Journal of Applied Physiology, Vol 80, Issue 5 1708-1715, Copyright © 1996 by American Physiological Society
Alteration of human cutaneous afferent discharges as the result of long-lasting vibration
E. Ribot-Ciscar, J. P. Roll, M. F. Tardy-Gervet and F. Harlay
Laboratoire de Neurobiologie humaine, Universite de Provence, Marseille, France.
The unitary activities of slowly (15 SAI) and fast-adapting type I (12 FAI)
skin mechanoreceptive afferent units innervating the anterior part of the
human leg and foot were recorded by using the microneurographic method. The
recordings were performed both at rest and on application of cutaneous
stimuli of various intensities before and after exposure of the
corresponding receptive fields to vibration (0.5 mm peak to peak, 100
pulses/s, 10 min). The results show that 11% of the units tested, which
were previously silent, developed a bursting pattern of postvibratory
activity, which lasted 12 min on average. This induced resting activity may
account for the tingling sensations usually perceived after exposure to
vibration. Furthermore, application of vibration to the cutaneous receptive
fields impaired the response properties of the corresponding cutaneous
fibers much more markedly in the case of the SAI than in the FAI units.
More specifically, less than one-half of the FAI fibers tested showed a
postvibratory depressed sensitivity to skin stroking applied at various
velocities that persisted for only a few minutes, whereas the responses of
all the SAI units to suprathreshold maintained skin indentations applied
with increasing amplitudes decreased significantly for 20 min. These fairly
durable changes in the transductive properties of the mechanoreceptive
afferent units probably lead to an impairment of perceptual and
sensorimotor processes and consequently may at least partly account for the
alterations in sensorimotor performance that have been reported to occur in
humans after exposure to vibration.
