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.
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
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, Spearman's
correlation coefficient), while the MEP amplitude and latency were unchanged.
The results suggested that shortening of the CSP was associated with neural processes
related to preparation for voluntary movement during the paradigm.