Biology subjects

Johnson, M. H.

Publications and source records attributed to Johnson, M. H..

7 recordsLinked to original sources

bioRxiv2026

Caregiver-infant interactions selectively shape emerging functional connectivity in the neonatal brain

From birth, human infants engage in multi-modal social exchanges with caregivers that involve the coordination of gaze and touch to guide attention and support neurodevelopment. However, little is known about the association between these first interactive experiences and the functional organization of the developing brain during the first postnatal month, a window of remarkable brain growth in humans. We address this gap by combining microanalytic coding of caregiver- infant interactions with task-free functional connectivity (FC), measured using high-density diffuse optical tomography (HD-DOT) in infants homes during the first postnatal month. Task-free FC measures the intrinsic functional organization of the developing brain, shedding light on the early development of neural systems supporting perception, regulation, and social interactions. Infants were assessed up to three times (1 week, 2 weeks, 1 month), enabling characterization of both early FC and its rapid developmental change. Caregiver-infant interactions were associated with both concurrent organization and rapid longitudinal change in FC. Dyadic engagement in the context of face-to-face interaction was associated with the refinement of short-range connectivity and the integration of long-range connectivity particularly between social brain regions, while affectionate touch was associated with general increases in long-distance connectivity. These results demonstrate that caregiving experiences influence the development of the brains functional architecture in the first postnatal month, highlighting a critical window for shaping infant brain function. Significance StatementThe first postnatal weeks are a period of rapid brain development, when the brain may be especially sensitive to experience. A key early experience is social interaction between infants and their caregivers, yet it remains unknown if these interactions influence neonate brain function. By combining observations of caregiver-infant interactions at one month with repeated home-based brain imaging, we show that variations in dyadic engagement and affectionate touch influence how infant brain functional connectivity is organized and develops. These findings highlight the importance of supporting perinatal life and early interactions for infant brain development.

neuroscience↗

bioRxiv2025

Cortical Excitability during Fixations Drives Frequency-Specific Neural Activity in Children and Adults

Extensive previous research has examined how neuronal oscillations support basic cognitive processes, from early development into adulthood. However, the question of how these oscillations originate and are maintained remains relatively underexplored. Here, we examine how transient increases in cortical excitability that occur time-locked to the offsets of spontaneous eye movements associate with frequency-specific neural activity, and how these relationships change over development and between contexts (social vs non-social). We examine two datasets of combined EEG and eye-tracking data from 24-month-old children (N=114) and adults (N=108) while they watched stimuli that were either social (an actor singing nursery rhythms) or non-social (dynamic toys). EEG data was time-locked to the offsets of eye movements and analysed using a spectrum of methods designed to highlight the progression of various neural signals across time, frequency, and space (topography). Fixation-related potentials (FRPs) manifest as a differentiable combination of eye movement-related artifact and genuine neural activity. Child FRPs are slower and unfold over longer time periods, which manifests as differences in the frequency domain. Even after removing artifact, dipoles associated with fixation-related P1 and N170 components manifest as Theta activity over fronto-central areas, along with activity in other frequencies, in children but not adults. Data sections where no fixation-related potentials are present show strongly attenuated oscillatory activity. Our results show that a variety of previously documented developmental effects in the frequency domain may be better understood as fine-grained, movement-induced brain states.

animal behavior and cognition↗

bioRxiv2025

Epigenome-wide analysis reveals novel DNA methylation signatures significantly associated with the infant pupillary light reflex, a candidate intermediate phenotype for autism.

Autism is a highly heterogeneous neurodevelopmental condition, currently diagnosed based on behavioural characteristics. Candidate early intermediate phenotypes, such as the Pupillary Light Reflex (PLR), a reflexive constriction of the pupil in response to increased optical luminance, may provide insights into etiological factors and potential biomarkers, such as DNA methylation (DNAm), involved in the emergence of autism. We conducted epigenome-wide DNAm association analyses of 9-, 14-, 24-month PLR onset latency and constriction amplitude in a sample of 51 infants enriched for autism family history, using buccal DNA collected at 9-months. Our epigenome-wide analysis (EWAS) identified four stringently significant differentially methylated probes (p < 2.4 x 10-7) associated with cross-section PLR latency measurements at 14- and 24-months, and with 14-to 24-month PLR latency developmental change. Differentially methylated probes associated with PLR amplitude were identified, but at a less stringent discovery threshold (p < 5 x 10-5). Our region analyses identified several significant differentially methylated regions associated with both PLR latency and amplitude Downstream exploratory pathway analysis identified enrichment for multiple developmental biological processes, as well as several susceptibility genes to autism and related neurodevelopmental conditions including NR4A2, HNRNPU and NAV2. Our findings provide novel insight into the role of DNAm in PLR development and illuminate biological mechanisms underpinning altered PLR in infancy in emerging autism.

