Infant frontal EEG asymmetry moderates the association between maternal behavior and toddler negative affectivity

Relatively little work has examined potential interactions between child intrinsic factors and extrinsic environmental factors in the development of negative affect in early life. This work is important because high levels of early negative affectivity have been associated with difficulties in later childhood adjustment. We examined associations between infant frontal electroencephalogram (EEG), maternal parenting behaviors, and children’s negative affect across the first two years of life. Infant baseline frontal EEG asymmetry was measured at 5 months; maternal sensitivity and intrusiveness were observed during mother-child interaction at 5 and 24 months; and mothers provided reports of toddler negative affect at 24 months. Results indicated that maternal sensitive behaviors at 5 months were associated with less negative affect at 24 months, but only for infants with left frontal EEG asymmetry. Similarly, maternal sensitive behaviors at 24 months were associated with less toddler negative affect at 24 months, but only for infants with left frontal EEG asymmetry. In contrast, maternal intrusive behaviors at 5- and 24-months were associated with greater toddler negative affect, but only for infants with right frontal EEG asymmetry at 5-months. Findings suggest that levels of negative affect in toddlers may be at least partially a result of interactions between children’s own early neurophysiological functioning and maternal behavior during everyday interactions with children in the first two years of life.     

Modeling development of frontal electroencephalogram (EEG) asymmetry: Sex differences and links with temperament

Asymmetric patterns of frontal brain electrical activity reflect approach and avoidance tendencies, with stability of relative right activation associated with withdrawal emotions/motivation and left hemisphere activation linked with approach and positive affect. However, considerable shifts in approach/avoidance‐related lateralization have been reported for children not targeted because of extreme temperament. In this study, dynamic effects of frontal electroencephalogram (EEG) power within and across hemispheres were examined throughout early childhood. Specifically, EEG indicators at 5, 10, 24, 36, 48, and 72 months‐of‐age (n = 410) were analyzed via a hybrid of difference score and panel design models, with baseline measures and subsequent time‐to‐time differences modeled as potentially influencing all subsequent amounts of time‐to‐time change (i.e., predictively saturated). Infant sex was considered as a moderator of dynamic developmental effects, with temperament attributes measured at 5 months examined as predictors of EEG hemisphere development. Overall, change in left and right frontal EEG power predicted declining subsequent change in the same hemisphere, with effects on the opposing neurobehavioral system enhancing later growth. Infant sex moderated the pattern of within and across‐hemisphere effects, wherein for girls more prominent left hemisphere influences on the right hemisphere EEG changes were noted and right hemisphere effects were more salient for boys. Largely similar patterns of temperament prediction were observed for the left and the right EEG power changes, with limited sex differences in links between temperament and growth parameters. Results were interpreted in the context of comparable analyses using parietal power values, which provided evidence for unique frontal effects.     

Longitudinal stability of temperamental exuberance and social-emotional outcomes in early childhood

The goals of the current study were to investigate the stability of temperamental exuberance across infancy and toddlerhood and to examine the associations between exuberance and social-emotional outcomes in early childhood. The sample consisted of 291 4-month-olds followed at 9, 24, and 36 months and again at 5 years of age. Behavioral measures of exuberance were collected at 9, 24, and 36 months. At 36 months, frontal electroencephalogram (EEG) asymmetry was assessed. At 5 years, maternal reports of temperament and behavior problems were collected, as were observational measures of social behavior during an interaction with an unfamiliar peer in the laboratory. Latent profile analysis revealed a high, stable exuberance profile that was associated with greater ratings of 5-year externalizing behavior and surgency, as well as observed disruptive behavior and social competence with unfamiliar peers. These associations were particularly true for children who displayed left frontal EEG asymmetry. Multiple factors supported an approach bias for exuberant temperament but did not differentiate between adaptive and maladaptive social-emotional outcomes at 5 years of age.     

Frontal brain asymmetry predicts infants' response to maternal separation

Examined whether certain features of infant temperament might be related to individual differences in the asymmetry of resting frontal activation. EEG was recorded from the left and right frontal and parietal scalp regions of 13 normal 10-month-old infants. Infant behavior was then observed during a brief period of maternal separation. Those infants who cried in response to maternal separation showed greater right frontal activation during the preceding baseline period compared with infants who did not cry. Frontal activation asymmetry may be a state-independent marker for individual differences in threshold of reactivity to stressful events and vulnerability to particular emotions.     

