Social EEG: A novel neurodevelopmental approach to studying brain-behavior links and brain-to-brain synchrony during naturalistic toddler-parent interactions

Evaluating the Construct Validity of Sentence-Focused Diversity Measures With Late-Talking Toddlers and Same-Age Peers

PURPOSE

The purpose of this study was to evaluate the construct validity of three sentence-focused diversity measures, intransitive verb diversity, transitive verb diversity, and third person (3P) subject diversity, using two methods: (a) group differentiation of late-talking (LT) toddlers from peers with typically developing (TD) language and (b) associations with established measures of language development. A secondary purpose was to determine whether 3P subject diversity was more strongly associated with intransitive verbs than transitive verbs.

METHOD

Examiner-child language samples from 58 LT toddlers and 82 TD toddlers (ages 24-30 months) were collected using a structured language sampling protocol. Transcripts were coded to obtain measures of intransitive verb diversity, transitive verb diversity, and 3P subject diversity as well as mean length of utterance (MLU) and number of different words (NDW). We used nonparametric tests to examine differences between groups and associations between measures within each group. We also conducted an exploratory analysis using a generalized linear mixed model to determine the strength of associations for intransitive and transitive verb diversity with 3P subject diversity.

RESULTS

All sentence-focused diversity measures were significantly different between groups. They were also positively related to MLU, NDW, and to each other within each group. Both intransitive verb diversity and transitive verb diversity were significantly associated with 3P subject diversity, after accounting for NDW; however, the strength of association observed between intransitive verb diversity and 3P subject diversity was nearly twice as large.

CONCLUSIONS

These findings provide new evidence that sentence-focused diversity measures are valid indicators of early language development and that intransitive verbs have a stronger association with diverse 3P subjects than transitive verbs. The value of adopting measures of verb and subject diversity with LT toddlers is discussed.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.28577747.

Maternal Oral Reading Expressiveness in Relation to Toddlers' Concurrent Language Skills Across a Continuum of Early Language Abilities

PURPOSE

A rich body of evidence has illuminated the importance of caregivers' use of prosody in facilitating young children's language development. Although caregiver-child shared reading has been repeatedly linked to children's language skills, caregiver prosody during shared reading interactions (i.e., oral reading expressiveness) has been largely overlooked in research to date. Here, we investigated whether maternal oral reading expressiveness is associated with language skills among late-talking and typical-talking toddlers.

METHOD

Forty mother-child dyads, with toddlers classified as either late talkers (n = 18) or typical talkers (n = 22), engaged in a shared reading interaction. Acoustic measures of oral reading expressiveness (mean fundamental frequency [F0], rate) were compared between mothers of late versus typical talkers. Whole-group analyses then examined oral reading expressiveness in relation to toddlers' concurrent receptive and expressive language skills across the continuum.

RESULTS

Between-group comparisons of mothers of late versus typical talkers revealed no group differences in oral reading expressiveness. However, whole-group, continuous analyses of maternal oral reading expressiveness in relation to toddlers' concurrent language skills revealed that maternal oral reading expressiveness, specifically mean F0, significantly contributed to the prediction of toddlers' receptive language skills, accounting for demographic and socioeconomic factors.

CONCLUSIONS

Initial findings suggest that maternal oral reading expressiveness is associated with children's emerging language skills and warrant further investigation of how this relates to broader aspects of children's home language environments. This work carries implications for oral reading expressiveness as one facet of shared reading with potential to facilitate early language skill development.

Neural hyperscanning in caregiver-child dyads: A paradigm for studying the long-term effects of facilitated vs. disrupted attention on working memory and executive functioning in young children

