Rhythmic activity in resting-state EEG predicts trait anxiety.

Trait anxiety is characterized by heightened apprehension and worry about future events, with individuals experiencing it at varying levels. Identifying physiological markers of these differences could enhance our understanding of anxiety-related processes. We tested the hypothesis that resting-state rhythmic electroencephalography (EEG) activity (oscillations during alternating 1-minute eyes-open/eyes-closed rest conditions) predicts trait anxiety, as measured by the Behavioral Inhibition Scale (BIS). Multiple regression revealed that during eyes-open rest, higher frontal midline theta and lower frontal midline alpha activity significantly predicted BIS scores. A more stringent analysis confirmed that frontal midline theta and alpha activity met stricter criteria for rhythmicity. Interestingly, only parietal midline alpha power during eyes-open rest, but not oscillations, was predictive of BIS, suggesting that rhythmicity may differentiate the functional roles of frontal and posterior alpha in relation to anxiety. We also found that alpha asymmetry (power or oscillations) did not predict BIS scores. Our results suggest that heightened frontal midline theta during eyes-open rest may reflect increased baseline vigilance in individuals with high trait anxiety. Although speculative, lower frontal midline alpha may indicate greater cortical activation in regions involved in inhibition and cognitive control. Moreover, by differentiating power and oscillation effects, our findings help resolve ambiguities in related research.