Identifying individuals with high susceptibility to mental fatigue: A functional connectivity study

Substantial inter-individual differences in behavioral performance were repeatedly revealed during prolonged time-on-task (TOT), indicating complex neural mechanisms underlying mental fatigue. In this work, we provide a comprehensive investigation to identify individuals with high susceptibility to mental fatigue and to reveal its influence on brain network reorganization. Specifically, behavioral data and EEG signals were collected from 95 participants when they performed a 20-min psychomotor vigilance task (PVT). A composite index (F_index) was introduced, based upon which the participants were categorized into the fatigue-susceptible (FS, corresponding to top third F_index value) and the fatigue-resistant (FR, corresponding to bottom third F_index value) groups (N_FS/N_FR = 30/30). Functional connectivity was then estimated and set as input for the following analyses. As expect, significant impairment of behavioral performance was showed in the FS group, while the performance of the FR group remained relatively stable. Subsequent brain network analyses showed frequency-dependent reorganizations in both groups, whereas the FR group exhibited greater stability and higher integrity than the FS group. Further classification analyses revealed satisfactory accuracy for FS identification (95.61%) and the prominent centro-parietal distribution of contributing nodal features. In sum, this study provides further evidence to support the notion of substantial individual differences in fatigue susceptibility and provides a practical approach to identify the individuals whose performance is particularly prone to performance decline.