Context-specific freezing and associated physiological reactivity as a dysregulated fear response

Salivary cortisol captures endocrine response to an acute stressor in captive female tufted capuchin monkeys (Sapajus apella)

Measuring glucocorticoids such as cortisol is a useful tool for exploring relationships among behavior, physiology, and well-being in primates. As cortisol circulates in blood, it moves into biological matrices such as hair, urine, feces, and saliva. Saliva sampling is a simple, noninvasive method to measure cortisol that can be easily implemented by training animals to voluntarily provide samples. The temporal lag between elevation of cortisol in the blood and elevation of cortisol in saliva likely varies by species and must be characterized to identify appropriate sampling regimens. In the present study we characterized the time course of cortisol changes in saliva following an acute psychological stressor in captive tufted capuchin monkeys (Sapajus apella). We trained eight free-moving female tufted capuchin monkeys to voluntarily produce clean saliva samples. We exposed them to the acute stressor of a veterinary catch net and observed behavior pre and post exposure. We collected salivary samples immediately pre exposure (0 min) and 30, 45, 60, 75, 90, and 120 min after exposure. Salivary cortisol was quantified using a Salimetrics kit. Behavioral and cortisol measures were compared within individuals to a control condition in which no stressor was presented. Capuchins showed a clear behavioral response to the stressor by demonstrating increased freezing and pacing, decreased feed foraging, nonsocial play, and scratching, and decreased willingness to provide saliva samples after stressor presentation. After stressor presentation, average salivary cortisol began to increase at 30 min and continued to increase through the 120 min sample period. There was individual variation in absolute cortisol levels, the timing of the cortisol increase, and the timing of the peak. Our results suggest that no single time-point can be reliably used to evaluate salivary cortisol response to an acute stressor across individuals, and instead we recommend the collection of a prolonged time series.

Motivation as a Lens for Understanding Information-seeking Behaviors

Most prior research characterizes information-seeking behaviors as serving utilitarian purposes, such as whether the obtained information can help solve practical problems. However, information-seeking behaviors are sensitive to different contexts (i.e., threat vs. curiosity), despite having equivalent utility. Furthermore, these search behaviors can be modulated by individuals' life history and personality traits. Yet the emphasis on utilitarian utility has precluded the development of a unified model, which explains when and how individuals actively seek information. To account for this variability and flexibility, we propose a unified information-seeking framework that examines information-seeking through the lens of motivation. This unified model accounts for integration across individuals' internal goal states and the salient features of the environment to influence information-seeking behavior. We propose that information-seeking is determined by motivation for information, invigorated either by instrumental utility or hedonic utility, wherein one's personal or environmental context moderates this relationship. Furthermore, we speculate that the final common denominator in guiding information-seeking is the engagement of different neuromodulatory circuits centered on dopaminergic and noradrenergic tone. Our framework provides a unified framework for information-seeking behaviors and generates several testable predictions for future studies.

Social versus non-social behavioral inhibition: Differential prediction from early childhood of long-term psychosocial outcomes

Behavioral inhibition (BI) is a temperamental style characterized by cautious and fearful behaviors in novel situations. The present multi-method, longitudinal study examined whether young children's observed and parent-reported BI in social versus non-social contexts predicts different long-term psychosocial outcomes. Participants (N = 279) were drawn from a longitudinal study of socioemotional development. BI in social contexts ("social BI") was measured via children's observed wariness toward unfamiliar adults and peers at 24 and 36 months and parents' reports of children's social fear/shyness at 24, 36, and 48 months. BI in non-social contexts ("non-social BI") was measured via children's observed fearful responses to masks and novel toys, and parents' reports of children's distress to non-social novelty at 9 months and non-social fear at 48 months. At 15 years, anxiety was assessed via adolescent- and parent-reports, and global internalizing and externalizing problems were assessed via parent-reports. Confirmatory factor analysis showed that a two-factor model fit the BI data significantly better than a single-factor model, providing evidence for the dissociation of BI in social versus non-social contexts. Social BI was uniquely associated with adolescent social anxiety, whereas non-social BI was specifically associated with adolescent separation anxiety. Neither social BI nor non-social BI predicted global internalizing and externalizing problems, providing evidence for the specific relations between BI and anxiety problems. Together, these results suggest that young children's inhibited responses in social versus non-social situations predict different subtypes of anxiety problems in adolescence, highlighting the multifaceted nature of BI and the divergent trajectories of different anxiety problems.

Defensive responses: behaviour, the brain and the body

Most animals live under constant threat from predators, and predation has been a major selective force in shaping animal behaviour. Nevertheless, defence responses against predatory threats need to be balanced against other adaptive behaviours such as foraging, mating and recovering from infection. This behavioural balance in ethologically relevant contexts requires adequate integration of internal and external signals in a complex interplay between the brain and the body. Despite this complexity, research has often considered defensive behaviour as entirely mediated by the brain processing threat-related information obtained via perception of the external environment. However, accumulating evidence suggests that the endocrine, immune, gastrointestinal and reproductive systems have important roles in modulating behavioural responses to threat. In this Review, we focus on how predatory threat defence responses are shaped by threat imminence and review the circuitry between subcortical brain regions involved in mediating defensive behaviours. Then, we discuss the intersection of peripheral systems involved in internal states related to infection, hunger and mating with the neurocircuits that underlie defence responses against predatory threat. Through this process, we aim to elucidate the interconnections between the brain and body as an integrated network that facilitates appropriate defensive responses to threat and to discuss the implications for future behavioural research.

Problematic social media use is associated with depression and similar to behavioral addictions: Physiological and behavioral evidence

While many studies have examined the relationship between problematic social media use (PSMU) and mental health disorders, little is known about reward responsiveness mechanisms that might be driving this relationship and the neurophysiological characteristics of PSMU. We surveyed 96 undergraduate students at a private liberal arts college in upstate NY. PSMU was assessed using the Social Media Disorder Scale. Fourteen Individuals endorsing in five or more and three or less categories on the Social Media Disorder Scale were offered and underwent resting state QEEG. Mental health was assessed with the Center for Epidemiological Studies Depression Scale Short Form, Social Interaction Anxiety Scale, Penn State Worry Questionnaire, the 10-item Perceived Stress Scale, and a locally developed measure of Substance Use Disorder. Reward and motivational systems were studied using the Brief Sensation Seeking Scale, Behavioral Inhibition/Behavioral Activation Scale, and Temporal Experience of Pleasure Scale. SMDS scores were associated with poorer mental health on all measures except substance use. SMDS scores were positively associated with the behavioral inhibition scale, and the anticipatory pleasure scale. QEEG results revealed a negative association of high PSMU and right central and frontal lobeta, right central beta, and a positive association with frontal alpha asymmetry. The study replicates findings that PSMU is associated with mental health issues. Further the pattern of reward response is different compared with other addictive behaviors. QEEG results are consistent with previous work in substance use and depression.

