Cerebellar unit responses to repetitive stimulation of somatic nerves

Abstract

Unit responses to stimulation of somatic nerves at 5–10/sec were recorded in the paramedian lobe of the cerebellum of unanesthetized cats. The results confirmed the model of afferent and interneuronal connections in the cerebellar cortex suggested previously. Three types of granule cells are distinguished. Fibers of the fast-conducting spino (cuneo)-cerebellar tracts, whose neurons transmit high frequencies of impulses, terminate on type I cells. Reticulo-cerebellar fibers, whose neurons cannot transmit frequencies higher than 4–5 stimuli/sec, terminate on type II cells. Type I granule cells excite all the other neurons in the cerebellar cortex. Responses of Purkinje cells, neurons of the molecular layer, and Golgi cells which they evoke are reproduced during repetitive nerve stimulation. Type II cells activate only Golgi cells. This component of the response is absent during repetitive stimulation.