HUMAN INTRAMUSCULAR AND CUTANEOUS PAIN - PSYCHOPHYSICAL COMPARISONS

We used psychophysical methods to compare the central processing of no ciceptive inputs from skin and muscle in ten normal humans. Both intra muscular electrical and infrared CO2 laser cutaneous stimulation showe d increasing but decelerating (downward concave) stimulus-response cur ves and similar temporal summation characteristics. Intramuscular stim ulation was rated significantly more unpleasant than cutaneous stimula tion. The results are consistent with a common mode of central nocicep tive processing for skin and muscle pain intensity but suggest a relat ively larger activation of affective mechanisms by muscle afferents.