Parent-child interactions shape children's cognitive outcomes such that caregivers can guide attention and facilitate learning opportunities. These interactions provide infants and toddlers with rich, naturalistic experiences that engage complex cognitive functions and lay the groundwork for the development of mature executive functions. Although most caregivers seek to engage children optimally, they can unintentionally impede this developmental process by being under-engaged or intrusive. When caregivers are under engaged, children do not have the proper scaffolding to know what to attend to in a complex environment. When parents are intrusive, they inadvertently disrupt the child's attention and direct learning to information that the parent deems important, but the child may find uninteresting or irrelevant. This disruption can impede the learning process even if the child's behavior does not appear to be negatively affected during the unfolding parent-child interaction. Understanding the moment-to-moment neural basis of these processes is critical to uncover the role that caregivers play in the development of attention and learning, which in turn impacts the development of working memory and executive function. Simultaneous brain recording, called hyperscanning, is a burgeoning method that measures brain synchrony across parent-child dyads when engaged in a shared task. In this opinion piece, we first review existing literature that highlights the important role caregivers play in guiding attention and learning in infants and toddlers and how these interactions contribute to the development of working memory and executive function in young children. Next, we review the existing literature using hyperscanning and dual eye tracking paradigms to uncover the patterning of interactions when caregivers guide attention in a manner that either matches the expectations of the child or over- or under-directs the child's attention. We provide best-practices for employing hyperscanning techniques to uncover how caregivers optimally engage infant and toddlers' attention in the moment, and how children's developing memory of these patterns of interaction build their executive function abilities, both with their caregivers and with other adults and children.

Mother-Infant Dyadic Neural Synchrony Measured Using EEG Hyperscanning and Validated Using Behavioral Measures

BACKGROUND/OBJECTIVE

Greater parent-infant synchrony is associated with improved child outcomes. Behavioral measures of synchrony are still developing in young infants; thus, researchers need tools to quantify synchrony between parents and their young infants. We examined parent-infant neural synchrony measured using dual EEG hyperscanning and associations between neural synchrony, infant behavioral measures of synchrony, and maternal bondedness and depression.

METHODS

Our prospective cohort study included mother-infant dyads at 2-4 months of age. We collected time-locked dual EEG recordings of mother and infant and simultaneous video-recordings during a scaffolded interaction where the mother sequentially layered sensory modalities to the interaction. Neural synchrony measured using EEG hyperscanning was analyzed using the circular correlation coefficient (CCorr), infant behavioral synchrony was measured using the validated Welch Emotional Connection Screen (WECS) scores, and maternal bondedness and depression were measured using standardized questionnaires.

RESULTS

Our study included n = 47 dyads. Dyadic CCorr increased across the interaction as the mother added tactile stimulation to visual stimulation. We also found associations between behavioral and neural measures of dyadic synchrony such that infants with higher scores on behavioral measures of emotional connection on the WECS showed greater increases in CCorr indicative of dyadic synchrony with their mother across this interaction. We found no associations between neural synchrony and maternal bondedness or depression.

CONCLUSION

These findings support the construct validity of mother-infant dyadic neural synchrony measured using EEG hyperscanning and analyzed using CCorr. Opportunities for future research on quantification of neural synchrony between parents and young infants abound.

The neurosociological paradigm of the metaverse

Metaverse integrates people into the virtual world, and challenges depend on advances in human, technological, and procedural dimensions. Until now, solutions to these challenges have not involved extensive neurosociological research. The study explores the pioneering neurosociological paradigm in metaverse, emphasizing its potential to revolutionize our understanding of social interactions through advanced methodologies such as hyperscanning and interbrain synchrony. This convergence presents unprecedented opportunities for neurotypical and neurodivergent individuals due to technology personalization. Traditional face-to-face, interbrain coupling, and metaverse interactions are empirically substantiated. Biomarkers of social interaction as feedback between social brain networks and metaverse is presented. The innovative contribution of findings to the broader literature on metaverse and neurosociology is substantiated. This article also discusses the ethical aspects of integrating the neurosociological paradigm into the metaverse.

From behavioral synchrony to language and beyond

Decades of research on joint attention, coordinated joint engagement, and social contingency identify caregiver-child interaction in infancy as a foundation for language. These patterns of early behavioral synchrony contribute to the structure and connectivity of the brain in the temporoparietal regions typically associated with language skills. Thus, children attune to their communication partner and subsequently build cognitive skills directly relating to comprehension and production of language, literacy skills, and beyond. This has yielded marked interest in measuring this contingent, synchronous social behavior neurally. Neurological measures of early social interactions between caregiver and child have become a hotbed for research. In this paper, we review that research and suggest that these early neural couplings between adults and children lay the foundation for a broader cognitive system that includes attention, problem solving, and executive function skills. This review describes the role of behavioral synchrony in language development, asks what the relationship is between neural synchrony and language growth, and how neural synchrony may play a role in the development of a broader cognitive system founded in a socially-gated brain. We address the known neural correlates of these processes with an emphasis on work that examines the tight temporal contingency between communicative partners during these rich social interactions, with a focus on EEG and fNIRS and brief survey of MRI and MEG.

