Characteristics of habituation of the sympathetic skin response to repeated electrical stimuli in man.
OBJECTIVE
To study the effect of repeating electrical peripheral nerve stimulation on latency, duration and amplitude of the sympathetic skin response (SSR).


METHODS
SSRs were elicited in all limbs by median and peroneal nerves stimuli. In 10 subjects, 20 stimuli were applied at random time intervals (15-20 s). Another test was performed in 7 subjects using the same protocol, but switching the stimulation site every 5 or 10 stimuli without warning.


RESULTS
The mean amplitude of right palmar response to right peroneal nerve stimulation decreased from 5.05+/-0.76 (SEM) mV at the first stimulus to 1.23+/-0.42 mV at the 20th stimulus (P<0.001). The latency did not change significantly (1473+/-82 to 1550+/-90 ms, P>0.1), while the duration increased (1872+/-356 to 3170+/-681 ms, P<0.001). Stimulation and recording at other sites showed similar trends. Changing the stimulation site failed to alter the adaptation process in terms of amplitude, latency or duration.


CONCLUSIONS
Changes in amplitude and duration of the SSRs to repeated electrical stimuli can occur in presence of constant latency and appear to be independent of the source of sensory input. Peripheral sweat gland mechanisms may be involved in the loss of amplitude and increase in duration of the SSR during habituation.
Cariga
P
P
Department of Sensorimotor Systems, Division of Neuroscience and Psychological Medicine, Imperial College School of Medicine, Charing Cross Hospital, Fulham Palace Road, W6 8RF, London, UK. p.cariga@ic.ac.uk
Catley
M
M
Mathias
C J
CJ
Ellaway
P H
PH
D000328:Adult; D004558:Electric Stimulation; D004562:Electrocardiography; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D006185:Habituation, Psychophysiologic / Q000502:physiology*; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D008475:Median Nerve / Q000502:physiology*; D008663:Metacarpus / Q000502:physiology; D008684:Metatarsus / Q000502:physiology; D008875:Middle Aged; D010543:Peroneal Nerve / Q000502:physiology*; D012867:Skin / Q000294:innervation*; D013564:Sympathetic Nervous System / Q000502:physiology*; D014955:Wrist Joint