Human maternal responsiveness is a complex repertoire of infant-related behaviours and attitudes, which vary between and within mothers. Environmental and socioeconomic factors undoubtedly influence maternal care, but less is known about how genetic variation associates with maternal responsiveness. Where genetic variation has been examined in relation to mothering, the moderating effects of early life experiences in the mother have not been explored. Additionally, studies tend to focus on maternal sensitivity, neglecting to explore other dimensions of maternal responsiveness. The purpose of the present thesis was to explore genetic variation in three gene families – dopamine (DA), serotonin (5-HT), and oxytocin (OXT) – in relation to differences in maternal care in a Caucasian sample of new mothers recruited in early pregnancy from Hamilton, Ontario (N=187). Furthermore, interactions between early experiences in the mothers’ lives and their genetic polymorphic variants were examined. Early experience was a combined measure of the Parental Bonding Instrument and the Childhood Trauma Questionnaire. Maternal behaviour during mother-infant interaction was assessed at 6 months postpartum and derived from a video-recorded 30-minute mother-infant interaction. The behavioural outcomes of interest maternal sensitivity (assessed using the Ainsworth Maternal Care Scales) and maternal behaviors (vocalizing, orienting away from infant, instrumental caregiving). We also assessed maternal attitudes about parenting the infant at 6 months postpartum. Multiple polymorphisms on DA receptors D1 (rs686, rs4532, rs265981, rs265976, rs5326) and D2 (rs6277, rs1799732, rs1799978, rs1800497) associated with maternal vocalizing and orienting away from the infant, respectively. The OXT polymorphisms rs2740210 and rs4813627 associated with infant-directed vocalizing. A major polymorphism on the 5-HT transporter (5HTTLPR and a related rs25531 polymorphism) associated significantly with maternal sensitivity. There were gene-environment interactions between this 5-HT polymorphism and early adversity in association with maternal orienting away and maternal attitudes. Gene-environment interactions were also found between the OXT polymorphisms rs2740210 and rs4813627 and instrumental care of the infant. These results suggest that variations in genes encoding major brain neurotransmitters and neurohormones are related to observed maternal behaviour and self-reported maternal attitudes. These results showcase the importance of exploring multiple dimensions of complex behavioural phenotypes like mothering.

The current study compared infant cortisol responses during the still-face procedure with those shown during other parent-infant interactions. It also examined how stress hormones can affect memory retention. Six-month-old infants (n = 38) were exposed to either a repeated still-face procedure, normal face-to-face interaction, or a divided-attention task. Salivary cortisol was collected at multiple time points. Infants were assigned to a memory demonstration (n = 30) or a no-demonstration (n = 8) group. Infants in the demonstration group were shown 3 target actions with a puppet, and subsequently given a chance to repeat the target actions. Infants in the no demonstration group were not shown the target actions. Only the infants who experienced the still-face procedure showed a significant change in salivary cortisol throughout the procedure. Cortisol values did not significantly predict memory performance. There are still many questions regarding how stress induction during memory consolidation affects memory performance.

Research in developmental psychopathology has advanced our understanding of emotional dysregulation underlying children’s behavioural problems and their association with maternal depression. Neurophysiological measures may further clarify these relations. The ERN (error-related negativity) is an event-related potential commonly used to assess self-monitoring, with large amplitudes reflecting internalizing and small amplitudes reflecting externalizing symptoms. The present study investigated the effect of ERN amplitude on the relation between maternal depression and internalizing and externalizing problems in a sample of children referred for aggressive behaviour. ERN amplitudes were recorded while 50 children (8-10 years of age) engaged in a go/no-go emotion induction task. Results indicated an association between high ERN amplitudes and internalizing behaviour and between small ERN amplitudes and externalizing behaviours for children with depressed mothers. These findings suggest that the degree of self-monitoring (indexed by ERN amplitude) moderates the relation between maternal depression and psychopathological outcomes in children.

This study examined whether cortical changes underlying treatment for children with aggressive behaviour problems are related to changes in executive function (EF) performance. Fifty-five 8- to 12-year-old clinically-referred children were tested before and after a 14-week treatment intervention. Performance on four EF tasks varying in affective relevance was assessed at each session. EEG was also used to record peak amplitudes for the “inhibitory” N2, an event-related potential, while the children completed an emotion-induction Go/Nogo task. Results showed that changes in N2 amplitudes significantly predicted changes in performance only for the Iowa Gambling Task (IGT) – an affectively relevant task. Subsequent analysis revealed that only children who improved with treatment displayed significant decreases in N2 amplitudes and significant improvement in IGT performance from pre- to post-treatment. These findings suggest that cortical changes underlying successful treatment for children’s aggressive behaviour problems tap improvement in executive functions recruited for emotionally demanding events.

