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. 2013 Oct 23;111(2):405–414. doi: 10.1152/jn.00322.2013

Fig. 2.

Fig. 2.

A: raw EMG traces recorded from the triceps brachii muscles in a representative subject during all conditions tested (extension-rest, extension-extension, and extension-flexion) with TMS applied to the ipsilateral motor cortex. Traces show the average rectified (left column) and unrectified (right column) EMG data in 30 trials. The onset and offset of the ipsilateral silent period (iSP) are shown between broken lines. The same time period is also shown on the unrectified data. Notice that the subject shows more inhibition of the EMG during bilateral extension-extension and less inhibition of the EMG during bilateral extension-flexion compared with unilateral elbow extension. B shows individual subject data in all conditions tested; in C, group data (n = 15) show the depth of the iSP in all conditions tested. The abscissa shows the conditions tested, and the ordinate shows the depth of the iSP calculated from the mean EMG activity during the iSP divided by the mean of the prestimulus EMG and subtracted from 100. Note the increase in the iSP during bilateral activation of agonist muscles (extension-extension) and a decrease during bilateral activation of antagonist muscles (extension-flexion) compared with a unilateral contraction. Error bars indicate SE. *P < 0.05. Ext, extension; Flex, flexion.