Response of cells in feline nucleus centrum medianum to tooth pulp stimulation.

Nucleus centrum medianum (CM) has been implicated in the processing of nociceptive information based on behavioral, physiological and clinical data. Although the responses of neurons in CM have been extensively studied using spinal stimuli, few data are available concerning their responses to trigeminal stimuli. This investigation was designed to determine the responses of cells in CM to tooth pulp stimulation, which has been demonstrated to be an effective and relatively specific trigeminal nociceptive stimulus. Responses were recorded from 378 neurons in 38 pentobarbital-anesthetized cats. Most cells responded at a latency of 5 to 40 msec with one to six spikes for each stimulus. Cells in the dorsal portion of CM tended to respond only to maxillary teeth, while cells in the ventral portion of the nucleus tended to respond only to mandibular teeth. Cells in the central portion of CM generally responded to both maxillary and mandibular teeth. Cells in CM generally responded to both ipsilateral and contralateral teeth, without a preference for one side. These data differ from those reported using spinal stimulation, since a topographic organization has not been identified with spinal stimulation.