Saccades to visual targets are uncompensated after cerebellar stimulation.

Electrical stimulation of the posterior vermis produces a saccadic perturbation of the eyes. If this stimulation occurs after presentation of a visual target but before a trained saccade is initiated, the ensuing movement misses the target by an amount approximating the perturbation (uncompensated). These observations differ from those obtained after stimulation of the superior colliculus or frontal eye fields which result in compensated saccades that land on target. It is suggested that vermal stimulation may be acting outside the pontine burst feedback system.