The Relationship Between Temperament Characteristics and Emotion Regulation Abilities in Institutionalized and Noninstitutionalized Children

This study examined the role of institutionalization and temperament dimensions on emotion regulation and negative lability in school-aged (6-10 years) children. Participants were 46 institutionalized (22 boys; 24 girls) and 48 noninstitutionalized children (23 boys; 25 girls), matched in age and sex. Emotion regulation and negative lability were assessed with the Emotion Regulation Checklist (ERC). The School-Age Temperament Inventory (SATI) was used to measure temperament dimensions. No significant between-group differences emerged in temperament dimensions, emotion regulation and negative lability. After controlling for institutionalization status, results indicated that (a) approach/withdrawal (sociability) and persistence positively predicted emotion regulation, (b) negative reactivity positively predicted negative lability, and (c) persistence negatively predicted negative lability. Institutionalization did not predict emotion regulation or negative lability. The protective role that specific temperament characteristics, such as persistence and approach/withdrawal (sociability), may have for at risk populations (e.g., institutionalized) and typically developing (e.g., noninstitutionalized) children is highlighted.

Are fearful boys at higher risk for anxiety? Person-centered profiles of toddler fearful behavior predict anxious behaviors at age 6

Dysregulated fear (DF), the presence of fearful behaviors in both low-threat and high-threat contexts, is associated with child anxiety symptoms during early childhood (e.g., Buss et al., 2013). However, not all children with DF go on to develop an anxiety disorder (Buss and McDoniel, 2016). This study leveraged the data from two longitudinal cohorts (N = 261) to (1) use person-centered methods to identify profiles of fearful temperament, (2) replicate the findings linking DF to anxiety behaviors in kindergarten, (3) test if child sex moderates associations between DF and anxiety behaviors, and (4) examine the consistency of findings across multiple informants of child anxiety behaviors. We identified a normative fear profile (low fear in low-threat contexts; high fear in high-threat contexts), a low fear profile (low fear across both low- and high-threat contexts) and a DF profile (high fear across both low- and high-threat contexts). Results showed that probability of DF profile membership was significantly associated with child self-reported overanxiousness, but not with parent-reported overanxiousness. Associations between DF profile membership and overanxiousness was moderated by child sex such that these associations were significant for boys only. Additionally, results showed that probability of DF profile membership was associated with both parent-reported social withdrawal and observations of social reticence, but there were no significant associations with child self-report of social withdrawal. Results highlight the importance of considering person-centered profiles of fearful temperament across different emotion-eliciting contexts, and the importance of using multiple informants to understand associations with temperamental risk for child anxiety.

The gene environment aetiology of freezing and its relationship with internalizing symptoms during adolescence

BACKGROUND

The freezing response is a universal response to threat, linked to attentive immobility and action preparation. It is relevant for acute stress coping in animals and humans, and subtle deviations in toddler freezing duration (absence of, or excessively long reactions) have been linked to higher risk for internalizing symptoms in adolescence. Yet, while individual freezing tendencies are relatively stable throughout life, little is known about their gene-environment aetiology.

METHODS

We investigated the heritability of toddler freezing in the Quebec Newborn Twin Study (QNTS; n=508 twins) by fitting behavioural genetic models to video-coded freezing responses during a robot confrontation. Furthermore, we examined the predictive associations between toddler freezing and internalizing symptoms (anxiety and depressive symptoms), as they unfold during adolescence (ages 12-19 years) using linear mixed-effects models.

FINDINGS

Freezing was found to be moderately heritable (45% of the variance accounted for by genetic factors). The remaining variance was explained by unique environmental factors, including measurement error. No significant contribution of shared environmental factors was noted. Additionally, shorter freezing was associated with more internalizing symptoms in adolescence at trend level, a pattern that was significant for depressive but not anxiety symptoms.

INTERPRETATION

Freezing is an adaptive coping mechanism in early childhood, which is partly driven by genetic factors. Crucially, the absence or shorter duration of these behaviours may signal vulnerability to depressive problems later in life.

FUNDING

Canadian Institutes of Health Research and Research Fund of Quebec-Health and Society and Culture. Consolidator grant from the European Research Council (ERC_CoG-2017_772337).

A non-canonical GABAergic pathway to the VTA promotes unconditioned freezing

Freezing is a conserved defensive behaviour that constitutes a major stress-coping mechanism. Decades of research have demonstrated a role of the amygdala, periaqueductal grey and hypothalamus as core actuators of the control of fear responses, including freezing. However, the role that other modulatory sites provide to this hardwired scaffold is not known. Here, we show that freezing elicited by exposure to electrical foot shocks activates laterodorsal tegmentum (LDTg) GABAergic neurons projecting to the VTA, without altering the excitability of cholinergic and glutamatergic LDTg neurons. Selective chemogenetic silencing of this inhibitory projection, but not other LDTg neuronal subtypes, dampens freezing responses but does not prevent the formation of conditioned fear memories. Conversely, optogenetic-activation of LDTg GABA terminals within the VTA drives freezing responses and elicits bradycardia, a common hallmark of freezing. Notably, this aversive information is subsequently conveyed from the VTA to the amygdala via a discrete GABAergic pathway. Hence, we unveiled a circuit mechanism linking LDTg-VTA-amygdala regions, which holds potential translational relevance for pathological freezing states such as post-traumatic stress disorders, panic attacks and social phobias.

