Figure 1.

A representative example of a tooth pulp neuron that responded to noxious heat and cold stimulation. (A) The cutaneous receptive field and camera lucida drawing of the cell’s location within the trigeminal nucleus. The receptive field was located in the right facial area and the upper lip. The cell was classified as a WDR neuron and was located in lamina II. (B) Peristimulus histogram of electrical stimulation of the tooth. The neuron received Aδ afferent input. (C) Responses to noxious cold and heat stimulation of the upper canine. A computer-controlled probe delivered heat stimuli that were applied in a staircase manner, from an adapting temperature of 40°C, increasing to 60°C in 5°C increments every 25 sec, or as a single pulse for 60 sec. This particular neuron was excited by both noxious heat and cold stimulation of the tooth.