Chronic motion perception deficits from midline cerebellar lesions in human.

A selective motion perception deficit is seen in patients with acute midline cerebellar lesions. Patients with more lateralized acute cerebellar damage do not demonstrate such a deficit (Nawrot M, Rizzo M. Vis Res 1995;35:723-731). However, as these patients were tested only between 10 and 14 days post-ictus, the stability of this perceptual deficit into the chronic phase remained undetermined. The current study extends the previous findings by showing that the motion perception deficit caused by mid-line cerebellar lesions remains permanent at least 2 years into the chronic phase. The extent and longevity of this deficit resembles that of the well known motion-blind patient LM who has a large cerebellar lesion in addition to her extensive cortical damage. Again, we propose that the mid-line cerebellar damage may produce a severe motion perception deficit by disruption the visual-motor integration mechanisms involved in perceptual stabilization, even though cortical motion processing mechanisms are unaffected.