Reliability of an "At-Home" Method for Monitoring Resting and Reactive Autonomic Nervous System Activity in Children: A Pilot Study

BACKGROUND

Heart rate variability (HRV), an index of the functional status of the autonomic nervous system (ANS), provides an opportunity for early detection of ANS dysfunction. Lower resting, vagally related HRV parameters are associated with increased risk of physical and mental illness. External factors influencing the ANS, such as the testing environment, may impact the interpretation of HRV. This study's main aim was to determine the reliability of HRV resting and reactivity tests performed at home with children aged 4-9 years.

METHODS

Fourteen healthy children (female n = 8) aged 6.8 ± 1.5 years participated. Two HRV tests were performed at home via online supervision 7 days apart using a Polar H10 heart rate monitor. The absolute and relative reliability of the pre-exercise resting (5 min) and sub-maximal exercise step test recovery (4 × 30 s segments) HRV time and frequency domains were calculated.

RESULTS

The Pearson correlation coefficients for day 1 versus day 7 for the vagal activity HRV domains (RMSSD log) at rest and in the first 30 s and 30-60 s of recovery indicated good-to-excellent relative reliability (r > 0.8, p < 0.01). Absolute reliability was moderate for the resting RMSSD log, with a coefficient of variation (CV) of 5.2% (90% CI: 3.9, 7.8%), high for the first 30 s of standing recovery, with a CV of 10.7% (90% CI: 8.2, 15.7%), and moderate for 30-60 s of recovery, with a CV of 8.7% (90% CI: 6.6, 12.9%).

CONCLUSIONS

The findings of this pilot study indicate that the resting and exercise recovery HRV measures of vagal activity can be measured reliably at home in children. This represents a novel "at-home" protocol for monitoring ANS health and development in children.

Insight and non-insight problem solving: A heart rate variability study

Occasionally, problems are solved with a sudden Aha! moment (insight), while the mundane approach to solving problems is analytical (non-insight). At first glance, non-insight appears to depend on the availability and taxation of cognitive resources to execute the step-by-step approach, whereas insight does not, or to a lesser extent. However, this remains debated. To investigate the reliance of both solution types on cognitive resources, we assessed the involvement of the prefrontal cortex using vagally mediated heart rate variability (vmHRV) as an index. Participants (N = 68) solved 70 compound remote associates word puzzles solvable with insight and non-insight. Before, during, and after solving the word puzzles, we measured the vmHRV. Our results showed that resting-state vmHRV (trait) showed a negative association with behavioural performance for both solution types. This might reflect inter-individual differences in inhibitory control. As the solution search requires one to think of remote associations, inhibitory control might hamper rather than aid this process. Furthermore, we observed, for both solution types, a vmHRV increase from resting-state to solution search (state), lingering on in the post-task recovery period. This could mark the increase of prefrontal resources to promote an open-minded stance, essential for divergent thinking, which arguably is crucial for this task. Our findings suggest that, at a general level, both solution types share common aspects. However, a closer analysis of early and late solutions and puzzle difficulty suggested that metacognitive differentiation between insight and non-insight improved with higher trait vmHRV, and that a unique association between trait vmHRV and puzzle difficulty was present for each solution type.

Variation in coupling across neural and cardiac systems of regulation is linked to markers of anxiety risk in preschool

Both cortical and parasympathetic systems are believed to regulate emotional arousal in the service of healthy development. Systemic coordination, or coupling, between putative regulatory functions begins in early childhood. Yet the degree of coupling between cortical and parasympathetic systems in young children remains unclear, particularly in relation to the development of typical or atypical emotion function. We tested whether cortical (ERN) and parasympathetic (respiratory sinus arrhythmia [RSA]) markers of regulation were coupled during cognitive challenge in preschoolers (N = 121). We found no main effect of RSA predicting ERN. We then tested children's typical and atypical emotion behavior (context-appropriate/context-inappropriate fear, anxiety symptoms, neuroendocrine reactivity) as moderators of early coupling in an effort to link patterns of coupling to adaptive emotional development. Negative coupling (i.e., smaller ERN, more RSA suppression or larger ERN, less RSA suppression) at age 3 was associated with greater atypical and less typical emotion behaviors, indicative of greater risk. Negative age 3 coupling was also visible for children who had greater Generalized Anxiety Disorder symptoms and blunted cortisol reactivity at age 5. Results suggest that negative coupling may reflect a maladaptive pattern across regulatory systems that is identifiable during the preschool years.

Examining transactional associations between maternal internalizing symptoms, infant negative emotionality, and infant respiratory sinus arrhythmia

The current study examined transactional associations between maternal internalizing symptoms, infant negative emotionality, and infant resting respiratory sinus arrhythmia (RSA). We used data from the Longitudinal Attention and Temperament Study (N = 217) to examine the associations between maternal internalizing symptoms, infant negative emotionality, and infant resting RSA from 4-months to 18-months using a random-intercepts cross-lagged panel model. We found that mothers with higher average internalizing symptoms have infants with higher levels of resting RSA. However, there were no stable, between-individual differences in infant negative emotionality across time. Additionally, we found significant negative within-dyad cross-lagged associations from maternal internalizing symptoms to subsequent measures of infant negative emotionality, as well as a significant negative cross-lagged association from maternal internalizing symptoms to child resting RSA after 12-months of age. Lastly, we find evidence for infant-directed effects of negative emotionality and resting RSA to maternal internalizing symptoms. Results highlight the complex, bidirectional associations in maternal-infant dyads during the first two years of life, and the importance of considering the co-development of infant reactivity and regulatory processes in the context of maternal internalizing symptoms.

Preschoolers' emotion reactivity and regulation: Links with maternal psychological distress and child behavior problems

Maladaptive offspring emotion regulation has been identified as one pathway linking maternal and child psychological well-being in school-aged children. Whether such a pathway is present earlier in life still remains unclear. The present study investigated the role of preschoolers' emotion reactivity and regulation in the association between maternal psychological distress and child internalizing and externalizing problems. Children's emotion reactivity and regulation were assessed through both observed behavior and physiology. At 42 months of age, children (n = 251; 128 girls) completed a fear induction task during which their heart-rate variability was assessed and their behavior was monitored, and maternal self-reports on depressive mood and anxiety were collected. At 48 months mothers and fathers reported on their children's internalizing and externalizing problems. Higher maternal depressive mood was associated with lower child fear-related reactivity and regulation, as indexed by heart-rate variability. The latter mediated the association between higher maternal depressive mood and higher preschoolers' externalizing problems. Overall, our findings support the role of preschoolers' emotion reactivity and regulation in the relationship between maternal psychological distress and children's socio-emotional difficulties. This role may also depend on the discrete emotion to which children react or seek to regulate as, here, we only assessed fear-related reactivity and regulation.

