Emotion regulation in mother-child dyads is associated with interbrain synchrony during imagined shared emotional experiences

Parents play an important role in the development of children's emotion regulation (ER) skills - not only through their responses to children's emotions themselves, but also as role models by demonstrating their own ER strategies. Recent studies suggest that interbrain synchrony (IBS) can provide deeper insights into such parent-child dynamics at the neural level. IBS has been suggested as a neural marker of interpersonal processes such as bond formation and information exchange, and is known to vary by emotional valence and social context. This work aimed to investigate IBS during shared mother-child emotional experiences across different social contexts to study the neural mechanisms underlying mothers' and children's ER skills. An emotional imagery task, in which 36 mother-child dyads (child age 10-14 years) imagined experiencing emotional situations both with and without each other, was applied. Brain activity was simultaneously recorded using functional near-infrared spectroscopy (fNIRS) over the right frontopolar cortex, dorsolateral prefrontal cortex (rdlPFC) and temporoparietal junction (rTPJ). Results revealed that for all the regions analysed IBS only varied across valences in the with each other social condition, with higher IBS observed in negative and neutral scenarios compared to positive ones. Furthermore, IBS in the with each other social condition was positively associated with children's use of cognitive reappraisal (i.e., psychological reframing situations) across valences. For the negative valence, IBS also showed a positive association with mothers' ER difficulties. These findings suggest that dyadic IBS might reflect personal traits related to ER and provide a foundation for future investigations into the neural mechanisms underlying ER development.