UEL Baby Dev Lab

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

Georgieva, S., Lester, S., Yilmaz, M. N., Wass, S., & Leongi, V. 2017. BioRxiv,

Electroencephalography (EEG) is perhaps the most widely used brain-imaging
technique for paediatric populations. However, EEG signals are prone to distortion by
motion-related artifacts, which can severely confound interpretation. Compared to adult EEG,
motion during infant EEG acquisition is both more frequent and less stereotypical. Yet the
diverse effects of motion on the infant EEG signal have not been documented. This work
represents the first systematic assessment of the effects of naturalistic motion on infant and
adult EEG signals. In Study 1, five mother-infant pairs were video-recorded during
naturalistic joint- and solo-play with toys. The frequency of occurrence of 27 different facial
and body motions was time-coded for both adults and infants. Our results suggested that
movement was continuously present within dyads, and that different types of movement were
observed when comparing social and non-social play, as well as adults and infants. In Study
2, one adult and one infant actor each re-created the most commonly occurring facial, limb
and postural motions from Study 1, allowing us to assess the topological and spectral features
of motion-related EEG artifacts, as compared to resting state EEG measurements. For the
adult, all movement types (facial, limb and postural) generated significant increases in
spectral power relative to resting state. Topographically and spectrally, the strongest
contamination occurred at peripheral recording sites, and affected delta and high-beta
frequency bands most severely. Exceptionally, at certain central and centro-parietal channels,
virtually no motion-induced power changes were observed in theta, alpha and low-beta
frequencies. By contrast, infant motions mainly produced a decrease in alpha power over
fronto-central and centro-parietal regions, and was most pronounced for talking and upper
limb movements. However, with the exception of peripheral channels, the infant theta band
(3-6 Hz) showed little contamination by face and limb motions. It is intended that this work
will inform future development of methods for EEG motion-artifact detection and removal,
and contribute toward the development of common artifact-related resources and bestpractice guidelines for EEG researchers in social and developmental neuroscience.

DEEP: A dual EEG pipeline for developmental hyperscanning studies

Kayhan, E., Matthes, D., Haresign, I. M., Bánki, A., Michel, C., Langeloh, M., ... & Hoehl, S. 2022. Developmental Cognitive Neuroscience

Cutting-edge hyperscanning methods led to a paradigm shift in social neuroscience. It allowed researchers to
measure dynamic mutual alignment of neural processes between two or more individuals in naturalistic contexts.
The ever-growing interest in hyperscanning research calls for the development of transparent and validated data
analysis methods to further advance the field. We have developed and tested a dual electroencephalography
(EEG) analysis pipeline, namely DEEP. Following the preprocessing of the data, DEEP allows users to calculate
Phase Locking Values (PLVs) and cross-frequency PLVs as indices of inter-brain phase alignment of dyads as well
as time-frequency responses and EEG power for each participant. The pipeline also includes scripts to control for
spurious correlations. Our goal is to contribute to open and reproducible science practices by making DEEP
publicly available together with an example mother-infant EEG hyperscanning dataset.

Mother-infant interpersonal neural connectivity predicts infants’ social learning.

Leong, V., Noreika, V., Clackson, K., Georgieva, S., Brightman, L., Nutbrown, R., ... & Wass, S. 2019. PsyArXiv

Social learning allows infants to learn vicariously by observing adult behaviour, but how the infant brain accomplishes this feat remains unknown. Here, electroencephalography (EEG) signals were simultaneously measured from forty-seven mothers and infants (10.7 months) during a live social learning task. First, infants observed mothers demonstrate positive or negative emotions toward novel toys. Next, infants’ own toy interaction (learning) was measured. Infants’ social learning likelihood was robustly predicted by mother-infant interpersonal neural connectivity in the Alpha (6-9 Hz) band. Stronger dyadic neural connectedness predicted increased learning, and was associated with extended ostensive eye contact and maternal utterances. Intra-infant neural connectivity predicted learning valence (positive/negative) but was unrelated to learning likelihood. Therefore, interpersonal connectivity is a neural mechanism by which infants learn from their social partners.

14 challenges and their solutions for conducting social neuroscience and longitudinal EEG research with infants

Noreika, V., Georgieva, S., Wass, S., & Leong, V. 2020. Infant Behaviour & Development

