Response of one nociceptive PBil–PC neuron to transcutaneous electrical stimulation (30 mA, 2 msec duration).A1, PSTH made without stimulation. A2, PSTH made from responses to repetitive electrical stimulation (0.66 Hz, 30 trials) applied in the preferential receptive field.B1, Electrical stimulation (0.66 Hz, 30 trials; eachline is one shock). B2, Continuous response of the neuron to transcutaneous electrical stimulation (synchronous to B1). C, Response of the same neuron to noxious thermal stimulus (46°C) applied for 24 secbetween the two arrows.