Alpha-band temporal variability in the Fronto-parietal network facilitates active recovery from mental fatigue

Mental fatigue from prolonged cognitive tasks impairs performance, yet this decline is often non-linear. This suggests the brain engages active self-regulatory mechanisms to recover, though the neural basis of this recovery process remains unclear. We investigated this phenomenon using electroencephalography (EEG) during a continuous 120-minute boundary avoidance task. Behaviorally, we confirmed a non-linear performance curve that featured a significant recovery stage following an initial decline. The decline stage showed classic neural fatigue signatures, including increased delta and alpha power alongside reduced brain network efficiency. However, the recovery stage did not simply reverse these patterns. Instead, it involved a distinct increase in the temporal variability of alpha-band functional connectivity within the fronto-parietal network (FPN). We found that this heightened FPN variability, interacting with alpha power, directly predicted behavioral recovery. These findings expand our view of cognitive resilience. We propose that resilience is not merely passive resistance to fatigue but an active process of compensatory control driven by dynamic network flexibility. Thus, increased FPN variability likely serves as an intrinsic neural response that facilitates behavioral recovery.