Early Caregiver Predictability Shapes Neural Indices of Statistical Learning Later in Infancy.

Caregivers play an outsized role in shaping early life experiences and development, but we often lack mechanistic insight into how exactly caregiver behavior scaffolds the neurodevelopment of specific learning processes. Here, we capitalized on the fact that caregivers differ in how predictable their behavior is to ask if infants' early environmental input shapes their brains' later ability to learn about predictable information. As part of an ongoing longitudinal study in South Africa, we recorded naturalistic, dyadic interactions between 103 (46 females and 57 males) infants and their primary caregivers at 3-6 months of age, from which we calculated the predictability of caregivers' behavior, following caregiver vocalization and overall. When the same infants were 6-12-months-old they participated in an auditory statistical learning task during EEG. We found evidence of learning-related change in infants' neural responses to predictable information during the statistical learning task. The magnitude of statistical learning-related change in infants' EEG responses was associated with the predictability of their caregiver's vocalizations several months earlier, such that infants with more predictable caregiver vocalization patterns showed more evidence of statistical learning later in the first year of life. These results suggest that early experiences with caregiver predictability influence learning, providing support for the hypothesis that the neurodevelopment of core learning and memory systems is closely tied to infants' experiences during key developmental windows.

Infants' neural responses to emotional faces are related to maternal anxiety.

BACKGROUND: Postnatal maternal anxiety is common (estimates as high as 40% prevalence) and is associated with altered mother-infant interactions (e.g., reduced maternal emotional expression and engagement). Neural circuitry supporting infants' face and emotion processing develops in their first year. Thus, early exposure to maternal anxiety may impact infants' developing understanding of emotional displays. We examine whether maternal anxiety is associated with individual differences in typically developing infants' neural responses to emotional faces. METHODS: One hundred and forty two mother-infant dyads were assessed when infants were 5, 7, or 12 months old. Infants' electroencephalographic (EEG) data were recorded while passively viewing female happy, fearful, and angry faces. Three event-related potential (ERP) components, each linked to face and emotion processing, were evaluated: NC, N290, and P400. Infant ERP amplitude was related to concurrent maternal-report anxiety assessed with the Spielberger State-Trait Anxiety Inventory (Trait form). RESULTS: Greater maternal anxiety predicted more negative NC amplitude for happy and fearful faces in left and mid-central scalp regions, beyond covarying influences of maternal depression symptoms, infant negative emotionality, and infant age. CONCLUSIONS: Postnatal maternal anxiety is related to infants' neural processing of emotional expressions. Infants of mothers endorsing high trait anxiety may need additional attentional resources to process happy and fearful faces (expressions less likely experienced in mother-infant interactions). Future research should investigate mechanisms underlying this association, given possibilities include experiential, genetic, and prenatal factors.

Parenting and Children's Executive Function Stability Across the Transition to School.

When children transition to school between the ages of 4 and 6 years, they must learn to control their attention and behavior to be successful. Concurrently, executive function (EF) is an important skill undergoing significant development in childhood. To understand changes occurring during this period, we examined the role of parenting in the development of children's EF from 4 to 6 years old. Participants were mother and child dyads (N = 151). Children completed cognitive tasks to assess overall EF at age 4 and age 6. At both time points, mothers and children completed interaction tasks which were videotaped and coded to assess various parenting dimensions. Results indicated that children with high EF at age 4 were more likely to have high EF at age 6. In addition, results suggested that higher levels of positive parenting across the transition to school promote stability of individual differences in EF.

Neural correlates of facial emotion processing in infancy.