neuroscience↗

bioRxiv2023

Objective assessment of visual attention in toddlerhood

Visual attention is an important mechanism through which children learn about their environment, and individual differences could substantially shape later development. Eyetracking provides a sensitive and scalable tool for assessing visual attention that has potential for objective assessment of child development, but to date the majority of studies are small and replication attempts are rare. This study investigates the feasibility of a comprehensive eye-tracking assessment of visual attention and introduces a shared data resource for the scientific community. Data from eight eyetracking tasks were collected from 350 term-born (166 females) 18-month-olds recruited as neonates http://www.developingconnectome.org/). Analyses showed expected condition effects for seven of eight tasks (p-values from <.001 to .04), an important indication of replicability. Consistent with some theoretical models of visual attention, structural equation modelling indicated participants performance could be explained by two factors representing social and non-social attention. Comprehensive eye-tracking batteries can objectively measure individual differences in core components of visual attention in large-scale toddlerhood studies. This is the first large-scale comprehensive study to present high-quality normative eye-tracking data from a large task battery in toddlers and make them freely available to the scientific community.

neuroscience↗

bioRxiv2022

Mapping human social brain specialisation beyond the neuron using multimodal imaging in human infants

The specialised regional functionality of the mature human cortex partly emerges through experience-dependent specialisation during early development. Our existing understanding of this process is based on evidence from unitary imaging modalities and has thus focused on isolated changes in spatial or temporal precision of neural or haemodynamic activation alone, giving an incomplete picture of the process. We speculate that neural specialisation of function will be underpinned by better coordinated haemodynamic and metabolic changes in a broader orchestrated physiological response. Thus, we present a harmonised framework in which specialisation is indexed by the emergence of coupling between neuronal activity and vascular supply of oxygen and energy. Here, we combine simultaneous measures of coordinated neural activity (EEG), metabolic rate and oxygenated blood supply (broadband near-infrared spectroscopy) to measure emerging specialisation in the infant brain. In 4-to-7-month-old infants, we show that social processing is accompanied by spatially and temporally specific increases in coupled activation in the temporal-parietal junction, a core hub region of the adult social brain. During non-social processing coupled activation decreased in the same region, indicating specificity to social processing. Coupling was strongest with high frequency brain activity (beta and gamma), consistent with the greater energetic requirements and more localised action of high frequency brain activity. We conclude that functional specialisation of the brain is a coordinated activity across neural, haemodynamic, and metabolic changes, and our ability to measure these simultaneously opens new vistas in understanding how the brain is shaped by its environment.

developmental biology↗

bioRxiv2020

Attenuated Anticipation of Social and Monetary Rewards in Autism Spectrum Disorders

BackgroundReward processing has been proposed to underpin atypical social behavior, a core feature of autism spectrum disorder (ASD). However, previous neuroimaging studies have yielded inconsistent results regarding the specificity of atypicalities for social rewards in ASD. Utilizing a large sample, we aimed to assess altered reward processing in response to reward type (social, monetary) and reward phase (anticipation, delivery) in ASD. MethodsFunctional magnetic resonance imaging during social and monetary reward anticipation and delivery was performed in 212 individuals with ASD (7.6-30.5 years) and 181 typically developing (TD) participants (7.6-30.8 years). ResultsAcross social and monetary reward anticipation, whole-brain analyses (p<0.05, family-wise error-corrected) showed hypoactivation of the right ventral striatum (VS) in ASD. Further, region of interest (ROI) analysis across both reward types yielded hypoactivation in ASD in both the left and right VS. Across delivery of social and monetary reward, hyperactivation of the VS in individuals with ASD did not survive correction for multiple comparisons. Reward type by diagnostic group interactions, and a dimensional analysis of autism trait scores were not significant during anticipation or delivery. Levels of attention-deficit/hyperactivity disorder (ADHD) symptoms did not affect reward processing in ASD. ConclusionsOur results do not support current theories linking atypical social interaction in ASD to specific alterations in processing of social rewards. Instead, they point towards a generalized hypoactivity of VS in ASD during anticipation of both social and monetary rewards. We suggest that this indicates attenuated subjective reward value in ASD independent of social content and ADHD symptoms.

neuroscience↗

bioRxiv2020

Differential functional neural circuitry behind autism subtypes with marked imbalance between social-communicative and restricted repetitive behavior symptom domains

Social-communication (SC) and restricted repetitive behaviors (RRB) are autism diagnostic symptom domains. SC and RRB severity can markedly differ within and between individuals and may be underpinned by different neural circuitry and genetic mechanisms. Modeling SC-RRB balance could help identify how neural circuitry and genetic mechanisms map onto such phenotypic heterogeneity. Here we developed a phenotypic stratification model that makes highly accurate (97-99%) out-of-sample SC=RRB, SC>RRB, and RRB>SC subtype predictions. Applying this model to resting state fMRI data from the EU-AIMS LEAP dataset (n=509), we find that while the phenotypic subtypes share many commonalities in terms of intrinsic functional connectivity, they also show replicable differences within some networks compared to a typically-developing group (TD). Specifically, the somatomotor network is hypoconnected with perisylvian circuitry in SC>RRB and visual association circuitry in SC=RRB. The SC=RRB subtype show hyperconnectivity between medial motor and anterior salience circuitry. Genes that are highly expressed within these networks show a differential enrichment pattern with known autism-associated genes, indicating that such circuits are affected by differing autism-associated genomic mechanisms. These results suggest that SC-RRB imbalance subtypes share many commonalities, but also express subtle differences in functional neural circuitry and the genomic underpinnings behind such circuitry.

neuroscience↗