Purkinje Cell Activity in Medial and Lateral Cerebellum During Suppression of Voluntary Eye Movements in Rhesus Macaques

Consciously suppressing responses to distracting external stimuli helps us to reach our goals. This volitional inhibition of a specific behavior is supposed to be mainly mediated by the cerebral cortex; however recent evidence supports the involvement of the cerebellum in this process. It is currently not known whether different parts of the cerebellar cortex play differential or synergistic roles in planning and execution of this behavior. Here, we measured Purkinje cell (PC) responses in the medial and lateral cerebellum in two rhesus macaques during the antisaccade task. In this task the non-human primates were instructed to make a saccadic eye movement away from a target, rather than towards it. Our data shows that the cerebellum plays an important role not only during execution of the antisaccades, but also during the volitional inhibition of eye movements towards the target. Simple Spike (SS) modulation during the instruction and execution period of pro- and antisaccades is prominent in PCs of both medial and lateral cerebellum. However, only the SS activity in the lateral cerebellar cortex contains information about trial identity and shows a stronger reciprocal interaction with complex spikes. Moreover, SS activity of different PC groups modulate bidirectionally in both regions, but the PCs that show facilitating and suppressive activity are predominantly associated with instruction and execution, respectively. These findings show that different cerebellar regions and PC groups contribute to goal-directed behavior and volitional inhibition, but with different propensities, highlighting the rich repertoire of cerebellar control in executive functions.