Neuroadaptive dynamics in prefrontal cortex during negative emotion regulation: A combined fNIRS-rTMS study

The prefrontal cortex (PFC) is central to negative emotion regulation, yet the fine-grained temporal dynamics of its subregions during automatic and voluntary processing remain poorly understood. Using fNIRS in 55 healthy participants randomly assigned to receive either offline 1-Hz rTMS over the right DLPFC or no-rTMS, we characterized the spatiotemporal dynamics of prefrontal hemodynamic responses across task contexts and regulatory strategies. During automatic emotional processing, a biphasic hemodynamic pattern was observed in bilateral DLPFC and left VLPFC. Both distraction and reappraisal reduced self-reported negative affect but engaged distinct neural profiles: distraction elicited a monophasic activation, whereas reappraisal attenuated the biphasic response. Shorter interpeak intervals in the right VLPFC significantly correlated with better reappraisal outcomes. We also observed a marginally positive association between right DLPFC-VLPFC functional connectivity and reappraisal outcomes. Compared to the no-rTMS group, the rTMS group showed more stable hemodynamic responses during automatic processing and accelerated recovery during reappraisal, alongside modest behavioral improvements. Specifically, the rTMS group exhibited accelerated hemodynamic recovery in the DLPFC and reduced hemodynamic variability in the VLPFC during reappraisal. Network analyses showed that distraction promoted locally clustered processing, reappraisal strengthened right DLPFC-VLPFC coupling, and rTMS suppressed global prefrontal connectivity during regulation. Collectively, our findings reveal task-specific spatiotemporal signatures of prefrontal engagement and suggest that offline rTMS may influence prefrontal network dynamics in healthy adults. Although these results deepen our understanding of prefrontal mechanisms in emotion regulation, their translational potential for clinical populations remains to be established through replication in patient cohorts.