An investigation into the mechanisms of inter-brain synchrony during early social interactions

Over the last 20 years there has been a growing increase in the amount of research investigating how and why two or more individual’s brain activity can synchronise during social interaction. What we know so far from this research is that inter-brain synchrony (defined through temporally coordinated patterns of brain activity between two interacting individuals, Holroyd 2022) tends to associate with moments of behavioural coordination (i.e., when two individuals are doing or attending to the same thing at the same time) and task cooperation (i.e., the action or process of two individuals working together to the same end). These observations have led many researchers to theorise over whether and how behavioural coordination mechanistically drives inter-brain synchrony (Wass et al., 2020; Hamilton, 2021). There is also some very recent evidence to suggest that increased inter-brain synchrony actually facilitates/ supports aspects of social interaction. For example, inter-brain synchrony has been shown to predict team performance (Reinero et al., 2021), although this research is primarily based on correlational study designs. Taken together however the field of inter-brain synchrony shares one fundamental limitation; that is that it does not account (although see recent animal research e.g., Kingsbury et al., 2019; Zhang et al., 2019), empirically for the mechanisms that give rise to inter-brain synchrony, which would help to falsify claims that inter-brain synchrony is a core mechanism facilitating social interaction. This is because of two main reasons; Firstly, the study of inter-brain synchrony has primarily been investigated as a time-invariant property, almost no studies have explored how inter-brain synchrony varies over time relative to individual moments of behavioural coordination. Secondly, little attention has been paid to the changes in the underlying signal properties (i.e., increases in power, changes in frequency) that must take place for two unsynchronised signals to become synchronised (e.g., Haresign et al., 2022). Using two-person naturalistic biobehavioural recording techniques, coupled with state of the art, EEG pre-processing and analyses procedures (see chapters 5 and 6), the present thesis examines the mechanisms that give rise to inter-brain synchrony during parent-infant social interactions. Evidence is presented showing how inter-brain synchrony does not arise around individual moments of gaze coordination. This is despite previous investigations suggesting that increased inter-brain synchrony (averaged over all moments of eye contact) associates with gaze synchrony. Evidence also shows the contribution of behavioural coordination across multiple modalities to inter-brain synchrony during parent-infant social interaction. Discussion is focused on the contribution of these findings to our understanding of the mechanisms that give rise to inter-brain synchrony

Finding a Mate With No Social Skills

Sexual reproductive behavior has a necessary social coordination component as willing and capable partners must both be in the right place at the right time. While there are many known social behavioral adaptations to support solutions to this problem, we explore the possibility and likelihood of solutions that rely only on non-social mechanisms. We find three kinds of social organization that help solve this social coordination problem (herding, assortative mating, and natal philopatry) emerge in populations of simulated agents with no social mechanisms available to support these organizations. We conclude that the non-social origins of these social organizations around sexual reproduction may provide the environment for the development of social solutions to the same and different problems.Comment: 8 pages, 5 figures, GECCO'1

Computational information geometry in statistics: foundations

This paper lays the foundations for a new framework for numerically and computationally applying information geometric methods to statistical modelling

Interpersonal Neural Entrainment during Early Social Interaction

Currently, we understand much about how children’s brains attend to and learn from information presented while they are alone, viewing a screen – but less about how interpersonal social influences are substantiated in the brain. Here, we consider research that examines how social behaviors affect not one, but both partners in a dyad. We review studies that measured interpersonal neural entrainment during early social interaction, considering two ways of measuring entrainment: concurrent entrainment (e.g., ‘when A is high, B is high’ – also known as synchrony) and sequential entrainment (‘changes in A forward-predict changes in B’). We discuss possible causes of interpersonal neural entrainment, and consider whether it is merely an epiphenomenon, or whether it plays an independent, mechanistic role in early attention and learning

The development of the relationship between auditory and visual neural sensitivity and autonomic arousal from 6 m to 12 m

The differential sensitivity hypothesis argues that environmental sensitivity has the bivalent effect of predisposing individuals to both the risk-inducing and development-enhancing influences of early social environments. However, the hypothesis requires that this variation in environmental sensitivity be general across domains. In this study, we focused on neural sensitivity and autonomic arousal to test domain generality. Neural sensitivity can be assessed by correlating measures of perceptual sensitivity, as indexed by event-related potentials (ERP) in electrophysiology. The sensitivity of autonomic arousal can be tested via heart rate changes. Domain generality was tested by comparing associations in perceptual sensitivity across auditory and visual domains, and associations between sensitivity in sensory domains and heart rate. We contrasted ERP components in auditory (P3) and visual (P1, N290 and P4) detection-of-difference tasks for N = 68 infants longitudinally at 6 and 12 months of age. Domain generality should produce correlated individual differences in sensitivity across the two modalities, with higher levels of autonomic arousal associating with increased perceptual sensitivity. Having controlled for multiple comparisons, at 6 months of age, the difference in amplitude of the P3 component evoked in response to standard and deviant tones correlated with the difference in amplitude of the P1 N290 and P4 face-sensitive components evoked in response to fearful and neutral faces. However, this correlation was not found at 12 months of age. Similarly, autonomic arousal correlated with neural sensitivity at 6 months but not at 12 months. The results suggest bottom-up neural perceptual sensitivity is domain-general across auditory and visual domains and is related to autonomic arousal at 6 months but not at 12 months of age. We interpret the development of the association of these markers of ES within a neuroconstructivist framework and with respect to the concept of interactive specialisation. By 12 months of age, more experience of visual processing may have led to top-down endogenous attention mechanisms that process visual information in a way that no longer associates with automatic auditory perceptual sensitivity

