The Differences among Eyes-Closed, Eyes-Open and Attention States: An EEG Study

Electroencephalographic (EEG) activity was recorded in normal adults during a three sessions' paradigm, including eyes-closed (EC), eyes-open (EO) resting condition with binocular fixation on a center cross, and a visual attention task. In attention task, subjects were required to keep binocular fixation on a center cross, focus on right or left visual field per block, and respond to the infrequent targets at the attended visual field. Mean theta (4-7 Hz) and beta (14-30 Hz) powers over 128 channels were weaker in the EO than in the EC and attention task, respectively. Mean alpha (8-13 Hz) power was stronger in the EC than in the EO and attention task. Comparisons of theta, alpha and beta rhythms powers between EC, EO and attention task were calculated by the standardized low resolution brain electromagnetic tomography (sLORETA). The results revealed that alpha rhythms in frontal, parietal, and occipital areas were stronger in power in EC than in EO and attention task, but no significant differences in theta and beta rhythms. Furthermore, normalized powers showed that distributive alpha rhythms powers decreased gradually from EC, EO to attention task. The present results suggest that alpha rhythms power and its allocation index human different brain states.