Cortical Circuits for Control of Voluntary Arm Movements

Abstract

A model of voluntary movement and motor proprioception is developed to address data from neurophysiology and psychophysics. Model elements correspond to cell types reported in cortical areas 4 and 5, basal ganglia, and spinal cord. The functional scope of the model includes voluntary movement, posture maintenance, exertion of forces against obstacles, passive relaxation, and load compensation. Movements are generated by composing complex commands in area 4, which effect gradual shifts of the limb’s equilibrium posture via descending pathways. Movement direction is computed in area 5 using a representation of limb position based upon corollary discharges and spindle feedback. Predictions are made regarding cell responses in novel experimental paradigms.