13-2. Load Compensation and Reaction Time Task

Load compensation task. In Gilbert and Thach’s (1977) test, a monkey was trained to hold a lever stationary in the face of flexion and extension wrist forces developed by a torque motor. A change of load at some unpredictable time induced complex spikes in Purkinje cells located in the intermediate cortex of lobules III to V. These spikes occurred just after the load switch (at 50–150 milliseconds), and they apparently represented errors caused by the sudden change. Simple-spike discharge in these Purkinje cells changed inversely to their complex-spike discharge, and it remained decreased after the latter discharge had returned to normal. These observations provided early experimental evidence supporting Albus’ (1971) theoretical hypothesis (Chapters 3, 9).