Biology subjects

Stevenson, R. A.

Publications and source records attributed to Stevenson, R. A..

7 recordsLinked to original sources

bioRxiv2026

Differentiating neural mechanisms in response to emotional expressions on real and virtual faces

As avatars become more commonplace, understanding how the brain processes emotional expressions in virtual faces is critical. We compared behavioral and neural responses to real and virtual faces expressing seven emotions (anger, disgust, fear, joy, sadness, surprise, neutral). In Experiment 1 (n=61), participants rated the similarity between paired faces. Expressions conveying the same emotion were rated as highly similar across face types, whereas mismatched emotions yielded substantially lower similarity ratings, indicating perceived emotional meaning was preserved despite differences in face realism. In Experiment 2 (n=91), functional near-infrared spectroscopy was used to measure brain activity while participants viewed the same stimuli. General-linear-model analyses revealed greater activation limited to visual areas for 1) virtual faces and 2) surprise and neutral expressions. Functional connectivity analyses, however, revealed network level differences between face type and emotion across the brain. Real faces elicited stronger connectivity patterns across frontal, central-temporal, and parietal regions, whereas high-arousal emotions (fear, anger, and joy) were associated with broader network engagement than other expressions. Our results suggest face-type processing occur in early visual areas, and despite perceptual similarity, different emotions on real and virtual faces are associated with distinct patterns of network level connectivity across the brain.

neuroscience↗

bioRxiv2025

Rate of functional network maturity and the role of environmental factors

The developmental period from childhood to adolescence is marked by significant changes to the functional properties of the brain that support various aspects of higher-level cognition. Environmental factors such as socioeconomic status and adversity can have an outsized influence on neurocognitive development. However, not all environmental factors have the same influence on cognitive and brain development. In the current study, we examined the differential influences of SES (i.e., parental education and neighbourhood safety) and adversity on the maturation rate of functional networks in children and adolescents. Using resting-state fMRI data, independent component analysis with dual regression was computed to identify six networks (Default Mode Network (DMN), Left Executive Control Network (ECN), Right ECN, Hippocampal (HPC), Salience, and Sensorimotor networks) of interest in children and adolescents aged 7 to 15 (N=216, acquired from the Healthy Brain Network). A neural maturity index was generated based on the degree of similarity between the spatial configuration of the six networks in each youth brain to that of an adult template (1243 total, with a mean age of 26; independently by sex). Regression analyses were used to determine the association between neural maturity, social-cognitive abilities and environmental factors such as parental education, neighbourhood safety and number of negative life events (adversity). We found one sensory (sensorimotor) and two association (default mode and executive control) networks matured faster than other networks. Only the rate of maturity of the DMN and HPC were associated with environmental factors. Maturity of the DMN was associated with less adversity and better social cognitive ability, whereas maturity of the HPC network was associated with younger participants with higher IQs. Moreover, these effects were stronger in females than males. Our results highlight the importance of examining the unique contributions of distinct dimensions of childhood environments on neurocognitive development.

neuroscience↗

bioRxiv2025

Functional organization of multisensory integration network in children and youth with neurodevelopmental disorders predicts clinical sensory issues

Differences in sensory processing in neurodevelopmental conditions, including Autism Spectrum Disorder (ASD) and Attention-deficit/Hyperactivity Disorder (ADHD), cascade into downstream clinical symptomatology. This includes differences in combining sensory information from multiple modalities into a unified percept, known as multisensory integration. Little is known about the functional organization of multisensory network (MSN) in these groups, its relation to clinical sensory issues, or its interaction with other higher-order cortical networks. We examined resting-state fMRI data from 417 participants in the Province of Ontario Neurodevelopmental Network (ASD=174, ADHD=130, Typical Development=113; Mean age=11.96{+/-}4.10). Timeseries data were extracted from the MSN and seven additional resting-state cortical networks (RSNs). Undirected and directed functional connectivity (FC) metrics were computed within the MSN and between the MSN and other RSNs. FC was compared across diagnoses and related to clinical sensory characteristics. The thalamus emerged as a hub region in both undirected and directed FC within the MSN and between the MSN-RSNs. Some diagnosis-related differences were observed, with increased MSN-RSN FC particularly in ADHD; however, associations with sensory characteristics were stronger in both undirected and directed FC within the MSN and between the MSN-RSNs, regardless of diagnosis. Converging evidence was seen in data-driven clusters based on FC metrics, which did not align with diagnosis, but instead mapped on to the overall level of sensory issues reported. That the data-driven clusters sorted not by diagnosis but by sensory characteristics suggests that these sensory characteristics and their underlying neurobiology are transdiagnostic in nature as opposed to specific to ASD or ADHD.

neuroscience↗

bioRxiv2025

Auditory Brainstem Development in Autism: From Childhood Hypo-Responsivity to Adult Hyper-Reactivity

