Electrophysiological investigations on the projections from the cerebral cortex to the vermal posterior lobe of the cerebellum.
The following cerebrocortical areas have been electrically stimulated in cats under Nembutal anaesthesia: forelimb and hindlimb areas of the primary sensorimotor cortex, primary and secondary acoustic areas and visual area. Stimulation of these regions evokes in the vermal portion of lobuli VI and VII of the cerebellum potentials at a short latency (2.8-3.5 ms) and at a longer latency (12-22 ms), which have been identified as due to mossy and climbing fibre inputs respectively. Each point of the cerebellar cortex receives usually projections by some and never by all the stimulated cerebrocortical areas. The different cortical regions don't project predominantly to separate parts of the cerebellar cortex, but they project in an apparently random manner with a patchy arrangement. In the anterior lobe we have confirmed the known somatotopy from the primary sensorimotor cortex and we have found no projections from the other cerebrocortical areas.