Vertex potentials evoked by nociceptive laser stimulation of oral mucosa: relationship to stimulus intensity.

The present study investigated the relationship between stimulus intensity and size of vertex potentials (VPs) and methods for quantification of VPs elicited by nociceptive argon laser stimulation of the oral mucosa. VPs were evoked by warning and self-triggered stimulation of the tongue and hand. A significant increase was found in amplitude, power, and root-mean-square (RMS) values of the averaged VPs as the intensity of the laser stimuli increased. The latency of the major negative peak decreased significantly with increased stimulus intensity. The use of a warning light stimulus prior to the laser stimulus elicited a visually evoked vertex potential, which served as a control. The power and RMS values of the VPs elicited by warning stimulation of the tongue showed the largest increase and only a small variation when calculated in the 0.2 to 0.7 seconds time interval.