Maternal buffering of human amygdala-prefrontal circuitry during childhood but not during adolescence

Mature amygdala-prefrontal circuitry regulates affect in adulthood but shows protracted development. In altricial and semialtricial species, caregivers provide potent affect regulation when mature neurocircuitry is absent. The present investigation examined a potential mechanism through which caregivers provide regulatory influences in childhood. Children, but not adolescents, showed evidence of maternal buffering, such that maternal stimuli suppressed amygdala reactivity. In the absence of maternal stimuli, children exhibited immature amygdala-prefrontal connectivity. However, in the presence of maternal stimuli, children's connectivity was more mature, resembling adolescents' connectivity. Children showed improved affect-related regulation in the presence of their mothers. Individual differences emerged, with greater maternal influence on amygdala-prefrontal circuitry associated with stronger mother-child relationships and maternal modulation of behavioral regulation. These findings suggest a neural mechanism through which caregivers modulate children's regulatory behavior by inducing more mature connectivity and buffering against heightened reactivity. Maternal buffering in childhood, but not adolescence, suggests that childhood may be a sensitive period for amygdala-prefrontal development.

Normative development of ventral striatal resting state connectivity in humans

Incentives play a crucial role in guiding behavior throughout our lives, but perhaps no more so than during the early years of life. The ventral striatum is a critical piece of an incentive-based learning circuit, sharing robust anatomical connections with subcortical (e.g., amygdala, hippocampus) and cortical structures (e.g., medial prefrontal cortex (mPFC), insula) that collectively support incentive valuation and learning. Resting-state functional connectivity (rsFC) is a powerful method that provides insight into the development of the functional architecture of these connections involved in incentive-based learning. We employed a seed-based correlation approach to investigate ventral striatal rsFC in a cross-sectional sample of typically developing individuals between the ages of 4.5 and 23-years old (n=66). Ventral striatal rsFC with the mPFC showed regionally specific linear age-related changes in connectivity that were associated with age-related increases in circulating testosterone levels. Further, ventral striatal connectivity with the posterior hippocampus and posterior insula demonstrated quadratic age-related changes characterized by negative connectivity in adolescence. Finally, across this age range, the ventral striatum demonstrated positive coupling with the amygdala beginning during childhood and remaining consistently positive across age. In sum, our findings suggest that normative ventral striatal rsFC development is dynamic and characterized by early establishment of connectivity with medial prefrontal and limbic structures supporting incentive-based learning, as well as substantial functional reorganization with later developing regions during transitions into and out of adolescence.

Longitudinal changes in amygdala, hippocampus and cortisol development following early caregiving adversity

Although decades of research have shown associations between early caregiving adversity, stress physiology and limbic brain volume (e.g., amygdala, hippocampus), the developmental trajectories of these phenotypes are not well characterized. In the current study, we used an accelerated longitudinal design to assess the development of stress physiology, amygdala, and hippocampal volume following early institutional care. Previously Institutionalized (PI; N = 93) and comparison (COMP; N = 161) youth (ages 4–20 years old) completed 1–3 waves of data collection, each spaced approximately 2 years apart, for diurnal cortisol (N = 239) and structural MRI (N = 156). We observed a developmental shift in morning cortisol in the PI group, with blunted levels in childhood and heightened levels in late adolescence. PI history was associated with reduced hippocampal volume and reduced growth rate of the amygdala, resulting in smaller volumes by adolescence. Amygdala and hippocampal volumes were also prospectively associated with future morning cortisol in both groups. These results indicate that adversity-related physiological and neural phenotypes are not stationary during development but instead exhibit dynamic and interdependent changes from early childhood to early adulthood.

Parental presence switches avoidance to attraction learning in children

Attachment-related learning (that is, forming preferences for cues associated with the parent) defies the traditional rules of learning in that it seems to occur independently of apparent reinforcement¹-young children prefer cues associated with their parent, regardless of valence (rewarding or aversive), despite the diversity of parenting styles². This obligatory attraction for parental cues keeps the child nearby and safe to explore the environment; thus, it is critical for survival and sets the foundation for normal human cognitive-emotional behaviour. Here we examined the learning underlying this attraction in preschool-age children. Young children underwent an aversive conditioning procedure either in the parent's presence or alone. We showed that despite disliking the aversive unconditioned stimulus, children exhibited a behavioural approach for conditioned stimuli that were acquired in the parent's presence and an avoidance for stimuli acquired in the parent's absence, an effect that was strongest among those with the lowest cortisol levels. The results suggest that learning systems during early childhood are constructed to permit modification by parental presence.

