Vigilance performance and the amplitude of EEG activity.

Abstract

Abstract The relationships between vigilance measures and amplitudes of different EEG frequency components, obtained by frequency analysis, were examined in an auditory vigilance task. Thirteen subjects detected a faint change of intensity of 800 Hz tone during 40min with recording EEG potential from Cz and Oi. There was a four second epoch and two categories of response were allowed. Analysis of group results showed that there were no significant changes in detection of auditory signals and EEG activity as a function of time. By correlation analysis of EEG data and detection of signals during a run characteristic relationship between theta and alpha activity with detection parameters was discovered. Decrement of correct detection and sensitivity d' was in very close relation with decrease of amplitude theta and alpha activity. On the other hand, the decision aspect of detection expressed by index beta was in negative relation with the amplitude of EEG activity. Decrease in amplitude alpha and theta activity was accompanied by increase of index beta. i.e. increase of cautiousness during detection of signals. The results were partially in accord with Welford's hypothesis of relation of statistical decision theory and activation.