In the present study we examined the neural correlates of facial emotion processing in the first year of life using ERP measures and cortical source analysis. EEG data were collected cross-sectionally from 5- (N = 49), 7- (N = 50), and 12-month-old (N = 51) infants while they were viewing images of angry, fearful, and happy faces. The N290 component was found to be larger in amplitude in response to fearful and happy than angry faces in all posterior clusters and showed largest response to fear than the other two emotions only over the right occipital area. The P400 and Nc components were found to be larger in amplitude in response to angry than happy and fearful faces over central and frontal scalp. Cortical source analysis of the N290 component revealed greater cortical activation in the right fusiform face area in response to fearful faces. This effect started to emerge at 5 months and became well established at 7 months, but it disappeared at 12 months. The P400 and Nc components were primarily localized to the PCC/Precuneus where heightened responses to angry faces were observed. The current results suggest the detection of a fearful face in infants' brain can happen shortly (~200-290 ms) after the stimulus onset, and this process may rely on the face network and develop substantially between 5 to 7 months of age. The current findings also suggest the differential processing of angry faces occurred later in the P400/Nc time window, which recruits the PCC/Precuneus and is associated with the allocation of infants' attention.

Advancing the reporting of pediatric EEG data: Tools for estimating reliability, effect size, and data quality metrics.

EEG studies play a crucial role in enhancing our understanding of brain development across the lifespan. The increasing clinical and policy implications of EEG research underscore the importance of utilizing reliable EEG measures and increasing the reproducibility of EEG studies. However, important data characteristics like reliability, effect sizes, and data quality metrics are often underreported in pediatric EEG studies. This gap in reporting could stem from the lack of accessible computational tools for quantifying these metrics for EEG data. To help address the lack of reporting, we developed a toolbox that facilitates the estimation of internal consistency reliability, effect size, and standardized measurement error with user-friendly software that facilitates both computing and interpreting these measures. In addition, our tool provides subsampled reliability and effect size in increasing numbers of trials. These estimates offer insights into the number of trials needed for detecting significant effects and reliable measures, informing the minimum number of trial thresholds for the inclusion of participants in individual difference analyses and the optimal trial number for future study designs. Importantly, our toolbox is integrated into commonly used preprocessing pipelines to increase the estimation and reporting of data quality metrics in developmental neuroscience.

Evaluating a novel high-density EEG sensor net structure for improving inclusivity in infants with curly or tightly coiled hair.

Electroencephalography (EEG) is an important tool in the field of developmental cognitive neuroscience for indexing neural activity. However, racial biases persist in EEG research that limit the utility of this tool. One bias comes from the structure of EEG nets/caps that do not facilitate equitable data collection across hair textures and types. Recent efforts have improved EEG net/cap design, but these solutions can be time-intensive, reduce sensor density, and are more difficult to implement in younger populations. The present study focused on testing EEG sensor net designs over infancy. Specifically, we compared EEG data quality and retention between two high-density saline-based EEG sensor net designs from the same company (Magstim EGI, Whitland, UK) within the same infants during a baseline EEG paradigm. We found that within infants, the tall sensor nets resulted in lower impedances during collection, including lower impedances in the key online reference electrode for those with greater hair heights and resulted in a greater number of usable EEG channels and data segments retained during pre-processing. These results suggest that along with other best practices, the modified tall sensor net design is useful for improving data quality and retention in infant participants with curly or tightly-coiled hair.

Household clutter and crowding constrain associations between maternal sensitivity and child theory of mind.

Social interactions between parents and children are important for developing theory of mind, but these may be disrupted by aspects of the proximal home environment. The current study observed maternal sensitivity and its associations with child theory of mind and the housing environment (index by clutter and crowding) in a sample of mothers and their 3.5-year-old twins (N = 250 children). Maternal sensitivity and housing environment were measured from experimenter report and child theory of mind was measured through behavioural tasks. Results show that the association between maternal sensitivity and child theory of mind was moderated by the housing environment, where the positive associations between maternal sensitivity and child theory of mind were only observed at lower levels of clutter and crowding in the housing environment. Additional contextual variables and processes are discussed.

Household Chaos, Parental Responses to Emotion, and Child Emotion Regulation in Middle Childhood.

