Fig. 1

Intermittent control. Sensorimotor control of sustained tasks is a process of closed loop feedback in which a controller uses sensory output to control muscle activations which determine movement of the mechanical body. The controller uses sensory analysis (SA) to estimate states and uses a motor system (MS) to generate activations of the muscles. According to the intermittent control hypothesis, a process of refractory response planning occurs between sensory analysis and the motor system. The refractory response planner uses current states to plan a time-varying trajectory of muscle activations which are executed without feedback. Refractoriness means this control trajectory is not updated until the next trajectory is planned using updated sensory measurements. This refractory response planner is postulated to reside with the basal ganglia and associated motor decision-making regions of the frontal cortex