Frontal Electroencephalogram Asymmetry and Temperament Across Infancy and Early Childhood: An Exploration of Stability and Bidirectional Relations

Behavioral and neural measures of infant responsivity increase with maternal multisensory input in non-irritable infants

INTRODUCTION

Parents often use sensory stimulation during early-life interactions with infants. These interactions, including gazing, rocking, or singing, scaffold child development. Previous studies have examined infant neural processing during highly controlled sensory stimulus presentation paradigms.

OBJECTIVE

In this study, we investigated infant behavioral and neural responsiveness during a mother-child social interaction during which the mother provided infant stimulation with a progressive increase in the number of sensory modalities.

METHODS

We prospectively collected and analyzed video-coded behavioral interactions and electroencephalogram (EEG) frontal asymmetry (FAS) from infants (n = 60) at 2-4 months born at ≥ 34 weeks gestation. As the number of sensory modalities progressively increased during the interaction, infant behaviors of emotional connection in facial expressiveness, sensitivity to mother, and vocal communication increased significantly. Conversely, infant FAS for the entire cohort did not change significantly. However, when we accounted for infant irritability, both video-coded behaviors and EEG FAS markers of infant responsiveness increased across the interaction in the non-irritable infants. The non-irritable infants (49%) demonstrated positive FAS, indicating readiness to engage with, rather than to withdraw from, multisensory but not unisensory interactions with their mothers.

RESULTS

These results suggest that multisensory input from mothers is associated with greater infant neural approach state and highlight the importance of infant behavioral state during neural measures of infant responsiveness.

Annual Research Review: Emotion processing in offspring of mothers with depression diagnoses - a systematic review of neural and physiological research

BACKGROUND

Theories of the intergenerational transmission of depression emphasize alterations in emotion processing among offspring of depressed mothers as a key risk mechanism, raising questions about biological processes contributing to these alterations. The objective of this systematic annual research review was to examine and integrate studies of the associations between maternal depression diagnoses and offspring's emotion processing from birth through adolescence across biological measures including autonomic psychophysiology, electroencephalography (EEG), magnetoencephalography (MEG), event-related potentials (ERP), and structural and functional magnetic resonance imaging (MRI).

METHODS

The review was conducted in accordance with the PRISMA 2020 standards. A systematic search was conducted in PsycInfo and PubMed in 2022 for studies that included, 1) mothers with and without DSM-defined depressive disorders assessed via a clinical or diagnostic interview, and 2) measures of offspring emotion processing assessed at the psychophysiological or neural level between birth and 18 years of age.

RESULTS

Findings from 64 studies indicated that young offspring of mothers with depression histories exhibit heightened corticolimbic activation to negative emotional stimuli, reduced left frontal brain activation, and reduced ERP and mesocorticolimbic responses to reward cues compared to offspring of never-depressed mothers. Further, activation of resting-state networks involved in affective processing differentiate offspring of depressed relative to nondepressed mothers. Some of these alterations were only apparent among youth of depressed mothers exposed to negative environmental contexts or exhibiting current emotional problems. Further, some of these patterns were observable in infancy, reflecting very early emerging vulnerabilities.

CONCLUSIONS

This systematic review provides evidence that maternal depression is associated with alterations in emotion processing across several biological units of analysis in offspring. We present a preliminary conceptual model of the role of deficient emotion processing in pathways from maternal depression to offspring psychopathology and discuss future research avenues addressing limitations of the existing research and clinical implications.

Frontal Alpha Asymmetry in Response to Stressor Moderates the Relation Between Parenting Hassles and Child Externalizing Problems

Inequitable urban environments are associated with toxic stress and altered neural social stress processing that threatens the development of self-regulation. Some children in these environments struggle with early onset externalizing problems that are associated with a variety of negative long-term outcomes. While previous research has linked parenting daily hassles to child externalizing problems, the role of frontal alpha asymmetry (FAA) as a potential modifier of this relationship has scarcely been explored. The present study examined mother-child dyads, most of whom were living in low socioeconomic status households in an urban environment and self-identified as members of racial minority groups. Analyses focused on frustration task electroencephalography (EEG) data from 67 children (mean age = 59.0 months, SD = 2.6). Mothers reported the frequency of their daily parenting hassles and their child's externalizing problems. Frustration task FAA moderated the relationship between parenting daily hassles and child externalizing problems, but resting FAA did not. More specifically, children with left frontal asymmetry had more externalizing problems as their mothers perceived more hassles in their parenting role, but parenting hassles and externalizing problems were not associated among children with right frontal asymmetry. These findings lend support to the motivational direction hypothesis and capability model of FAA. More generally, this study reveals how individual differences in lateralization of cortical activity in response to a stressor may confer differential susceptibility to child behavioral problems with approach motivation (i.e., left frontal asymmetry) predicting externalizing problems under conditions of parental stress.

