Normal spatial attention but impaired saccades and visual motion perception after lesions of the monkey cerebellum.

Lesions of the cerebellum produce deficits in movement and motor learning. Saccadic dysmetria, for example, is caused by lesions of the posterior cerebellar vermis. Monkeys and patients with such lesions are unable to modify the amplitude of saccades. Some have suggested that the effects on eye movements might reflect a more global cognitive deficit caused by the cerebellar lesion. We tested that idea by studying the effects of vermis lesions on attention as well as saccadic eye movements, visual motion perception, and luminance change detection. Lesions in posterior vermis of four monkeys caused the known deficits in saccadic control. Attention tested by examination of acuity threshold changes induced by prior cueing of the location of the targets remained normal after vermis lesions. Luminance change detection was also unaffected by the lesions. In one case, after a lesion restricted to lobulus VIII, the animal had impaired visual motion perception.