Shortening of the cortical silent period following transcranial magnetic brain stimulation during an experimental paradigm for generating contingent negative variation (CNV)

Objectives: We investigated changes in the cortical silent period (CSP) following transcranial magnetic cortical stimulation (TCMS) during a standard paradigm which was designed to evoke contingent negative variation (CNV) in ten normal subjects. Methods: We recorded the motor evoked potentials (MEP) and CSP during the inter-stimulus interval (ISI) of a CNV paradigm in ten normal subjects. The CNV paradigm consisted of a visual warning stimulus (S1) followed by a visual response stimulus (S2). The CSP following TCMS on the hand motor area was recorded from mildly contracted first dorsal interosseous muscles. Results: The CSP was significantly shortened during the ISI (P<0.01, t test) with a highly significant correlation with the TCMS timing during the ISI (P<0.02, Spearmanʹs correlation coefficient), while the MEP amplitude and latency were unchanged. Conclusions: The results suggested that shortening of the CSP was associated with neural processes related to preparation for voluntary movement during the paradigm.