The effect of hand muscle vibration on the somatosensory evoked potential in man: an interaction between lemniscal and spinocerebellar inputs?

The effect of hand muscle mechanical vibration on the somatosensory potential (SEP) evoked by median nerve stimulation, was investigated in 10 healthy subjects. A marked decrease in the amplitude of the N17, N20 and P25 components of the cerebral SEP was observed, while the S11 and S13 components of the cervical response did not change. The amplitude reduction of the SEP components was larger when low frequency vibration was used. Recordings performed after cooling the hand further suggest that the reduction of the amplitude of the SEP components induced by vibration is likely to depend on activation of muscle receptors. These findings could reflect an interaction between limniscal and spino-cerebellar inputs, possibly occurring at the thalamo-cortical levels, a concept compatible with the hypothesis that muscle spindle afferents do contribute to kinaesthesia or position-sense.