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
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.