Parents' responses to children's negative emotional states play a key role in the socialization of emotion regulation skills in childhood. Much of the prior research on child ER has focused on early development using cross-sectional designs. The current study addresses these gaps by using a longitudinal design to examine individual differences of ER at two times points in middle childhood. We examined the development of children's ER by testing hypotheses about the interplay of parent response to emotions and household chaos in the prediction of individual differences in children's ER. Participants were the mothers of children at 6 and 9 years of age among 224 families in a socioeconomically diverse sample that was part of an ongoing longitudinal study. Mothers completed questionnaires regarding themselves, their children, and their home environment. Mothers' reports of better child ER at both time points were positively associated with mothers' more supportive responses and negatively associated with mothers' less non-supportive responses, as well as lower household chaos. Chaos statistically moderated the link between non-supportive parental responses to emotion and child ER, but only at 6 years of age. The strength of the link between child ER and non-supportive parental responses to emotions was strong only at lower levels of household chaos. At the beginning of middle childhood, family processes linking parent responses to child emotions and children's developing ER may not function at higher levels of household chaos.

Rapid face processing for positive and negative emotions in 5-, 7-, and 12-month-old infants: An exploratory study.

Processing of positive and negative facial expressions in infancy follows a distinct course with a bias towards fearful facial expressions starting at 7 months of age; however, little is known about the developmental trajectory of fear processing and other facial expressions, and if this bias is driven by specific regions of the face. This study used eye tracking to examine the processing of positive and negative emotional faces in independent groups of 5- (n = 43), 7- (n = 60), and 12-month-old infants (n = 70). Methods: Infants were shown static images of female faces exhibiting happy, anger, and fear expressions, for one-second each. Total looking time and looking time for areas of interest (AOIs) including forehead and eyes (top), mouth and chin (bottom), and contour of each image were computed. Infants across all ages looked longer to fear faces than angry or happy faces. Negative emotions generally elicited greater looking times for the top of the face than did happy faces. In addition, we also found that at 12 months of age infants looked longer for the bottom of the faces than did 5-month-olds. Our study suggests that the visual bias to attend longer to fearful faces may be in place by 5 months of age, and between 5 and 12 months of age, there seems to be a developmental shift towards looking more to the bottom of the faces. STATEMENT OF CONTRIBUTION: What is already known in this subject? Bias for fear face processing is present at 7 months of age. Using older data collection systems, we have some idea about which facial features recruit infant attention. What the present study adds? Well-controlled paradigm that examines both positive and negative facial expressions, to different areas of interest in the face. Use of the same paradigm to test a cross-sectional sample of infants in distinct developmental stages - 5, 7, and 12 months.

Looking to the eyes influences the processing of emotion on face-sensitive event-related potentials in 7-month-old infants.

Previous studies in infants have shown that face-sensitive components of the ongoing electroencephalogram (the event-related potential, or ERP) are larger in amplitude to negative emotions (e.g., fear, anger) versus positive emotions (e.g., happy). However, it is still unclear whether the negative emotions linked with the face or the negative emotions alone contribute to these amplitude differences. We simultaneously recorded infant looking behaviors (via eye-tracking) and face-sensitive ERPs while 7-month-old infants viewed human faces or animals displaying happy, fear, or angry expressions. We observed that the amplitude of the N290 was greater (i.e., more negative) to angry animals compared to happy or fearful animals; no such differences were obtained for human faces. Eye-tracking data highlighted the importance of the eye region in processing emotional human faces. Infants that spent more time looking to the eye region of human faces showing fearful or angry expressions had greater N290 or P400 amplitudes, respectively.

Extraction of heart rate from functional near-infrared spectroscopy in infants.

Changes in heart rate are a useful physiological measure in infant studies. We present an algorithm for calculating the heart rate (HR) from oxyhemoglobin pulsation in functional near-infrared spectroscopy (fNIRS) signals. The algorithm is applied to data collected from 10 infants, and the HR derived from the fNIRS signals is compared against the HR as calculated by electrocardiography. We show high agreement between the two HR signals for all infants (r > 0.90), and also compare stimulus-related HR responses as measured by the two methods and find good agreement despite high levels of movement in the infants. This algorithm can be used to measure changes in HR in infants participating in fNIRS studies without the need for additional HR sensors.