Bed nucleus of the stria terminalis and amygdala responses to unpredictable threat in children

The Impact of Early Life Experiences on Stress Neurobiology and the Development of Anxiety

We examine the association between stress exposure during early development (i.e., the prenatal period through the first two postnatal years) and variation in brain structure and function relevant to anxiety. Evidence of stress-related effects occurring in regions essential for emotional processing and regulation may increase susceptibility to anxiety.

Bed nucleus of the stria terminalis network responses to unpredictable threat in early alcohol abstinence

BACKGROUND

Anxiety during early alcohol abstinence, likely resulting from neural changes caused by chronic alcohol use, contributes to high relapse rates. Studies in rodents show heightened activation during early abstinence in the bed nucleus of the stria terminalis (BNST)-a neural hub for anxiety-and its extended anxiety-related corticolimbic network. Despite the clinical importance of early abstinence, few studies investigate the underlying neural mechanisms.

METHODS

To address this gap, we investigated brain function in early alcohol abstinence (EA = 20, 9 women) relative to controls (HC = 20, 11 women) using an unpredictable threat task shown to engage the BNST and corticolimbic brain regions involved in anxiety and alcohol use disorder (AUD). Group, anxiety, and sex were predictors used to determine whole-brain activation and BNST functional connectivity.

RESULTS

We found widespread interactions of group × anxiety and group × anxiety × sex for both activation and BNST connectivity during unpredictable threat. In the EA group, higher anxiety was correlated with activation in the BNST, rostral anterior cingulate cortex (ACC), insula (men only), and dorsal ACC (men only). In the HC group, higher anxiety was negatively correlated with activation in the BNST, nucleus accumbens, thalamus, and insula (men only). For connectivity, anxiety was positively correlated in EA and negatively correlated in HC, between the BNST and the amygdala, ventromedial prefrontal cortex (PFC), and dorsomedial PFC; EA men showed stronger BNST-vmPFC connectivity than HC men.

CONCLUSIONS

These novel findings provide preliminary evidence for alterations in the BNST and anxiety-related corticolimbic brain regions in early alcohol abstinence, adding to growing literature in humans supporting the BNST's role in anxiety and sex-dependent effects of chronic alcohol use.

Neural responding during uncertain threat anticipation in pediatric anxiety

Excessive fear responses to uncertain threat are a key feature of anxiety disorders (ADs), though most mechanistic work considers adults. As ADs onset in childhood and confer risk for later psychopathology, we sought to identify conditions of uncertain threat that distinguish 8-17-year-old youth with AD (n = 19) from those without AD (n = 33), and assess test-retest reliability of such responses in a companion sample of healthy adults across three sites (n = 19). In an adapted uncertainty of threat paradigm, visual cues parametrically signaled threat of aversive stimuli (fear faces) in 25 % increments (0 %, 25 %, 50 %, 100 %), while participants underwent functional magnetic resonance imaging (fMRI). We compared neural response elicited by cues signaling different degrees of probability regarding the subsequent delivery of fear faces. Overall, youth displayed greater engagement of bilateral inferior parietal cortex, fusiform gyrus, and lingual gyrus during uncertain threat anticipation in general. Relative to healthy youth, AD youth exhibited greater activation in ventrolateral prefrontal cortex (vlPFC)/BA47 during uncertain threat anticipation in general. Further, AD differed from healthy youth in scaling of ventral striatum/sgACC activation with threat probability and attenuated flexibility of responding during parametric uncertain threat. Complementing these results, significant, albeit modest, cross-site test-retest reliability in these regions was observed in an independent sample of healthy adults. While preliminary due to a small sample size, these findings suggest that during uncertainty of threat, AD youth engage vlPFC regions known to be involved in fear regulation, response inhibition, and cognitive control. Findings highlight the potential of isolating neural correlates of threat anticipation to guide treatment development and translational work in youth.

Chronic stress-induced synaptic changes to corticotropin-releasing factor-signaling in the bed nucleus of the stria terminalis

The sexually dimorphic bed nucleus of the stria terminalis (BNST) is comprised of several distinct regions, some of which act as a hub for stress-induced changes in neural circuitry and behavior. In rodents, the anterodorsal BNST is especially affected by chronic exposure to stress, which results in alterations to the corticotropin-releasing factor (CRF)-signaling pathway, including CRF receptors and upstream regulators. Stress increases cellular excitability in BNST CRF+ neurons by potentiating miniature excitatory postsynaptic current (mEPSC) amplitude, altering the resting membrane potential, and diminishing M-currents (a voltage-gated K+ current that stabilizes membrane potential). Rodent anterodorsal and anterolateral BNST neurons are also critical regulators of behavior, including avoidance of aversive contexts and fear learning (especially that of sustained threats). These rodent behaviors are historically associated with anxiety. Furthermore, BNST is implicated in stress-related mood disorders, including anxiety and Post-Traumatic Stress Disorders in humans, and may be linked to sex differences found in mood disorders.

