Jean Louis Gariépy

Parasympathetic and sympathetic responses to the strange situation in infants and mothers from avoidant and securely attached dyads

Vagal reactivity and salivary alpha-amylase (sAA) were assessed in infants (M age = 13.55 months) and their mothers during the Strange Situation Paradigm (SSP) to investigate differences in physiological responses in a sample of insecure-avoidant and securely-attached dyads (N = 132). Infants classified as insecure-avoidant had significantly higher vagal withdrawal during the SSP and higher sAA overall, suggesting that the avoidant attachment pattern is associated with a greater allostatic load. During separation episodes of the SSP, all mothers showed significant vagal withdrawal, suggesting greater attempts at regulation. During the last reunion, typically the most stressful episode for infants, mothers of secure infants showed greater vagal withdrawal than mothers of insecure-avoidant infants, suggesting greater attempts by these mothers at interactive repair. Results for mothers and infants supported the allostatic load theory.

Bidirectional genetic and environmental influences on mother and child behavior: The family system as the unit of analyses

Family systems theory proposes that an individuals functioning depends on interactive processes within the self and within the context of dyadic family subsystems. Previous research on these processes has focused largely on behavioral, cognitive, and psychophysiological properties of the individual and the dyad. The goals of this study were to explore genetic and environmental interactions within the family system by examining how the dopamine receptor D2 gene (DRD2) A1+ polymorphism in mothers and children relates to maternal sensitivity, how maternal and child characteristics might mediate those effects, and whether maternal sensitivity moderates the association between DRD2 A1+ and child affective problems. Evidence is found for an evocative effect of child polymorphism on parenting behavior, and for a moderating effect of child polymorphism on the association between maternal sensitivity and later child affective problems. Findings are discussed from a family systems perspective, highlighting the role of the family as a context for gene expression in both mothers and children.

Development, Microevolution, and Social Behavior

The central questions of social development--from the roots of mother-infant attachment to the plasticity of aggressive behavior--pivot on the relations between genetic and ontogenetic sources of variance. It is proposed that (a) developmental, experiential, and microevolutionary processes typically collaborate, rather than compete, in achieving social adaptation; (b) social behavior patterns are mostly closed to modification in the course of development and across generations, but avenues of vulnerability exist in ontogeny and microevolution for dynamic, rapid, and reversible changes in key features; (c) a general avenue for change is delay or acceleration in the developmental onset of one or more features of the behavior pattern, which in turn modifies the functions and properties of the adaptive configuration; and (d) the features of social behavior that are open to rapid change in ontogeny should be open as well to rapid changes in microevolution, although different underlying processes may be involved. Empirical findings from the investigation of aggressive interactions are used to illustrate this proposal on the dual genesis and coincident adaptation of social behaviors.

Psychophysiological correlates of parenting behavior in mothers of young children

This study investigated HPA and vagal functioning as correlates of parenting in mothers of 175 six-month-old children. Salivary cortisol indexed HPA functioning and respiratory sinus arrhythmia (RSA) reduction indexed vagal regulation. Positive engagement and negative intrusiveness were observed during the Face-to-Face Still Face Paradigm (FFSFP) reunion and a semi-structured free play episode. Mixed modeling was used to examine differences in maternal behaviors across contexts as a function of psychophysiology. Main effects of cortisol levels, as well as interactions with RSA reduction and context, predicted negative intrusiveness. Mothers with high cortisol exhibited more negative intrusiveness if they also had lower RSA reduction. Mothers were also less negatively intrusive during the FFSFP than the free play if they had lower cortisol levels. There were no associations between psychophysiological measures and positive engagement. The findings suggest: (1) that parenting behaviors are associated with maternal stress physiology; (2) considerations of single physiological systems related to parenting behaviors may be incomplete; and (3) type and context of behaviors must be considered when examining biobehavioral associations with parenting.

