On climbing fibre projections to cerebellar paramedian lobule activated from mesencephalon in the cat.

Climbing fibre projections to cerebellar paramedian lobule activated from structures in medial midbrain tegmentum were studied in chloralose anaesthetized cats. Three sagittal zones were identified, from medial to lateral c1, c2 and d1 zones. The c1 and d1 zones were activated, at the same short latency, from a dorsal tegmental region with a location similar to the composite bundle called the central tegmental tract. The d1 zone is probably activated via rubro-olivary fibres and the c1 zone via some other fibres in this bundle. The path to the c2 zone seemed to proceed only partly within this dorsal tegmental region. The d1 zone was also activated, at longer latency, from a region ventral to the red nucleus.