Anticipatory response-relevant muscle activity, CNV amplitude and simple reaction time.

The present experiment was aimed at whether subjects, performing a forewarned simple reaction time (RT) task, do voluntarily tense agonist and antagonist muscles during the foreperiod; if so, would such muscle tension co-vary with CNV amplitude or RT? Although excessive eye movements caused 30% of the subjects to be removed from the analysis, it was still possible after the experiment to differentiate between subjects who gradually tensed their agonist during the foreperiod and subjects who did not. The former group showed higher CNV early and late wave amplitudes as compared with the latter group. A similar effect was found on the N1 amplitude of the potential evoked by the warning stimulus. The increased EMG in the agonist muscle at the end of the foreperiod was not concomitant with faster RTs. In addition, fast RTs were preceded by higher CNV late wave amplitudes at pre- and postcentral electrode positions. The observed relationships between CNV, EMG, and RT were discussed in terms of specific and general motor preparation.