Handling, genetic and housing effects on the mouse stress system, dopamine function, and behavior

This research was designed to examine how early stimulation (i.e., handling), subsequent housing conditions and genetic factors interact to produce adult differences in stress regulation. High-aggressive (NC900) and low-aggressive (NC100) mice were handled for 3 weeks potspartum and were subsequently isolated or grouped until observed as adults in an open field or a dyadic test. In NC100, handling abolished the temporal variations seen in open-field activity among the nonhandled subjects and reduced corticosterone (CORT) activation. In NC900, these two measures were unaffected by handling. Only among handled NC100 did subsequent group rearing further reduce CORT activation. By contrast, handling caused an up-regulation of D1 dopamine receptors in both lines, and, in NC100, this effect was increased by group rearing. In a dyadic encounter with another male mouse, subjects of both lines showed handling effects. NC100 froze less rapidly and NC900 attacked more rapidly. This multifactorial design showed that the systemic effects of handling are modulated by genetic background, and that measures of these effects are affected by experience beyond infancy. Our findings also showed that the effects of handling vary when assessed across different physiological systems and across social and nonsocial testing conditions.

Association of genetic differences in social behavior and cellular immune responsiveness: effects of social experience.

We have recently demonstrated that selective breeding of ICR mice for differences in social behavior (i.e., high versus low levels of social isolation-induced aggression) are related to increased susceptibility to tumor development and reduced levels of natural killer (NK) cell activity. In the present investigation, we sought to extend examination of the line differences in immune status to T and B cell responsiveness. In addition, we also sought to determine if social experience contributes to line differences in immune responsiveness. A cosibial design was used to examine whether single vs group housing modified the magnitude of line differences in immune status. Compared to aggressive (NC900) mice, nonaggressive (NC100) mice had significantly lower T cell proliferative responses to concanavalin A, lower IL-2 and gamma-interferon production, as well as significantly lower NK activity. Of the various measures of cellular immune responsiveness, housing condition was found to have a significant effect only on NK activity. No significant line by housing interactions were found for any of the immune measures tested. The present data demonstrate that the genetic selection for differences in social behavior is associated with line differences in several parameters of cellular immune responsiveness. These mouse lines provide a valuable research model to examine the association between selection for genetic differences in social behavior and differences in immune responsiveness.

Maternal prenatal, postpartum, and concurrent stressors and temperament in 3-year-olds: a person and variable analysis.

The study was based on the assumption that stressors in the lives of pregnant and parenting women are processes that affect prenatal, postpartum, and concurrent maternal hormones and emotions and that these processes affect child temperament. The hypotheses were tested in a group of 67 young mothers and their 3-year-old children. Mothers were clustered into groups based on longitudinal patterns of hormones and emotions at prenatal, postpartum. and 3-year follow-up assessments. The analyses focused on relating maternal patterns of hormones and emotions to the childs temperament at age 3 years. Temperament was assessed by questionnaire and observation of behavior during a challenging situation. Illustrative findings included the following. Verbal aggression and nonverbal aggression were significantly higher in children of mothers in the low prenatal hormone cluster than children of mothers in the high prenatal hormone cluster. Children of mothers in the postpartum low testosterone (T), estradiol (E2), and androstenedione (delta4-A) and medium cortisol (Cort) cluster (mainly low hormone cluster) exhibited significantly more physical aggression than children of mothers in the medium T and A4-A, high E2 and low Cort cluster. Maternal patterns of hormones, emotions, and parenting attitudes and practices were related to multiple aspects of temperament when the children were age 3 years. The findings support the important role of maternal biological and psychological processes in the development of child temperament.