Coregulation: A Multilevel Approach via Biology and Behavior

In this article, we explore the concept of coregulation, which encompasses the mutual adaptation between partners in response to one another's biology and behavior. Coregulation operates at both biological (hormonal and nervous system) and behavioral (affective and cognitive) levels and plays a crucial role in the development of self-regulation. Coregulation extends beyond the actions of individuals in a dyad and involves interactive contributions of both partners. We use as an example parent-child coregulation, which is pervasive and expected, as it emerges from shared genetic relatedness, cohabitation, continuous interaction, and the influence of common factors like culture, which facilitate interpersonal coregulation. We also highlight the emerging field of neural attunement, which investigates the coordination of brain-based neural activities between individuals, particularly in social interactions. Understanding the mechanisms and significance of neural attunement adds a new dimension to our understanding of coregulation and its implications for parent-child relationships and child development.

Allostasis and metastasis: The yin and yang of childhood self-regulation

Most research has studied self-regulation by presenting experimenter-controlled test stimuli and measuring change between baseline and stimulus. In the real world, however, stressors do not flash on and off in a predetermined sequence, and there is no experimenter controlling things. Rather, the real world is continuous and stressful events can occur through self-sustaining interactive chain reactions. Self-regulation is an active process through which we adaptively select which aspects of the social environment we attend to from one moment to the next. Here, we describe this dynamic interactive process by contrasting two mechanisms that underpin it: the "yin" and "yang" of self-regulation. The first mechanism is allostasis, the dynamical principle underlying self-regulation, through which we compensate for change to maintain homeostasis. This involves upregulating in some situations and downregulating in others. The second mechanism is metastasis, the dynamical principle underling dysregulation. Through metastasis, small initial perturbations can become progressively amplified over time. We contrast these processes at the individual level (i.e., examining moment-to-moment change in one child, considered independently) and also at the inter-personal level (i.e., examining change across a dyad, such as a parent-child dyad). Finally, we discuss practical implications of this approach in improving the self-regulation of emotion and cognition, in typical development and psychopathology.

Childhood violence exposure and externalizing behaviors: A systematic review of the role of physiological biomarkers

Childhood exposure to violence has been consistently linked to externalizing behaviors like delinquency and aggression. Growing evidence indicates that physiological biomarkers from the parasympathetic and sympathetic nervous systems (PNS and SNS) and hypothalamic-pituitary-adrenal (HPA) axis may moderate or mediate the relation between childhood violence exposure and externalizing behaviors. We conducted a systematic review to synthesize recent findings on physiological biomarkers as mediators and/or moderators of this association across the life course, using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Our search yielded 3878 articles, of which 44 met inclusion criteria (describing a total of 46 independent studies). We found consistent evidence for blunted HPA-axis reactivity as a mediator of the relation between childhood violence exposure and subsequent externalizing behaviors, and for non-reciprocal PNS/SNS activation as moderators exacerbating this relation. However, the results of the majority of included studies that demonstrated significant moderating effects of physiological biomarkers varied by participant sex, type of childhood violence exposure, and type of stimuli used to induce physiological reactivity. The observed mixed findings are consistent with some theories that emphasize that both high and low stress reactivity can be adaptive depending on one's early environment. These findings highlight the need for systematic explorations of heterogeneity, theory-driven research questions, and longitudinal studies that span multiple developmental periods and multiple biological systems. Clinical implications include the need to assess physiological biomarkers in treatment and intervention studies and the potential to target interventions based on both autonomic functioning and environmental contexts.

Developmental Pathways from Prenatal Substance Exposure to Reactive Aggression

Few studies have examined etiological pathways from prenatal substance exposure to adolescent reactive aggression. We tested a conceptual model that included hypothesized pathways from prenatal substance exposure to adolescent aggression via autonomic reactivity and violence exposure from infancy to early school age and maternal harshness across early childhood. The sample included 216 families (106 boys) who primarily self-identified as Black or Mixed Race. Results supported the hypothesized path from violence exposure across early childhood and early school age to school age autonomic reactivity and early adolescent reactive aggression. There was also a significant interaction effect of sympathetic and parasympathetic reactivity on adolescent reactive aggression, with sympathetic arousal and parasympathetic suppression at early school age associated with higher reactive relational and physical aggression in adolescence. Results emphasize the importance of early experiences and autonomic nervous system changes in contributing to the cascade of risk for reactive aggression in early adolescence.

Parents' Maltreatment Histories, Dimensions of Emotion Regulation, and Connections to Offspring Self-Regulation: A Sex-Specific Transmission Pathway

Introduction

Parents with childhood maltreatment histories are at risk for emotion regulation (ER) problems, which are associated with reduced self-regulation among their offspring. However, gaps remain in the literature regarding this indirect transmission pathway. First, ER consists of multiple dimensions and it is unclear which dimension is most affected by childhood maltreatment. Second, less is known regarding which parental ER dimension is linked to offspring self-regulation. Thus, the present study aimed to examine the direct and indirect associations between parental maltreatment histories and child self-regulatory capacity via dimensions of parental ER.

Methods

In this cross-sectional study, 101 youth (75% African American/Black; 53% female; M _age = 10.28; SD = 1.19) and their primary caregivers were recruited from a low-income community in the Southeastern United States. Structural equation modeling was used to model the effect of parents' self-reported childhood maltreatment on youth physiological self-regulation (measured by heart rate variability reactivity [HRV-R]), via parents' self-reported ER.

Results

Parental maltreatment history was significantly associated with five of the six components of ER. Further, the indirect effect of parents' childhood maltreatment on child HRV-R was significant when parents reported more difficulty engaging goal-directed behaviors. Moderation analyses by sex showed that daughters had greater dysregulation regardless of parental maltreatment histories, while parents' ER was found to play a more significant role in the intergenerational transmission of dysregulation to sons.

Conclusions

The current study extends the literature on self-regulation development in children of low-income, maltreatment-exposed parents. Our study may inform parent-child interventions for improving self-regulation.

Infant physiological activity and the early emergence of social communication

Early in life, social engagement is facilitated by effective regulation during times of rest and stress. Physiological regulation during social play and in response to sudden environmental changes or social stressors may play an important role in sustaining social engagement in infancy and facilitate the acquisition of early social-communication skills. The aim of this study was to investigate the role of physiological activity during social play, including respiratory sinus arrhythsmia (RSA) and heart rate-defined attention, in the early emergence of social-communication skills. Using RSA as an index of vagal tone, we measured vagal tone, vagal suppression, and heart rate-defined sustained attention during a social interaction with a caregiver (i.e., the Still-Face procedure) in 21 infants aged 3-4 months. At 9 months, caregivers reported on their infant's early social-communication skills. Results suggest that RSA, RSA suppression, and heart rate-defined sustained attention to a caregiver are significantly associated with early-emerging social-communication skills at 9 months. In addition, RSA and heart rate-defined sustained attention during social play were highly related. Suppression of RSA during the Still-Face phase of the infant-caregiver interaction emerged as a particularly strong predictor of later-developing social-communication skills, including 9-month-olds' ability to use eye gaze, facial expression, and gestures to communicate.

