Biology subjects

Wass, S.

Publications and source records attributed to Wass, S..

9 recordsLinked to original sources

bioRxiv2024

Examining speech-brain tracking during early bidirectional, free-flowing caregiver-infant interactions

Neural entrainment to slow modulations in the amplitude envelope of infant-directed speech is thought to drive early language learning. Most previous research with infants examining speech-brain tracking has been conducted in controlled, experimental settings, which are far from the complex environments of everyday interactions. Whilst recent work has begun to investigate speech-brain tracking to naturalistic speech, this work has been conducted in semi-structured paradigms, where infants listen to live adult speakers, without engaging in free-flowing social interactions. Here, we test the applicability of mTRF modelling to measure speech-brain tracking in naturalistic and bidirectional free-play interactions of 9-12-month-olds with their caregivers. Using a backwards modelling approach, we test individual and generic training procedures, and examine the effects of data quantity and quality on model fitting. We show model fitting is most optimal using an individual approach, trained on continuous segments of interaction data. Corresponding to previous findings, individual models showed significant speech-brain tracking at delta modulation frequencies, but not in alpha and theta bands. These findings open new methods for studying the interpersonal micro-processes that support early language learning. In future work, it will be important to develop a mechanistic framework for understanding how our brains track naturalistic speech during infancy.

neuroscience↗

bioRxiv2023

Endogenous oscillatory rhythms and interactive contingencies jointly influence infant attention during early infant-caregiver interaction

Almost all early cognitive development takes place in social contexts. At the moment, however, we know little about the neural and micro-interactive mechanisms that support infants attention during social interactions. Recording EEG during naturalistic caregiver-infant interactions (N=66), we compare two different accounts. Traditional, didactic perspectives emphasise the role of the caregiver in structuring the interaction, whilst active learning models focus on motivational factors, endogenous to the infant, that guide their attention. Our results show that, already by 12-months, intrinsic cognitive processes control infants attention: fluctuations in endogenous oscillatory neural activity associated with changes in infant attentiveness. In comparison, infant attention was not forwards-predicted by caregiver gaze or vocal behaviours. Instead, caregivers rapidly modulated their behaviours in response to changes in infant attention and cognitive engagement, and greater reactive changes associated with longer infant attention. Our findings suggest that shared attention develops through interactive but asymmetric, infant-led processes that operate across the caregiver-child dyad.

neuroscience↗

bioRxiv2021

Synchrony of mind and body are distinct in mother-child dyads

Hyperscanning studies have begun to unravel the brain mechanisms underlying social interaction, indicating a functional role for interpersonal neural synchronization (INS), yet the mechanisms that drive INS are poorly understood. While interpersonal synchrony is considered a multimodal phenomenon, it is not clear how different biological and behavioral synchrony markers are related to each other. The current study, thus, addresses whether INS is functionally-distinct from synchrony in other systems - specifically the autonomic nervous system (ANS) and motor behavior. To test this, we used a novel methodological approach, based on concurrent functional near-infrared spectroscopy-electrocardiography, recorded while N = 34 mother-child and stranger-child dyads (child mean age 14 years) engaged in cooperative and competitive tasks. Results showed a marked differentiation between neural, ANS and behavioral synchrony. Importantly, only in the neural domain was higher synchrony for mother-child compared to stranger-child dyads observed. Further, ANS and neural synchrony were positively related during competition but not during cooperation. These results suggest that synchrony in different behavioral and biological systems may reflect distinct processes. Mother-child INS may arise due to neural processes related to social affiliation, which go beyond shared arousal and similarities in behavior.

neuroscience↗

bioRxiv2019

Emotional valence modulates the topology of the parent-infant inter-brain network

