Brief pulses of Laser emitted radiant heat were used to induce cutaneous painful sensations in human volunteers. Accurate timing of the stimuli permitted recording of scalp averaged evoked potentials. A late negative-positive component of the EP which correlated in amplitude with the subjective sensation was observed in four subjects. The latency of this component (130-160 msec) correlated with stimulus intensity.

Controlled radiant heat stimulation for a combined psychophysical and electrophysiological research in pain was achieved by the use of an infrared Laser beam. The computer controlled stimuli, being of very brief duration (down to 5 msec) and sharply localized, are suitable for recording of averaged evoked responses as well as for determination of pain and thermal thresholds. These stimuli can be applied to any locus on the skin. The threshold energy delivered by this technique is similar to that obtained by the Hardy-Wolff-Goodell method. Special precautions were taken to avoid injury to the skin and the eyes.