Neighborhood Disadvantage Associated With Blunted Amygdala Reactivity to Predictable and Unpredictable Threat in a Community Sample of Youth

BACKGROUND

Childhood socioeconomic disadvantage is a form of adversity associated with alterations in critical frontolimbic circuits involved in the pathophysiology of psychiatric disorders. Most work has focused on individual-level socioeconomic position, yet individuals living in deprived communities typically encounter additional environmental stressors that have unique effects on the brain and health outcomes. Notably, chronic and unpredictable stressors experienced in the everyday lives of youth living in disadvantaged neighborhoods may impact neural responsivity to uncertain threat.

METHODS

A community sample of children (N = 254) ages 8 to 15 years (mean = 12.15) completed a picture anticipation task during a functional magnetic resonance imaging scan, during which neutral and negatively valenced photos were presented in a temporally predictable or unpredictable manner. Area Deprivation Index (ADI) scores were derived from participants' home addresses as an index of relative neighborhood disadvantage. Voxelwise analyses examined interactions of ADI, valence, and predictability on neural response to picture presentation.

RESULTS

There was a significant ADI × valence interaction in the middle temporal gyrus, anterior cingulate cortex, hippocampus, and amygdala. Higher ADI was associated with less amygdala activation to negatively valenced images. ADI also interacted with predictability. Higher ADI was associated with greater activation of lingual and calcarine gyri for unpredictably presented stimuli. There was no three-way interaction of ADI, valence, and predictability.

CONCLUSIONS

Neighborhood disadvantage may impact how the brain perceives and responds to potential threats. Future longitudinal work is critical for delineating how such effects may persist across the life span and how health outcomes may be modifiable with community-based interventions and policies.

The effects of early life adversity on children's mental health and cognitive functioning

Emerging evidence suggests that partially distinct mechanisms may underlie the association between different dimensions of early life adversity (ELA) and psychopathology in children and adolescents. While there is minimal evidence that different types of ELA are associated with specific psychopathology outcomes, there are partially unique cognitive and socioemotional consequences of specific dimensions of ELA that increase transdiagnostic risk of mental health problems across the internalizing and externalizing spectra. The current review provides an overview of recent findings examining the cognitive (e.g., language, executive function), socioemotional (e.g., attention bias, emotion regulation), and mental health correlates of ELA along the dimensions of threat/harshness, deprivation, and unpredictability. We underscore similarities and differences in the mechanisms connecting different dimensions of ELA to particular mental health outcomes, and identify gaps and future directions that may help to clarify inconsistencies in the literature. This review focuses on childhood and adolescence, periods of exquisite neurobiological change and sensitivity to the environment. The utility of dimensional models of ELA in better understanding the mechanistic pathways towards the expression of psychopathology is discussed, with the review supporting the value of such models in better understanding the developmental sequelae associated with ELA. Integration of dimensional models of ELA with existing models focused on psychiatric classification and biobehavioral mechanisms may advance our understanding of the etiology, phenomenology, and treatment of mental health difficulties in children and youth.

Early experience unpredictability in child development as a model for understanding the impact of the COVID-19 pandemic: A translational neuroscience perspective

Extensive evidence links adverse experiences during childhood to a wide range of negative consequences in biological, socioemotional, and cognitive development. Unpredictability is a core element underlying most forms of early adversity; it has been a focus of developmental research for many years and has been receiving increasing attention recently. In this article, we propose a conceptual model to describe how unpredictable and adverse early experiences affect children's neurobiological, behavioral, and psychological development in the context of the COVID-19 pandemic. We first highlight the critical role of unpredictability in child development by reviewing existing conceptual models of early adversity as they relate to subsequent development across the lifespan. Then, we employ a translational neuroscience framework to summarize the current animal- and human-based evidence on the neurobiological alterations induced by early experience unpredictability. We further argue that the COVID-19 pandemic serves as a global "natural experiment" that provides rare insight to the investigation of the negative developmental consequences of widespread, clustered, and unpredictable adverse events among children. We discuss how the pandemic helps advance the science of unpredictable early adverse experiences. As unpredictability research continues to grow, we highlight several directions for future studies and implications for policymaking and intervention practices.