The effects of manufacturing tolerances and assembly force on the volumetric wear at the taper junction in modular total hip arthroplasty

Item does not contain fulltextFretting and corrosion at the taper-head interface in total hip arthroplasty has been reported as a potential cause of early failure of the implant system. The finite element (FE) method can be used to study the mechanics at the taper junction that are difficult to assess experimentally. Taper mismatch is one of the factors that can influence the performance of the taper junction. In this study we have assessed the effect of taper mismatch, in combination with assembly force on the volumetric wear. The study showed that higher assembly forces and smaller mismatches result in the least volumetric wear

Trigeneration in food retail: An energetic, economic and environmental evaluation for a supermarket application; Applied Thermal Engineering

This paper presents results on the evaluation of energy utilisation efficiency and economic and environmental performance of a micro-gas turbine (MGT) based trigeneration system for supermarket applications. A spreadsheet energy model has been developed for the analysis of trigeneration systems and a 2800 m2 sales area supermarket was selected for the feasibility study. Historical energy demand data were used for the analysis, which considered factors such as the fraction of the heat output used to drive the absorption chillers, the chiller COP and the difference between electricity and gas prices. The results showed that energy and environmental benefits can be obtained from the application of trigeneration systems to supermarkets compared to conventional systems. The payback period of natural gas driven trigeneration systems and greenhouse gas emissions savings will depend on the relative gas and electricity prices and the COP of the vapour compression and absorption systems. It was also shown that operation at full electrical output gives a better performance than a heat load-following strategy due to the reduction of the electrical generation efficiency of the MGT unit at part load conditions

Automatic classification of ICA components from infant EEG using MARA.

Automated systems for identifying and removing non-neural ICA components are growing in popularity among EEG researchers of adult populations. Infant EEG data differs in many ways from adult EEG data, but there exists almost no specific system for automated classification of source components from paediatric populations. Here, we adapt one of the most popular systems for adult ICA component classification for use with infant EEG data. Our adapted classifier significantly outperformed the original adult classifier on samples of naturalistic free play EEG data recorded from 10 to 12-month-old infants, achieving agreement rates with the manual classification of over 75% across two validation studies (n = 44, n = 25). Additionally, we examined both classifiers' ability to remove stereotyped ocular artifact from a basic visual processing ERP dataset compared to manual ICA data cleaning. Here, the new classifier performed on level with expert manual cleaning and was again significantly better than the adult classifier at removing artifact whilst retaining a greater amount of genuine neural signal operationalised through comparing ERP activations in time and space. Our new system (iMARA) offers developmental EEG researchers a flexible tool for automatic identification and removal of artifactual ICA components

DEEP: A dual EEG pipeline for developmental hyperscanning studies

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

Molecular epidemiology of imported cases of leishmaniasis in Australia from 2008 to 2014

© 2015 Roberts et al. Leishmaniasis is a vector borne disease caused by protozoa of the genus Leishmania. Human leishmaniasis is not endemic in Australia though imported cases are regularly encountered. This study aimed to provide an update on the molecular epidemiology of imported leishmaniasis in Australia. Of a total of 206 biopsies and bone marrow specimens submitted to St Vincent's Hospital Sydney for leishmaniasis diagnosis by PCR, 55 were found to be positive for Leishmania DNA. All PCR products were subjected to restriction fragment length polymorphism analysis for identification of the causative species. Five Leishmania species/species complexes were identified with Leishmania tropica being the most common (30/55). Travel or prior residence in a Leishmania endemic region was the most common route of acquisition with ∼47% of patients having lived in or travelled to Afghanistan. Cutaneous leishmaniasis was the most common manifestation (94%) with only 3 cases of visceral leishmaniasis and no cases of mucocutaneous leishmaniasis encountered. This report indicates that imported leishmaniasis is becoming increasingly common in Australia due to an increase in global travel and immigration. As such, Australian clinicians must be made aware of this trend and consider leishmaniasis in patients with suspicious symptoms and a history of travel in endemic areas. This study also discusses the recent identification of a unique Leishmania species found in native kangaroos and a potential vector host which could create the opportunity for the establishment of a local transmission cycle within humans