Saccadic dysmetria induced by transient functional decortication of the cerebellar vermis [corrected].

Saccadic dysmetria is seen in patients with cerebellar diseases as well as in monkeys whose vermis and fastigial nucleus are experimentally lesioned. We investigated the oculomotor signs of the vermis by blocking cerebellar impulses with bicuculline injections into the fastigial nucleus. The oculomotor abnormalities associated with the bicuculline treatment (in effect, functional as well as reversible, unilateral decortication of the vermis) were hypometric saccades toward the injection side and gaze deviation toward the opposite side. These oculomotor signs disappeared with the withdrawal of the bicuculline effect.