BackgroundAutism Spectrum Disorder (ASD) is characterized by sensory disruptions, including auditory processing differences, which can significantly impact social, emotional, and cognitive development. This study investigates auditory brainstem development in Autistic children and adults using auditory brainstem responses (ABRs) and acoustic startle responses (ASRs), two key measures of auditory processing. We hypothesize that early hypo-responsivity in children, measured with ABRs, may lead to compensatory neural adaptations, resulting in hyper-reactivity in adulthood, measured by ASRs. MethodsThe study included 40 Autistic children, 57 non-Autistic children, 20 Autistic adults, and 21 non-Autistic adults. Participants underwent peripheral hearing screening, ABR testing at slow and fast click-rates, and ASR measurements. ABR wave and ASR amplitude were analyzed. Statistical analyses included mixed-model ANOVAs and Spearmans correlations to examine group differences and associations with age. ResultsAutistic participants showed trending differences in auditory brainstem timing relative to non-autistic participants, with no differences in brainstem amplitude at any wave or rate. Post hoc slope comparisons revealed that non-Autistic participants showed positive developmental trajectories in Wave I latency at both rates, while Autistic participants showed flat trajectories, a pattern directionally consistent with developmental convergence. A sex-specific group difference was observed at Wave I slow rate, with Autistic females showing longer latencies than non-Autistic females (d = 1.69), with no difference in males. In contrast, ASR amplitude showed diverging developmental trajectories between groups, with Autistic participants showing a positive age-related increase and non-Autistic participants showing a negative age-related decrease (slope contrast: t(99) = 2.16, p = .033, 2p = .05), consistent with a group difference emerging in adulthood. ABR amplitude was positively correlated with ASR amplitude in non-Autistic participants (Wave I: rho = +0.30; Wave V: rho = +0.25) but negatively correlated in Autistic participants (Wave I: rho = -0.19; Wave V: rho = -0.20), with the between-group difference in correlation direction surviving FDR correction for both waves (Fishers z padj = .035). ConclusionThe findings are consistent with the hypothesis that Autistic children experience auditory brainstem hypo-responsivity, which may normalize in adulthood but lead to maladaptive hyper-reactivity. These results highlight the role of early auditory disruptions in shaping long-term sensory processing and reactivity in Autism, emphasizing the need for further research into the neural mechanisms underlying these differences.

neuroscience↗

bioRxiv2024

On the same wavelength: The relationship between neural synchrony and cognitive ability during movie watching in late childhood and early adolescence

Cognitive development in late childhood and adolescence occurs alongside increasingly complex environments. To examine how cognitive abilities relate to neural processing of naturalistic experiences, we analyzed fMRI data from 309 children and adolescents (ages 7-15; majority White) in the Healthy Brain Biobank. Participants watched a 10-minute clip of Despicable Me during scanning and completed the WISC. Intersubject correlation (ISC) was used to measure brain synchrony during viewing. Adolescents (11-15) with higher cognitive scores showed greater ISC in default mode and frontoparietal networks. In contrast, younger children (7-11) with high scores showed increased synchrony only in somatosensory regions. These findings suggest age- and cognition-related differences in how children and adolescents process complex, real-world stimuli.

neuroscience↗

bioRxiv2020

The relationship between multisensory associative learning and multisensory integration

Our perception of the world around us is inherently multisensory, and integrating sensory information from multiple modalities leads to more precise and efficient perception and behaviour. Determining which sensory information from different modalities should be perceptually bound is a key component of multisensory integration. To accomplish this feat, our sensory systems rely on both low-level stimulus features, as well as multisensory associations learned throughout development based on the statistics of our environment. The present study explored the relationship between multisensory associative learning and multisensory integration using encephalography (EEG) and behavioural measures. Sixty-one participants completed a three-phase study. First, participants were exposed to novel pairings audiovisual shape-tone pairings with frequent and infrequent stimulus pairings and complete a target detection task. EEG recordings of the mismatch negativity (MMN) and P3 were calculated as neural indices of multisensory associative learning. Next, the same learned stimulus pairs presented in audiovisual as well as unisensory auditory and visual modalities while both early (<120 ms) and late neural indices of multisensory integration were recorded. Finally, participants completed an analogous behavioural speeded-response task, with behavioural indices of multisensory gain calculated using the race model. Significant relationships were found in fronto-central and occipital areas between neural measures of associative learning and both early and late indices of multisensory integration in frontal and centro-parietal areas, respectively. Participants who showed stronger indices of associative learning also exhibited stronger indices of multisensory integration of the stimuli they learned to associate. Furthermore, a significant relationship was found between neural index of early multisensory integration and behavioural indices of multisensory gain. These results provide insight into the neural underpinnings of how higher-order processes such as associative learning guide multisensory integration.

neuroscience↗

bioRxiv2020

Examining the relationship between social cognition and neural synchrony during movies in children with and without autism

Children who have been diagnosed with autism spectrum disorder (ASD) often show a marked deficit in measures of social cognition. In autistic adults, measures of social cognition have been shown to relate to differences in brain synchronization (as measured by fMRI) when individuals are processing naturalistic stimuli, such as movies. However, whether children with social impairments, with or without a diagnosis of ASD, differ in their neural responses to movies has not yet been investigated. In the current study, neural synchrony, measured using fMRI, was examined in three groups of children aged 7 to 12, who differed with respect to scores on a measure of autistic traits associated with social impairment and whether or not they had been diagnosed with ASD. While watching the movie Despicable Me, those diagnosed with ASD had significantly less neural synchrony in areas that have been previously shown to be associated with social cognition (e.g. areas related to theory of mind), and plot following (e.g. the lateral prefrontal cortex), than those who did not have an ASD diagnosis. In contrast, two groups who differed in their degree of social impairment, but did not have a diagnosis of ASD, showed no significant differences in neural synchrony across the whole brain. These results shed some light on how autistic traits may contribute to an individuals conscious experience of the world, and how, for children with ASD, that experience may differ markedly from that of those without ASD.

neuroscience↗