Nociceptive visceral stimulation modulates the activity of cerebellar Purkinje cells.

The cerebellum is a system with various input and output functions that influence motor, sensory, cognitive, and other processes. In a previous study, we showed that cerebellar cortical stimulation increases spinal neuronal responses to visceral noxious stimulation by colorectal distension (CRD). However, the neuronal network underlying the cerebellar modulation of nociceptive phenomena is largely unknown. Purkinje cells of the cerebellar cortex receive ascending and descending inputs and exert a major inhibitory control over neurons in the underlying cerebellar nuclei that constitute the cerebellar output. Therefore, in this study, we tested the effect of CRD and other somatic stimuli on the firing rate of Purkinje cells using in vivo extracellular recording techniques. The results suggest that Purkinje cells respond to nociceptive visceral and somatic stimulation in the form of early and delayed changes in activity. Based on these and previous findings, we propose a negative feedback circuitry involving the cerebellum for the modulation of peripheral nociceptive events.