Responses of neurons in the rat ventrolateral orbital cortex to phasic and tonic nociceptive stimulation.

Responses of ventrolateral orbital cortex (VLO) neurons to innocuous touch and pressure, and noxious pinch and cold were examined by extracellular recordings. Eight neurons increased their firing rate in a graded fashion to all stimuli applied, 4 units decreased their discharges, and 6 neurons remained unaffected. All responsive units displayed the greatest change in firing rate during noxious cold, and all exhibited whole-body receptive fields. These data further implicate the VLO in nonciception.