Human maternal responsiveness is a complex repertoire of infant-related behaviours and attitudes, which vary between and within mothers. Environmental and socioeconomic factors undoubtedly influence maternal care, but less is known about how genetic variation associates with maternal responsiveness. Where genetic variation has been examined in relation to mothering, the moderating effects of early life experiences in the mother have not been explored. Additionally, studies tend to focus on maternal sensitivity, neglecting to explore other dimensions of maternal responsiveness. The purpose of the present thesis was to explore genetic variation in three gene families – dopamine (DA), serotonin (5-HT), and oxytocin (OXT) – in relation to differences in maternal care in a Caucasian sample of new mothers recruited in early pregnancy from Hamilton, Ontario (N=187). Furthermore, interactions between early experiences in the mothers’ lives and their genetic polymorphic variants were examined. Early experience was a combined measure of the Parental Bonding Instrument and the Childhood Trauma Questionnaire. Maternal behaviour during mother-infant interaction was assessed at 6 months postpartum and derived from a video-recorded 30-minute mother-infant interaction. The behavioural outcomes of interest maternal sensitivity (assessed using the Ainsworth Maternal Care Scales) and maternal behaviors (vocalizing, orienting away from infant, instrumental caregiving). We also assessed maternal attitudes about parenting the infant at 6 months postpartum. Multiple polymorphisms on DA receptors D1 (rs686, rs4532, rs265981, rs265976, rs5326) and D2 (rs6277, rs1799732, rs1799978, rs1800497) associated with maternal vocalizing and orienting away from the infant, respectively. The OXT polymorphisms rs2740210 and rs4813627 associated with infant-directed vocalizing. A major polymorphism on the 5-HT transporter (5HTTLPR and a related rs25531 polymorphism) associated significantly with maternal sensitivity. There were gene-environment interactions between this 5-HT polymorphism and early adversity in association with maternal orienting away and maternal attitudes. Gene-environment interactions were also found between the OXT polymorphisms rs2740210 and rs4813627 and instrumental care of the infant. These results suggest that variations in genes encoding major brain neurotransmitters and neurohormones are related to observed maternal behaviour and self-reported maternal attitudes. These results showcase the importance of exploring multiple dimensions of complex behavioural phenotypes like mothering.

The current study compared infant cortisol responses during the still-face procedure with those shown during other parent-infant interactions. It also examined how stress hormones can affect memory retention. Six-month-old infants (n = 38) were exposed to either a repeated still-face procedure, normal face-to-face interaction, or a divided-attention task. Salivary cortisol was collected at multiple time points. Infants were assigned to a memory demonstration (n = 30) or a no-demonstration (n = 8) group. Infants in the demonstration group were shown 3 target actions with a puppet, and subsequently given a chance to repeat the target actions. Infants in the no demonstration group were not shown the target actions. Only the infants who experienced the still-face procedure showed a significant change in salivary cortisol throughout the procedure. Cortisol values did not significantly predict memory performance. There are still many questions regarding how stress induction during memory consolidation affects memory performance.

Research in developmental psychopathology has advanced our understanding of emotional dysregulation underlying children’s behavioural problems and their association with maternal depression. Neurophysiological measures may further clarify these relations. The ERN (error-related negativity) is an event-related potential commonly used to assess self-monitoring, with large amplitudes reflecting internalizing and small amplitudes reflecting externalizing symptoms. The present study investigated the effect of ERN amplitude on the relation between maternal depression and internalizing and externalizing problems in a sample of children referred for aggressive behaviour. ERN amplitudes were recorded while 50 children (8-10 years of age) engaged in a go/no-go emotion induction task. Results indicated an association between high ERN amplitudes and internalizing behaviour and between small ERN amplitudes and externalizing behaviours for children with depressed mothers. These findings suggest that the degree of self-monitoring (indexed by ERN amplitude) moderates the relation between maternal depression and psychopathological outcomes in children.

