Effect of Topical Capsaicin on Pain Ratings and Amplitude of Cortical Potentials Evoked by Infrared Diode Laser Pulses. A. 1% capsaicin did not affect numerical pain ratings evoked by a 60 ms suprathreshold laser stimulus. B. Similarly capsaicin did not affect evoked potential responses to short laser pulses. C. Capsaicin did however, induce a significant (p < 0.05) hyperalgesia for pain evoked by longer (1.5 s) laser pulses. D. Similarly, topical capsaicin increased the amplitude of cortical evoked responses to 1.5 s laser pulses, significantly (p < 0.05) in the case of the second negative peak.