Electrophysiological correlates of vigilance during a continuous performance test in healthy adults.

The present study evaluated patterns of electrophysiological activity associated with sustained vigilance in healthy adults. Quantitative electroencephalographs (QEEG) were recorded during the performance of a Continuous Performance Test (CPT). Participants were divided into low and high vigilance groups based upon their reaction time changes between the early and late portions of the CPT. Coherence measures were calculated from the QEEG across the baseline, early CPT, and late CPT experimental conditions. Participants in the low vigilance group had higher baseline and CPT frontal to posterior coherence in the alpha and beta bands suggestive of a less vigilant state throughout the entire study. Additionally, the low vigilance group had a significantly greater beta 1 band coherence drop from baseline to the initial portion of the CPT than the high vigilance group. The combined groups had significantly lower amounts of right hemisphere frontal to posterior coherence across a number of frequency bands throughout all of the phases of the study when compared to the homologous left hemisphere sites. These interhemispheric coherence differences are consistent with vigilance network theories that implicate the right frontal and parietal lobes in the maintenance of sustained attention (M. I. Posner & M. E. Raichle, 1994).