Development of the Paternal Brain in Humans throughout Pregnancy

Hormonal changes in first-time human fathers in relation to paternal investment

In many biparental species, males experience hormonal changes across the transition to fatherhood that prepare them for their new caregiving role. In humans, cross-sectional comparisons have revealed hormonal differences between fathers and nonfathers, however it is not clear when hormone levels change in new fathers, how such changes relate to paternal involvement and attachment, or even whether men with particular hormonal profiles are more likely to become fathers. In this longitudinal study, we aimed to elucidate the trajectory of hormonal changes in new fathers with greater temporal resolution than previous studies, and to provide further insight into the direction of causality between hormone levels and paternal behavior by asking whether hormone levels predict behavior at subsequent time points, or vice-versa. We recruited a sample of 51 first-time expecting fathers and measured levels of plasma testosterone, oxytocin, vasopressin and cortisol at four time points spanning 4-5 months gestation through 4 months postnatally, and we compared these changes to those found in a control sample of 57 adult male nonfathers. We also examined the concurrent and lagged relationships between hormone levels and fathers' self-reported paternal behaviors. From early in the prenatal period, fathers showed lower levels of both testosterone and vasopressin compared with nonfathers, and lower levels of these hormones during the prenatal period predicted greater postnatal paternal investment in the mother and child. Similar to what is known for human mothers, oxytocin levels increased across the gestational period in new fathers, but oxytocin levels were not associated with greater self-reported paternal involvement or attachment. Finally, cortisol levels did not differ between fathers and nonfathers, and were not predictive of paternal involvement or attachment. Our findings raise the possibility that low levels of vasopressin and testosterone found in expecting fathers anticipate a shift in life history strategy toward greater investment in parenting.

How the Paternal Brain Is Wired by Pregnancy

This Viewpoint describes morphologic and functional changes in the paternal brain after childbirth.

Father contribution to human resilience

Fathers have been an important source of child endurance and prosperity since the dawn of civilization, promoting adaptation to social rules, defining cultural meaning systems, teaching daily living skills, and providing the material background against which children developed; still, the recent reformulation in the role of the father requires theory-building. Paternal caregiving is rare in mammals, occurring in 3-5% of species, expresses in multiple formats, and involves flexible neurobiological accommodations to ecological conditions and active caregiving. Here, we discuss father contribution to resilience across development. Our model proposes three tenets of resilience - plasticity, sociality, and meaning - and discussion focuses on father-specific contributions to each tenet at different developmental stages; newborn, infant, preschooler, child, and adolescent. Father's style of high arousal, energetic physicality, guided participation in daily skills, joint adventure, and conflict resolution promotes children's flexible approach and social competence within intimate bonds and social groups. By expanding children's interests, sharpening cognitions, tuning affect regulation, encouraging exploration, and accompanying the search for identity, fathers support the sense of meaning, enhancing the human-specific dimension of resilience. We end by highlighting pitfalls to paternal contribution, including absence, abuse, rigidity, expectations, and gender typing, and the need to formulate novel theories to accommodate the "involved dad."

Parents regulate arousal while sharing experiences with their child: a study of pupil diameter change responses

Introduction

Parents provide their children with their first exposures to reciprocal shared experiences, and parental modeling of socio-emotional behaviors and regulatory responses largely influences their child's behavioral and neurological development. Some parental reactions are conscious, while others are non-volitional. This project aimed to explore parent-child pupil dilation change responses during shared interactions, specifically, whether parents' neuro-regulatory responses when sharing experiences with their child are different than responses of children interacting with their parents or children and adult peers sharing with each other.

Methods

To test this, four distinct interacting groups were recruited: (1) Parents sharing with their child; (2) Children sharing with their parent; (3) Children sharing with peers; and (4) Adults sharing with peers. All dyads engaged in a computerized shared imagery task, which facilitates communication and mental imagery during a shared experience. During the task, pupil diameter change was recorded as a measure of regulatory response.

Results

Findings highlight that parents sharing with their child have lower pupil diameter change than children sharing with their parents (p < 0.01), children sharing with peers (p < 0.01), and adults sharing with peers (p < 0.05), While no differences were seen between children sharing with parents, children sharing with peers or adults sharing with peers.

Discussion

Findings deepen the understanding of the neuroscience of parenting, by suggesting that parents, even of older children and adolescents, tend to regulate their arousal when interacting with their child, a response that proves to be unique compared to other dyad types for sharing experiences. Considering this dynamic, findings may direct future parent-led intervention methods to improve the child's socio-emotional development.