Cerebellar cortical stimulation increases spinal visceral nociceptive responses

The role of the cerebellum in modulating nociceptive phenomena is unclear. In this study, we focus on the effects of cerebellar cortical stimulation o n the responses of midline neurons of the lumbosacral spinal cord to graded nonnoxious and noxious visceral (colorectal distension) as well as somatic (brush, pressure, pinch) stimuli. Extracellular recording was used for the isolation and recording of spinal nociceptive neurons, while electrical cu rrent pulses and chemical injection of D, L-homocysteic acid were used to s timulate the cortex of the posterior cerebellar vermis. Cerebellar cortical stimulation increased the responses of all isolated cells to colorectal di stension, whereas the effect on the responses to somatic stimuli was variab le. These findings indicate that the posterior cerebellar vermis may exert a pro-nociceptive effect on spinal visceroceptive neurons.