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- BMC Medicine
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- National Science Foundation
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The contribution of nature versus nurture to the development of human behavior has been debated for centuries. Here, we offer a piece to this complex puzzle by identifying the human endogenous oxytocin system—known for its critical role in mammalian sociality—as a system sensitive to its early environment and subject to epigenetic change. Recent animal work suggests that early parental care is associated with changes in DNA methylation of conserved regulatory sites within the oxytocin receptor gene ( OXTR m). Through dyadic modeling of behavior and OXTR m status across the first year and a half of life, we translated these findings to 101 human mother-infant dyads. We show that OXTR m is dynamic in infancy and its change is predicted by maternal engagement and reflective of behavioral temperament. We provide evidence for an early window of environmental epigenetic regulation of the oxytocin system, facilitating the emergence of individual differences in human behavior.
Much of infant development occurs in the home and in the context of caregiving support. Babies learn through their everyday interactions with parents—from watching, listening, communicating, cuddling, and playing with them. Foundations for cognitive skills such as attention, perception, learning, and language are all built in the brain during the first year of life. Socioemotional development, including the ability to self-regulate behaviors and emotions, also begins during infancy. Recent advances have allowed researchers to answer questions about the developing brain and how it is impacted by experience and environmental systems, including parental sensitivity and consistency, the home environment, socio-cultural factors, community support systems, and public policies. Giving parents the opportunity to support healthy infant development through paid parental leave programs that are accessible, flexible, and equitable, will positively impact early trajectories of brain and behavioral development.
The present study explored behavioral norms for infant social attention in typically developing human and nonhuman primate infants. We examined the normative development of attention to dynamic social and nonsocial stimuli longitudinally in macaques (Macaca mulatta) at 1, 3, and 5 months of age (N = 75) and humans at 2, 4, 6, 8, and 13 months of age (N = 69) using eye tracking. All infants viewed concurrently played silent videos—one social video and one nonsocial video. Both macaque and human infants were faster to look to the social than the nonsocial stimulus, and both species grew faster to orient to the social stimulus with age. Further, macaque infants’ social attention increased linearly from 1 to 5 months. In contrast, human infants displayed a nonlinear pattern of social interest, with initially greater attention to the social stimulus, followed by a period of greater interest in the nonsocial stimulus, and then a rise in social interest from 6 to 13 months. Overall, human infants looked longer than macaque infants, suggesting humans have more sustained attention in the first year of life. These findings highlight potential species similarities and differences, and reflect a first step in establishing baseline patterns of earlymore »
Variability in Infants' Functional Brain Network Connectivity Is Associated With Differences in Affect and BehaviorVariability in functional brain network connectivity has been linked to individual differences in cognitive, affective, and behavioral traits in adults. However, little is known about the developmental origins of such brain-behavior correlations. The current study examined functional brain network connectivity and its link to behavioral temperament in typically developing newborn and 1-month-old infants ( M [age] = 25 days; N = 75) using functional near-infrared spectroscopy (fNIRS). Specifically, we measured long-range connectivity between cortical regions approximating fronto-parietal, default mode, and homologous-interhemispheric networks. Our results show that connectivity in these functional brain networks varies across infants and maps onto individual differences in behavioral temperament. Specifically, connectivity in the fronto-parietal network was positively associated with regulation and orienting behaviors, whereas connectivity in the default mode network showed the opposite effect on these behaviors. Our analysis also revealed a significant positive association between the homologous-interhemispheric network and infants' negative affect. The current results suggest that variability in long-range intra-hemispheric and cross-hemispheric functional connectivity between frontal, parietal, and temporal cortex is associated with individual differences in affect and behavior. These findings shed new light on the brain origins of individual differences in early-emerging behavioral traits and thus represent a viable novel approach for investigatingmore »
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