Neuronal responses to noxious stimulation in rat somatosensory cortex.

Neuronal responses to noxious stimulation applied on the skin of the limbs or of the tail were studied in the somatosensory cortex of rats under Fluothane/nitrous oxyde anesthesia. Among 694 neurons, 56 responded to noxious stimulation only and 35 to noxious as well as non-noxious stimulation. The receptive fields of these neurons were often larger than those of neurons recorded during the same penetration but unresponsive to noxious stimulation. They were able to encode stimulus parameters such as temperature of a hot water bath or size of the skin area stimulated. They were more frequently found in the deepest half of the cortex. These results suggest that the cerebral somatosensory cortex plays a role in pain mechanisms.