Mother–Infant Brain-to-Brain Synchrony Patterns Reflect Caregiving Profiles

Biobehavioral synchrony, the coordination of physiological and behavioral signals between mother and infant during social contact, tunes the child’s brain to the social world. Probing this mechanism from a two-brain perspective, we examine the associations between patterns of mother–infant inter-brain synchrony and the two well-studied maternal behavioral orientations—sensitivity and intrusiveness—which have repeatedly been shown to predict positive and negative socio-emotional outcomes, respectively. Using dual-electroencephalogram (EEG) recordings, we measure inter-brain connectivity between 60 mothers and their 5- to 12-month-old infants during face-to-face interaction. Thirty inter-brain connections show significantly higher correlations during the real mother–infant face-to-face interaction compared to surrogate data. Brain–behavior correlations indicate that higher maternal sensitivity linked with greater mother–infant neural synchrony, whereas higher maternal intrusiveness is associated with lower inter-brain coordination. Post hoc analysis reveals that the mother-right-frontal–infant-left-temporal connection is particularly sensitive to the mother’s sensitive style, while the mother-left-frontal–infant-right-temporal connection indexes the intrusive style. Our results support the perspective that inter-brain synchrony is a mechanism by which mature brains externally regulate immature brains to social living and suggest that one pathway by which sensitivity and intrusiveness exert their long-term effect may relate to the provision of coordinated inputs to the social brain during its sensitive period of maturation.