Connections between the cerebellum and hypothalamus in the tree shrew (Tupaia glis).

Following injections of a wheat germ agglutinin-horseradish peroxidase (WGA-HRP) conjugate into representative areas of cerebellar cortex of tree shrew (Tupaia glis) retrogradely labeled cells were found in posterior, lateral and dorsal hypothalamic areas and in the lateral mammillary nucleus. These represent monosynaptic hypothalamocerebellar cortical projections. Anterogradely labeled axons were also traced into various areas of the contralateral hypothalamus subsequent to injections of WGA-HRP into the cerebellar nuclei. These results identify a direct cerebellar nucleohypothalamic pathway. These hypothalamocerebellar and cerebellohypothalamic connections represent potential circuits through which the cerebellum may interact with visceral centers.