Electrophysiological activity from the eye muscles, cerebellum and cerebrum during reflexive and voluntarily timed blinks

Abstract

Abstract We report an experiment to investigate the role of the cerebellum and cerebrum in motor learning of timed movements. Eleven healthy human subjects were recruited to perform two experiments, the first a classical eye-blink conditioning procedure with an auditory tone as conditional stimulus (CS) and vestibular unconditional stimulus (US) in the form of a double head-tap. In the second experiment subjects were asked to blink voluntarily in synchrony with the double head-tap US preceded by a CS. Electrophysiological recordings were made of extra-ocular EMG and EOG at infra-ocular sites (IO1/2), EEG from over the frontal eye-fields (C3’/C4’) and from over the posterior fossa over the cerebellum for the electro-cerebellogram (ECeG). The behavioural outcomes of the experiments showed weak reflexive conditioning for the first experiment despite the double tap but robust well-synchronised voluntary blinks for the second. Voluntary blinks were larger than the reflex ones. For the voluntary task a contingent negative variation (CNV) was also present in the EEG leads prior to movement, and modulation of the high-frequency EEG occurred during movement. Stimulus-related cerebellar activity was prominent in the high-frequency ECeG for both conditions, while movement-related cerebellar activity was additionally present in the voluntary condition. These results demonstrate a role for the cerebellum in voluntary timed movement analogous to that in classical conditioning.