Characterizing change in vagal tone during the first three years of life: A systematic review and empirical examination across two longitudinal samples

Functioning of the parasympathetic nervous system (PNS), most often indexed by respiratory sinus arrhythmia (RSA), influences the volitional, cognitively-mediated forms of self-regulation across development. However, despite its clear relevance to children's self-regulation, and its utility as a transdiagnostic biomarker of emotion dysregulation and psychopathology, the ontogeny of vagal tone under conditions of homeostasis across infancy and early childhood is not well understood. The current research is comprised of two complementary studies. The first aims to address this gap by conducting a systematic review of the literature which has assessed resting RSA in the first three years of life. The second study uses data from two diverse, longitudinal datasets (n = 203 and n = 370) to model change in RSA from infancy to toddlerhood. Results from a systematic review of 62 studies meeting inclusion criteria suggest that measures of resting RSA increase over time and demonstrate moderate stability across infancy, toddlerhood, and preschool ages. Results from a series of models fit to longitudinal data in study two suggest that baseline RSA is characterized by stable increases across infancy and early childhood. Moreover, although there was equivocal evidence for individual variability in trajectories of RSA, the findings suggest that the individual differences in resting RSA may become entrenched in early life based on observed significant variance in growth model intercepts. In all, the current study contributes to our understanding of the developmental trajectories of baseline RSA across infancy and early childhood and should support future research examining links between children's parasympathetic regulation and their adjustment in early life.

Prenatal origins of temperament: Fetal cardiac development & infant surgency, negative affectivity, and regulation/orienting

Temperament, i.e. individual differences in reactivity and self-regulation, emerges early in infancy; might temperament originate during fetal development? Mixed findings and methodological issues in the literature examining this consideration limit our understanding of the continuity between these fetal indices and infant temperament. The primary aims of the current study were to improve on published studies by (a) using standardized and well-accepted fetal cardiac (actocardiograph) and infant temperament measures (the Infant Behavior Questionnaire-Revised; IBQ-R) (b) expanding fetal assessments to include coupling (the cross correlation of heart rate with movement), and (c) examining a diverse sample to determine if findings of associations between fetal neurobehavior and infant temperament generalize beyond cohorts that are demographically well-resourced and predominantly white. Building on theory and empirical findings, we hypothesized that (1) FHR would be positively associated with Surgency and Negative Affectivity, (2) FHRV would be positively associated with Surgency, and Regulation/Orienting and inversely associated with Negative Affectivity, and (3) fetal coupling would be positively associated with Regulation/Orienting and Surgency and inversely associated with Negative Affectivity. We collected 20 min of fetal data (m gestational age = 34.42 weeks) and mothers completed the IBQ-R (n = 90 women; 60 % non-Caucasian race; 63 % Latina ethnicity). We found that FHR was positively associated with Negative Affectivity but not associated with Surgency (or Regulation/Orienting). FHRV was inversely associated with Surgency but not associated with Negative Affectivity or Regulation/Orienting. Coupling was positively associated with Regulation/Orienting and Surgency but not associated with Negative Affectivity. Our findings, from a more diverse sample and with established measures, provide further evidence that individual differences in reactivity and regulation can be identified in the in-utero period and show theory-based continuity to specific infant temperament constructs.

An examination of the reciprocal and concurrent relations between behavioral and cardiac indicators of acute pain in toddlerhood

The aim of this study was to examine the concurrent and predictive relations between healthy toddlers' pain behavior and cardiac indicators (ie, heart rate [HR] and respiratory sinus arrhythmia [RSA]) during routine vaccinations. Caregiver-infant dyads were part of a longitudinal cohort observed during their 12- and 18-month vaccinations. Behavioral and cardiac data were simultaneously collected for 1-minute preneedle and 3-minutes postneedle. Videotapes were coded for pain behaviors (FLACC; Merkel et al., 1997), and cardiac data were analyzed (HR, RSA) during sequential 30-second epochs. Four separate cross-lagged path models were estimated using data from the 12- (n = 147) and 18-month (n = 122) vaccinations. Across 12- and 18-month vaccinations, predictive within-measure relations were consistent for FLACC, HR, and RSA, reflecting good stability of these pain indicators. Behavioral indicators predicted subsequent HR and RSA within the immediate postneedle period. Both baseline behavior and HR/RSA predicted future pain scores. Concurrent residual relations between behavioral and cardiac indicators were inconsistent across time and indicators. Results suggest that behavioral and cardiac indicators reflect unique aspects of the nociceptive response. As such, multimodal assessment tools should be used and contextualized by child age, cardiac indicator, baseline behavior/physiology, and pain phase.

Trajectories of sleep problems in childhood: associations with mental health in adolescence

STUDY OBJECTIVES

We examined initial levels (intercepts) of sleep-wake problems in childhood and changes in sleep-wake problems across late childhood (slopes) as predictors of externalizing behavior problems, depressive symptoms, and anxiety in adolescence. To ascertain the unique effects of childhood sleep problems on adolescent mental health, we controlled for both childhood mental health and adolescent sleep problems.

METHODS

Participants were 199 youth (52% boys; 65% White/European American, 35% Black/African American). Sleep-wake problems (e.g. difficulty sleeping and waking up in the morning) were assessed during three time points in late childhood (ages 9, 10, and 11) with self-reports on the well-established School Sleep Habits Survey. At age 18, multiple domains of mental health (externalizing behavior problems, depressive symptoms, and anxiety) and sleep-wake problems were assessed.

RESULTS

Latent growth curve modeling revealed that children with higher levels of sleep-wake problems at age 9 had consistently higher levels of such problems between ages 9 and 11. The initial level of sleep-wake problems at age 9 predicted externalizing behaviors, depressive symptoms, and anxiety at age 18, controlling for mental health in childhood and concurrent sleep-wake problems in adolescence. The slope of sleep-wake problems from ages 9 to 11 did not predict age 18 mental health.

CONCLUSIONS

Youth who had higher sleep-wake problems during late childhood had higher levels of mental health problems in adolescence even after controlling for childhood mental health and concurrent sleep-wake problems. Findings illustrate that childhood sleep problems may persist and predict adolescent mental health even when potentially confounding variables are rigorously controlled.

Maternal dynamic respiratory sinus arrhythmia during toddlers' interactions with novelty

Maternal psychophysiological responses to toddlers' distress to novelty may have important implications for parenting during early childhood that are relevant to children's eventual development of social withdrawal and anxiety. Likely, these responses depend on intrapersonal, interpersonal, and contextual factors. The current study investigated the time course of respiratory sinus arrhythmia (RSA) across two laboratory novelty episodes, one low threat and one moderate threat, in 120 mothers of 2-year-old toddlers. Growth models tested context differences in and correlates of dynamic patterns of RSA. Dynamic patterns differed between tasks and according to mothers' perceptions of and distress about toddler shyness. Thus, changes in mothers' RSA across toddlers' interactions with novelty seem to depend on the context as well as how mothers perceive and respond to their toddlers' shyness.

