Beyond neural oscillations: Stress-related aperiodic activity and aperiodic-oscillatory spectral covariation

Conventional electroencephalography analyses do not distinguish neural oscillations from aperiodic activity, limiting our ability to elucidate specific neural processes underlying acute stress. The present study addressed this gap by disentangling aperiodic and oscillatory activity to examine their associations with acute stress. One hundred and forty-four adults completed a baseline session and the Montreal Imaging Stress Task, during which electroencephalography was recorded. Results revealed a flatter 1/f exponent over the lateral centrotemporoparietal scalp regions during the stress condition. Additionally, there was widespread attenuation of beta activity and enhancement of delta activity during the stress condition. There was also a stress-related decrease in theta activity, but only over the prefrontal, midline frontocentral, and lateral temporoparietal regions. Notably, stress-related shift in aperiodic activity was differentially associated with stress-related changes in these oscillatory bands. By separating aperiodic and oscillatory activity, the study provides a clearer view of the complex neural dynamics underlying psychological stress.