The inferior olive of a prosimian primate, Galago senegalensis. II. Olivocerebellar projections to the vestibulocerebellum.
Olivocerebellar projections to the vestibulocerebellum of Galago senegalensis, a prosimian primate, were studied by using a horseradish peroxidase (HRP) method. Following implants of HRP into the flocculus, labeled cells are found in subgroup d of contralateral medial accessory olive (MAO), while labeled somata are present throughout subgroups c and d after injections of HRP into the nodulus and adjacent parts of the uvula. Labeled cells are also located throughout the dorsomedial cell column (DMCC) and a small contingent of HRP-filled cells are seen in dorsomedial areas of the ventral lamellae of the principal olivary nucleus (PO) after HRP placements in nodulus and uvula. Subsequent to injections of paraflocculus, labeled cells are found in subgroup a of MAO, in the lateral bend of PO, and in its ventral lamella (VLPO). Collectively these data indicate a topographically organized projection of olivocerebellar fibers to the flocculonodular lobe and adjacent areas of paraflocculus and uvula. The paraflocculus receives input from subgroup a of MAO, the lateral bend of PO, and VLPO. Subgroup d of MAO projects to the flocculus and nodulus with a relatively minor contribution to uvula. Neurons in subgroups c and DMCC of MAO project to specific portions of nodulus and adjacent uvula. These data are in general agreement with those from other species. In contrast to earlier reports, however, this study describes a projection from VLPO to lateral areas of the contralateral nodulus and uvula. A zonal organization of olivocerebellar terminations in the nodulus and ventral portions of uvula is suggested. A medial zone is subdivided into medial and lateral parts which receive projections from subgroups c and d of MAO, and from cells in DMCC, respectively. A more lateral area receives axons from cells in VLPO.
D000818:Animals; D001370:Axonal Transport; D002525:Cerebellar Cortex / Q000502:physiology; D002531:Cerebellum / Q000033:anatomy & histology / Q000502:physiology*; D005701:Galago; D006735:Horseradish Peroxidase; D009847:Olivary Nucleus / Q000033:anatomy & histology / Q000502:physiology*
D006735:Horseradish Peroxidase