Interbrain electroencephalographic and autonomic synchronization during reunion after negative emotional stimulation in romantic couples: An EEG hyperscanning study

Background Neural and physiological synchronization plays a role in emotional regulation within romantic partners. The present study aimed to investigate electroencephalographic (EEG) interbrain synchronization (IBS) and heart rate (HR) coherence in romantic couples during reunion following the exposure to negative emotional stimuli for one partner, and the association between IBS and HRcoherence with attachment dimensions. Methods An EEG hyperscanning study was conducted on 24 heterosexual couples (Institutional Ethics Committee ID: 0000518). The experimental procedure lasted 13 minutes and included five phases: direct eye contact (Resting State), joint positive emotional stimulation, second direct eye contact (Emotional Baseline), negative emotional stimulation in one partner, and third direct eye contact (Reunion). At the end, participants completed the Experiences in Close Relationships–Revised questionnaire. Results The results showed increased left and right frontal IBS during reunion and left frontal IBS during emotional baseline compared to resting state, right temporoparietal IBS during reunion compared to emotional baseline. No significant differences were observed in HRcoherence. Attachment avoidance was positively associated with IBS, while attachment anxiety was negatively associated with IBS. Discussions The increase in frontal and temporoparietal IBS could suggest shared emotional regulation and processing, as an attempt to interpret and align the partner’s mental and affective states at reunion, with insecure attachment dimensions potentially shaping IBS. Conclusions These findings contribute to identifying the neural oscillations and brain regions that seem to underlie synchronization in romantic couples, suggesting that reunion after negative emotional stimulation in one partner could increase synchronization as part of a regulatory process.