Cerebello-thalamo-cerebral projection from the dentate nucleus onto the frontal eye field in the cat.

To elucidate the role of the cerebellar dentate nucleus in oculomotor system, we investigated the dentato-cerebral projection onto the frontal cortex around the fundus of the presylvian sulcus corresponding to a subregion of the frontal eye field (FEF) in the cat. Stimulation of the dentate nucleus induced laminar field potentials consisting of mainly a surface positive-depth negative wave and a subsequent depth positive wave with or without a surface negative wave in the contralateral FEF. Thalamic relay neurones, identified by collision test, were mainly distributed in the dorsal part of the ventromedial (VM) nucleus. Injection of wheat germ agglutinin conjugated horseradish peroxidase into the thalamic VM nucleus anterogradely labelled afferent terminals in layers I and III of the FEF and retrogradely labelled somata of cerebello-thalamic neurones in the contralateral dentate nucleus. Both electrophysiological and morphological results consistently revealed cerebello-thalamo-cerebral projection onto the FEF which may be implicated in eye-limb coordination control.