Maturation of the Cardiac Autonomic Nervous System Activity in Children and Adolescents

Background

Despite the increasing interest in cardiac autonomic nervous activity, the normal development is not fully understood. The main aim was to determine the maturation of different cardiac sympathetic‐(SNS) and parasympathetic nervous system (PNS) activity parameters in healthy patients aged 0.5 to 20 years. A second aim was to determine potential sex differences.

Methods and Results

Five studies covering the 0.5‐ to 20‐year age range provided impedance‐ and electrocardiography recordings from which heart rate, different PNS‐parameters (eg, respiratory sinus arrhythmia) and an SNS‐parameter (pre‐ejection period) were collected. Age trends were computed in the mean values across 12 age‐bins and in the age‐specific variances. Age was associated with changes in mean and variance of all parameters. PNS‐activity followed a cubic trend, with an exponential increase from infancy, a plateau phase during middle childhood, followed by a decrease to adolescence. SNS‐activity showed a more linear trend, with a gradual decrease from infancy to adolescence. Boys had higher SNS‐activity at ages 11 to 15 years, while PNS‐activity was higher at 5 and 11 to 12 years with the plateau level reached earlier in girls. Interindividual variation was high at all ages. Variance was reasonably stable for SNS‐ and the log‐transformed PNS‐parameters.

Conclusions

Cardiac PNS‐ and SNS‐activity in childhood follows different maturational trajectories. Whereas PNS‐activity shows a cubic trend with a plateau phase during middle childhood, SNS‐activity shows a linear decrease from 0.5 to 20 years. Despite the large samples used, clinical use of the sex‐specific centile and percentile normative values is modest in view of the large individual differences, even within narrow age bands.

Physiological measurement of emotion from infancy to preschool: A systematic review and meta-analysis

INTRODUCTION

Emotion regulation, the ability to regulate emotional responses to environmental stimuli, develops in the first years of life and plays an important role in the development of personality, social competence, and behavior. Substantial literature suggests a relationship between emotion regulation and cardiac physiology; specifically, heart rate changes in response to positive or negative emotion-eliciting stimuli.

METHOD

This systematic review and meta-analysis provide an in-depth examination of research that has measured physiological responding during emotional-evoking tasks in children from birth to 4 years of age.

RESULTS

The review had three main findings. First, meta-regressions resulted in an age-related decrease in baseline and task-related heart rate (HR) and increases in baseline and task-related respiratory sinus arrhythmia (RSA). Second, meta-analyses suggest task-related increases in HR and decreases in RSA and heart rate variability (HRV), regardless of emotional valence of the task. Third, associations between physiological responding and observed behavioral regulation are not consistently present in children aged 4 and younger. The review also provides a summary of the various methodology used to measure physiological reactions to emotional-evoking tasks, including number of sensors used and placement, various baseline and emotional-evoking tasks used, methods for extracting RSA, as well as percentage of loss and reasons for loss for each study.

CONCLUSION

Characterizing the physiological reactivity of typically developing children is important to understanding the role emotional regulation plays in typical and atypical development.

Brain and motor synchrony in children and adolescents with ASD-a fNIRS hyperscanning study

Brain-to-brain synchrony has been proposed as an important mechanism underlying social interaction. While first findings indicate that it may be modulated in children with autism spectrum disorder (ASD), no study to date has investigated the influence of different interaction partners and task characteristics. Using functional near-infrared spectroscopy hyperscanning, we assessed brain-to-brain synchrony in 41 male typically developing (TD) children (8-18 years; control sample), as well as 18 children with ASD and age-matched TD children (matched sample), while performing cooperative and competitive tasks with their parents and an adult stranger. Dyads were instructed either to respond jointly in response to a target (cooperation) or to respond faster than the other player (competition). Wavelet coherence was calculated for oxy- and deoxyhemoglobin brain signals. In the control sample, a widespread enhanced coherence was observed for parent-child competition, and a more localized coherence for parent-child cooperation in the frontopolar cortex. While behaviorally, children with ASD showed a lower motor synchrony than children in the TD group, no significant group differences were observed on the neural level. In order to identify biomarkers for typical and atypical social interactions in the long run, more research is needed to investigate the neurobiological underpinnings of reduced synchrony in ASD.

A systematic review of caregiver-child physiological synchrony across systems: Associations with behavior and child functioning

Extensive research has established a positive association between caregiver-child behavioral synchrony and child developmental functioning. Burgeoning research examining physiological synchrony has yet to elucidate its impact for children's developing self-regulation. The objectives of this systematic review were to: 1) determine whether there is evidence that caregiver-child physiological synchrony promotes positive child development, 2) examine developmental differences in physiological synchrony and its correlates, and 3) explore whether context, risk, and/or stress influence patterns of synchrony. Sixty-nine studies met the following criteria on PubMed and PsycINFO: 1) peer-reviewed empirical articles in English that 2) examine autonomic, hypothalamic-pituitary-adrenocortical, and/or central nervous system activity 3) for caregivers and children 4) in response to a task and 5) directly examine the association between caregiver and child physiology. Findings varied based on developmental period and current behavioral context. Functional differences may exist across physiological systems and contexts. Synchrony may have different developmental consequences for dyads with and without certain risk factors. Few studies examine physiological synchrony across multiple systems or contexts, nor do they measure child characteristics associated with synchrony. Statistical and methodological challenges impede interpretation. Findings generally support the idea that physiological synchrony may support children's developing self-regulation. Longitudinal research is needed to examine child developmental outcomes over time.

Respiratory sinus arrhythmia as a dyadic protective factor in the transition to parenthood

Considerable heterogeneity has been observed in couples' adjustment to the transition to parenthood (TTP). One potential yet understudied predictor of emotional adjustment to the TTP is the new parents' capacity for regulation. A widely accepted biological marker of this capacity is respiratory sinus arrhythmia (RSA), which is closely tied to parasympathetic activation. In the present work, we sought to examine the role of tonic RSA and RSA reactivity as possible protective dyadic factors in the TTP. As part of a larger study, we recruited a sample (N = 100) of TTP couples. At 15 weeks postpartum, the couples took part in a lab session during which their RSA was assessed both at rest (tonic RSA) and during four affiliative dyadic interactions (RSA reactivity). Following this session, couples completed daily diaries over a period of 3 weeks, reporting their daily levels of negative affect and stress. A Multivariate Actor Partner Interdependence Model was used to examine the extent to which each partner's RSA predicted their own and their partner's negative affect (NA) level, as well as NA stress-reactivity (i.e., the strength of the within-person stress-affect association). New mothers' tonic RSA predicted their own lower NA level and NA stress-reactivity; both their tonic RSA and RSA reactivity predicted their (male) partners' lower NA level; and finally, new fathers' tonic RSA and RSA reactivity predicted their (female) partners' lower NA stress-reactivity. These results suggest that RSA may serve as a personal and dyadic protective factor.