The use of electroencephalography (EEG) to study infant brain development is a growing trend. In
addition to classical longitudinal designs that study the development of neural, cognitive and behavioural functions, new areas of EEG application are emerging, such as novel social neuroscience
paradigms using dual infant-adult EEG recordings. However, most of the experimental designs, analysis
methods, as well as EEG hardware were originally developed for single-person adult research. When
applied to study infant development, adult-based solutions often pose unique problems that may go
unrecognised. Here, we identify 14 challenges that infant EEG researchers may encounter when designing new experiments, collecting data, and conducting data analysis. Challenges related to the
experimental design are: (1) small sample size and data attrition, and (2) varying arousal in younger
infants. Challenges related to data acquisition are: (3) determining the optimal location for reference
and ground electrodes, (4) control of impedance when testing with the high-density sponge electrode
nets, (5) poor fit of standard EEG caps to the varying infant head shapes, and (6) ensuring a high
degree of temporal synchronisation between amplifiers and recording devices during dual-EEG acquisition. Challenges related to the analysis of longitudinal and social neuroscience datasets are: (7)
developmental changes in head anatomy, (8) prevalence and diversity of infant myogenic artefacts, (9)
a lack of stereotypical topography of eye movements needed for the ICA-based data cleaning, (10) and
relatively high inter-individual variability of EEG responses in younger cohorts. Additional challenges
for the analysis of dual EEG data are: (11) developmental shifts in canonical EEG rhythms and difficulties in differentiating true inter-personal synchrony from spurious synchrony due to (12) common
intrinsic properties of the signal and (13) shared external perturbation. Finally, (14) there is a lack of
test-retest reliability studies of infant EEG. We describe each of these challenges and suggest possible
solutions. While we focus specifically on the social neuroscience and longitudinal research, many of the
issues we raise are relevant for all fields of infant EEG research.

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

Santamaria, L., Noreika, V., Georgieva, S., Clackson, K., Wass, S., & Leong, V. 2020. Neuroimage

Emotional communication between parents and children is crucial during early life, yet little is known about its
neural underpinnings. Here, we adopt a dual connectivity approach to assess how positive and negative emotions
modulate the interpersonal neural network between infants and their mothers during naturalistic interaction.
Fifteen mothers were asked to model positive and negative emotions toward pairs of objects during social
interaction with their infants (mean age 10.3 months) whilst the neural activity of both mothers and infants was
concurrently measured using dual electroencephalography (EEG). Intra-brain and inter-brain network connectivity in the 6–9 Hz range (i.e. infant Alpha band) during maternal expression of positive and negative emotions
was computed using directed (partial directed coherence, PDC) and non-directed (phase-locking value, PLV)
connectivity metrics. Graph theoretical measures were used to quantify differences in network topology as a
function of emotional valence. We found that inter-brain network indices (Density, Strength and Divisibility)
consistently revealed strong effects of emotional valence on the parent-child neural network. Parents and children
showed stronger integration of their neural processes during maternal demonstrations of positive than negative
emotions. Further, directed inter-brain metrics (PDC) indicated that mother to infant directional influences were
stronger during the expression of positive than negative emotional states. These results suggest that the parentinfant 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 parent-infant inter-brain
network topology.

Measuring the temporal dynamics of inter-personal neural entrainment in continuous child-adult EEG hyperscanning data

I.Marriott Haresign, E.A.M.Phillips, M.Whitehorn, L.Goupil, V.Noreika, V.Leong, S.V.Wass 2022. Developmental Cognitive Neuroscience

Current approaches to analysing EEG hyperscanning data in the developmental literature typically consider interpersonal entrainment between interacting physiological systems as a time-invariant property. This approach obscures crucial information about how entrainment between interacting systems is established and maintained over time. Here, we describe methods, and present computational algorithms, that will allow researchers to address this gap in the literature. We focus on how two different approaches to measuring entrainment, namely concurrent (e.g., power correlations, phase locking) and sequential (e.g., Granger causality) measures, can be applied to three aspects of the brain signal: amplitude, power, and phase. We guide the reader through worked examples using simulated data on how to leverage these methods to measure changes in interbrain entrainment. For each, we aim to provide a detailed explanation of the interpretation and application of these analyses when studying neural entrainment during early social interactions.

Gaze onsets during naturalistic infant-caregiver interaction associate with ‘sender’ but not ‘receiver’ neural responses, and do not lead to changes in inter-brain synchrony

I. Marriott Haresign, E.A.M Phillips, M. Whitehorn, F. Lamagna, M. Eliano, L. Goupil, E.J.H. Jones, S.V. Wass 2022. bioRxiv

Temporal coordination during infant-caregiver social interaction is thought to be crucial for supporting early language acquisition and cognitive development. Despite a growing prevalence of theories suggesting that increased inter-brain synchrony associates with many key aspects of social interactions such as mutual gaze, little is known about how this arises during development. Here, we investigated the role of mutual gaze onsets as a potential driver of inter-brain synchrony. We extracted dual EEG activity around naturally occurring gaze onsets during infant-caregiver social interactions in N=55 dyads (mean age 12 months). We differentiated between two types of gaze onset, depending on each partner's role. 'Sender' gaze onsets were defined at a time when either the adult or the infant made a gaze shift towards their partner at a time when their partner was either already looking at them (mutual) or not looking at them (non-mutual). 'Receiver' gaze onsets were defined at a time when their partner made a gaze shift towards them at a time when either the adult or the infant was already looking at their partner (mutual) or not (non-mutual). Contrary to our hypothesis we found that, during a naturalistic interaction, both mutual and non-mutual gaze onsets were associated with changes in the sender, but not the receiver's brain activity and were not associated with increases in inter-brain synchrony above baseline. Further, we found that mutual, compared to non-mutual gaze onsets were not associated with increased inter-brain synchrony. Overall, our results suggest that the effects of mutual gaze are strongest at the intra-brain level, in the 'sender' but not the 'receiver' of the mutual gaze.