Using different methods for calculating frontal alpha asymmetry to study its development from infancy to 3 years of age in a large longitudinal sample

Frontal electroencephalography (EEG) alpha asymmetry (FAA), defined as the difference in frontal alpha power observed over the right and left frontal scalp regions, has been widely used in developmental research as a measure of multiple aspects of child behavior, such as temperament. Studies have used different equations to calculate FAA, which renders comparison of results across studies challenging. Furthermore, few studies have examined FAA's longitudinal stability across infancy and early childhood, which is a desirable feature of a temperament measure. We investigated the cross-sectional and the longitudinal correlations of FAA values from four different equations to calculate FAA used in the literature. We used baseline EEG data from a longitudinal sample of 321 infants and 168 3-year-old children (149 of whom had data at both timepoints). Consistent with previous work, FAA values calculated using two commonly used equations were highly correlated with each other cross-sectionally but not with values from a different equation that used log-transformed relative power. The log-transformed relative power FAA values were the only values that showed significant longitudinal stability. These findings suggest that researchers interested in FAA as a trait-like measure in children should consider using the relative power equation that renders stability across ages.

Infant electroencephalogram coherence and early childhood inhibitory control: Foundations for social cognition in late childhood

Social cognition is a set of complex processes that mediate much of human behavior. The development of these skills is related to and interdependent on other cognitive processes, particularly inhibitory control. Brain regions associated with inhibitory control and social cognition overlap functionally and structurally, especially with respect to frontal brain areas. We proposed that the neural foundations of inhibitory control and social cognition are measurable in infancy. We used structural equation modeling and showed that 10-month frontotemporal neuroconnectivity measured using electroencephalogram coherence predicts social cognition at 9 years of age through age-4 inhibitory control. These findings provide insight into the neurodevelopmental trajectory of cognition and suggest that connectivity from frontal regions to other parts of the brain is a foundation for the development of these skills. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Longitudinal investigation of shyness and physiological vulnerability: Moderating influences of attention biases to threat and safety

Shyness has long been identified as a vulnerability factor to developing psychosocial problems, but there is heterogeneity in these observed outcomes. One potential factor underlying these relations is individual differences in threat sensitivity. Using a longitudinal design, we examined whether attentional biases toward social threat and safety measured during adulthood moderated the association between shyness measured in emerging adulthood (N = 83, n_female = 48; M_age = 23.56 years, SD_age = 1.09 years) and frontal electroencephalogram (EEG) asymmetry at rest, a physiological index of vulnerability to psychopathology, measured nearly a decade later in adulthood (M_age = 31.68 years, SD_age = 2.27 years). We found that only biases to threat moderated the association between shyness and resting frontal EEG asymmetry longitudinally. In individuals who displayed relative vigilance to social threat, shyness was associated with greater relative right frontal EEG activity at rest (i.e., increased physiological vulnerability). These findings suggest that attentional biases to threat may play a role in understanding the relation between shyness and some known physiological vulnerabilities to psychopathology in adults.

Psychometric properties of infant electroencephalography: Developmental stability, reliability, and construct validity of frontal alpha asymmetry and delta-beta coupling

Resting-state electroencephalography (EEG) provides developmental neuroscientists a noninvasive view into the neural underpinnings of cognition and emotion. Recently, the psychometric properties of two widely used neural measures in early childhood-frontal alpha asymmetry and delta-beta coupling-have come under scrutiny. Despite their growing use, additional work examining how the psychometric properties of these neural signatures may change across infancy is needed. The current study examined the developmental stability, split-half reliability, and construct validity of infant frontal alpha asymmetry and delta-beta coupling. Infants provided resting-state EEG data at 8, 12, and 18 months of age (N = 213). Frontal alpha asymmetry and delta-beta coupling showed significant developmental change from 8 to 18 months. Reliability for alpha asymmetry, and alpha, delta, and beta power, individually, was generally good. In contrast, the reliability of delta-beta coupling scores was poor. Associations between frontal alpha asymmetry and approach tendencies generally emerged, whereas stronger (over-coupled) delta-beta coupling scores were associated with profiles of dysregulation and low inhibition. However, the individual associations varied across time and specific measures of interest. We discuss these findings with a developmental lens, highlighting the importance of repeated measures to better understand links between neural signatures and typical and atypical development.