Altered ventral striatal-medial prefrontal cortex resting-state connectivity mediates adolescent social problems after early institutional care

Early caregiving adversity is associated with increased risk for social difficulties. The ventral striatum and associated corticostriatal circuitry, which have demonstrated vulnerability to early exposures to adversity, are implicated in many aspects of social behavior, including social play, aggression, and valuation of social stimuli across development. Here, we used resting-state functional magnetic resonance imaging to assess the degree to which early caregiving adversity was associated with altered coritocostriatal resting connectivity in previously institutionalized youth (n = 41) relative to youth who were raised with their biological families from birth (n = 47), and the degree to which this connectivity was associated with parent-reported social problems. Using a seed-based approach, we observed increased positive coupling between the ventral striatum and anterior regions of medial prefrontal cortex (mPFC) in previously institutionalized youth. Stronger ventral striatum-mPFC coupling was associated with parent reports of social problems. A moderated-mediation analysis showed that ventral striatal-mPFC connectivity mediated group differences in social problems, and more so with increasing age. These findings show that early institutional care is associated with differences in resting-state connectivity between the ventral striatum and the mPFC, and this connectivity seems to play an increasingly important role in social behaviors as youth enter adolescence.

Decreased Amygdala Reactivity to Parent Cues Protects Against Anxiety Following Early Adversity: An Examination Across 3 Years

BACKGROUND

The human brain remains highly plastic for a protracted developmental period. Thus, although early caregiving adversities that alter amygdala development can result in enduring emotion regulation difficulties, these trajectories should respond to subsequent enriched caregiving. Exposure to high-quality parenting can regulate (i.e., decrease) children's amygdala reactivity, a process that, over the long term, is hypothesized to enhance emotion regulation. We tested the hypothesis that even following adversity, the parent-child relationship would be associated with decreases in amygdala reactivity to parent cues, which would in turn predict lower future anxiety.

METHODS

Participants were 102 children (6-10 years of age) and adolescents (11-17 years of age), for whom data were collected at one or two time points and who either had experienced institutional care before adoption (n = 45) or had lived always with their biological parents (comparison; n = 57). We examined how amygdala reactivity to visual cues of the parent at time 1 predicted longitudinal change (from time 1 to time 2) in parent-reported child anxiety across 3 years.

RESULTS

At time 1, on average, amygdala reactivity decrements to parent cues were not seen in children who had received institutional care but were seen in children in the comparison group. However, some children who previously experienced institutional care did show decreased amygdala reactivity to parent cues (∼40%), which was associated with greater child-reported feelings of security with their parent. Amygdala decreases at time 1 were followed by steeper anxiety reductions from time 1 to time 2 (i.e., 3 years).

CONCLUSIONS

These data provide a neurobiological mechanism by which the parent-child relationship can increase resilience, even in children at significant risk for anxiety symptoms.

Vigilance, the Amygdala, and Anxiety in Youths with a History of Institutional Care

BACKGROUND

Early adversity is commonly associated with alterations of amygdala circuitry and increased anxiety. While many theoretical and clinical accounts of early adversity suggest that it increases vigilance to threatening stimuli, the present study tested whether heightened anxiety and amygdala reactivity associated with early adversity enhanced goal-directed attention for threatening stimuli. Showing this association would provide support that these adversity-induced alterations are developmental adaptations of the individual.

METHODS

34 children and adolescents who experienced early adversity in the form of previous institutionalization (PI) (26 female, mean age=13.49 years) and a comparison group of 33 children and adolescents who were reared by their biological parents since birth (16 female, mean age=13.40 years) underwent fMRI scanning while completing a visual search task that involved quickly locating a negative (fearful face) or positive target (happy face) in an array of neutral distractor stimuli (neutral faces).

RESULTS

Across both groups, individual differences in vigilant behavior were positively associated with amygdala responses for negative versus positive stimuli. However, a moderation analysis revealed that the degree to which amygdala responses were greater for negative versus positive stimuli was associated with greater anxiety symptomology for PI youth, but not comparison youth.

CONCLUSIONS

Together, these findings suggest that institutional care strengthens linkages between amygdala reactivity and anxiety, perhaps serving to enhance goal-directed attention. The findings are discussed as both adaptations as well as risk to the individual.

Diurnal cortisol after early institutional care-Age matters

Several studies have shown that young children who have experienced early caregiving adversity (e.g. previously institutionalization (PI)) exhibit flattened diurnal cortisol slopes; however, less is known about how these patterns might differ between children and adolescents, since the transition between childhood and adolescence is a time of purported plasticity in the hypothalamic-pituitary-adrenal (HPA) axis. PI youth experience a massive improvement in caregiving environment once adopted into families; therefore we anticipated that a developmental increase in HPA axis plasticity during adolescence might additionally allow for an enhanced enrichment effect by the adoptive family. In a cross-sectional sample of 197 youths (PI and Comparison; 4–15 years old) we observed age-related group differences in diurnal slope. First replicating previous findings, PI children exhibited flattened diurnal slope. This group difference, however, was not observed in adolescents. Moderation analyses showed that pubertal development, increased time with family, and early adoption contributed to the steeper diurnal cortisol slope in PI adolescents. These findings add support to existing theories positing that the transition between middle childhood and adolescence may mark an additional sensitive period for diurnal cortisol patterning, allowing PI youth to benefit from the enriched environment provided by adoptive parents during this period of development.