Emotional communication between parents and children is crucial during early life, yet little is known about its neural underpinnings. Here, we adopt a dual-brain connectivity approach to assess how emotional valence modulates the parent-infant neural network. Fifteen mothers modelled positive and negative emotions toward pairs of objects during social interaction with their infants (aged 10.3 months) whilst their neural activity was concurrently measured using dual-EEG. Intra-brain and inter-brain network connectivity in the 6-9 Hz (infant Alpha) range was computed during maternal expression of positive and negative emotions using directed (partial directed coherence) and non-directed (phase-locking value) connectivity metrics. Graph theoretical metrics were used to quantify differences in network topology as a function of emotional valence. Inter-brain network indices (Density, Strength and Divisibility) consistently revealed that the integration of parents and childrens neural processes was significantly stronger during maternal demonstrations of positive than negative emotions. Further, directed inter-brain metrics indicated that mother-to-infant directional influences were stronger during the expression of positive than negative emotions. These results suggest that the parent-infant inter-brain network is modulated by the emotional quality and tone of dyadic social interactions, and that inter-brain graph metrics may be successfully applied to examine these changes in interpersonal network topology.

neuroscience↗

bioRxiv2017

Topographical and spectral signatures of infant and adult movement artifacts in naturalistic EEG

Electroencephalography (EEG) is perhaps the most widely used brain-imaging technique for paediatric populations. However, EEG signals are prone to distortion by motion. Compared to adults, infants motion is both more frequent and less stereotypical yet motion effects on the infant EEG signal are largely undocumented. Here, we present a systematic assessment of naturalistic motion effects on the infant and adult EEG signal. In Study 1, we documented the prevalence of 27 naturally occurring facial and body motions by video-coding five mother-infant pairs during naturalistic play. In Study 2, we elicited a subset of the most common facial, limb and postural motions from one adult and one infant actor while their EEG was recorded. In Study 3, we recorded EEG signals from a larger group of 12 infants whilst they produced the same motions spontaneously. Our findings from Study 2 suggested that adult movements mainly generated increases in spectral power relative to resting state, primarily at peripheral sites and in delta and high-beta frequency bands. In infants, both elicited motions (N=1, Study 2) and spontaneously-occurring motions (N=12, Study 3) produced decreases in theta, alpha and beta power over central regions and increased beta/delta power at peripheral sites. We also observed that infants jaw and upper limb movements generated more pronounced EEG artifacts than lower limb movements. It is intended that this work will inform future development of methods for addressing EEG motion-related artifacts and support wider use of naturalistic paradigms in social and developmental neuroscience.

neuroscience↗

bioRxiv2017

Towards a neuroscientific understanding of play: A neuropsychological coding framework for analysing infant-adult play patterns

During early life, play is a ubiquitous activity, and an individuals propensity for play is positively related to cognitive development and emotional well-being. Play behaviour is diverse and multi-faceted. A challenge for current research is to converge on a common definition and measurement system for play - whether examined at a behavioural, cognitive or neurological level. Combining these different approaches in a multi-level analysis could yield significant advances in understanding the neurocognitive mechanisms of play, and provide the basis for developing biologically-grounded play models. However, there is currently no integrated framework for conducting a multi-level analysis of play that spans brain, cognition and behaviour. The proposed neuropsychological coding framework uses grounded and observable behaviours along three neuropsychological dimensions (sensorimotor, cognitive and socio-emotional), to compute inferences about playful behaviour and related social interactional states. Here, we illustrate the sensitivity and utility of the proposed coding framework using two contrasting dyadic corpora (N=5) of mother-infant object-oriented interactions during experimental conditions that were either conducive (Condition 1) or non-conducive (Condition 2) to the emergence of playful behaviour. We find that the framework accurately identifies the modal form of social interaction as being either playful (Condition 1) or non-playful (Condition 2), and further provides useful insights about differences in the quality of social interaction and temporal synchronicity within the dyad. In conclusion, here, we present a novel neuropsychological framework for analysing the continuous time-evolution of adult-infant play patterns, underpinned by biologically informed state coding along sensorimotor, cognitive and socio-emotional dimensions. We expect that the proposed framework will have wide utility amongst researchers wishing to employ an integrated, multi-level approach to the study of play, and lead towards a greater understanding of the neuroscientific basis of play and may yield insights into a new biologically-grounded taxonomy of play interactions.

neuroscience↗

bioRxiv2017

Understanding short-term interactions between arousal and attention in infants and children: applying the Aston-Jones framework.

