suggests how the nervous system might efficiently control a motor plant in the presence of noise and feedback delay. Another critical observation is that stochastic- ity in a motor control problem makes the optimal control policy essen- tially different from the optimal control policy for the deterministic case. We use a simplified dynamic model of an arm and address rapid aimed arm movements. We use reinforcement learning as a tool to approximate the optimal policy in the presence of noise and feedback delay.