Frontal Brain Electrical Activity in Shyness and Sociability

A number of studies have shown that shyness and sociability may be two independent personality traits that are distinguishable across a variety of measures and cultures. Utilizing recent frontal activation–emotion models as a theoretical framework, this study examined the pattern of resting frontal electroencephalographic (EEG) activity in undergraduates who self-reported high and low shyness and sociability. Analyses revealed that shyness was associated with greater relative right frontal EEG activity, whereas sociability was associated with greater relative left frontal EEG activity. Also, different combinations of shyness and sociability were distinguishable on the basis of resting frontal EEG power. Although high-shy/high-social and high-shy/low-social subjects both exhibited greater relative right frontal EEG activity, they differed significantly on EEG power in the left, but not right, frontal lead. High-shy/high-social subjects exhibited significantly less EEG power (i.e., more activity) in the left frontal lead compared with the high-shy/low-social subjects. These findings suggest that in distinguishing individual differences in personality and personality subtypes, it is important to consider not only frontal EEG asymmetry measures, but also the pattern of absolute EEG power in each frontal hemisphere.     

Maternal sensitivity and infant response to frustration: The moderating role of EEG asymmetry

Two hundred and thirty-three 5-month-old infants and their mothers participated in a study designed to examine the influence of maternal sensitivity and infant neurophysiology, as well as interactions between these, on infants’ regulatory behavior and reactivity to emotional challenge. Maternal sensitivity was measured during two mother–child free-play episodes prior to the challenge task. Infant neurophysiology was derived from a measure of resting EEG asymmetry collected during a baseline episode. Infant regulatory behaviors (mother orienting and distraction) and reactivity to challenge (negative affect) were assessed during an arm restraint procedure. Maternal sensitivity predicted mother-orienting behavior for all infants, regardless of baseline EEG asymmetry. Maternal sensitivity also predicted more distraction behaviors for infants with left frontal EEG asymmetry at baseline. In contrast, maternal sensitivity predicted more negative affect for infants with right frontal EEG asymmetry at baseline. These findings lend support for the hypothesis that maternal sensitivity and infant neurophysiological functioning interact to predict regulatory behavior and reactivity and are discussed in terms of the significance for understanding infant regulatory development in the first year of life.     

Children’s Depressive Symptoms in Relation to EEG Frontal Asymmetry and Maternal Depression

This study examined the relations of school-age children’s depressive symptoms, frontal EEG asymmetry, and maternal history of childhood-onset depression (COD). Participants were 73 children, 43 of whom had mothers with COD. Children’s EEG was recorded at baseline and while watching happy and sad film clips. Depressive symptoms were measured using parent-report of Children’s Depression Inventory. The key findings are the interaction effects between baseline and film frontal EEG asymmetry on child depressive symptoms. Specifically, relative right frontal EEG asymmetry while watching happy or sad film clip was associated with elevated depressive symptoms for children who also exhibited right frontal EEG asymmetry at baseline. Results suggest that right frontal EEG asymmetry that is consistent across situations may be an marker of depression-prone children.     

Children’s Affect Expression and Frontal EEG Asymmetry: Transactional Associations with Mothers’ Depressive Symptoms

Although parents and children are thought to influence one another's affect and behavior, few studies have examined the direction of effects from children to parents, particularly with respect to parental psychopathology. We tested the hypothesis that children's affective characteristics are associated with the course of mothers' depressive symptoms. Children's affect expression was observed during a series of mother-child interaction tasks, and children's resting frontal electroencephalogram (EEG) asymmetry was assessed in a psychophysiology laboratory. Mothers' depressive symptoms were assessed at two time points, approximately one year apart, at the mother-child interaction visits. Depressive symptoms increased over time for mothers with a history of childhood-onset depression whose children exhibited right frontal EEG asymmetry. Depressive symptoms were associated with high child negative affect at both time points for mothers whose children exhibited right frontal EEG asymmetry. Cross-lagged models with a subset of participants provided some evidence of both parent-to-child and child-to-parent directions of effects. Findings suggest that akin to other interpersonal stressors, children's affective characteristics may contribute to maternal depressive symptoms.     