Differential Susceptibility Theory explains long-term associations between neurobiological sensitivity and cognitive outcomes, but no comparable theoretical framework exists to understand how neurobiological sensitivity and cognitive performance inter-relate on shorter time-frames. Here, we evaluate a framework proposed by Aston-Jones and colleagues, building on the Yerkes-Dodson model, to understand these associations. The framework describes how slow-moving (tonic) changes in autonomic arousal relate to fast (phasic) changes, as observed for example relative to experimenter-determined events, and how phasic changes relate to attention. Larger phasic changes, which associate with better selective attention, are most likely at mid-level tonic arousal. Smaller phasic changes, and worse selective attention, are observed at hypo-and hyper-arousal. We review the fit of this model to typical and atypical development, during infancy and childhood.

neuroscience↗

bioRxiv2017

Infants’ neural oscillatory processing of theta-rate speech patterns exceeds adults’

During their early years, infants use the temporal statistics of the speech signal to boot-strap language learning, but the neural mechanisms that facilitate this temporal analysis are poorly understood. In adults, neural oscillatory entrainment to the speech amplitude envelope has been proposed to be a mechanism for multi-time resolution analysis of adult-directed speech, with a focus on Theta (syllable) and low Gamma (phoneme) rates. However, it is not known whether developing infants perform multi-time oscillatory analysis of infant-directed speech with the same temporal focus. Here, we examined infants processing of the temporal structure of sung nursery rhymes, and compared their neural entrainment across multiple timescales with that of well-matched adults (their mothers). Typical infants and their mothers (N=58, median age 8.3 months) viewed videos of sung nursery rhymes while their neural activity at C3 and C4 was concurrently monitored using dual-electroencephalography (dual-EEG). The accuracy of infants and adults neural oscillatory entrainment to speech was compared by calculating their phase-locking values (PLVs) across the EEG-speech frequency spectrum. Infants showed better phase-locking than adults at Theta (~4.5 Hz)and Alpha (~9.3 Hz) rates, corresponding to rhyme and phoneme patterns in our stimuli. Infant entrainment levels matched adults for syllables and prosodic stress patterns (Delta,~1-2 Hz). By contrast, infants were less accurate than adults at tracking slow (~0.5 Hz) phrasal patterns. Therefore, compared to adults, language-learning infants temporal parsing of the speech signal shows highest relative acuity at Theta-Alpha rates. This temporal focus could support the accurate encoding of syllable and rhyme patterns during infants sensitive period for phonetic and phonotactic learning. Therefore, oscillatory entrainment could be one neural mechanism that supports early bootstrapping of language learning from infant-directed speech (such as nursery rhymes).

neuroscience↗

bioRxiv2017

Speaker gaze changes information coupling between infant and adult brains

When infants and adults communicate, they exchange social signals of availability and communicative intention such as eye gaze. Previous research indicates that when communication is successful, close temporal dependencies arise between adult speakers and listeners neural activity. However, it is not known whether similar neural contingencies exist within adult-infant dyads. Here, we used dual-electroencephalography to assess whether direct gaze increases neural coupling between adults and infants during screen-based and live interactions. In Experiment 1 (N=17), infants viewed videos of an adult who was singing nursery rhymes with (a) Direct gaze (looking forward); (b) Indirect gaze (head and eyes averted by 20{degrees}); or (c) Direct-Oblique gaze (head averted but eyes orientated forward). In Experiment 2 (N=19), infants viewed the same adult in a live context, singing with Direct or Indirect gaze. Gaze-related changes in adult-infant neural network connectivity were measured using Partial Directed Coherence. Across both experiments, the adult had a significant (Granger)-causal influence on infants neural activity, which was stronger during Direct and Direct-Oblique gaze relative to Indirect gaze. During live interactions, infants also influenced the adult more during Direct than Indirect gaze. Further, infants vocalised more frequently during live Direct gaze, and individual infants who vocalized longer also elicited stronger synchronisation from the adult. These results demonstrate that direct gaze strengthens bi-directional adult-infant neural connectivity during communication. Thus, ostensive social signals could act to bring brains into mutual temporal alignment, creating a joint-networked state that is structured to facilitate information transfer during early communication and learning.

neuroscience↗