Locomotion coincides with c-Fos expression in related areas of inferior olive and cerebellar nuclei in the rat.

Rats that had been walking on a rotating drum for a period of 75 min, demonstrated expression of the immediate early gene c-Fos in specific areas of the inferior olive and cerebellar nuclei. Non-walking control rats did not show consistent Fos-like immunoreactive labelling in these nuclei. Fos-like immunoreactive olivary neurons were consistently found in the caudolateral parts of the dorsal accessory olive and in its dorsal fold, and within specific areas of the medial accessory and principal olives. In the cerebellar nuclei, immunoreactive cells were found in the medial part of the anterior interposed nucleus, in the interstitial cell groups, and within specific parts of the medial, posterior interposed, and lateral nuclei. The lateral vestibular nucleus as well as the ventral part of the magnocellular red nucleus also displayed positive neurons. Most of these positive areas are known (1) to be related to the spinal cord and (2) to be anatomically linked. These results are in line with a presumptive role of the olivo-cerebellar system in ongoing movement control.