Human defensive freezing: Associations with hair cortisol and trait anxiety

The anticipation of threat facilitates innate defensive behaviours including freezing reactions. Freezing in humans is characterised by reductions in body sway and heart rate. Limited evidence suggests that individual differences in freezing reactions are associated with predictors of anxiety-related psychopathology including trait anxiety and hypothalamic-pituitary-adrenal (HPA) axis activity. However, previous human studies focused on acutely circulating cortisol levels, leaving the link between freezing and more stable, individual trait markers of HPA axis activity unclear. We investigated whether individual differences in anticipatory freezing reactions are predicted by accumulated hair cortisol concentrations (HCC) and trait anxiety, in a well-powered mixed sample of police recruits at the start of the police training, and age, sex and education matched controls (total N = 419, mean age = 24, N_women = 106, N_{police recruits} = 337). Freezing-related reactions were assessed with posturographic and heart rate measurements during an active shooting task under threat of shock. The anticipation of threat of shock elicited the expected reductions in body sway and heart rate, indicative of human freezing. Individual differences in threat-related reductions in body sway, but not heart rate, were related to lower HCC and higher trait anxiety. The observed links between postural freezing and predictors of anxiety-related psychopathology suggest the potential value of defensive freezing as a somatic marker for individual differences in stress-vulnerability and resilience. DATA AVAILABILITY: The datasets analysed during the current study are available from the corresponding authors upon reasonable request.

Distinguishing selective mutism and social anxiety in children: a multi-method study

Selective mutism (SM) is an anxiety disorder in which a child fails to speak in some situations (e.g., school) despite the ability to speak in other situations (e.g., home). Some work has conceptualized SM as a variant of social anxiety disorder (SAD) characterized by higher levels of social anxiety. Here, we empirically tested this hypothesis to see whether there were differences in social anxiety (SA) between SM and SAD across behavioral, psychophysiological, self-, parent-, and teacher-report measures. Participants included 158 children (M_age = 8.76 years, SD = 3.23) who were classified into three groups: children with SM and who were also highly socially anxious (SM + HSA; n = 48), highly socially anxious children without SM (HSA; n = 48), and control children (n = 62). Children participated in a videotaped self-presentation task, following which observed SA behaviors were coded, and salivary cortisol reactivity was measured. We also collected child, parent, and teacher reports of children's trait SA symptoms. The SM + HSA and HSA groups had similar observed non-verbal SA behavior, cortisol reactivity, and trait SA symptom levels according to parent and child reports, but SM + HSA children had significantly higher SA according to teacher report and observer-rated verbal SA behavior relative to the HSA group. As expected, control children had lower cortisol reactivity and SA across all measures relative to the other groups. Although SM and SAD in children share many similarities, SM may be characterized by greater SA in certain social contexts (e.g., school) and is distinguishable from SAD on behavioral measures of verbal SA.

Freeze-like responses to pain in humans and its modulation by social context

Background

Maladaptive defensive responses such as excessive avoidance behavior have received increasing attention as a main mechanism for the development and maintenance of chronic pain complaints. However, another defensive response which is commonly studied in animals as a proxy for fear is freezing behavior. No research to date has investigated human freezing behavior in the context of pain. In addition, there is an increasing realization that social context can affect pain-relevant processes such as pain experience and pain behavior but less is known about the effects of social context on defensive responses to pain. Hence, this study investigated freezing behavior and facial pain expression in the context of pain, and their modulation by social context.

Methods

Healthy, pain-free participants (N = 39) stood on a stabilometric force platform in a threatening or safe social context, which was manipulated using angry or happy facial stimuli. In some trials, an auditory cue (conditioned stimulus; CS) predicted the occurrence of painful electrocutaneous stimulus (unconditioned stimulus; pain-US). We assessed body sway (an index of freezing), heart rate, facial pain expression, self-reported pain intensity, unpleasantness, and pain-US expectancy during the CS and the context alone (no CS).

Results

The results were mixed. Neither the anticipation of pain, nor social context affected body sway. Heart rate and painful facial expression were reduced in the threatening social context at high anxiety levels. A threatening social context also elicited higher pain-US expectancy ratings. In sum, a threatening social context increases the expectation of pain, but reduces the facial expression of pain and lowers heart rate in highly anxious individuals.

Trajectories of Observed Shyness and Psychosocial Adjustment in Children

Shyness can manifest as inhibition, fear, and avoidance in the context of social novelty and situations of perceived social evaluation. In the present study, 130 children (M_age = 7.6 years, SD = 1.8) participated in a videotaped self-presentation task across three separate visits spanning approximately 3 years in early and middle childhood. Children's observed shyness was best characterized by two trajectories, including a high-stable class (19%) and a low-stable class (81%). Girls were more likely than boys to follow a pattern of high-stable observed shyness. Further, children in the high-stable observed shyness class were rated by parents and teachers as more socially anxious relative to children in the low-stable class, and boys in the high-stable observed shyness class were rated by their teachers as displaying more depressive symptoms relative to girls. These findings suggest that a subset of children display stable behavioral shyness, and this is correlated with psychosocial functioning.

Capturing temporal dynamics of fear behaviors on a moment-to-moment basis

Identifying patterns of fearful behaviors early and accurately is essential to identify children who may be at increased risk for psychopathology. Previous work focused on the total amount of fear by using composites across time. However, considering the temporal dynamics of fear expression might offer novel insights into the identification of children at risk. One hundred and twenty-five toddlers participated in high- and low-fear tasks. Data were modeled using a novel two-step approach. First, a hidden Markov model estimated latent fear states and transitions across states over time. Results revealed children's behavior was best represented by six behavioral states. Next, these states were analyzed using sequence clustering to identify groups of children with similar dynamic trajectories through the states. A four-cluster solution found groups of children varied in fear response and regulation process: "external regulators" (using the caregiver as a regulation tool), "low reactive" (low reaction to stimulus), "fearful explorers" (managing their own internal state with minimal assistance from the caregiver), and "high fear" (fearful/at-caregiver state regardless of task). The combination of analytic tools enabled fine-grained examination of the processes of fearful temperament. These insights may help prevention programs target behaviors that perpetuate anxious behavior in the moment.

Fear in infancy: Lessons from snakes, spiders, heights, and strangers

This review challenges the traditional interpretation of infants' and young children's responses to three types of potentially "fear-inducing" stimuli-snakes and spiders, heights, and strangers. The traditional account is that these stimuli are the objects of infants' earliest developing fears. We present evidence against the traditional account, and provide an alternative explanation of infants' behaviors toward each stimulus. Specifically, we propose that behaviors typically interpreted as "fearful" really reflect an array of stimulus-specific responses that are highly dependent on context, learning, and the perceptual features of the stimuli. We speculate about why researchers so commonly misinterpret these behaviors, and conclude with future directions for studying the development of fear in infants and young children. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Maternal stress and adolescent brain structure and function

INTRODUCTION

Adolescence is a time of heightened sensitivity in biological stress systems and the emergence of stress-related psychopathology. Thus, understanding environmental factors in adolescence that might be associated with adolescents'' stress systems is important. Maternal stress levels may be involved. However, the relationship between maternal stress and the adolescent brain is unknown.

