The tecto-olivo-cerebellar pathway in the rat.

The olivo-cerebellar projection to the vermis of cerebellar lobule VII, and the projection of the midbrain tectum onto the inferior olive (IO), were examined in the rat employing, respectively, retrograde and anterograde transport of horseradish peroxidase (HRP). Olivary neurons afferent to lobule VII vermis are located in a restricted region of the contralateral, caudomedial, medial accessory olive (MAO). The termination of the olivary projection demonstrated after HRP placement in the superior colliculus (SC), corresponds closely with this region.