Negative affectivity and EEG asymmetry interact to predict emotional interference on attention in early school-aged children

Negative affectivity (NA) is a broad construct that has been associated with the development of psychopathologies, such as anxiety, and with exaggerated attention to threatening stimuli. EEG asymmetry reflects biological individual differences in emotional reactivity that may underlie the association between NA and attention to threat. The present study included a sample of 31 five-seven year olds (M age in months = 74.39, SD = 6.57) to test the hypothesis that greater NA, combined with greater right anterior and posterior asymmetries, predicts increased attention interference following threat stimuli. Children completed an executive attention task which presented task-irrelevant threat (angry) and non-threat (neutral) faces prior to each trial. EEG asymmetry was measured at baseline for anterior, anterior-temporal and posterior scalp regions and child NA was measured via maternal report. As predicted, children showing greater NA and greater right anterior-temporal asymmetry showed more attention interference following angry faces. Additionally, two trend-level effects emerged: children showing greater NA and greater left anterior-temporal asymmetry showed less attention interference following angry faces, and children showing greater NA and greater left posterior asymmetry showed less attention interference, but only following neutral faces. Discussion focuses on the utility of using EEG asymmetry in the study of temperament, attentional biases, and the biological processes by which temperament confers risk for psychopathology.     

Intra- and interindividual differences in lateralized cognitive performance and asymmetrical EEG activity in the frontal cortex

The study shows that changes in relative verbal vs. figural working memory and fluency performance from one session to a second session two to 3 weeks apart covary with spontaneously occurring changes of cortical asymmetry in the lateral frontal and central cortex, measured by electroencephalography (EEG) in resting conditions before the execution of tasks. That is, it was examined whether the current state of cortical asymmetry predicts verbal vs. figural performance. The findings complete the circle from studies showing correlations between changes of EEG asymmetry in the lateral frontal cortex and changes of mood to studies showing correlations between changes of mood and changes of relative verbal vs. figural working memory and fluency performance. The study suggests that state-dependent changes of lateralized cortical activity may underlie certain cognitive-emotional interactions observed in previous studies, and supports the assumption of reciprocal influences of specific emotional and specific cognitive processes.     

Oppositional Children Differ from Healthy Children in Frontal Brain Activation

An atypical EEG pattern of frontal brain activation, which has been found in children and adults with emotional disorders, also is hypothesized to be present in disruptive behavior disorders. One hundred nineteen children (4 $\frac{1}{2}$ and 8 years of age) were examined with regard to the following questions: (1) Do children who are diagnosed with oppositional defiant disorder (ODD) exhibit an atypical pattern of frontal brain activation? (2) Can this pattern be demonstrated in preschool children (4 $\frac{1}{2}$ years of age) as well as in school children (8 years)? (3) Are there gender differences in these patterns similar to those that have been demonstrated in adults? Spontaneous EEG activity was subjected to power spectral analysis. In oppositional preschool and elementary school girls, the well-known pattern of lower left frontal than right frontal activation emerged that has been found previously in emotionally disordered children. Healthy girls showed no frontal brain asymmetry at 4 $\frac{1}{2}$ years of age, and left frontal activation at 8 years. In contrast, healthy boys demonstrated a greater right than left frontal activation, whereas ODD boys did not display any frontal brain asymmetry. Thus, the pattern of frontal brain activation seems to be gender-specific. The atypical activation pattern in oppositional children is hypothesized to be a biological substrate of negative affective style.     

Frontal brain electrical activity (EEG) distinguishes valence and intensity of musical emotions

Using recent regional brain activation/emotion models as a theoretical framework, we examined whether the pattern of regional EEG activity distinguished emotions induced by musical excerpts which were known to vary in affective valence (i.e., positive vs. negative) and intensity (i.e., intense vs. calm) in a group of undergraduates. We found that the pattern of asymmetrical frontal EEG activity distinguished valence of the musical excerpts. Subjects exhibited greater relative left frontal EEG activity to joy and happy musical excerpts and greater relative right frontal EEG activity to fear and sad musical excerpts. We also found that, although the pattern of frontal EEG asymmetry did not distinguish the intensity of the emotions, the pattern of overall frontal EEG activity did, with the amount of frontal activity decreasing from fear to joy to happy to sad excerpts. These data appear to be the first to distinguish valence and intensity of musical emotions on frontal electrocortical measures.     