METHOD

The present study examined the association between mothers' self-reported stress levels and mothers' cortisol stress reactivity and their early adolescents' brain structure and functional activation to stressful negative emotional images. Participants included 66 mothers and their 12- to 14-year old adolescents. Mother's perceived stress and salivary cortisol reactivity to a stressful task were collected. Then, adolescents' brain structure and function were assessed in a magnetic resonance imaging session.

RESULTS

Functional whole-brain analyses revealed that mothers' higher reported perceived stress, but not cortisol reactivity, predicted adolescents' higher responses in the medial prefrontal cortex (mPFC) to stressful negative emotional stimuli. There were no statistically significant associations for structural analyses.

CONCLUSIONS

Given the finding of maternal stress reactivity related to adolescent mPFC function-an integral structure related to stress responses-parent stress may play a role in the development of neural stress systems in adolescence, with potential implications for development of psychopathology.

Toward a Standardized Test of Fearful Temperament in Primates: A Sensitive Alternative to the Human Intruder Task for Laboratory-Housed Rhesus Macaques (Macaca mulatta)

Standardized and sensitive tests to assess differences in temperament among primates housed in captivity are essential for monitoring welfare and improving science outcomes through reduced noise in data. Fearful temperament in primates has traditionally been assessed using the Human Intruder Test (HIT) in which duration of bodily freeze in response to approach by an unknown human is measured. The HIT is susceptible to variation between facilities in execution, interpretation of data and could be stressful for animals with more fearful temperaments. We tested the applicability of a touch-screen task with putatively negative stimuli as a more standardizable and sensitive tool for measuring fearful temperament in laboratory primates. Seventeen adult male rhesus macaques were assessed for fearfulness using the HIT. They were then tested on a touch-screen task designed to measure two behavioral indices of fearfulness: behavioral inhibition and response-slowing. We predicted monkeys assessed as having more fearful temperament in the HIT, would show the greatest degree of behavioral inhibition and response-slowing to negative pictures in the touch-screen task. In Study 1, monkeys were rewarded with juice for touching gray squares on the screen (control trials). On test trials a picture of an unknown male conspecific face with direct-gaze (signaling threat) was shown. Monkeys were less likely to touch direct-gaze faces than control trials, indicating behavioral inhibition to threat. Behavioral inhibition was greatest amongst monkeys scored with most fearful temperament in the HIT. This primary result indicates the touch-screen task may be sensitive to a more subtle form of the bodily freeze behavior measured using the HIT. In Study 2, we tested whether these findings generalized to other classes of putatively negative stimuli; monkeys were shown pictures of the human intruder and objects associated with veterinary and husbandry procedures, interspersed with control trials (gray squares). There was no evidence of behavioral inhibition in Study 2. There was some evidence for response-slowing, which was greater for pictures of objects than pictures of the human intruder, and occurred independently of fearfulness in the HIT. We propose touch-screen tasks provide a more standardized and sensitive approach for assessing fearful temperament in laboratory primates.

Interaction Effects between the Cumulative Genetic Score and Psychosocial Stressor on Self-Reported Drinking Urge and Implicit Attentional Bias for Alcohol: A Human Laboratory Study

Aims

The current candidate gene and environment interaction (cGxE) study examined whether the effects of an experimentally manipulated psychosocial stressor on self-reported drinking urge and implicit attentional bias for alcohol cues differ as a function of a cumulative genetic score of 5-HTTLPR, MAO-A, DRD4, DAT1 and DRD2 genotypes. The current study also examined whether salivary alpha-amylase level or self-reported anxiety state mediate these cGxE effects.

Short Summary

Individuals with high cumulative genetic risk score of the five monoamergic genotypes showed greater attentional bias toward alcohol cues when exposed to a psychosocial stressor than when not exposed.

Methods

Frequent binge-drinking Caucasian young adults (N = 105; mean age = 19; 61% male) completed both the control condition and stress condition (using the Trier Social Stress Test) in order.

Results

Regarding attentional bias, individuals with high and medium cumulative genetic risk scores showed greater attentional bias toward alcohol stimuli in the stress condition than in the control condition, whereas, those with low genetic risk scores showed greater attentional bias toward alcohol stimuli in the control condition than in the stress condition. No mediating roles of salivary alpha-amylase and anxiety state in the cGxE effect were found. Regarding self-reported drinking urge, individuals with high cumulative genetic score reported greater drinking urge than those with low genetic score regardless of experimental conditions.

Conclusions

Although replication is necessary, the findings suggest that the association of a psychosocial stressor on implicit (but not explicit, self-reported) alcohol outcomes may differ as a function of the collective effects of five monoamine genes.

Maternal comforting behavior, toddlers' dysregulated fear, and toddlers' emotion regulatory behaviors

Developmental theories of emotion regulation suggest that influences from both extrinsic (e.g., from caregivers) and intrinsic (i.e., temperament) sources contribute to children's displays of emotion regulatory behaviors. Very few studies have examined specific caregiver behaviors in relation to specific regulatory behaviors. Further, few empirical investigations have tested theoretical notions that temperament may be an important context in which to understand the nature of the relation between caregiver behavior and toddlers' regulatory behaviors. The current study examined the specific maternal behavior of physical comfort in relation to three regulatory strategies exhibited by toddlers (attention-shifting, caregiver-focused behavior, and self-focused behavior) in 117 pairs of mothers and their 24-month-old toddlers. Further, we tested the temperament dimension of dysregulated fear, a more recent derivation of behavioral inhibition, both in relation to regulatory efforts and as a moderator of relations between maternal comforting and toddler regulatory behaviors. Dysregulated fear related directly and positively to attention-shifting, and it moderated the relation between maternal comforting and both caregiver-focused and self-focused behaviors. This study provides new evidence of the importance of both extrinsic and intrinsic correlates of emotion regulation in early childhood. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Understanding Emotion Inflexibility in Risk for Affective Disease: Integrating Current Research and Finding a Path Forward

