Skin potential and EMG changes induced by cutaneous electrical stimulation. I. Normal man in arousing and non-arousing environment.

Skin potential and EMG responses induced in normal man by electrical stimuli applied to the skin were recorded in the four limbs in order to study somato-sympathetic and somato-motor reflexes. Different patterns of responses were observed in different conditions: alarm, habituation, sensitization and arousal. During alarm, sensitization and arousal, the responses were present in the four limbs; during habituation, the responses were only present in the stimulated and in the contralateral limb. Three sensory thresholds to cutaneous electrical stimulation were identified in habituated subjects: tactile, tingling and pain. Cutaneous and EMG responses appeared at tingling threshold. A relationship between skin potential level and skin potential response was observed.