Increases in Arousal are More Long-Lasting than Decreases in Arousal: On Homeostatic Failures During Emotion Regulation in Infancy

Trajectories of brain and behaviour development in the womb, at birth and through infancy

Birth is often seen as the starting point for studying effects of the environment on human development, with much research focused on the capacities of young infants. However, recent imaging advances have revealed that the complex behaviours of the fetus and the uterine environment exert influence. Birth is now viewed as a punctuate event along a developmental pathway of increasing autonomy of the child from their mother. Here we highlight (1) increasing physiological autonomy and perceptual sensitivity in the fetus, (2) physiological and neurochemical processes associated with birth that influence future behaviour, (3) the recalibration of motor and sensory systems in the newborn to adapt to the world outside the womb and (4) the effect of the prenatal environment on later infant behaviours and brain function. Taken together, these lines of evidence move us beyond nature-nurture issues to a developmental human lifespan view beginning within the womb.

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.

Parent-to-Child Anxiety Transmission Through Dyadic Social Dynamics: A Dynamic Developmental Model

The intergenerational transmission of psychopathology is one of the strongest known risk factors for childhood disorder and may be a malleable target for prevention and intervention. Anxious parents have distinct parenting profiles that impact socioemotional development, and these parenting effects may result in broad alterations to the biological and cognitive functioning of their children. Better understanding the functional mechanisms by which parental risk is passed on to children can provide (1) novel markers of risk for socioemotional difficulties, (2) specific targets for intervention, and (3) behavioral and biological indices of treatment response. We propose a developmental model in which dyadic social dynamics serve as a key conduit in parent-to-child transmission of anxiety. Dyadic social dynamics capture the moment-to-moment interactions between parent and child that occur on a daily basis. In shaping the developmental trajectory from familial risk to actual symptoms, dyadic processes act on mechanisms of risk that are evident prior to, and in the absence of, any eventual disorder onset. First, we discuss dyadic synchrony or the moment-to-moment coordination between parent and child within different levels of analysis, including neural, autonomic, behavioral, and emotional processes. Second, we discuss how overt emotion modeling of distress is observed and internalized by children and later reflected in their own behavior. Thus, unlike synchrony, this is a more sequential process that cuts across levels of analysis. We also discuss maladaptive cognitive and affective processing that is often evident with increases in child anxiety symptoms. Finally, we discuss additional moderators (e.g., parent sex, child fearful temperament) that may impact dyadic processes. Our model is proposed as a conceptual framework for testing hypotheses regarding dynamic processes that may ultimately guide novel treatment approaches aimed at intervening on dyadically linked biobehavioral mechanisms before symptom onset.

In infancy, it's the extremes of arousal that are 'sticky': Naturalistic data challenge purely homeostatic approaches to studying self-regulation

Most theoretical models of arousal/regulatory function emphasise the maintenance of homeostasis; consistent with this, most previous research into arousal has concentrated on examining individuals' recovery following the administration of experimentally administered stressors. Here, we take a different approach: we recorded day-long spontaneous fluctuations in autonomic arousal (indexed via electrocardiogram, heart rate variability and actigraphy) in a cohort of 82 typically developing 12-month-old infants while they were at home and awake. Based on the aforementioned models, we hypothesised that extreme high or low arousal states might be more short-lived than intermediate arousal states. Our results suggested that, contrary to this, both low- and high-arousal states were more persistent than intermediate arousal states. The same pattern was present when the data were viewed over multiple epoch sizes from 1 s to 5 min; over 10-15-minute time-scales, high-arousal states were more persistent than low- and intermediate states. One possible explanation for these findings is that extreme arousal states have intrinsically greater hysteresis; another is that, through 'metastatic' processes, small initial increases and decreases in arousal can become progressively amplified over time. Rather than exclusively using experimental paradigms to study recovery, we argue that future research should also use naturalistic data to study the mechanisms through which states can be maintained or amplified over time.