Frontal and parietal EEG asymmetries interact to predict attentional bias to threat

Frontal and parietal electroencephalographic (EEG) asymmetries mark vulnerability to depression and anxiety. Drawing on cognitive theories of vulnerability, we hypothesise that cortical asymmetries predict attention to threat. Participants completed a dot-probe task in which bilateral face displays were followed by lateralised targets at either short (300 ms) or long (1050 ms) SOA. We also measured N2pc to face onset as an index of early attentional capture. At long SOA only, frontal and parietal asymmetry interacted to predict attentional bias to angry faces. Those with leftward frontal asymmetry showed no attentional bias. Among those with rightward frontal asymmetry those with low right parietal activity showed vigilance for threat, and those with high right parietal activity showed avoidance. Asymmetry was not related to the N2pc or to attentional bias at the short SOA. Findings suggest that trait asymmetries reflect function in a fronto-parietal network that controls attention to threat.     

Anger style, psychopathology, and regional brain activity

Depression and anxiety often involve high levels of trait anger and disturbances in anger expression. Reported anger experience and outward anger expression have recently been associated with left-biased asymmetry of frontal cortical activity, assumed to reflect approach motivation. However, different styles of anger expression could presumably involve different brain mechanisms and/or interact with psychopathology to produce various patterns of brain asymmetry. The present study explored these issues by comparing resting regional electroencephalographic activity in participants high in trait anger who differed in anger expression style (high anger-in, high anger-out, both) and participants low in trait anger, with depression and anxiety systematically assessed. Trait anger, not anger-in or anger-out, predicted left-biased asymmetry at medial frontal EEG sites. The anger-in group reported higher levels of anxious apprehension than did the anger-out group. Furthermore, anxious apprehension moderated the relationship between trait anger, anger-in, and asymmetry in favor of the left hemisphere. Results suggest that motivational direction is not always the driving force behind the relationship of anger and left frontal asymmetry. Findings also support a distinction between anxious apprehension and anxious arousal.     

Depression, anxiety, and resting frontal EEG asymmetry: a meta-analytic review

Emotion-related disturbances, such as depression and anxiety, have been linked to relative right-sided resting frontal electroencephalograph (EEG) asymmetry among adults and infants of afflicted mothers. However, a somewhat inconsistent pattern of findings has emerged. A meta-analysis was undertaken to (a) evaluate the magnitude of effects across EEG studies of resting frontal asymmetry and depression, anxiety, and comorbid depression and anxiety and (b) determine whether certain moderator variables could help reconcile inconsistent findings. Moderate effects of similar magnitude were obtained for the depression and anxiety studies, whereas a smaller effect emerged for comorbid studies. Three moderating variables predicted effect sizes: (a) Shorter EEG recording periods were associated with larger effects among adults, (b) different operationalizations of depression yielded effects of marginally different magnitudes, and (c) younger infant samples showed larger effects than older ones. The current data support a link between resting frontal EEG asymmetry and depression and anxiety and provide a partial account of inconsistent findings across studies.     

Frontal brain asymmetry and reward responsiveness: a source-localization study

The influence of approach and avoidance tendencies on affect, reasoning, and behavior has attracted substantial interest from researchers across various areas of psychology. Currently, frontal electroencephalographic (EEG) asymmetry in favor of left prefrontal regions is assumed to reflect the propensity to respond with approach-related tendencies. To test this hypothesis, we recorded resting EEG in 18 subjects, who separately performed a verbal memory task under three incentive conditions (neutral, reward, and punishment). Using a source-localization technique, we found that higher task-independent alpha2 (10.5-12 Hz) activity within left dorsolateral prefrontal and medial orbitofrontal regions was associated with stronger bias to respond to reward-related cues. Left prefrontal resting activity accounted for 54.8% of the variance in reward bias. These findings not only confirm that frontal EEG asymmetry modulates the propensity to engage in appetitively motivated behavior, but also provide anatomical details about the underlying brain systems.     