Social Reactivity and D1 Dopamine Receptors: Studies in Mice Selectively Bred for High and Low Levels of Aggression

Robust individual differences in social behavior have been obtained by selectively breeding Institute for Cancer Research mice for high and low levels of aggression. As previously shown, when paired with a non-selected, group-housed partner mouse, NC900 mice exhibit isolation-induced aggression. Conversely, NC100 mice fail to attack, freezing upon social contact. Previous studies have established that NC100 mice have lower dopamine concentrations in nucleus accumbens and caudate nucleus, with increased dopamine receptor densities in these same regions. Thus, we wished to determine the effect of administration of a dopamine receptor agonist on social behavior. Mice of both lines were administered 0, 1, 3, or 10 mg/kg (SC) of the full efficacy D1 receptor agonist dihydrexidine, and their behavior was assessed in a social interaction test. Dihydrexidine reduced aggression in NC900 mice and nonagonistic approach in NC100 mice in a dose dependent manner. In both cases, this resulted from induction of a marked reactivity to mild social stimulation as measured by increases in behaviors such as escape, reflexive kicking, and vocalizations. Oihydrexidine had no systematic effect on the freezing behavior characteristic of the low-aggressive line. In independent experiments, mice were pretreated with either the D1 antagonist SCH-23390 (.1 mg/kg) or the selective D2 antagonist remoxipride (1.0 mg/kg), after which they received dihydrexidine (10 mg/kg) and were tested as above. The effects of dihydrexidine on social reactivity in mice of both lines were significantly antagonized by SCH-23390 but not attenuated by remoxipride. Antagonist pretreatment neither reinstated attack in the NC900 line nor nonagonistic approach behavior in the NC100 line, which suggests the importance of D1/D2 interactions to the initiation of action. These studies suggest an important role for D1 dopamine receptors in the emotional response to social stimuli.

Changes in maternal sensitivity across the first three years: are mothers from different attachment dyads differentially influenced by depressive symptomatology?

Hierarchical linear modeling was used to describe longitudinal relations between maternal sensitivity and depressive symptomatology for mothers of children with differing attachment classifications at 36 months of child age using data from the NICHD Study of Early Child Care. Attachment during toddlerhood was assessed using a modified Strange Situation Paradigm developed by the MacArthur Working Group on Attachment. On average, maternal sensitivity increased longitudinally from 6 to 36 months for groups with children classified as secure or resistant, but not for groups classified as avoidant or disorganized. Higher maternal depressive symptoms were associated with lower levels of sensitivity for all mothers, although this effect was significantly less severe for mothers of securely attached children. In addition, higher maternal depressive symptoms were associated with decreases in sensitivity from 6 to 36 months for mothers of children who at 36 months showed disorganized attachments combined with underlying patterns of avoidant or resistant behavior.

D2-like dopamine receptor mediation of social-emotional reactivity in a mouse model of anxiety: strain and experience effects.

We examined the effects of the D2-like dopamine receptor agonist quinpirole on social-emotional reactivity in two inbred mouse strains. An important objective of this study was to determine whether these effects could be modulated by differential housing conditions (i.e., isolation versus group housing). Moreover, as motor activity is an important control for the assessment of drug effects on emotional behavior, the effects of quinpirole were tested in two inbred mouse strains (A/J and C57BL/6J) low and high in motor activity, respectively. Levels of emotional reactivity were assessed in response to mild social stimulation provided by a nonaggressive conspecific. Quinpirole increased stationary forms of reactivity (i.e., startle, kicking, defensive posture, vocalization) in both isolated and group-housed A/J mice. This effect was more pronounced and observed at lower doses in isolated than in group-housed A/J mice. Quinpirole also induced jump behavior in isolated but not group-housed A/J mice. The shift to the left in the dose-response curve of quinpirole in isolated A/J mice indicated that D2-like dopamine receptor functions can be altered by social experience. Quinpirole only marginally increased stationary and locomotor reactivity (i.e., jump) in isolated C57BL/6J mice, whereas it markedly reduced motor activity in group-housed mice of this strain. The investigation of emotional reactivity within a social context and using strains that differ in motor activity permitted the effects of drugs on emotional reactivity to be dissociated from the effects on motor activity. Given that social-emotional reactivity was elicited by what typically should have been mild and nonthreatening stimuli, this model may be highly relevant to understanding the neurobiology of anxiety. Finally, these data support an important role for dopamine in the mediation of social-emotional reactivity.