Nociceptive visceral stimulation modulates the activity of cerebellar Purkinje cells

The cerebellum is a system with various input and output functions that inf luence motor, sensory, cognitive, and other processes. In a previous study, we showed that cerebellar cortical stimulation increases spinal neuronal r esponses to visceral noxious stimulation by colorectal distension (CRD). Ho wever, the neuronal network underlying the cerebellar modulation of nocicep tive phenomena is largely unknown. Purkinje cells of the cerebellar cortex receive ascending and descending inputs and exert a major inhibitory contro l over neurons in the underlying cerebellar nuclei that constitute the cere bellar output. Therefore, in this study, we tested the effect of CRD and ot her somatic stimuli on the firing rate of Purkinje cells using in vivo extr acellular recording techniques. The results suggest that Purkinje cells res pond to nociceptive visceral and somatic stimulation in the form of early a nd delayed changes in activity. Based on these and previous findings, we pr opose a negative feedback circuitry involving the cerebellum for the modula tion of peripheral nociceptive events.