Sensitization and habituation of AMH and C-fiber related percepts of repetitive radiant heat stimulation.
OBJECTIVE
Pain perception involves neuronal plasticity at peripheral and central stages, resulting in sensitization or habituation, depending on intensity and temporal features of stimulation. Concurrent assessment of perceptual change over different time spans is therefore important for understanding the dynamics of pain processing.


METHODS
A new psychophysical procedure was established to assess sensitization and habituation during repetitive radiant heat stimulation. Short-term perceptual change (<1 min) during trials with 10 stimuli applied at 3 frequencies (0.2-0.6-1.8 Hz) and 3 intensities was assessed for AMH-II or C-fiber related percepts. Perceptual changes were monitored for medium-term (1-15 min) and for long-term (15-90 min) time spans.


RESULTS
Short-term sensitization occurred only at frequencies above 0.3 Hz and was affected by both stimulus frequency and intensity, but the AMH-fiber related sensitization depended on intensity only above 0.6 Hz. Multiple stimulation of the same skin area during medium-term time spans resulted in habituation. No long-term perceptual changes occurred.


CONCLUSIONS
The procedure permits concurrent assessment of short-term sensitization and medium-term habituation, assumed to be related to spinal windup and cutaneous nociceptive fiber fatigue, respectively.


CONCLUSIONS
The method is suitable for quantitative sensory testing of dynamic pain processing over different time spans, relevant in clinical testing of pain and in drug assessment.
Kleinböhl
Dieter
D
Laboratory for Clinical Psychophysiology, Otto-Selz-Institute, University of Mannheim, Schloss EW 184, D-68131 Mannheim, Germany. kleinboehl@osi.uni-mannheim.de
Trojan
Jörg
J
Konrad
Christoph
C
Hölzl
Rupert
R
D000328:Adult; D000704:Analysis of Variance; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006185:Habituation, Psychophysiologic / Q000528:radiation effects*; D006358:Hot Temperature / Q000009:adverse effects*; D006801:Humans; D008297:Male; D036421:Nerve Fibers, Unmyelinated / Q000502:physiology / Q000528:radiation effects*; D010146:Pain / Q000209:etiology* / Q000503:physiopathology; D010147:Pain Measurement; D011601:Psychophysics / Q000379:methods; D012677:Sensation / Q000502:physiology*; D011795:Surveys and Questionnaires; D013997:Time Factors