Leveraging mixed-effects location scale models to assess the ERP mismatch negativity's psychometric properties and trial-by-trial neural variability in toddler-mother dyads

Trial-by-trial neural variability, a measure of neural response stability, has been examined in relation to behavioral indicators using summary measures, but these methods do not characterize meaningful processes underlying variability. Mixed-effects location scale models (MELSMs) overcome these limitations by accounting for predictors and covariates of variability but have been rarely used in developmental studies. Here, we applied MELSMs to the ERP auditory mismatch negativity (MMN), a neural measure often related to language and psychopathology. 84 toddlers and 76 mothers completed a speech-syllable MMN paradigm. We extracted early and late MMN mean amplitudes from trial-level waveforms. We first characterized our sample's psychometric properties using MELSMs and found a wide range of subject-level internal consistency. Next, we examined the relation between toddler MMNs with theoretically relevant child behavioral and maternal variables. MELSMs offered better model fit than analyses that assumed constant variability. We found significant individual differences in trial-by-trial variability but no significant associations between toddler variability and their language, irritability, or mother variability indices. Overall, we illustrate how MELSMs can characterize psychometric properties and answer questions about individual differences in variability. We provide recommendations and resources as well as example code for analyzing trial-by-trial neural variability in future studies.

Is frontal EEG gamma power a neural correlate of language in toddlerhood? An examination of late talking and expressive language ability

Few studies have examined neural correlates of late talking in toddlers, which could aid in understanding etiology and improving diagnosis of developmental language disorder (DLD). Greater frontal gamma activity has been linked to better language skills, but findings vary by risk for developmental disorders, and this has not been investigated in late talkers. This study examined whether frontal gamma power (30-50 Hz), from baseline-state electroencephalography (EEG), was related to DLD risk (categorical late talking status) and a continuous measure of expressive language in n = 124 toddlers. Frontal gamma power was significantly associated with late talker status when controlling for demographic factors and concurrent receptive language (β = 1.96, McFadden's Pseudo R2 = 0.21). Demographic factors and receptive language did not significantly moderate the association between frontal gamma power and late talker status. A continuous measure of expressive language ability was not significantly associated with gamma (r = -0.07). Findings suggest that frontal gamma power may be useful in discriminating between groups of children that differ in DLD risk, but not for expressive language along a continuous spectrum of ability.

Getting closer to social interactions using electroencephalography in developmental cognitive neuroscience

The field of developmental cognitive neuroscience is advancing rapidly, with large-scale, population-wide, longitudinal studies emerging as a key means of unraveling the complexity of the developing brain and cognitive processes in children. While numerous neuroscientific techniques like functional magnetic resonance imaging (fMRI), functional near-infrared spectroscopy (fNIRS), magnetoencephalography (MEG), and transcranial magnetic stimulation (TMS) have proved advantageous in such investigations, this perspective proposes a renewed focus on electroencephalography (EEG), leveraging underexplored possibilities of EEG. In addition to its temporal precision, low costs, and ease of application, EEG distinguishes itself with its ability to capture neural activity linked to social interactions in increasingly ecologically valid settings. Specifically, EEG can be measured during social interactions in the lab, hyperscanning can be used to study brain activity in two (or more) people simultaneously, and mobile EEG can be used to measure brain activity in real-life settings. This perspective paper summarizes research in these three areas, making a persuasive argument for the renewed inclusion of EEG into the toolkit of developmental cognitive and social neuroscientists.

Investigating mother-child inter-brain synchrony in a naturalistic paradigm: A functional near infrared spectroscopy (fNIRS) hyperscanning study

Successful social interactions between mothers and children are hypothesised to play a significant role in a child's social, cognitive and language development. Earlier research has confirmed, through structured experimental paradigms, that these interactions could be underpinned by coordinated neural activity. Nevertheless, the extent of neural synchrony during real-life, ecologically valid interactions between mothers and their children remains largely unexplored. In this study, we investigated mother-child inter-brain synchrony using a naturalistic free-play paradigm. We also examined the relationship between neural synchrony, verbal communication patterns and personality traits to further understand the underpinnings of brain synchrony. Twelve children aged between 3 and 5 years old and their mothers participated in this study. Neural synchrony in mother-child dyads were measured bilaterally over frontal and temporal areas using functional Near Infra-red Spectroscopy (fNIRS) whilst the dyads were asked to play with child-friendly toys together (interactive condition) and separately (independent condition). Communication patterns were captured via video recordings and conversational turns were coded. Compared to the independent condition, mother-child dyads showed increased neural synchrony in the interactive condition across the prefrontal cortex and temporo-parietal junction. There was no significant relationship found between neural synchrony and turn-taking and between neural synchrony and the personality traits of each member of the dyad. Overall, we demonstrate the feasibility of measuring inter-brain synchrony between mothers and children in a naturalistic environment. These findings can inform future study designs to assess inter-brain synchrony between parents and pre-lingual children and/or children with communication needs.

