Role of the inferior olivary complex in motor skills and motor learning in the adult rat.

The inferior olivary complex of adult rats was chemically destroyed using intraperitoneal injection of 3-acetylpyridine. Animals were submitted to different motor tasks: hanging test, equilibrium test and motor co-ordination test. The different scores show that 3-acetylpyridine-treated rats had motor co-ordination and static equilibrium deficiencies, whereas their rod suspension capabilities were intact. Animals were also trained on an unrotated rod or on a rod rotating at 5, 10 or 20 r.p.m. 3-Acetylpyridine-treated rats were able to maintain their equilibrium on the unrotated rod and at 5 r.p.m. Moreover, after motor training at 5 r.p.m., rats were able to improve their motor skills and reached the same score as controls. Despite their good motor skills, animals were unable to maintain their equilibrium when rotated at 10 and 20 r.p.m. These results suggest that the inferior olivary complex is needed for motor learning involving the temporal organization of movement.