Previous work from our lab has used the Dutch Ambulatory Monitoring System (AMS) to assess the cardiovascular responses and motility of large free-ranging species (e.g. horses). To further examine the utility of using the AMS with non-humans, a study investigating the heart rate (HR) and heart period variability (HRV) of a large canine undergoing behavioral modification therapy was undertaken. This treatment emulated a restraint and tactile pressure technique that has previously been used in horses. Cardiovascular responses and motility were continuously measured pre-treatment (exposure to a stimulus dog), during treatment (in-box), and post-treatment. The treatment consisted of placing the dog in a 110 cm (long) by 45 cm (wide) by 102 cm (height) wooden box that only covered the animals’ torso and legs and allowed the head to be free. Once the dog was in the box, the body was covered with a lightweight material (grain product) to effect restraint and tactile pressure, which was followed by a repeat exposure to the stimulus animal. Results indicated decreased heart rate and an increased HRV during the intervention as compared to baseline with indices of motility changing in the expected directions. Estimates of respiratory frequency derived from the autoregressive spectral analysis indicated changes in respiration did not account for the cardiovascular effects. In conclusion, tactile pressure and restraint may be an important tool for behavioral modification in both humans and animals, and the AMS is a useful tool for collecting cardiovascular data on a variety of species in a great many contexts.

Autonomic underarousal, indicated by low heart rate (HR) and skin conductance level (SCL), is related to childhood aggression. However, results are inconsistent in preschoolers. We assessed HR, SCL, heart rate reactivity and skin conductance reactivity in four-year-old children. Comparisons were made between children with a high level and with a low level of aggressive behavior according to the Child Behavior Checklist 1½–5 as well as between children who were diagnosed with Oppositional Defiant Disorder or Conduct Disorder (ODD/CD) and children with a low level of aggression. Preschool children with a high level of aggressive behavior showed lower SCL and SCR and children with ODD/CD showed lower SCL. In contrast, we did not find lower HR and HRR in preschool children with a high level of aggressive behavior or ODD/CD. Thus, results suggest that decreased SCL, but not HR, is a characteristic of preschool children with aggressive behavior or ODD/CD.

Exposure to prenatal adversity is associated with aggression later in life. Individual differences in autonomic nervous system (ANS) functioning, specifically nonreciprocal activation of the parasympathetic (PNS) and sympathetic (SNS) nervous systems, increase susceptibility to aggression, especially in the context of adversity. Previous work examining interactions between early adversity and ANS functioning in infancy is scarce and has not examined interaction between PNS and SNS. This study examined whether the PNS and SNS moderate the relation between cumulative prenatal risk and early physical aggression in 124 children (57% male). Cumulative risk (e.g., maternal psychiatric disorder, substance (ab)use, and social adversity) was assessed during pregnancy. Parasympathetic respiratory sinus arrhythmia (RSA) and sympathetic pre-ejection period (PEP) at baseline, in response to and during recovery from emotional challenge were measured at 6 months. Physical aggression and non-physical aggression/oppositional behavior were measured at 30 months. The results showed that cumulative prenatal risk predicted elevated physical aggression and non-physical aggression/oppositional behavior in toddlerhood; however, the effects on physical aggression were moderated by PNS and SNS functioning. Specifically, the effects of cumulative risk on physical aggression were particularly evident in children characterized by low baseline PNS activity and/or by nonreciprocal activity of the PNS and SNS, characterized by decreased activity (i.e., coinhibition) or increased activity (i.e., coactivation) of both systems at baseline and/or in response to emotional challenge. These findings extend our understanding of the interaction between perinatal risk and infant ANS functioning on developmental outcome.

Nonreciprocal action of the parasympathetic (PNS) and sympathetic (SNS) nervous systems, increases susceptibility to emotional and behavioral problems in children exposed to adversity. Little is known about the PNS and SNS in interaction with early adversity during infancy. Yet this is when the physiological systems involved in emotion regulation are emerging and presumably most responsive to environmental influences. We examined whether parasympathetic respiratory sinus arrhythmia (RSA) and sympathetic pre-ejection period (PEP) response and recovery at six months, moderate the association between cumulative prenatal risk and physical aggression at 20 months (N=113). Prenatal risk predicted physical aggression, but only in infants exhibiting coactivation of PNS and SNS (i.e., increase in RSA and decrease in PEP) in response to stress. These findings indicate that coactivation of the PNS and SNS in combination with prenatal risk is a biological marker for the development of aggression.

Research indicates that impaired empathy is a risk factor of aggression and that social attention is important for empathy. The role of social attention in associations between empathy and aggression has not yet been fully elucidated. Therefore, indicators of affective empathy, cognitive empathy, social attention, and aggression were simultaneously assessed in children aged 45 months. A total of 61 mother–child dyads participated in a lab visit, during which maternal reports of aggression were obtained. Children watched three clips showing a sad, scared, and happy child, respectively, and a neutral social clip while heart rate was recorded. Heart rate change from nonsocial baseline clips to emotional clips was calculated as an index of affective empathy. Questions about the emotions of the children in the clips were asked to assess cognitive empathy. Social attention was defined as time spent looking at faces during the clips. Correlation analyses revealed negative associations between affective empathy and aggression and between social attention and aggression. Furthermore, multivariate linear regression analyses indicated that the association between affective empathy and aggression was moderated by social attention; the negative association between affective empathy and aggression was stronger in children with relatively reduced social attention. No association was found between cognitive empathy and aggression. Therefore, both affective empathy and social attention are important targets for early interventions that aim to prevent or reduce aggression.

Impaired empathy has been associated with aggression in children, adolescents and adults, but results have been contradictory for the preschool period. Impaired inhibitory control also increases the risk of aggression, and possibly moderates empathy-aggression associations. The current study investigated whether empathy and inhibitory control are associated with aggression in toddlerhood. Furthermore, we aimed to clarify the role of inhibitory control in empathy and aggression, specifically, whether inhibitory control moderates the association between empathy and aggression. During a laboratory visit at age 30 months (N = 103), maternal reports of physical aggression were obtained and child inhibitory control was examined using a gift delay task. Empathy was examined by obtaining behavioral observations and recording physiological responses (heart rate response and respiratory sinus arrhythmia response) to an empathy-eliciting event (i.e., simulated distress). Reduced inhibitory control was associated with more aggression. Behavioral and physiological indicators of empathy were not associated with aggression. Hierarchical regression analyses revealed an interaction effect of heart rate response to distress simulation with inhibitory control in the prediction of aggression. Post hoc analyses indicated a negative association between heart rate response and aggression when inhibitory control was high, but a positive association was found in toddlers who demonstrated low inhibitory control. These results suggest that children are less aggressive when they have both high levels of empathy and inhibitory control. Therefore, both empathy and inhibition are important targets for interventions aiming to reduce or prevent aggression at a young age.