The response of neurons of the medial pontomedullary reticular formation of rats to peripheral thermal stimuli.

The thermal responses of 70 medial pontomedullary neurons were studied using 0.15 degrees C/s ramp thermal stimuli applied to the glabrous skin on the ventral surface of the hindpaw of rats. Fifty-two neurons (74%) responded to an ipsilateral and/or contralateral thermal stimulus by increased action potential discharge rates. Eleven units (16%) responded by decreasing their discharge. The remaining 7 units (10%) were unaffected. The thresholds of 61 neurons responsive to thermal stimulation of the ipsilateral hindpaw ranged from 36.5 to 46 degrees C. Ninety percent of thermally responsive neurons had bilateral receptive fields. The thresholds of the ipsilateral and contralateral responses were significantly positively correlated.