Fatigue Leads to Dynamic Shift in Fronto-parietal Sustained Attention Network

Recently, the gamma band (γ; 70-100 Hz) has been implicated in sustained attention decay across a vigil consistent with computational models of fatigue. Frontal γ indexing centrally controlled sustained attention and parietal γ linked to gated sensory processes declined across a 10-minute vigilance task, a pattern observed for faster but not slower performers. The anatomical distribution of γ activity indicates neural communication, or connectivity, within the fronto-parietal network. We used Granger Prediction to evaluate fatigue effects on network γ connectivity. Results showed stronger directional connectivity for frontal→parietal versus parietal→frontal over time, indicating that top-down control of attention largely remained intact. However, parietal→frontal early γ connectivity increased with time, suggesting a network shift to enhanced sensory-directed processes after only 8 minutes. This pattern of connectivity was mirrored by fast but not slower performers. Our findings provide new directions for computational accounts of fatigue mechanisms and highlight the importance of individual differences.