Biological sensitivity to context: A test of the hypothesized U-shaped relation between early adversity and stress responsivity

We conducted signal detection analyses to test for curvilinear, U-shaped relations between early experiences of adversity and heightened physiological responses to challenge, as proposed by biological sensitivity to context theory. Based on analysis of an ethnically diverse sample of 338 kindergarten children (4-6 years old) and their families, we identified levels and types of adversity that, singly and interactively, predicted high (top 25%) and low (bottom 25%) rates of stress reactivity. The results offered support for the hypothesized U-shaped curve and conceptually replicated and extended the work of Ellis, Essex, and Boyce (2005). Across both sympathetic and adrenocortical systems, a disproportionate number of children growing up under conditions characterized by either low or high adversity (as indexed by restrictive parenting, family stress, and family economic condition) displayed heightened stress reactivity, compared with peers growing up under conditions of moderate adversity. Finally, as hypothesized by the adaptive calibration model, a disproportionate number of children who experienced exceptionally stressful family conditions displayed blunted cortisol reactivity to stress.

Towards an understanding of neurophysiological self-regulation in early childhood: A heuristic and a new approach

Self-regulation in early childhood encompasses both "top down," volitional processes, as well as the "bottom up" activity of three neurophysiological systems: the parasympathetic nervous system (PNS), the sympathetic nervous system (SNS), and the hypothalamic-pituitary-adrenal (HPA) axis. In this paper we briefly review the structure, function, and early development of each of these systems and then explain why neurophysiological self-regulation is most accurately defined as a function of their joint activity. We note that while there are a number of predictive models that employ this definition, the field would benefit from a straightforward heuristic and aligned methods of visualization and analysis. We then present one such heuristic, which we call neurophysiological space, and outline how it may facilitate a new, collaborative approach to building a better understanding of self-regulation in early childhood. We conclude with a presentation of early education as one setting in which our heuristic and methods could be applied.

Investigating convergence of cardiac and behavioral indicators of distress during routine vaccinations over the second year of life

There is considerable variability regarding the convergence between behavioral and biological aspects of distress responses in toddlerhood, and little research has investigated the convergence of these measures in high distress. The aim of the current study was to describe patterns of distress responses to vaccinations as indexed by both pain-related behavioral distress and heart rate (HR) at 12 and 18 months. Caregiver-toddler dyads were part of an ongoing longitudinal cohort observed during 12- (N = 158) and 18-month (N = 122) well-baby vaccinations. Parallel-process growth mixture models discerned two distinct groups at 12 months and three distinct groups at 18 months. All groups had comparable pain-related behavioral distress and HR responses post-vaccination, with most participants displaying high arousal and regulation to baseline levels following the vaccination. However, at 18 months, an important minority had a blunted response or did not regulate to a low level of distress by 3 min post-needle. Post hoc analyses revealed that higher baseline pain-related behavioral distress predicted membership in the majority groups at 12 and 18 months. These results highlight the developmental differences and variability in behavioral and cardiac indicators of distress regulation across the second year of life.

Integrating a multilevel approach to examine family conflict and parent-adolescent physiological synchrony

The present study investigated physiological synchrony across mothers, fathers, and adolescents during a conflict discussion. In particular, a multilevel, within-dyad approach was used to parameterize synchrony within the parasympathetic nervous system. Moreover, we examined how domains of conflict within the larger family system influenced the level of synchrony between family members. Participants were 191 families with adolescents (M age = 12.4 years), whose respiratory sinus arrhythmia (RSA) were measured during a triadic family conflict discussion. On the minute-to-minute basis, mothers and adolescents as well as mothers and fathers exhibited positive RSA concurrent synchrony, whereas no such concordance was observed between adolescents and fathers. In addition, the presence of conflict between parents with respect to coparenting moderated the level of mother-adolescent synchrony such that no concordant RSA synchrony emerged between mother and adolescents under high levels of coparenting conflict. In contrast, general interparental conflict did not moderate levels of physiological synchrony among any of the dyads. Findings suggest that mothers may be particularly physiologically in tune with family members in the context of conflict discussions and specific domains of family conflict may influence concordant physiological dynamics. Taken together, this is one of the first studies to examine physiological synchrony during the adolescent period and results suggest this may be an important developmental period for these dynamics. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Person-centered profiles of parasympathetic physiology, anxiety symptoms, and depressive symptoms in mothers and fathers of young children

Respiratory sinus arrhythmia (RSA) is a biomarker of mental health, but RSA-symptom relations in parents of young children are understudied. We examined how anxiety symptoms, depressive symptoms, resting RSA, and RSA reactivity during challenging parent-child interactions clustered in a community sample of mothers (N = 126) and fathers (N = 87) of 3-year-olds and whether profiles predicted child emotional and behavioral dysregulation at age 4. Mothers fit four profiles (Typical, Mild Risk, Moderate Risk/Withdrawal, and Moderate Risk/Augmentation), suggesting that RSA reactivity was distinct by predominant symptom type at higher levels of risk: specifically, heightened RSA withdrawal was associated with a higher probability of anxiety symptoms and RSA augmentation was associated with a higher probability of depressive symptoms. Fathers fit three profiles (Typical, Mild Risk, and Moderate Risk) where Moderate Risk was characterized by RSA augmentation and a higher probability of both anxiety and depressive symptoms. Mild risk profiles showed heightened resting RSA for mothers and fathers but no differences in RSA reactivity. Both mild and moderate risk profiles predicted higher child dysregulation 1 year later compared to typical profiles. Findings offer preliminary evidence that parasympathetic physiology covaries with symptoms differently for mothers and fathers and that parental profiles of physiology and symptoms inform children's developmental psychopathology.

Socioemotional Mechanisms of Children's Differential Response to the Effects of Maternal Sensitivity on Child Adjustment

OBJECTIVE

Children differ in the extent to which they reap the benefits of maternal sensitive care or suffer the adverse consequences of insensitive care, and these differences can be accounted for by biological characteristics. However, how susceptible children adapt to maternal sensitivity in ways that either maximize positive development or lead to maladjustment has yet to be determined. Here, we propose a novel model of socioemotional mechanisms by which the joint influences of maternal sensitivity and child biological characteristics influence child adjustment.

DESIGN

We propose a theoretical model, in which children's vagal functioning and polymorphisms in serotonin transporter (5-HTTLPR) and dopamine receptor D4 (DRD4) genes confer susceptibility to the effects of maternal sensitivity on internalizing, externalizing, prosocial and moral behavior via changes in interpersonal strategies for emotion regulation, the threat response system, and empathy.

RESULTS

Theoretical and empirical support for the proposed mechanisms are provided.