The Early Construction of Spatial Attention: Culture, Space, and Gesture in Parent-Child Interactions

American and Israeli toddler-caregiver dyads (mean age of toddler = 26 months) were presented with naturalistic tasks in which they must watch a short video (N = 97) or concoct a visual story together (N = 66). English-speaking American caregivers were more likely to use left to right spatial structuring than right to left, especially for well-ordered letters and numbers. Hebrew-speaking Israeli parents were more likely than Americans to use right to left spatial structuring, especially for letters. When constructing a pictorial narrative for their children, Americans were more likely to place pictures from left to right than Israelis. These spatial structure biases exhibited by caregivers are a potential route for the development of spatial biases in early childhood, before children have developed automatic reading and writing habits.

Positive valence bias and parent-child relationship security moderate the association between early institutional caregiving and internalizing symptoms

Institutional caregiving is associated with significant deviations from species-expected caregiving, altering the normative sequence of attachment formation and placing children at risk for long-term emotional difficulties. However, little is known about factors that can promote resilience following early institutional caregiving. In the current study, we investigated how adaptations in affective processing (i.e., positive valence bias) and family-level protective factors (i.e., secure parent-child relationships) moderate risk for internalizing symptoms in previously institutionalized (PI) youth. Children and adolescents with and without a history of institutional care performed a laboratory-based affective processing task and self-reported measures of parent-child relationship security. PI youth were more likely than comparison youth to show positive valence biases when interpreting ambiguous facial expressions. Both positive valence bias and parent-child relationship security moderated the association between institutional care and parent-reported internalizing symptoms, such that greater positive valence bias and more secure parent-child relationships predicted fewer symptoms in PI youth. However, when both factors were tested concurrently, parent-child relationship security more strongly moderated the link between PI status and internalizing symptoms. These findings suggest that both individual-level adaptations in affective processing and family-level factors of secure parent-child relationships may ameliorate risk for internalizing psychopathology following early institutional caregiving.

Age-related change in task-evoked amygdala-prefrontal circuitry: A multiverse approach with an accelerated longitudinal cohort aged 4-22 years

The amygdala and its connections with medial prefrontal cortex (mPFC) play central roles in the development of emotional processes. While several studies have suggested that this circuitry exhibits functional changes across the first two decades of life, findings have been mixed - perhaps resulting from differences in analytic choices across studies. Here we used multiverse analyses to examine the robustness of task-based amygdala-mPFC function findings to analytic choices within the context of an accelerated longitudinal design (4-22 years-old; N = 98; 183 scans; 1-3 scans/participant). Participants recruited from the greater Los Angeles area completed an event-related emotional face (fear, neutral) task. Parallel analyses varying in preprocessing and modeling choices found that age-related change estimates for amygdala reactivity were more robust than task-evoked amygdala-mPFC functional connectivity to varied analytical choices. Specification curves indicated evidence for age-related decreases in amygdala reactivity to faces, though within-participant changes in amygdala reactivity could not be differentiated from between-participant differences. In contrast, amygdala-mPFC functional connectivity results varied across methods much more, and evidence for age-related change in amygdala-mPFC connectivity was not consistent. Generalized psychophysiological interaction (gPPI) measurements of connectivity were especially sensitive to whether a deconvolution step was applied. Our findings demonstrate the importance of assessing the robustness of findings to analysis choices, although the age-related changes in our current work cannot be overinterpreted given low test-retest reliability. Together, these findings highlight both the challenges in estimating developmental change in longitudinal cohorts and the value of multiverse approaches in developmental neuroimaging for assessing robustness of results.

Telomere Erosion and Depressive Symptoms Across Development Following Institutional Care

OBJECTIVE

A large literature has identified exposure to early caregiving adversities as a potent risk for developing affective psychopathology, with depression, in particular, increasing across childhood into adolescence. Evidence suggests telomere erosion, a marker of biological aging, may underlie associations between adverse early-life experiences and later depressive behavior; yet, little is understood about this association during development.

METHOD

The current accelerated longitudinal study examined concurrent telomere length and depressive symptoms concurrently, 2 and 4 years later, from the preschool period through adolescence among children exposed (n =116) and not exposed (n = 242) to early previous institutional (PI) care.

RESULTS

PI care was associated with shorter telomeres on average and with quadratic age-related growth in depressive symptoms, indicating a steeper association between PI care and depressive symptoms in younger age groups that leveled off in adolescence. Contrary to studies in adult samples, telomere length was not associated with depressive symptoms, and it did not predict future symptoms.

CONCLUSION

These findings indicate that early caregiving disruptions increase the risk for both accelerated biological aging and depressive symptoms, although these variables did not correlate with each other during this age range.