The effects of stimulating locus coeruleus (LC) on neuronal activity of cerebellar fastigii nucleus (FN) was investigated. Stimulation of LC elicited inhibitory, excitatory and biphasic (inhibition-excitation) responses from FN cells. The majority of responsive cells showed an inhibitory response with a latency of less than 10 ms. Injection of a adrenoreceptor antagonists phentolamine (iV) could block the inhibitory response of FN cells to the LC stimulation, but propranolol (IV), a β adrenoreceptor antagonist, could not. These results suggest that LC-cerebellar noradrenergic afferent fibers may be involved in the cerebellar sensorimotor integration process by exerting their modulatory action on the cerebellar nuclear cells’ activities.