Emotion-related disorders (e.g., depression, anxiety, stress, eating, substance and some personality disorders) include some of the most common, burdensome, and costly diseases worldwide. Central to many, if not all of these disorders, may be patterns of rigid or inflexible emotion responses. Indeed, theorists point to emotion in-flexibility as a potential cause or maintaining factor in emotion-related diseases. Despite the increasing prominence of emotion inflexibility in theories of affective disease, a comprehensive review of the developing empirical literature has not yet been conducted. Accordingly, this review will examine the three dominant lines of inquiry assessing emotion flexibility. These include: (1) the capacity to use and vary deliberate emotion regulation strategies, (2) the context sensitivity of spontaneous emotional responses, and (3) flexibility in the appraisal of emotional events and experiences. Moreover, current evidence suggests that each of these three lines of research may converge to suggest the interplay of two key biological dimensions in emotion inflexibility, threat sensitivity, and cognitive control, known to be impaired in patients with affective disorders. In short, this developing body of work suggests a path by which future research could explicate and even exploit the ties between emotion inflexibility and affective disease, contributing to the development of improved models of risk, assessment, and intervention, with broad implications for psychological health.

The psychobiology of emotional development: The case for examining sociocultural processes

Psychobiological techniques to assess emotional responding have revolutionized the field of emotional development in recent decades by equipping researchers with the tools to quantify children's emotional reactivity and regulation more directly than behavioral approaches allow. Knowledge gained from the incorporation of methods spanning levels of analysis has been substantial, yet many open questions remain. In this prospective review, we (a) describe the major conceptual and empirical advances that have resulted from this methodological innovation, and (b) lay out a case for what we view as the most pressing challenge for the next decades of research into the psychobiology of emotional development: focusing empirical efforts toward understanding the implications of the broader sociocultural contexts in which children develop that shape the psychobiology of emotion. Thus, this review integrates previous knowledge about the psychobiology of emotion with a forward-looking set of recommendations for incorporating sociocultural processes into future investigations.

Age-related changes in the dynamics of fear-related regulation in early childhood

Self-regulation is a dynamic process wherein executive processes (EP) delay, minimize or desist prepotent responses (PR) that arise in situations that threaten well-being. It is generally assumed that, over the course of early childhood, children expand and more effectively deploy their repertoire of EP-related strategies to regulate PR. However, longitudinal tests of these assumptions are scarce in part because self-regulation has been mostly studied as a static construct. This study engages dynamic systems modeling to examine developmental changes in self-regulation between ages 2 and 5 years. Second-by-second time-series data derived from behavioral observations of 112 children (63 boys) faced with novel laboratory-based situations designed to elicit wariness, hesitation, and fear were modeled using differential equation models designed to capture age-related changes in the intrinsic dynamics and bidirectional coupling of PR (fear/wariness) and EP (strategy use). Results revealed that dynamic models allow for the conceptualization and measurement of fear regulation as intrinsic processes as well as direct and indirect coupling between PR and EP. Several patterns of age-related changes were in line with developmental theory suggesting that PR weakened and was regulated more quickly and efficiently by EP at age 5 than at age 2. However, most findings were in the intrinsic dynamics and moderating influences between PR and EP rather than direct influences. The findings illustrate the precision with which specific aspects of self-regulation can be articulated using dynamic systems models, and how such models can be used to describe the development of self-regulation in nuanced and theoretically meaningful ways.

Immune and neuroendocrine correlates of temperament in infancy

There is now a clear focus on incorporating, and integrating, multiple levels of analysis in developmental science. The current study adds to research in this area by including markers of the immune and neuroendocrine systems in a longitudinal study of temperament in infants. Observational and parent-reported ratings of infant temperament, serum markers of the innate immune system, and cortisol reactivity from repeated salivary collections were examined in a sample of 123 infants who were assessed at 6 months and again when they were, on average, 17 months old. Blood from venipuncture was collected for analyses of nine select innate immune cytokines; salivary cortisol collected prior to and 15 min and 30 min following a physical exam including blood draw was used as an index of neuroendocrine functioning. Analyses indicated fairly minimal significant associations between biological markers and temperament at 6 months. However, by 17 months of age, we found reliable and nonoverlapping associations between observed fearful temperament and biological markers of the immune and neuroendocrine systems. The findings provide some of the earliest evidence of robust biological correlates of fear behavior with the immune system, and identify possible immune and neuroendocrine mechanisms for understanding the origins of behavioral development.

Non-linear Heart Rate Variability as a Discriminator of Internalizing Psychopathology and Negative Affect in Children With Internalizing Problems and Healthy Controls

Background: Internalizing psychopathology and dysregulated negative affect are characterized by dysregulation in the autonomic nervous system and reduced heart rate variability (HRV) due to increases in sympathetic activity alongside reduced vagal tone. The neurovisceral system is however, a complex nonlinear system, and nonlinear indices related to psychopathology are so far less studied in children. Essential nonlinear properties of a system can be found in two main domains: the informational domain and the invariant domain. sample entropy (SampEn) is a much-used method from the informational domain, while detrended fluctuation analysis (DFA) represents a widely-used method from the invariant domain. To see if nonlinear HRV can provide information beyond linear indices of autonomic activation, this study investigated SampEn and DFA as discriminators of internalizing psychopathology and negative affect alongside measures of vagally-mediated HRV and sympathetic activation. Material and Methods: Thirty-Two children with internalizing difficulties and 25 healthy controls (aged 9-13) were assessed with the Child Behavior Checklist and the Early Adolescent Temperament Questionnaire, Revised, giving an estimate of internalizing psychopathology, negative affect and effortful control, a protective factor against psychopathology. Five minute electrocardiogram and impedance cardiography recordings were collected during a resting baseline, giving estimates of SampEn, DFA short-term scaling exponent α1, root mean square of successive differences (RMSSD), and pre-ejection period (PEP). Between-group differences and correlations were assessed with parametric and non-parametric tests, and the relationships between cardiac variables, psychopathology and negative affect were assessed using generalized linear modeling. Results: SampEn and DFA were not significantly different between the groups. SampEn was weakly negatively related to heart rate (HR) in the controls, while DFA was moderately negatively related to RMSSD in both groups, and moderately positively related to HR in the clinical sample. SampEn was significantly associated with internalizing psychopathology and negative affect. DFA was significantly related to internalizing psychopathology. Conclusions: Higher invariant self-similarity was linked to less psychopathology. Higher informational entropy was related to less psychopathology and less negative affect, and may provide an index of the organizational flexibility of the neurovisceral system.