How parent-child brain-to-brain synchrony can inform the study of child development

It is well established that parent-child dyadic synchrony (e.g., mutual emotions, behaviors) can support development across cognitive and socioemotional domains. The advent of simultaneous two-brain hyperscanning (i.e., neuroimaging techniques to measure the brain activity of two individuals at the same time) allows further insight into dyadic neural synchrony. In this article, we review 16 recent studies of naturalistic, parent-child brain-to-brain synchrony, finding relations with the nature of interactions (collaborative versus competitive, parent versus stranger), proximal social cues (gaze, affect, touch, reciprocity), child-level variables (irritability, self-regulation), and environmental factors (parental stress, family cohesion, adversity). We then discuss how neural synchrony may provide a biological mechanism for refining broader theories on developmental benefits of dyadic synchrony. We also highlight critical areas for future study, including examining synchrony trajectories longitudinally, including more diverse participants and interaction contexts, and studying caregivers beyond mothers (e.g., other family members, teachers). We conclude that neural synchrony is an exciting and important window into understanding how caregiver-child dyadic synchrony supports children's social and cognitive development.

Communicative signals during joint attention promote neural processes of infants and caregivers

Communicative signals such as eye contact increase infants' brain activation to visual stimuli and promote joint attention. Our study assessed whether communicative signals during joint attention enhance infant-caregiver dyads' neural responses to objects, and their neural synchrony. To track mutual attention processes, we applied rhythmic visual stimulation (RVS), presenting images of objects to 12-month-old infants and their mothers (n = 37 dyads), while we recorded dyads' brain activity (i.e., steady-state visual evoked potentials, SSVEPs) with electroencephalography (EEG) hyperscanning. Within dyads, mothers either communicatively showed the images to their infant or watched the images without communicative engagement. Communicative cues increased infants' and mothers' SSVEPs at central-occipital-parietal, and central electrode sites, respectively. Infants showed significantly more gaze behaviour to images during communicative engagement. Dyadic neural synchrony (SSVEP amplitude envelope correlations, AECs) was not modulated by communicative cues. Taken together, maternal communicative cues in joint attention increase infants' neural responses to objects, and shape mothers' own attention processes. We show that communicative cues enhance cortical visual processing, thus play an essential role in social learning. Future studies need to elucidate the effect of communicative cues on neural synchrony during joint attention. Finally, our study introduces RVS to study infant-caregiver neural dynamics in social contexts.

Caregiver-child interaction as an effective tool for identifying autism spectrum disorder: evidence from EEG analysis

BACKGROUND

Autism Spectrum Disorder (ASD) is a complex neurodevelopmental disorder that affects individuals across their lifespan. Early diagnosis and intervention are crucial for improving outcomes. However, current diagnostic methods are often time-consuming, and costly, making them inaccessible to many families. In the current study, we aim to test caregiver-child interaction as a potential tool for screening children with ASD in clinic.

METHODS

We enrolled 85 preschool children (Mean age: 4.90 ± 0.65 years, 70.6% male), including ASD children with or without developmental delay (DD), and typical development (TD) children, along with their caregivers. ASD core symptoms were evaluated by Childhood Autism Rating Scale (CARS) and Autism Diagnostic Observation Schedule-Calibrated Severity Scores (ADOS-CSS). Behavioral indicators were derived from video encoding of caregiver-child interaction, including social involvement of children (SIC), interaction time (IT), response of children to social cues (RSC), time for caregiver initiated social interactions (GIS) and time for children initiated social interactions (CIS)). Power spectral density (PSD) values were calculated by EEG signals simultaneously recorded. Partial Pearson correlation analysis was used in both ASD groups to investigate the correlation among behavioral indicators scores and ASD symptom severity and PSD values. Receiver operating characteristic (ROC) analysis was used to describe the discrimination accuracy of behavioral indicators.

