Activity increases in empathy-related brain regions when children contribute to peers' sadness and happiness.

Responding empathically when causing peers' emotions is critical to children's interpersonal functioning, yet there are surprising gaps in the literature. Previous research has focused on empathy when witnessing others' emotions instead of causing others' emotions, on negative emotions instead of positive emotions, and on behavioral correlates instead of neural correlates. In this study, children (N = 38; Mage = 9.28 years; 50% female) completed a functional magnetic resonance imaging block design task in which they played a rigged game where they won and lost coins for themselves or peers and viewed their peers' happiness and sadness. We used a region of interest approach to test whether activity in brain regions associated with positive and negative empathy in adults showed significantly greater activity in each condition (i.e., when children won and lost tokens for themselves and peers) compared with a fixation baseline. We predicted that experiencing self-conscious emotions, such as pride and guilt, would heighten the experience of empathy. Activity in the amygdala, which is associated with visceral arousal, and in the anterior insula and dorsal anterior cingulate cortex, which are associated with integrated arousal, increased significantly when winning and losing for oneself and peers and observing their resulting happy and sad facial expressions. Activity did not differ when playing for oneself versus peers, indicating that self-conscious emotions do not heighten empathy and instead support similar neural processes underlying firsthand and secondhand (empathic) emotions. These findings support that empathy during middle childhood involves the same brain regions as empathy during adulthood and that children experience firsthand and secondhand positive and negative emotions in similar ways.

Processing third-party social interactions in the human infant brain.

The understanding of developing social brain functions during infancy relies on research that has focused on studying how infants engage in first-person social interactions or view individual agents and their actions. Behavioral research suggests that observing and learning from third-party social interactions plays a foundational role in early social and moral development. However, the brain systems involved in observing third-party social interactions during infancy are unknown. The current study tested the hypothesis that brain systems in prefrontal and temporal cortex, previously identified in adults and children, begin to specialize in third-party social interaction processing during infancy. Infants (N = 62), ranging from 6 to 13 months in age, had their brain responses measured using functional near-infrared spectroscopy (fNIRS) while viewing third-party social interactions and two control conditions, infants viewing two individual actions and infants viewing inverted social interactions. The results show that infants preferentially engage brain regions localized within the dorsomedial prefrontal cortex when viewing third-party social interactions. These findings suggest that brain systems processing third-party social interaction begin to develop early in human ontogeny and may thus play a foundational role in supporting the interpretation of and learning from social interactions.

Variability in Infants' Functional Brain Network Connectivity Is Associated With Differences in Affect and Behavior.

Variability 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 investigating developmental trajectories in typical and atypical neurodevelopment.

Amygdala Reward Reactivity Mediates the Association Between Preschool Stress Response and Depression Severity.

BACKGROUND: Research in adolescents and adults has suggested that altered neural processing of reward following early life adversity is a highly promising depressive intermediate phenotype. However, very little is known about how stress response, neural processing of reward, and depression are related in very young children. The present study examined the concurrent associations between cortisol response following a stressor, functional brain activity to reward, and depression severity in children 4 to 6 years old. METHODS: Medication-naïve children 4 to 6 years old (N = 52) participated in a study using functional magnetic resonance imaging to assess neural reactivity to reward, including gain, loss, and neutral outcomes. Parent-reported child depression severity and child cortisol response following stress were also measured. RESULTS: Greater caudate and medial prefrontal cortex reactivity to gain outcomes and increased amygdala reactivity to salient (i.e., both gain and loss) outcomes were observed. Higher total cortisol output following a stressor was associated with increased depression severity and reduced amygdala reactivity to salient outcomes. Amygdala reactivity was also inversely associated with depression severity and was found to mediate the relationship between cortisol output and depression severity. CONCLUSIONS: Results suggest that altered neural processing of reward is already related to increased cortisol output and depression severity in preschoolers. These results also demonstrate an important role for amygdala function as a mediator of this relationship at a very early age. Our results further underscore early childhood as an important developmental period for understanding the neurobiological correlates of early stress and increased risk for depression.