Investigation of the Stability of Human Freezing-Like Responses to Social Threat From Mid to Late Adolescence

Freezing behavior, a commonly observed defensive stress response, shows relatively high stability over time in animals. Given the relevance of freezing for stress-coping and human psychopathology, it is relevant to know whether freezing behavior is also stable in humans, particularly during adolescence, when most affective symptoms develop. In a prospective longitudinal study, we investigated freezing-like behavior in response to social threat in 75 adolescents at age 14, repeated 3 years later at age 17. We used a well-established method combining electrocardiography (ECG; heart rate) and posturography (body sway) in response to emotional picture-viewing of angry, happy, and neutral faces. We hypothesized that individual differences in freezing-like behavior in response to social threat—operationalized by contrasting angry vs. neutral faces—would be relatively stable over time. Our results indeed showed relative stability between ages 14 and 17 in individual differences in freezing-like behavior in heart rate (r = 0.82), as well as in combined heart rate and body sway measures (r = 0.65). These effects were not specific for the angry vs. neutral contrast; they were also visible in other emotion contrasts. Exploratory analysis in males and females separately showed stability in body sway specifically for angry vs. neutral faces only in females. Together, these results suggest moderate to strong stability in human freezing-like behavior in response to social threat from mid to late adolescence (with exception for the body sway measure in males). This relative stability was not specific for threat-induction and may reflect a general stability that is particularly strong for heart rate. The fact that this relative stability was found over a relatively long time range of 3 years is promising for studies aiming to use freezing-like behavior as a marker for internalizing symptoms in adolescent development.

Dysregulated Fear, Social Inhibition, and Respiratory Sinus Arrhythmia: A Replication and Extension

Behavioral inhibition indicates increased risk for development of social anxiety. Recent work has identified a pattern of dysregulated fear (DF), characterized by high fear in low-threat situations, that provides a more precise marker of developmental risk through early childhood. This study tested a new longitudinal sample of children (n = 124) from ages 24 to 48 months. Replicating prior findings, at 24 months, we identified a pattern of fearful behavior across contexts marked by higher fear to putatively low-threat situations. DF was associated with higher parental report of social inhibition at 24, 36, and 48 months. Extending prior findings, we observed differences in cardiac physiology during fear-eliciting situations, suggesting that the neurobiological underpinnings of DF relate to difficulty with regulation.

Freeze for action: neurobiological mechanisms in animal and human freezing

Upon increasing levels of threat, animals activate qualitatively different defensive modes, including freezing and active fight-or-flight reactions. Whereas freezing is a form of behavioural inhibition accompanied by parasympathetically dominated heart rate deceleration, fight-or-flight reactions are associated with sympathetically driven heart rate acceleration. Despite the potential relevance of freezing for human stress-coping, its phenomenology and neurobiological underpinnings remain largely unexplored in humans. Studies in rodents have shown that freezing depends on amygdala projections to the brainstem (periaqueductal grey). Recent neuroimaging studies in humans have indicated that similar brain regions may be involved in human freezing. In addition, flexibly shifting between freezing and active defensive modes is critical for adequate stress-coping and relies on fronto-amygdala connections. This review paper presents a model detailing these neural mechanisms involved in freezing and the shift to fight-or-flight action. Freezing is not a passive state but rather a parasympathetic brake on the motor system, relevant to perception and action preparation. Study of these defensive responses in humans may advance insights into human stress-related psychopathologies characterized by rigidity in behavioural stress reactions. The paper therefore concludes with a research agenda to stimulate translational animal–human research in this emerging field of human defensive stress responses.

This article is part of the themed issue ‘Movement suppression: brain mechanisms for stopping and stillness’.

A theoretical and empirical modeling of anxiety integrated with RDoC and temporal dynamics

The newly launched Research Domain Criteria (RDoC) emphasize specific mechanisms over diagnostic categories of psychopathology. In our view, RDoC provides a useful heuristic for mental health disorders, but does not capture the complexity of psychological data when proposed mechanisms are viewed as static entities. However, temporal and complex system dynamics may advance RDoC's utility. By investigating temporal patterns within trajectories and the interaction of complex networks, we propose that dynamic modeling provides comprehensive methods with which to investigate the etiopathology and maintenance of mental health disorders. We examine applications of dynamical systems to periphery physiology, an RDoC construct that has been widely used in psychological science. A review of the literature suggests methodological problems with aggregate and reductive models. We present a dynamical systems modeling of anxiety which suggests avenues for future biomarker research. This model appears congruent with RDoC and recent learning theory.

Defensive freezing links Hypothalamic-Pituitary-Adrenal-axis activity and internalizing symptoms in humans

The Hypothalamic-Pituitary-Adrenal (HPA)-axis plays an important role in the expression of defensive freezing. Adaptive freezing reactivity, characterized by an immediate increase in acute stress and timely termination upon threat offset or need to act, is essential for adequate stress coping. Blunted HPA-axis activity in animals is associated with blunted freezing reactivity and internalizing symptoms. Despite their potential relevance, it remains unknown whether these mechanisms apply to humans and human psychopathology. Using a well-established method combining electrocardiography and posturography, we assessed freezing before, immediately after, and one hour after a stress induction in 92 human adolescents. In line with animal models, human adolescents showed stress-induced freezing, as quantified by relative reductions in heart rate and body sway after, as compared to before, stress. Moreover, relatively lower basal cortisol was associated with reduced stress-induced freezing reactivity (i.e., less immediate freezing and less recovery). Path analyses showed that decreased freezing recovery in individuals with reduced cortisol levels was associated with increased levels of internalizing symptoms. These findings suggest that reduced freezing recovery may be a promising marker for the etiology of internalizing symptoms.

If You Go Down to the Woods Today: Infants' Distress During a Teddy Bear's Picnic in Relation to Peer Relations and Later Emotional Problems

Infants' emotional reactions to an unusual event were assessed at a simulated birthday party during which two costumed characters enacted a Teddy Bear's Picnic. Two hundred and fifty-eight firstborn infants in a representative British community sample were observed at a mean age of 12.8 months in the presence of their parents and other participating families, in a laboratory sitting room decorated with balloons and banners. The picnic scenario was followed by free play with the other participating infants. At a mean of 36 months of age, mothers, fathers, and another informant who knew the child well completed the Child Behaviour Check List (CBCL). The majority of infants showed no vocal distress during the picnic scenario. A minority of infants expressed strong distress, which was correlated with elevated heart rate and production of cortisol. Infants who were not distressed were more likely to direct social behavior to their peers and especially likely to use physical force against peers. In comparison with strongly distressed and nondistressed infants, those who had shown mild distress during the picnic scenario were least likely to manifest later emotional problems. This pattern was particularly marked for boys. Taken together, the findings indicate that infants' strong distress during naturalistic encounters that are meant to be entertaining can suppress sociability and might indicate risk for subsequent emotional problems.

