Mother-Infant Biobehavioral Synchrony and Postpartum Depression - ABSTRACT Infant brain and regulatory systems develop rapidly in the first months of life and set the stage for healthy behavioral and emotional development. Research shows that these systems are shaped, to a large extent, by the postpartum caregiving environment. In particular, mother-infant interactions that are characterized by shared positive affect and mutually responsive behavior facilitate the development of infant emotional self-regulation via mother-infant co-regulation of homeostatic and neural systems. In the context of postpartum depression (PPD) however, growing evidence suggests that these processes are disrupted with potentially long-term adverse implications for the infant. However, several critical gaps remain. First, little is known about the neural substrates of dyadic co-regulation despite the promise of recent advances in portable neuroimaging tools (i.e., near-infrared spectroscopy [NIRS] hyperscanning). Second, although positively valenced systems are fundamental to healthy adjustment and to strengths-based parent-child behavioral interventions, research has focused predominantly on negative affect and deficit models. Third, there is a lack of longitudinal research examining developmental change in co-regulatory behaviors and PPD severity that could inform preventive interventions. The proposed study aims to fill these gaps, and is supported by preliminary proof-of-concept data that mothers and children show concordant responding in medial frontal and lateral frontal regions, which are implicated in social cognition, bonding, and mentalizing, and that positive synchronous interactions heighten these concordant responses. The Specific Aims are to: 1) Characterize mother-infant bio-behavioral synchrony (matching of affective behavior and brain response) at 3 months postpartum; 2) Examine concurrent and prospective associations between PPD severity and mother-infant positive bio-behavioral synchrony; and 3) Examine the extent to which improvements in mother-infant positive bio-behavioral synchrony predict infant emotional regulation. Using a case-control design, we will recruit 176 women endorsing PPD (n=140 at study completion) and 87 women with no prior history of depression (n=70 at study completion) with their 3-month-old infants and conduct three research visits in the home environment to increase participation of difficult-to-reach and vulnerable families. We will assess bio-behavioral synchrony in mother-infant face-to-face interactions at 3-, 6- and 9-months during simultaneous mother-infant NIRS. Micro-analytic coding will provide moment-to-moment measures of positive and negative affect and contingent responding, and NIRS will provide measures of dyadic concordance in mother and infant anterior medial and lateral prefrontal cortical activity. Change in PPD will be assessed via clinical interviews at each home visit, in addition to monthly screening from 3 to 9 months. Infant emotional self-regulation will be assessed at 9 months via independent observations and maternal report.
