Evidence of normal cerebellar control of the vestibulo-ocular reflex (VOR)in children with high-functioning autism

The effect of "tilt-suppression" on post-rotatory vestibular nystagmus was investigated to assess the function of the caudal cerebellar vermis (lobule s IX and X, or nodulus and uvula) in 13 school-age children with high-funct ioning autism (HFA) and 10 normal controls. Tilt-suppression of the vestibu le-ocular reflex (VOR) refers to the decreasing of the duration of post-rot atory vestibular nystagmus that occurs when the head is moved out of the pl ane in which it was located during the previous sustained constant-velocity rotation. The participant is rotated in a vestibular chair with the head u pright and then the head is tilted forward just after the chair stops rotat ing. Such tilt-suppression is impaired with lesions of the cerebellar nodul us and portions of the uvula. Results show that children with HFA have norm al post-rotatory nystasmus with the head upright and normal attenuation of postrotatory nystagmus induced by head tilt. These behavioral findings sugg est that lobules IX and X of the cerebellum are spared in high-functioning autism.