Contextual influences on concordance between maternal report and laboratory observation of toddler fear

Emotion and temperament researchers have faced an enduring issue of how to best measure children's tendencies to express specific emotions. Inconsistencies between laboratory observation and parental report have made it challenging for researchers to determine the utility of these different forms of measurement. The current study examined the effect of laboratory episode characteristics (i.e., threat level of the episode, maternal involvement) on concordance between maternal report and laboratory observation of toddler fear. The sample included 111 mother-toddler dyads who participated in a laboratory assessment when toddlers were approximately 24 months old. Toddler fear was assessed both via maternal report and observation from a number of laboratory episodes that varied in their level of threat and whether mothers were free or constrained in their involvement in the task. Results indicated that maternal report related to the observed fear composites for low threat, but not high threat episodes. On the contrary, maternal involvement in the laboratory episodes did not moderate the relation between maternal report and laboratory observation of fear. These results suggest that the threat level of laboratory episodes designed to elicit fear, but not maternal involvement in these episodes, may be important to take into consideration when assessing their relation to maternal report of fear and fearful temperament. (PsycINFO Database Record

Toddler parasympathetic regulation and fear: Links to maternal appraisal and behavior

There is a growing recognition that parental socialization influences interact with young children's emerging capacity for physiological regulation and shape children's developmental trajectories. Nevertheless, the transactional processes linking parental socialization and physiological regulatory processes remain not well understood, particularly for fear-prone toddlers. To address this gap in the literature, the present study investigated the biopsychosocial processes that underlie toddlers' fear regulation by examining the relations among toddler parasympathetic regulation, maternal appraisal, and parenting behaviors. Participants included 124 mothers and their toddlers (Mage  = 24.43 months), who participated in a longitudinal study of temperament and socio-emotional development. Toddlers' parasympathetic reactivity was found to moderate the links between maternal anticipatory appraisal of child fearfulness and (a) maternal provision of physical comfort and (b) preschool-age child inhibition. Additionally, maternal comforting behaviors during the low-threat task predicted preschool-age separation distress, specifically for toddlers demonstrating a low baseline RSA.

Clinical anxiety promotes excessive response inhibition

BACKGROUND

Laboratory tasks to delineate anxiety disorder features are used to refine classification and inform our understanding of etiological mechanisms. The present study examines laboratory measures of response inhibition, specifically the inhibition of a pre-potent motor response, in clinical anxiety. Data on associations between anxiety and response inhibition remain inconsistent, perhaps because of dissociable effects of clinical anxiety and experimentally manipulated state anxiety. Few studies directly assess the independent and interacting effects of these two anxiety types (state v. disorder) on response inhibition. The current study accomplished this goal, by manipulating state anxiety in healthy and clinically anxious individuals while they complete a response inhibition task.

METHOD

The study employs the threat-of-shock paradigm, one of the best-established manipulations for robustly increasing state anxiety. Participants included 82 adults (41 healthy; 41 patients with an anxiety disorder). A go/nogo task with highly frequent go trials was administered during alternating periods of safety and shock threat. Signal detection theory was used to quantify response bias and signal-detection sensitivity.

RESULTS

There were independent effects of anxiety and clinical anxiety on response inhibition. In both groups, heightened anxiety facilitated response inhibition, leading to reduced nogo commission errors. Compared with the healthy group, clinical anxiety was associated with excessive response inhibition and increased go omission errors in both the safe and threat conditions.

CONCLUSIONS

Response inhibition and its impact on go omission errors appear to be a promising behavioral marker of clinical anxiety. These results have implications for a dimensional view of clinical anxiety.

Prenatal Stress, Fearfulness, and the Epigenome: Exploratory Analysis of Sex Differences in DNA Methylation of the Glucocorticoid Receptor Gene

Exposure to stress in utero is a risk factor for the development of problem behavior in the offspring, though precise pathways are unknown. We examined whether DNA methylation of the glucocorticoid receptor gene, NR3C1, was associated with experiences of stress by an expectant mother and fearfulness in her infant. Mothers reported on prenatal stress and infant temperament when infants were 5 months old (n = 68). Buccal cells for methylation analysis were collected from each infant. Prenatal stress was not related to infant fearfulness or NR3C1 methylation in the sample as a whole. Exploratory sex-specific analysis revealed a trend-level association between prenatal stress and increased methylation of NR3C1 exon 1F for female, but not male, infants. In addition, increased methylation was significantly associated with greater fearfulness for females. Results suggest an experience-dependent pathway to fearfulness for female infants via epigenetic modification of the glucocorticoid receptor gene. Future studies should examine prenatal stress in a comprehensive fashion while considering sex differences in epigenetic processes underlying infant temperament.

Attention Biases Towards and Away from Threat Mark the Relation between Early Dysregulated Fear and the Later Emergence of Social Withdrawal

Fearful temperament, mostly studied as behavioral inhibition (BI), has been extensively associated with social withdrawal in childhood and the later emergence of anxiety disorders, especially social anxiety disorder (SAD). Recent studies have characterized a distinct type of fearful temperament marked by high levels of fear in low threat situations - labeled dysregulated fear. Dysregulated fear has been related to SAD over and above risks associated with BI. However, the mechanism by which dysregulated fear is related to SAD has not been studied. Cognitive mechanisms, such as attentional bias towards threat, may be a possible conduit. We examined differences in attentional bias towards threat in six-year-olds who displayed a pattern of dysregulated fear at age two (N = 23) compared with children who did not display dysregulated fear (N = 33). Moreover, we examined the concurrent relation between attentional bias and social withdrawal. Results indicated that children characterized by dysregulated fear showed a significant bias away from threat, and that this bias was significantly different from the children without dysregulated fear, who showed no significant bias. Moreover, attentional bias towards threat was positively related to social withdrawal only for the dysregulated fear group. These results are discussed in consideration of the existing knowledge of attentional bias to threat in the developmental and pediatric anxiety literatures, as well as recent studies that find important heterogeneity in attentional bias.

