Altered dynamic functional connectivity in adults with rural left-behind experience: a resting-state fMRI study.

BACKGROUND: Early-life parental separation due to rural labor migration represents a prevalent form of early-life social adversity; however, its neural correlates in adulthood remain insufficiently understood, particularly from the perspective of dynamic brain network organization. METHODS: In this study, resting-state fMRI data were analyzed in adults with left-behind experience (LBE, n = 152) and participants in the non-left-behind comparison group (NLB, n = 145). Group independent component analysis was first used to extract major resting-state networks. Dynamic functional network connectivity was then estimated with a sliding-window approach, and recurrent connectivity configurations were identified using clustering analysis. Group differences in static connectivity, dynamic connectivity states, and temporal properties were examined while accounting for demographic and motion-related covariates. Associations of State 6 temporal properties with LBE duration, psychological resilience, and depressive symptom severity were further explored. RESULTS: No significant group differences were observed in static functional connectivity or in state-wise connectivity strength. In contrast, significant group differences were identified only in the temporal properties of State 6. Specifically, individuals with LBE exhibited reduced fraction of time (FT) and mean dwell time (MDT) in State 6 after FDR correction, reflecting less frequent and shorter engagement with this connectivity pattern. Among LBE participants who exhibited State 6, longer LBE duration was associated with lower FT in this state after controlling for covariates. Furthermore, MDT in this state was positively associated with optimism scores after controlling for covariates. CONCLUSIONS: These findings suggested that rural left-behind experience was associated with differences in the temporal engagement of a specific dynamic connectivity state in adulthood, despite the absence of detectable group differences in static connectivity or state-wise connectivity strength. The associations of State 6 temporal properties with LBE duration and optimism provided preliminary correlational evidence that dynamic brain-state measures may be related to both characteristics of early-life experience and adaptive capacity.