Association between EEG asymmetry and the error-related negativity across middle childhood

Resting frontal EEG alpha asymmetry has been extensively examined as a marker of motivational disposition. Recent research has examined how this trait-level marker of motivation influences an individual's internal error monitoring (indexed by the error-related negativity; ERN), with mixed findings as to whether more negative ERNs are associated with greater left or right alpha power. Data from 339 children who completed an incentivized Go/No-Go task annually from Kindergarten through 2nd grade were examined for an association between ERN amplitude and EEG asymmetry, and for whether the association was developmentally stable. Results indicate an association between left-dominant activation and a more negative amplitude in Kindergarten, with an inversion of this association emerging by 2nd grade, such that a more negative ERNs were associated with right-dominant activation. We suggest that the association between EEG asymmetry and ERN amplitude is likely modulated by task condition (e.g., incentivization) and experience over time (e.g., habituation).

Consistency of EEG asymmetry patterns in infants of depressed mothers

We evaluated frontal electroencephalogram (EEG) asymmetry across multiple contexts as an index of a general affective response predisposition in 12-month-old infants whose mothers were at elevated risk for perinatal depression due to their mother's history of depression. We further examined mothers' prenatal, postnatal, and concurrent depressive symptom levels in relation to infants' frontal EEG asymmetry consistency. Mothers (n = 132) with a history of depression prior to pregnancy completed depressive symptom scales repeatedly during pregnancy and the first year postpartum. Their 12-month-old infants' frontal EEG asymmetry was recorded across five contexts (baseline/bubbles, peek-a-boo, play, feeding, and distract). Frontal EEG asymmetries showed small to moderate correlations across contexts. Mothers' prenatal depression symptom levels (not postnatal or concurrent) were associated with infants having consistent right, rather than left, frontal EEG asymmetry, even after controlling for infants' observed affect. These findings demonstrate the consistency of EEG asymmetry scores across contexts in 12-month-old infants at risk for the development of psychopathology, providing support for relative right frontal EEG asymmetry as a trait marker of vulnerability to depression. Findings also suggest the importance of mothers' prenatal, rather than postnatal or concurrent depression, in predicting infants' consistent patterns of relative right frontal EEG asymmetry across contexts.

Frontal Brain Asymmetry and the Trajectory of Shyness Across the Early School Years

Although resting right frontal electroencephalogram (EEG) asymmetry has been linked to avoidance and withdrawal-related behaviors such as shyness in previous cross-sectional studies, relatively little research has examined the influence of frontal brain electrical activity on the development of shyness in children using a prospective, longitudinal study design. Here, we tested whether resting frontal EEG asymmetry predicted the trajectory of children's shyness across five assessments. Children were enrolled in the study during the summer prior to grade 1 (N = 37; M_age = 6.39 years, S.D. = 0.15 years), at which time resting frontal EEG activity and maternal report of children's shyness were collected. Mothers then reported on their child's shyness over another four follow-up assessments, spanning 2 years (winter of grade 1, summer prior to grade 2 entry, winter of grade 2, and summer prior to grade 3). Growth curve analysis revealed that children displaying greater relative right frontal EEG activity had lower levels of shyness relative to children exhibiting greater relative left frontal EEG activity at study enrollment (i.e., age 6), but displayed statistically significant linear increases in shyness across time, with the highest levels of shyness by the summer prior to grade 3 (i.e., age 8). There was, however, no relation between left frontal EEG asymmetry and change in shyness across time. These preliminary findings suggest that right frontal EEG asymmetry may reflect a biological diathesis for the growth of shyness during the early school years.

Frontal EEG asymmetry moderates the associations between negative temperament and behavioral problems during childhood

Fearful inhibition and impulsivity-anger significantly predict internalizing and externalizing problems, respectively. An important moderator that may affect these associations is frontal EEG asymmetry (FA). We examined how temperament and FA at 6 years interactively predicted behavioral problems at 9 years. A community sample of 186 children (93 boys, 93 girls) participated in the study. Results indicated that the effect of fearful inhibition on parent-reported internalizing problems increased as children exhibited greater right FA. The effect of impulsivity-anger on parent-reported externalizing problems increased as children showed greater left FA. Because FA was allowed to vary rather than children being dichotomized into membership in left FA and right FA groups, we observed that children's FA contributed to the resilience process only when FA reached specific asymmetry levels. These findings highlight the importance of considering the different functions of FA in combination with specific dimensions of temperament in predicting children's socioemotional outcomes. Clinical implications include providing suggestions for intervention services by demonstrating the role of FA in developing behavioral problems and inspiring research on whether it is possible to alter EEG activation and thus potentially improve developmental outcomes.

