My Baby Versus the World: Fathers' Neural Processing of Own-Infant, Unfamiliar-Infant, and Romantic Partner Stimuli

Parents activate brain regions linked with social cognition, reward processing, and emotion when viewing their own infant. Neural responses to own-infant stimuli may be driven by familiarity, self-relevance, or by the unique features of infant faces. The current study sought to clarify these distinctions in first-time fathers by contrasting video stimuli of their infant, an unfamiliar infant, and their pregnant partner. In addition, we examined associations with fathers' self-reported bonding and parenting stress. Fathers (n = 32) scanned approximately 8 months after the birth of their first child completed an fMRI scan while watching videos of their infant, an unfamiliar infant, their pregnant partner, and an unfamiliar pregnant woman. We compared neural responses to the participant's own infant to these other stimuli using both traditional univariate methods and multivariate searchlight analyses. Lastly, we ran additional multivariate pattern analyses to determine discriminability between infant and adult stimuli, as well as familiar and unfamiliar stimuli. Consistent with previous studies, fathers showed greater activation to their own infant versus an unfamiliar infant in regions including the precuneus, posterior cingulate, orbitofrontal cortex, and inferior frontal gyrus. In addition, fathers exhibited heightened activation to their own infant versus their partner in the precuneus. Fathers who reported stronger antenatal and postpartum bonding and lower parenting stress 3 months after birth subsequently showed stronger activation in the precuneus and posterior cingulate to their own infant. Multivariate pattern analyses revealed that in addition to these regions, the parahippocampus differentiated own-infant stimuli versus other conditions. Neural patterns distinguished infant/adult and familiar/unfamiliar stimuli in mentalizing, visual, and affective areas. These findings replicate and extend previous research on the parental brain and suggest that cortical midline mentalizing network regions, as well as visual and reward areas, are particularly important in first-time fathers' processing of their own infants.