CONCLUSIONS

The proposed mechanistic model of susceptibility to maternal sensitivity offers a novel framework of for whom and how children are affected by early maternal care, highlighting multiple reciprocal, interacting influences across genes, physiology, behavior, and the environment.

Distribution, Stability, and Continuity of Autonomic Nervous System Responsivity at 18- and 36-Months of Age

OBJECTIVE

Cardiac autonomic nervous system (ANS) measures, respiratory sinus arrhythmia (RSA) and preejection period (PEP), are valid and reliable indicators of children's sensitivity to their environment; however, there are few studies of ANS measures in children less than three years of age. This study's aim was to summarize the distributions, stability, and continuity of RSA and PEP measures during resting, challenge, and reactivity for children at 18- and 36-months.

METHODS

This was a cohort study of racially- and ethnically-diverse, low-income children who completed a developmentally challenging protocol while we simultaneously assessed their RSA and PEP at 18-months (N = 134) and 36-months (N = 102).

RESULTS

The ANS resting, challenge, and reactivity measures at 18- and 36-months of age were normally distributed. The RSA resting (r = 0.29), RSA challenge (r = 0.44), PEP resting (r = 0.55) and PEP challenge (r = 0.58) measures were moderately stable but RSA (r = 0.01) and PEP reactivity (r = 0.02) were not stable from 18- to 36-months of age. There was no continuity in the ANS measures from 18- to 36-months of age with statistically significant changes in sample means for all of the ANS measures.

DISCUSSION

These developmental changes in ANS are shown at the sample level but there are individual differences in ANS responses from 18- to 36-months that may be affected by adversity or protective factors experienced early in life.

Convergence of behavioral and cardiac indicators of distress in toddlerhood: A systematic review and narrative synthesis

The objective of the current study was to systematically review the available literature on the relation between behavioral and cardiac indicators used to measure distress in toddlerhood. After ascertaining the eligibility of 2,424 articles through a Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and PROSPERO (International Prospective Register of Systematic Reviews) guided search process, 22 articles ( N = 2,504) that investigated associations between behavioral and cardiac indicators of distress in toddlerhood were identified. The narrative synthesis described the overall relation (direction [positive, negative], strength [Cohen’s D]) between behavioral and cardiac indicators and was organized by cardiac indicator (i.e., heart rate [HR], heart period, respiratory sinus arrhythmia, pre-ejection period) and type of behavior measured (i.e., coding for expressed emotion behaviors vs. emotion regulation behaviors). Methodological characteristics (i.e., timing of measurement for behavioral and cardiac indicators [concurrent, predictive], length of measurement epochs, inclusion of covariates and moderators) were also described. HR was consistently positively ( D = .05 to .54) related to expressed emotion behaviors. No other cardiac and behavioral indicators were consistently related. Methodological differences related to behavioral and cardiac indicators utilized, timing of measurement, and length of measurement epochs may be responsible for heterogeneity in findings. The findings suggest that researchers might get divergent results depending on whether distress is measured with cardiac or behavioral indicators of distress in toddlerhood. Suggestions for future psychophysiological research with young children are offered.

Evidence for discrete profiles of children's physiological activity across three neurobiological system and their transitions over time

The conceptualization of stress-responsive physiological systems as operating in an integrated manner is evident in several theoretical models of cross-system functioning. However, limited empirical research has modeled the complexity of multisystem activity. Moreover few studies have explored developmentally regulated changes in multisystem activity during early childhood when plasticity is particularly pronounced. The current study used latent profile analysis (LPA) to evaluate multisystem activity during fall and spring of children's transition to kindergarten in three biological systems: the parasympathetic nervous system (PNS), sympathetic nervous system (SNS), and hypothalamic pituitary adrenal (HPA) axis. Latent transition analysis (LTA) was then used to examine the stability of profile classification across time. Across both timepoints, three distinct profiles of multisystem activity emerged. One profile was characterized by heightened HPA axis activity (HPA Axis Responders), a second profile was characterized by moderate, typically adaptive patterns across the PNS, SNS, and HPA axis (Active Copers/Mobilizers), and a third profile was characterized by heightened baseline activity, particularly in the PNS and SNS (Anticipatory Arousal/ANS Responders). LTA of fall-to-spring profile classifications indicated higher probabilities that children remained in the same profile over time compared to probabilities of profile changes, suggesting stability in certain patterns of cross-system responsivity. Patterns of profile stability and change were associated with socioemotional outcomes at the end of the school year. Findings highlight the utility of LPA and LTA to detect meaningful patterns of complex multisystem physiological activity across three systems and their associations with early adjustment during an important developmental transition.

Adolescents at risk of anxiety in interaction with their fathers: Studying non-verbal and physiological synchrony

Adolescence is a vulnerable period in terms of the onset of anxiety disorders, and dyadic parent-adolescent interactions may play a key role in either increasing or reducing the risk of psychopathologies. This study examines the presence of physiological synchrony (specifically, linkage in interbeat interval series) and non-verbal synchrony in positive and negative interactions between adolescents (aged 13-16) and their fathers. Non-verbal synchrony was quantified through the coordination of the interactants' body movements, using an automated video-analysis algorithm (motion energy analysis). Participants were made up of 53 parent-adolescent dyads, the latter at either low (n = 28) or high (n = 25) risk of anxiety. Adolescents at low risk of anxiety displayed statistically significant levels of non-verbal synchrony with their fathers during positive interactions. Non-verbal synchrony was not found in the father-adolescent dyads featuring adolescents at high risk of anxiety. Physiological synchrony was not significantly present above chance level in either of the groups of adolescents. Overall, the results suggest that adolescents at high risk of anxiety may have difficulties in managing non-distressing interactions with their fathers. The results also suggest that physiological synchrony is not a straightforward phenomenon.

Parent-adolescent physiological synchrony: Moderating effects of adolescent emotional insecurity

The present study investigated physiological synchrony in the parasympathetic nervous system among fathers, mothers, and adolescents during a real-time family interaction, and child characteristics that may moderate the level of physiological synchrony. Our sample consisted of 191 families with adolescents (M_age  = 12.4 years) and both of their parents, who participated in a triadic family conflict discussion. During the discussion, respiratory sinus arrhythmia (RSA) was measured for all three family members. Multilevel analysis indicated a significant positive concurrent synchrony between adolescents and their mothers, as well as between fathers and mothers on a minute-to-minute basis. No RSA synchrony was found between adolescents and their fathers. Furthermore, adolescent emotional insecurity significantly moderated mother-adolescent RSA synchrony. Whereas adolescents with low emotional insecurity exhibited positive synchrony with their mothers, no synchrony was observed when adolescent emotional insecurity was high. In conclusion, findings of the present study illuminate the patterns of RSA synchrony among parents and adolescents and highlight a link between adolescent emotional insecurity and attenuated mother-adolescent physiological synchrony.