Early brain abnormalities in infants born very preterm predict under-reactive temperament

BACKGROUND

Early temperament may mediate the association between brain abnormalities following preterm birth and neurodevelopmental outcomes.

AIMS

This exploratory study investigated whether brain abnormalities in infants born very preterm predicted temperament.

STUDY DESIGN

Infants born prematurely underwent structural MRI at term. Mother self-reported depression symptoms at the scanning visit, and the Infant Behavior Questionnaire-Revised-Short (IBQ-R-S) about their infant at 3-months corrected age.

SUBJECTS

Infants (n = 214) born at ≤32 weeks gestation (M = 29.29, SD = 2.60). Average post-menstrual age at the MRI scan was 42.72 weeks (SD = 1.30). The majority of the infants were male (n = 115), and Caucasian (n = 145) or African American (n = 58). The average birthweight in grams was 1289.75 (SD = 448.5).

OUTCOME MEASURES

Infant Behavior Questionnaire-Revised-Short (IBQ-R-S) subscales.

RESULTS

Multivariate regression showed white matter abnormalities predicted lower ratings on High Intensity Pleasure and Vocal Reactivity, grey matter abnormalities predicted lower ratings on High Intensity Pleasure and Cuddliness, and cerebellar abnormalities predicted lower ratings on Fear and Sadness IBQ-R-S subscales adjusting for gestational age and sex. The pattern of results was essentially unchanged when maternal depression and socioeconomic status were included in the model.

CONCLUSIONS

Early MRI-diagnosed brain abnormalities in infants born very preterm were associated less vocalization and engagement during cuddling, decreased ability to take pleasure in stimulating activities, and lower emotionality in fear and sadness domains. Although replication is warranted, an under-reactive temperament in infants born preterm may have a neurobiological basis.

Maternal intrusiveness predicts infants' event-related potential responses to angry and happy prosody independent of infant frontal asymmetry

Infants' social-cognitive skills first develop within the parent-infant relationship, but large differences between parents exist in the way they approach and interact with their infant. These may have important consequences for infants' social-cognitive development. The current study investigated effects of maternal sensitive and intrusive behavior on 6- to 7-month-old infants' ERP responses to a socio-emotional cue that infants are often confronted with from an early age: emotional prosody in infant-directed speech. Infants may differ in their sensitivity to environmental (including parenting) influences on development, and the current study also explored whether infants' resting frontal asymmetry conveys differential susceptibility to effects of maternal sensitivity and intrusiveness. Results revealed that maternal intrusiveness was related to the difference in infants' ERP responses to happy and angry utterances. Specifically, P2 amplitudes in response to angry sounds were less positive than those in response to happy sounds for infants with less intrusive mothers. Whether this difference reflects an enhanced sensitivity to emotional prosody or a (processing) preference remains to be investigated. No evidence for differential susceptibility was found, as infant frontal asymmetry did not moderate effects of sensitivity or intrusiveness.

Intergenerational Transmission of Frontal Alpha Asymmetry Among Mother-Infant Dyads

BACKGROUND

Frontal alpha asymmetry (FAA) is a well-established neurobiological indicator of depression risk. Reduced FAA relates to current and remitted depression in adults and is seen in offspring of mothers with depression as young as 3 months of age, suggesting a potentially transmittable mechanism of depression risk. It is unclear, however, whether direct familial associations exist for FAA. To address this gap, we evaluated the intergenerational transmission of FAA in a nonclinical cohort of mother-infant dyads.

METHODS

Mothers and their 12-month-old infants (n = 34 dyads) completed parallel resting-state tasks while electroencephalography was recorded. We measured FAA across a range of putative frequency bands and calculated its reliability in mothers and infants. Finally, we evaluated the heritability of FAA based on the parent-offspring correlation.

RESULTS

Mother and infant FAA convergence was strongest in the high alpha range for mothers (11-13 Hz) and broad alpha range for infants (6-9 Hz). Mother high FAA exhibited excellent split-half reliability (r_SB = .99) and internal consistency after 80 seconds (α = .90); infant FAA exhibited good split-half reliability (r_SB = .81) and fair internal consistency after 70 seconds (α = .74). Mother-infant FAA were moderately correlated (r = .41), which indicates narrow-sense heritability of up to 82%.

