CEREBELLAR AFFERENCES FROM THE MESENCEPHALIC TRIGEMINAL NUCLEUS IN THE RAT

The aim of the present study was to test for and characterize the orga nization of a direct projection from neurones of the trigeminal mesenc ephalic nucleus (Vme) to the cerebellum. WGA-HRP was used as a retrogr ade tracer following injections in the cerebellar cortex. The extent o f each injection site within the sagittal zones was determined accordi ng to corticonuclear and olivocortical connections. Retrogradely label led neurones were observed in the caudal part of the ipsilateral Vme o nly following vermal injection. The Vme projections reached exclusivel y the ipsilateral sagittal zone X in the anterior lobe, lobule VI and lobule IX. This identification was confirmed by anterograde labelling of messy fibre terminals following a biocytin injection restricted to the Vme.