ArticlesPain-related laser-evoked potentials in awake monkeys: identification of components, behavioral correlates and drug effectsBeydoun, Aa,c,*; Morrow, J T.a,b,c; Casey, L K.a,b,cAuthor Information aDepartment of Neurology, University of Michigan Medical School, Ann Arbor, MI, USA bDepartment of Physiology, University of Michigan Medical School, Ann Arbor, MI, USA cNeurology Research Laboratories, Veterans Administration Medical Center, Ann Arbor, MI, USA *Corresponding author. University of Michigan Medical Center, University Hospital 1B300/0036, 1500 E. Medical Center Drive, Ann Arbor, MI 48109-0036, USA. Tel.: +1 313 9367310; fax: +1 313 9365520. Received August 28, 1996; revised version received April 5, 1997; accepted May 8, 1997. Pain: September 1997 - Volume 72 - Issue 3 - p 319-324 doi: 10.1016/S0304-3959(97)00056-0 Buy Metrics Abstract Cutaneous stimulation with CO2 laser pulses activates small diameter sensory afferents and evokes a pain-related potential best recorded from the vertex (Cz) of humans. We report here the first successful recording of pain-related laser evoked potentials (LEPs) from awake monkeys. Laser pulses with stimulus intensities adjusted to the lowest level giving reproducible cerebral responses were delivered to the shaved tail of three awake African green monkeys. The proximal and distal tail were stimulated to calculate the conduction velocity of the activated fibers. The effects of subcutaneous injections of morphine and cocaine on the LEPs were evaluated. The results indicate that reproducible LEPs, with a morphology similar to those obtained from humans, can be recorded from the awake monkey. The calculated conduction velocity of the activated fibers averaged 8.7 m/s, which is in the range of Aδ fibers. Following subcutaneous morphine injections, the LEPs disappeared and were quickly restored to their baseline amplitude following administration of naloxone. Cocaine administered subcutaneously led to a significant attenuation of LEP amplitudes without producing behavioral sedation. These findings suggest that the LEPs recorded from monkeys represent analgesic-sensitive, nociceptive-related potentials similar to those recorded from humans. © Lippincott-Raven Publishers.