Rapid reversible changes to multiple levels of the human somatosensory system following the cessation of repetitive contractions: a somatosensory evoked potential study

Objective: Numerous somatosensory evoked potential (SEP) studies have provided clear evidence that during repetitive voluntary movement, the transmission of somatosensory afferent information is attenuated. The objective of this work was to determine if this gating phenomenon could persist beyond the period of repetitive movement. Methods: We recorded spinal, brainstem, and cortical SEPs to median nerve stimulation before and immediately after a modified 20 min repetitive typing task that did not involve the thenar muscles. Results: There were significant decreases in pre-central cortical and subcortical SEP amplitudes for several minutes following task cessation. Conclusions: These results demonstrate the persistence of the gating phenomenon beyond the cessation of the actual repetitive movement. They also indicate that plastic changes do occur in cortical and subcortical components of the somatosensory system, following voluntary repetitive contractions. Significance: The persistence of changes in somatosensory processing beyond the period of repetitive activity may be relevant to the initiation of overuse injuries.