RESULTS

Compared to TD group, both ASD groups demonstrated significant lower scores of SIC, IT, RSC, CIS (all p values < 0.05), and significant higher time for GIS (all p values < 0.01). SIC scores negatively correlated with CARS (p = 0.006) and ADOS-CSS (p = 0.023) in the ASD with DD group. Compared to TD group, PSD values elevated in ASD groups (all p values < 0.05), and was associated with SIC (theta band: p = 0.005; alpha band: p = 0.003) but not IQ levels. SIC was effective in identifying both ASD groups (sensitivity/specificity: ASD children with DD, 76.5%/66.7%; ASD children without DD, 82.6%/82.2%).

CONCLUSION

Our results verified the behavioral paradigm of caregiver-child interaction as an efficient tool for early ASD screening.

Mother-child inter-brain synchrony during a mutual visual search task: A study of feedback valence and role

Parent and child have been shown to synchronize their behaviors and physiology during social interactions. This synchrony is an important marker of their relationship quality and subsequently the child's social and emotional development. Therefore, understanding the factors that influence parent-child synchrony is an important undertaking. Using EEG hyperscanning, this study investigated brain-to-brain synchrony in mother-child dyads when they took turns performing a visual search task and received positive or negative feedback. In addition to the effect of feedback valence, we studied how their assigned role, i.e., observing or performing the task, influenced synchrony. Results revealed that mother-child synchrony was higher during positive feedback relative to negative feedback in delta and gamma frequency bands. Furthermore, a main effect was found for role in the alpha band with higher synchrony when a child observed their mother performing the task compared to when the mother observed their child. These findings reveal that a positive social context could lead a mother and child to synchronize more on a neural level, which could subsequently improve the quality of their relationship. This study provides insight into mechanisms that underlie mother-child brain-to-brain synchrony, and establishes a framework by which the impact of emotion and task demand on a dyad's synchrony can be investigated.

From Recognizing Known Words to Learning New Ones: Comparing Online Speech Processing in Typically Developing and Late-Talking 2-Year-Olds

PURPOSE

This study examines online speech processing in typically developing and late-talking 2-year-old children, comparing both groups' word recognition, word prediction, and word learning.

METHOD

English-acquiring U.S. children, from the "When to Worry" study of language and social-emotional development, were identified as typical talkers (n = 67, M age = 27.0 months, SD = 1.4; Study 1) or late talkers (n = 30, M age = 27.0 months, SD = 2.0; Study 2). Children completed an eye-tracking task assessing their ability to recognize both nouns and verbs, to use verbs to predict an upcoming noun's referent, and to use verbs to infer the meaning of novel nouns.

RESULTS

Both typical and late talkers recognized nouns and verbs and used familiar verbs to predict the referents of upcoming nouns, whether the noun was familiar ("You can eat the apple") or novel ("You can eat the dax"). Late talkers were slower in using familiar nouns to orient to the target and were both slower and less accurate in using familiar verbs to identify the upcoming noun's referent. Notably, however, both groups learned and retained novel word meanings with similar success.

CONCLUSIONS

Late talkers demonstrated slower lexical processing, especially for verbs. Yet, their success in using familiar verbs to learn novel nouns suggests that, as a group, their slower processing did not impair word learning in this task. This sets the foundation for future work investigating whether these measures predict later language outcomes and can differentiate late talkers with transient delays from those with language disorders.

Envisioning translational hyperscanning: how applied neuroscience might improve family-centered care

From the very beginning of their life, human beings are immersed in a social and interactive environment that contributes to shaping their social and cognitive development under typical and at-risk conditions. In order to understand human development in its bidirectional relationship with the social environment, we need to develop a 'complexity-sensitive' approach in neuroscience. Recent advances have started to do so with the application of hyperscanning techniques which involve recording adult and child neural activity simultaneously and highlighting the presence of similar patterns of brain activity in the dyad. Numerous studies focused on typically developing children have been published in recent years with the application of this technique to different fields of developmental research. However, hyperscanning techniques could also be extremely beneficial and effective in studying development in atypical and clinical populations. Such application, namely translational hyperscanning, should foster the transition toward a two-brain translational neuroscience. In this paper, we envision how the application of hyperscanning to atypical and clinical child populations can inform family-centered care for children and their parents.