ADHD Symptoms in Post-Institutionalized Children Are Partially Mediated by Altered Frontal EEG Asymmetry

Individual differences in the propensity for left versus right frontal electroencephalogram (EEG) asymmetry may underlie differences in approach/withdrawal tendencies and mental health deficits. Growing evidence suggests that early life adversity may shape brain development and contribute to the emergence of mental health problems. The present study examined frontal EEG asymmetry (FEA) following the transition to family care in children adopted internationally from institutional care settings between 15 and 36 months of age (N = 82; 46 female, 36 male). Two comparison groups were included: an international adoption control consisting of children adopted from foster care with little to no institutional deprivation (N = 45; 17 female, 28 male) and a post-adoption condition control consisting of children reared in birth families of the same education and income as the adoptive families (N = 48; 23 female, 25 male). Consistent with evidence of greater approach and impulsivity-related behavior problems in post-institutionalized (PI) children, PI status was associated with greater left FEA than found in the other two groups. In addition, left FEA served as a mediator between institutionalization and age 5 ADHD symptoms for girls. Age at adoption and other preadoption factors were examined with results suggesting that earlier adoption into a supportive family resulted in a more typical pattern of brain functioning. Findings support the idea that the capacity of brain activity to evidence typical functioning following perturbation may differ in relation to the timing of intervention and suggest that the earlier the intervention of adoption, the better.     

Behavioral reactivity and approach-withdrawal bias in infancy

Seven hundred seventy-nine infants were screened at 4 months of age for motor and emotional reactivity. At age 9 months, infants who showed extreme patterns of motor and negative (n = 75) or motor and positive (n = 73) reactivity and an unselected control group (n = 86) were administered the Laboratory Temperament Assessment Battery, and baseline electroencephalogram data were collected. Negatively reactive infants showed significantly more avoidance than positively reactive infants and displayed a pattern of right frontal electroencephalogram asymmetry. Positively reactive infants exhibited significantly more approach behavior than controls and exhibited a pattern of left frontal asymmetry. Results support the notion that approach-withdrawal bias underlies reactivity in infancy.     

Withdrawn and intrusive maternal interaction style and infant frontal EEG asymmetry shifts in infants of depressed and non-depressed mothers

The effects of maternal interaction style (intrusive/withdrawn) on the development of brain electrical activity were studied in infants of depressed and non-depressed mothers shortly after birth and again at 3-6 months of age. Infants of depressed mothers exhibited significantly greater relative right frontal EEG activation than infants of non-depressed mothers. Infants of depressed withdrawn mothers exhibited greater relative right frontal EEG activation than infants of depressed intrusive mothers. Furthermore, while infants of depressed mothers with intrusive interaction styles showed a shift towards greater relative left frontal EEG activation from birth to 3-6 months, infants of depressed mothers with withdrawn interaction styles showed a shift towards greater relative right frontal EEG activation.     

The influence of parenting on infant emotionality: A multi-level psychobiological perspective

Infant temperament is theorized to have a strong genetic basis. Yet, studies of the stability of temperament and molecular genetics research on temperament have revealed inconsistent findings. One reason may be because research has not taken into account the influence of early social experiences. We review research on aspects of infant emotionality presumed to be temperamental in origin, emotion reactivity and emotion regulation, and integrate research addressing parenting influences on physiology and genetics of infant emotionality with traditional research on behavioral expression of emotionality. Empirical research supports the theory that sensitive and appropriately responsive parenting in infancy is related to more optimal patterns of behavioral and physiological reactivity and regulation. Molecular genetics research with both animal and human populations has produced consistent results when environmental experiences are taken into account. Findings suggest that the short allele of the serotonin transporter gene and the long allele of the DRD4 dopamine receptor gene may be related to distinct patterns of infant emotionality and to later problems with depression, impulse control problems, and externalizing/antisocial behaviors, primarily when paired with insensitive parenting, abuse or neglect, or other adverse family environments. Future directions and limitations in the field are discussed.