Working together to orient faster: The combined effects of alerting and orienting networks on pupillary responses at 8 months of age

Multiple visual attention mechanisms are active already in infancy, most notably one supporting orienting towards stimuli and another, maintaining appropriate levels of alertness, when exploring the environment. They are thought to depend on separate brain networks, but their effects are difficult to isolate in existing behavioural paradigms. Better understanding of the contribution of each network to individual differences in visual orienting may help to explain their role in attention development. Here, we tested whether alerting and spatial cues differentially modulate pupil dilation in 8-month-old infants in a visual orienting paradigm. We found differential effects in the time course of these responses depending on the cue type. Moreover, using Principal Component Analysis (PCA) we identified two main components of pupillary response, which may reflect the alerting and orienting network activity. In a regression analysis, these components together explained nearly 40 % of variance in saccadic latencies in the spatial cueing condition of the task. These results likely demonstrate that both networks work together in 8-month-old infants and that their activity can be indexed with pupil dilation combined with PCA, but not with raw changes in pupil diameter.

Infant Vagal Tone and Maternal Depressive Symptoms: A Bottom-Up Perspective

Children vary in their susceptibility to environmental exposures such as maternal depression, but little is known about how children shape those same environments. When raising an infant with low arousal, mothers at risk of depression may experience decreased parenting self-efficacy and increased depressive symptoms. We evaluated a longitudinal mediated moderation model that hypothesized interactive effects of infant vagal tone (indexed by respiratory sinus arrhythmia [RSA]) and maternal postpartum depressive (PPD) symptoms on maternal depressive symptoms in early childhood via parenting self-efficacy. Among a sample of 322 very low-income Mexican American mother-infant dyads (46% male infants), infant RSA was assessed at 6 weeks of age; mothers (M_age = 27.8, SD = 6.5) reported PPD symptoms every 3 weeks from 6 weeks to 6 months, parenting self-efficacy at 18 and 24 months, and depressive symptoms at 18 and 36 months. Higher PPD symptoms predicted higher maternal depressive symptoms at 36 months, especially among mothers whose infants had lower resting RSA. The interactive effect of PPD symptoms and infant RSA on 36-month depressive symptoms was partially mediated by lower parenting self-efficacy. Lower infant RSA may exacerbate the detrimental effects of PPD symptoms on subsequent maternal well-being via damage to mothers' beliefs in their ability to parent effectively.

Developmental trajectories of autonomic functioning in autism from birth to early childhood

Deficits in social engagement emerge in autism during the infant and toddler period and may be related to emotion regulation and stress response systems. This study examined patterns of growth in autonomic functioning related to autism diagnosis and addresses the hypothesis that there are differences in autonomic functioning related to autism in infancy. Heart rate (HR) and respiratory sinus arrhythmia (RSA) were measured at 8 time points from 1 to 72 months of age in infants later diagnosed with autism (n = 12) and a non-autistic comparison group (n = 106). Multilevel models were used to describe the developmental course of HR and RSA and to test the effect of autism diagnosis on growth trajectories. Both groups showed an expected age-related decrease in HR and increase in RSA. Groups did not differ in the rate of decrease of HR over time. However, infants with autism demonstrated a smaller linear increase in RSA, indicating slower growth in RSA over time in comparison to controls. These results suggest that differences in physiological regulation may develop with age in autism. The slowed RSA growth in autism was most evident after 18 months of age, at a time when behavioral symptoms become prominent. This is consistent with the view that RSA is a marker of functional status in autism rather than a cause of social deficits in autism.

Infants' Biological Sensitivity to the Effects of Maternal Social Support: Evidence Among Mexican American Families

The identification of infants who are most susceptible to both negative and positive social environments is critical for understanding early behavioral development. This study longitudinally assessed the interactive effects of infant vagal tone (respiratory sinus arrhythmia; RSA) and maternal social support on behavioral problems and competence among 322 low-income Mexican American mother-infant dyads (infants: 54.1% female) and explored sex differences. Infant RSA was calculated from resting HR data at 6 weeks of age. Mothers reported on general social support, partner support, and family support at 6 months, and infant behavioral problems and competence at 1 year. Two-way interactions (RSA × support source) were evaluated to predict behavioral problems and competence, adjusting for covariates. Results indicated higher competence among infants with lower RSA whose mothers reported higher general support or higher partner support. Interactive effects on behavior problems of RSA with maternal partner or family support were only found for female infants: Girls with higher RSA showed more behavior problems when mothers reported low support, but fewer problem levels in the context of high support. Our results suggest that infant RSA is an important moderator of the effects of the early social environment on early development.

Mothers' and fathers' mind-mindedness influences physiological emotion regulation of infants across the first year of life

The main aim of this study was to test whether mothers' (n = 116) and fathers' (n = 116) mind-mindedness predicts infants' physiological emotion regulation (heart rate variability; HRV) across the first year of life. Three hypotheses were examined: (a) parents' mind-mindedness at 4 and 12 months predicts infants' HRV at 12 months over and above infants' initial HRV levels at 4 months, (b) mothers' and fathers' mind-mindedness independently predict infant HRV, and (c) the effects of mind-mindedness on infant HRV (partially) operate via parenting behaviour. Infants' HRV was assessed during rest and a stranger approach. Mind-mindedness was assessed by calculating the proportions of appropriate and non-attuned mind-related comments during free-play interactions, and parenting quality was observed at 4 and 12 months in the same interactions. Path analyses showed that mothers' appropriate mind-related comments at 4 and 12 months predicted higher baseline HRV at 12 months, whereas mothers' non-attuned comments predicted lower baseline HRV at 12 months. Similar, but concurrent, relations were found for fathers' appropriate and non-attuned mind-related comments and infant baseline HRV at 12 months. In addition, fathers' appropriate mind-related comments showed an indirect association with infant baseline HRV at 12 months via fathers' parenting quality. With regard to infant HRV reactivity during the stranger approach, mothers' appropriate mind-related comments at 4 months and fathers' non-attuned mind-related comments at 12 months predicted a larger HRV decline during the stranger approach at 12 months. Infants' HRV at 4 months did not predict parents' later mind-mindedness. The results indicate that mothers' and fathers' appropriate and non-attuned mind-related speech uniquely impacts the development of infants' physiological emotion regulation.

Predicting child temperament and behavior from the fetus

There remains little debate that the period before birth sets the stage for subsequent development, yet scant evidence exists showing continuity from characteristics of the individual fetus to characteristics of the child. This report examines, in two studies, whether baseline and evoked fetal neurobehavioral functioning are predictive of features of child temperament and behavior as reported by mothers when offspring were between 7 and 14 years old (M = 10.1 years). Study 1 utilizes data generated from 333 maternal-fetal pairs collected during an undisturbed condition during the second half of gestation in relation to the child temperament dimensions of behavioral inhibition and exuberance. Associations at 32 weeks gestation were detected between all features of fetal neurobehavior and behavioral inhibition. In adjusted models, slower fetal heart rate and less fetal movement were associated with significant unique variance in predicting higher levels of childhood behavioral inhibition. No associations were detected for exuberance. Study 2 focuses on the association of evoked fetal reactivity and recovery to induced maternal arousal with subsequent child behavioral difficulties in a subset of the full sample (n = 130). Greater recovery in fetal heart rate following maternal stimulation was predictive of fewer behavioral difficulties and more prosocial behavior in childhood. Results from both studies provide support for gestational origins of core individual differences that portend childhood outcomes with foundational reactivity and regulatory components.