Dysfunctional Freezing Responses to Approaching Stimuli in Persons with a Looming Cognitive Style for Physical Threats

Immobilizing freezing responses are associated with anxiety and may be etiologically related to several anxiety disorders. Although recent studies have sought to investigate the underlying mechanisms in freezing responses that are so problematic in many forms of anxiety, cognitive factors related to anxiety have not been investigated. This study was designed to investigate the potential moderating role of a well-documented cognitive vulnerability to anxiety, the Looming Cognitive Style (i.e., LCS; Riskind et al., 2000), which assesses the extent to which individuals tend to routinely interpret ambiguous threats (e.g., physical or social threats) in a biased manner as approaching. We assessed participants' Reaction Times (RTs) when they made judgments about images of animals that differed in threat valence (threat or neutral) and motion direction (approach or recede). As expected, LCS for concerns about the approach of physical dangers appeared to moderate freeze reactions. Individuals who were high on this LCS factor tended to generally exhibit a freeze-response (slower RTs) and this was independent of the threat valence or motion direction of the animals. These general freezing reactions were in stark contrast to those of individuals who were low on the LCS factor for concerns about the approach of physical dangers. These participants tended to exhibit more selective and functional freezing responses that occurred only to threatening animals with approach motion; they did not exhibit freezing to neutral stimuli or any stimuli with receding motion. These findings did not appear to be explicable by a general slowing of RTs for the participants with high LCS. Moreover, the LCS factor for concerns about social threats (such as rejection or embarrassment) was not related to differences in freezing; there was also no additional relationship of freezing to behavioral inhibition scores on the Behavioral Inhibition System and the Behavioral Activation System Scales (BIS/BAS). It may prove fruitful to further explore cognitive factors related to anxiety to develop a more comprehensive understanding of how these factors are associated with anxiety-related freezing responses.

Improving the Prediction of Risk for Anxiety Development in Temperamentally Fearful Children

Pediatric anxiety disorders are among the most common disorders in children and adolescence resulting in both short-term and long-term negative consequences across a variety of domains including social and academic. Early fearful temperament has emerged as a strong predictor of anxiety development in childhood; however, not all fearful children become anxious. The current article summarizes theory and evidence for heterogeneity in the identification of temperamentally fearful children and trajectories of risk for anxiety. The findings presented in this article reveal that identification of subgroups of fearful temperament improves prediction of who is at risk for developing anxiety problems.

Emotion Evaluation and Response Slowing in a Non-Human Primate: New Directions for Cognitive Bias Measures of Animal Emotion?

The cognitive bias model of animal welfare assessment is informed by studies with humans demonstrating that the interaction between emotion and cognition can be detected using laboratory tasks. A limitation of cognitive bias tasks is the amount of training required by animals prior to testing. A potential solution is to use biologically relevant stimuli that trigger innate emotional responses. Here; we develop a new method to assess emotion in rhesus macaques; informed by paradigms used with humans: emotional Stroop; visual cueing and; in particular; response slowing. In humans; performance on a simple cognitive task can become impaired when emotional distractor content is displayed. Importantly; responses become slower in anxious individuals in the presence of mild threat; a pattern not seen in non-anxious individuals; who are able to effectively process and disengage from the distractor. Here; we present a proof-of-concept study; demonstrating that rhesus macaques show slowing of responses in a simple touch-screen task when emotional content is introduced; but only when they had recently experienced a presumably stressful veterinary inspection. Our results indicate the presence of a subtle “cognitive freeze” response; the measurement of which may provide a means of identifying negative shifts in emotion in animals.

Do Infant Temperament Characteristics Predict Core Academic Abilities in Preschool-Aged Children?

Examined relationships between temperament, measured via parent report at 4 months and structures laboratory observations at 12 months of age, and a school readiness battery administered at about 4 years of age (N=31). Scores on the School Readiness Assessment of the Bracken Basic Concept Scale (BBCS) were related to infant Positive Affectivity/Surgency (PAS), with infants described as demonstrating higher levels of PAS at 4 months of age later demonstrating greater school readiness in the domains of color, letter, and number skills. Regulatory Capacity/Orienting (RCO) at 4 months also predicted color skills, with more regulated infants demonstrating superior pre-academic functioning in this area. Analyses involving laboratory observations of temperament provided additional information concerning the importance of infant Positive Affectivity/Surgency, predictive of overall letter skills and overall school-readiness scores later in childhood. Results are discussed in the context of implications for theory and research, as well as early education settings.

Toddlers' dysregulated fear predicts delta-beta coupling during preschool

Dysregulated fear, or the persistence of high levels of fear in low-threat contexts, is an early risk factor for the development of anxiety symptoms. Previous work has suggested both propensities for over-control and under-control of fearfulness as risk factors for anxiety problems, each of which may be relevant to observations of dysregulated fear. Given difficulty disentangling over-control and under-control through traditional behavioral measures, we used delta–beta coupling to begin to understand the degree to which dysregulated fear may reflect propensities for over- or under-control. We found that toddlers who showed high levels of dysregulated fear evidenced greater delta–beta coupling at frontal and central electrode sites as preschoolers relative to children who were low in dysregulated fear. Importantly, these differences were not observed when comparisons were made based on fear levels in high threat contexts. Results suggest dysregulated fear may involve tendencies toward over-control at the neural level.

Early deprivation and autonomic nervous system functioning in post-institutionalized children

The relations between early deprivation and the development of the neuroendocrine and central components of the mammalian stress response have been examined frequently. However, little is known about the impact of early deprivation on the developmental trajectories of autonomic function. Children adopted between 15-36 months from institutional care were examined during their first 16 months post-adoption (N = 60). Comparison groups included same-aged peers reared in their birth families (N = 50) and children adopted internationally from overseas foster care (N = 46). The present study examined trajectories of baseline autonomic nervous system function longitudinally following entry into adopted families. Post-institutionalized children had higher sympathetic tone, measured by pre-ejection period (PEP). Individual differences in PEP soon after adoption served as a mediator between early deprivation and parent-reported behavioral problems 2 years post-adoption. There were no group differences in parasympathetic function, indexed by respiratory sinus arrhythmia. All three groups showed similar trajectories of ANS function across the 16 month period.