CONCLUSIONS

FAA can be assessed reliably and relatively quickly in both adults and infants. There is a robust association of FAA between mothers and their infants, supporting intergenerational transmission. This finding is consistent with the possibility that reduced FAA may directly confer depression risk at the individual-family level.

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.

Behavioral genetics of temperament and frontal asymmetry in early childhood

Temperament has been suggested to be influenced by genetic and environmental factors. The current study examined genetic shared environmental and unique environmental factors accounting for variation in Fear, Effortful Control (EC), and Frontal Asymmetry (FA) in 4- to 6-year-old children using bivariate behavioral genetic modeling. We included a total of 214 same-sex twin pairs: 127 monozygotic (MZ) and 87 dizygotic (DZ) pairs. FA was measured during a rest electroencephalogram (EEG) recording, and Fear and EC were measured using parent report. Results show that differences between twins were best explained by genetic factors (about a quarter of the variance) and unique environmental factors (about three quarters of the variance). However, the cross-trait, within-twin correlations were not significant, implying no overlapping genetic or environmental factors on Fear and EC or on Fear and FA. Future research should try to elucidate the large role of unique environmental factors in explaining variance in these temperament-related traits.

Frontal EEG asymmetry and later behavior vulnerability in infants with congenital visual impairment

OBJECTIVE

Young children with congenital visual impairment (VI) are at increased risk of behavioral vulnerabilities. Studies on 'at risk' populations suggest that frontal EEG asymmetry may be associated with behavioral risk. We investigated frontal asymmetry at 1year (Time 1), behavior at 2years (Time 2) and their longitudinal associations within a sample of infants with VI. Frontal asymmetry in the VI sample at 1year was also compared cross-sectionally to an age-matched typically sighted (TS) group.

METHODS

At Time 1, 22 infants with VI and 10 TS infants underwent 128-channel EEG recording. Frontal asymmetry ratios were calculated from power spectral density values in the alpha frequency band. At Time 2, Achenbach Child Behavior Checklist data was obtained for the VI sample.

RESULTS

63.6% of the VI sample and 50% of the TS sample showed left frontal asymmetry; no significant difference in frontal asymmetry was found between the two groups. 22.7% of the VI sample had subclinical to clinical range 'internalizing' behavior difficulties. Greater left frontal asymmetry at one year was significantly associated with greater emotionally reactive scores at two years within the VI sample (r=0.50, p=0.02).

CONCLUSIONS

Left frontal asymmetry correlates with later behavior risk within this vulnerable population.

SIGNIFICANCE

These findings make an important first contribution regarding the utility of frontal EEG asymmetry as a method to investigate risk in infants with VI.

Positive Affectivity and Fear Trajectories in Infancy: Contributions of Mother-Child Interaction Factors

Fear and positive emotionality were considered in a growth modeling context. Mothers, primarily Caucasian (91.9%) and of middle socioeconomic status, participated in play interactions with infants at 4 months (N = 148). Infant fear and positive affectivity were evaluated at 6, 8, 10, and 12 months of age. A linear trajectory was superior in explaining growth for parent report and observation-based indicators of positive affectivity and parent report of fearfulness; a piecewise model explained the nonlinear growth of observation-based fear. Responsiveness in mother-infant interactions emerged as a significant predictor of the fear trajectory, with higher sensitivity predicting lower levels of observed fear. Reciprocity, tempo, emotional tone, and intensity of mother-infant interactions also made significant contributions to temperament development; however, analyses addressing these were exploratory.

Short- and long-term stability of alpha asymmetry in infants: Baseline and affective measures

Asymmetry in cortical activity was tested for short- and long-term stability during the first year of life. Infants (N = 129) completed a total of four laboratory visits: two visits occurred about 1 week apart when infants were 6 months old, and two visits occurred about 1 week apart when infants were 12 months of age. At each laboratory visit, EEG readings were taken during five 1-min, neutral baselines as well as during a negative and a positive emotion-eliciting task. The stability of hemispheric asymmetry was assessed at midfrontal (F3/4, F7/8) and parietal (P3/4) electrode sites. Asymmetry in baseline and fear-eliciting episodes showed moderate short-term stability. Long-term stability was apparent when assessments were composited at 6 months and 12 months. Frontal asymmetry was greater than parietal asymmetry for baseline recordings. There was minimal evidence for stability in asymmetry during positive emotion tasks. Results are discussed with regard to the collection and interpretation of alpha asymmetry measures during infancy.