A systematic review of parent-child synchrony: It is more than skin deep

This manuscript provides a critical review of the literature on parent-child physiological synchrony-the matching of biological states between parents and children. All eligible studies found some evidence of physiological synchrony, though the magnitude and direction of synchrony varied according to methodological factors, including the physiological system examined (i.e., parasympathetic or sympathetic nervous system activity, adrenocortical functioning) and the statistical approach used (e.g., multilevel modeling, correlation). The review underscores the need to consider the context in which physiological synchrony occurs (e.g., family risk) to best understand its significance. Furthermore, the review delineates vital avenues for future research, including the need to assess synchrony across multiple physiological systems and the importance of documenting continuity/change in physiological synchrony across developmental periods. Such research is crucial for understanding how the parent-child relationship unfolds at a physiological level and, in turn, how this relationship can facilitate or hinder parent, child, and family adjustment.

Developmental dynamics of autonomic function in childhood

There is a paucity of developmental data examining the stability of autonomic function during childhood, and even less is known regarding the extent of coordination between autonomic branches. To address this, autonomic measures of sympathetic (cardiac pre-ejection period, PEP; electrodermal activity, and EDA) and parasympathetic (respiratory sinus arrhythmia and RSA) function were collected from 339 children annually from kindergarten to second grade. Physiology was quantified into 31 epochs 30 s in length, across a series of baselines and emotion-inducing films. Rank-order stability was observed for all three indices, but was higher for cardiac than electrodermal measures. A series of multilevel models was used to identify the proportion of variance in psychophysiological function attributable to the individual (trait), visit (potential developmental change), or epoch (reactivity to task). Both PEP and RSA had sizeable components of individual-level variance, with PEP showing very small variance attributable to experimental task. In contrast, variance in EDA was largely attributable to task epoch. Variance decompositions of the parasympathetic-sympathetic coordination (e.g., RSA-EDA) suggest that the branches of the autonomic system are prototypically cooperative, but evidence did not indicate traitlike stability or linear developmental change. The extent of coordination was moderated by emotional context, indicating that autonomic coordination varies dynamically within individuals. These findings have implications for future work attempting to identify the contextual, experiential, and demographic factors that modulate developmental trajectories of autonomic function and coordination, and for examination of how developmental changes in autonomic psychophysiology are related to or predict behavioral trajectories across a range of psychological domains.

Prenatal exposure to tobacco and cannabis: Effects on autonomic and emotion regulation

Tobacco and cannabis are often used together in pregnancy and both have effects on children's regulatory system. Yet, little is known about the impact of co-use on the development of emotion regulation at the developmentally salient age of 2 years. One pathway linking co-exposure to tobacco and cannabis to toddler regulation may be via poor autonomic regulation in infancy. In addition, substance using mothers may be more dysregulated themselves, which may have direct effects on toddler regulation, but may also affect parenting, particularly maternal sensitivity during mother-child interactions. Thus, a second pathway linking exposure to toddler regulation may be via maternal dysregulation and low maternal sensitivity. We examined a conceptual model linking prenatal exposure to toddler regulation via these two pathways in a prospective sample (N = 247) of mother-child dyads recruited in the first trimester of pregnancy. Results indicated significant effects of co-exposure on poor autonomic regulation in infancy, which in turn predicted poor toddler emotion regulation. Mothers who used both tobacco and cannabis displayed lower sensitivity during play interactions with their infants. Maternal sensitivity was modestly stable from infant to toddler period and was predictive of higher toddler emotion regulation. Continued postnatal exposure to tobacco was also a significant, unique predictor of lower toddler emotion regulation. Results highlight the importance of examining co-exposure effects and suggest that this common pattern of use may be associated with higher infant/toddler risks.

Approaches to modeling the development of physiological stress responsivity

Influential biopsychosocial theories have proposed that some developmental periods in the lifespan are potential pivot points or opportunities for recalibration of stress response systems. To date, however, there have been few longitudinal studies of physiological stress responsivity and no studies comparing change in physiological stress responsivity across developmental periods. Our goals were to (a) address conceptual and methodological issues in studying the development of physiological stress responsivity within and between individuals, and (b) provide an exemplar for evaluating development of responsivity to stress in the parasympathetic nervous system, comparing respiratory sinus arrhythmia (RSA) responsivity from middle to late childhood with middle to late adolescence. We propose the use of latent growth modeling of stress responsivity that includes time-varying covariates to account for conceptual and methodological issues in the measurement of physiological stress responsivity. Such models allow researchers to address key aspects of developmental sensitivity including within-individual variability, mean level change over time, and between-individual variability over time. In an empirical example, we found significant between-individual variability over time in RSA responsivity to stress during middle to late childhood but not during middle to late adolescence, suggesting that childhood may be a period of greater developmental sensitivity at the between-individual level.

Respiratory Sinus Arrhythmia Activity Predicts Internalizing and Externalizing Behaviors in Non-referred Boys

Atypical respiratory sinus arrhythmia (RSA), a biomarker of emotion dysregulation, is associated with both externalizing and internalizing behaviors. In addition, social adversity and gender may moderate this association. In this study, we investigated if RSA (both resting RSA and RSA reactivity in an emotion regulation task) predicts externalizing and/or internalizing behaviors and the extent to which social adversity moderates this relationship. Two hundred and fifty-three children (at Time 1, mean age = 9.05, SD = 0.60, 48% boys) and their caregivers from the community participated in this study. Resting RSA and RSA reactivity were assessed, and caregivers reported children’s externalizing and internalizing behaviors at both Time 1 and Time 2 (1 year later). We found that lower resting RSA (but not RSA reactivity) at Time 1 was associated with increased externalizing and internalizing behaviors at Time 2 in boys, even after controlling for the effects of Time 1 behavioral problems and Time 2 age. Moreover, there was a significant interaction effect between Time 1 resting RSA and social adversity such that lower resting RSA predicted higher externalizing and internalizing behaviors in boys only under conditions of high social adversity. Follow-up analyses revealed that these predictive effects were stronger for externalizing behavior than for internalizing behavior. No significant effects were found for girls. Our findings provide further evidence that low resting RSA may be a transdiagnostic biomarker of emotion dysregulation and a predisposing risk factor for both types of behavior problems, in particular for boys who grow up in adverse environments. We conclude that biosocial interaction effects and gender differences should be considered when examining the etiological mechanisms of child psychopathology.