Oscillatory activity in forelimb muscles of behaving monkeys evoked by microstimulation in the cerebellar nuclei*1

Abstract

Coherent 20–35 Hz (β) oscillations are a prominent feature of activity in primary motor cortex and muscles of monkeys and humans performing voluntary movements. We found that coherent β oscillations are also present in the cerebellar nuclei (CN). Two monkeys were operantly conditioned to perform a wrist flexion/extension step-tracking task while we recorded neuronal activity or microstimulated in CN and recorded EMG activity from forelimb muscles. Coherent β oscillations were found between discharges of some CN neurons and tonically active shoulder, elbow and wrist/finger flexion and extension muscles. Similarly, localized microstimulation pulses in CN evoked transient β oscillations in widespread forelimb muscles. We conclude that coherent motor system β oscillations are present in CN and that CN may be an important nodal point for the generation and/or propagation of β oscillations throughout the motor system.