This study examined whether cortical changes underlying treatment for children with aggressive behaviour problems are related to changes in executive function (EF) performance. Fifty-five 8- to 12-year-old clinically-referred children were tested before and after a 14-week treatment intervention. Performance on four EF tasks varying in affective relevance was assessed at each session. EEG was also used to record peak amplitudes for the “inhibitory” N2, an event-related potential, while the children completed an emotion-induction Go/Nogo task. Results showed that changes in N2 amplitudes significantly predicted changes in performance only for the Iowa Gambling Task (IGT) – an affectively relevant task. Subsequent analysis revealed that only children who improved with treatment displayed significant decreases in N2 amplitudes and significant improvement in IGT performance from pre- to post-treatment. These findings suggest that cortical changes underlying successful treatment for children’s aggressive behaviour problems tap improvement in executive functions recruited for emotionally demanding events.

The aim of this thesis was to examine the parent-child relationships and peer functioning of community-identified, 4-year-old boys with hyperactive behaviour problems. The sample consisted of 33 pervasively hyperactive boys and 34 control children. Parenting and child behaviours, and family life factors were assessed at home using a range of measures including the Parental Account of Children's Symptoms Interview (PACS), the Parenting Scale, the General Health Questionnaire (GHQ), and the Life Events Questionnaire. In addition, maternal directiveness and synchrony were coded from videotaped parent-child interaction during free play. Children's peer relations were assessed with teacher ratings on the Child Behavior Scale (CBS) and observer ratings of peer interactions at kindergarten. Results showed that parents of hyperactive boys used less effective parenting skills in disciplinary situations and in coping with child behaviour problems, and spent less time in positive parent-child interaction than comparison group parents. Mothers of hyperactive boys also engaged in fewer synchronous play interactions with their sons and gave more negative ratings on indices of life stress. Poor parent coping, father-child communication, maternal synchrony, negative disciplinary practices, and life stress were significantly associated with hyperactivity after adjusting for the effects of conduct problems. The best parenting predictor of hyperactivity was maternal coping. Compared with control children, the hyperactive boys received significantly higher ratings on exclusion by peers, aggressive, noncompliant, and non-social behaviours, as well as significantly lower ratings of prosocial behaviour and peer acceptance. These between-group differences in social functioning remained significant after statistical control for the effects of conduct problems. Further analysis suggested that the associations between hyperactivity and child social behaviours were partly or wholly explained by group differences in exposure to parenting behaviours that are important for children's social development. These findings highlight the need to examine more closely the role of parenting behaviours in shaping the course, prognosis and treatment outcomes in relation to the behavioural and social adjustment of preschool hyperactive children. The implications of these findings for early childhood intervention in hyperactive behaviour problems are discussed. / Subscription resource available via Digital Dissertations only.

The aim of this thesis was to examine the parent-child relationships and peer functioning of community-identified, 4-year-old boys with hyperactive behaviour problems. The sample consisted of 33 pervasively hyperactive boys and 34 control children. Parenting and child behaviours, and family life factors were assessed at home using a range of measures including the Parental Account of Children's Symptoms Interview (PACS), the Parenting Scale, the General Health Questionnaire (GHQ), and the Life Events Questionnaire. In addition, maternal directiveness and synchrony were coded from videotaped parent-child interaction during free play. Children's peer relations were assessed with teacher ratings on the Child Behavior Scale (CBS) and observer ratings of peer interactions at kindergarten. Results showed that parents of hyperactive boys used less effective parenting skills in disciplinary situations and in coping with child behaviour problems, and spent less time in positive parent-child interaction than comparison group parents. Mothers of hyperactive boys also engaged in fewer synchronous play interactions with their sons and gave more negative ratings on indices of life stress. Poor parent coping, father-child communication, maternal synchrony, negative disciplinary practices, and life stress were significantly associated with hyperactivity after adjusting for the effects of conduct problems. The best parenting predictor of hyperactivity was maternal coping. Compared with control children, the hyperactive boys received significantly higher ratings on exclusion by peers, aggressive, noncompliant, and non-social behaviours, as well as significantly lower ratings of prosocial behaviour and peer acceptance. These between-group differences in social functioning remained significant after statistical control for the effects of conduct problems. Further analysis suggested that the associations between hyperactivity and child social behaviours were partly or wholly explained by group differences in exposure to parenting behaviours that are important for children's social development. These findings highlight the need to examine more closely the role of parenting behaviours in shaping the course, prognosis and treatment outcomes in relation to the behavioural and social adjustment of preschool hyperactive children. The implications of these findings for early childhood intervention in hyperactive behaviour problems are discussed. / Subscription resource available via Digital Dissertations only.