Contingent negative variation indicates phasic arousal for externally cuedunilateral eye blink in human subjects

The contingent negative variation (CNV) as a slow cortical potential was us ed to investigate cortical processing of externally cued, voluntary unilate ral eye blink. Probands blinked as a response within a modified hive-stimul us reaction time paradigm. Reaction time and amplitudes of CNV were determi ned. The activity of the orbicularis oculi muscles (OO) was registered by s urface electromyography (EMG). Probands who performed unilateral eye blinks with accurately inhibiting contralateral OO activity showed a significantl y higher negativity of the early CNV component compared with the bilateral eye blink condition. This effect was confined to the beginning of unilatera l blinking performance. It is suggested that the unilateral eye blink is a challenging motor task, initially requiring an increased cortically driven arousal and attention as revealed by increased early CNV components. (C) 19 99 Elsevier Science Ireland Ltd. All rights reserved.