Intact neural representations of affective meaning of touch but lack of embodied resonance in autism: a multi-voxel pattern analysis study

Pupillary response during social emotion tasks in autism spectrum disorder

Autistic individuals encounter challenges in recognizing emotional expressions of others. Pupillary response has been proposed as an indicator of arousal dysregulation or cognitive load. The pupillary response of autistic individuals during socio-affective tasks remains unclear. This study investigated pupillary response in autistic adults when viewing emotional faces/eyes and recognizing emotions during the Reading the Mind in the Eyes Test (RMET) and watching interpersonal touch scenes in the social touch task. The study included 98 participants diagnosed with autism spectrum disorder and 37 typically developing controls (TD). Pupil size was measured using the Tobii X2-30 Eye Tracker. The results showed that autistic adults had larger maximal pupil sizes, smaller minimal pupil sizes, and greater change rates of pupil size, particularly during the RMET Eyes task. Clinical correlations revealed that attention switching difficulty positively correlated with mean pupil size in TD participants, while social communication deficits positively correlated with mean pupil size in autistic participants. In conclusion, our findings suggest atypical pupillary responses in autistic adults during socio-affective tasks, indicating heightened cognitive demand. Further investigation is necessary to understand the underlying mechanisms and their association with autistic traits.

Exploring social touch in autistic and non-autistic adults via a self-report body-painting task: The role of sex, social context and body area

LAY ABSTRACT

What is already known about the topic?At least in neurotypical individuals, social touch represents an important channel for emotional communication associated with social bonding and pain/anxiety modulation. Autistic adults report to avoid social touch more and to have different tactile sensitivity than their non-autistic comparisons.What this paper adds?Few studies specifically investigated social touch in autistic individuals, and none of them examined the role of participants' sex, social context in which social touch occurs, and specific body areas being touched. In our study, adult participants reported how pleasant, erogenous and appropriate they would consider touches delivered by another person over their entire body in intimate (date), friendly (dance class) and professional (physiotherapy-massage session) social contexts. Autistic adults reported social touch to be less pleasant, erogenous and appropriate specifically in intimate and friendly social contexts and in body areas typically touched in these situations. Importantly, autistic females seem more at risk to experience unpleasant social touch as, although they considered it more unpleasant than non-autistic females and autistic males, they did consider it similarly appropriate in professional social contexts where touch is normed to be socially appropriate.Implications for practice, research or policyOur results might improve awareness and understanding about autistic adults' different, and often more discomforting, experience of social touch and thus help consider and respect it during everyday social interactions. Our results might also benefit future research investigating, for instance, the neural underpinnings of social touch differences in autism or aiming at developing support for autistic individuals seeking help in the diverse spheres of social touch.

Psychometric evaluation of the Social Touch Questionnaire in Chinese adolescents

Social touch promotes psychological well-being through inducing positive effects on social affiliation and stress alleviation, especially in adolescence. However, there is a scarcity of instruments available for evaluating adolescents' attitude toward social touch in China. The present study aimed to investigate the validity and reliability of the Social Touch Questionnaire (STQ) in Chinese adolescents. A total of 2839 high school students were enrolled, ranging in age from 11 to 19 years. The dimensions of the scale were conducted by exploratory factor analysis, and validated by confirmatory factor analysis. A three-factor model showed the best fit and consisted of the following subgroups: liking of informal social touch, liking of general social touch, and dislike of social touch. Furthermore, positive associations were found between social touch and interaction anxiety, fear of negative evaluation, depressive and anxiety symptoms, and sleep quality. Short-term prediction of dislike of social touch in anxiety symptoms was determined, while no significant predictor of depressive symptoms was found. The STQ demonstrates reliability and validity as a self-report questionnaire designed to assess behaviors and attitudes toward social touch. It effectively adapts to the nuances of the Chinese context among adolescents.

Posterior default mode network is associated with the social performance in male children with autism spectrum disorder: A dynamic causal modeling analysis based on triple-network model

The triple-network model has been widely applied in neuropsychiatric disorders including autism spectrum disorder (ASD). However, the mechanism of causal regulations within the triple-network and their relations with symptoms of ASD remains unclear. 81 male ASD and 80 well matched typically developing control (TDC) were included in this study, recruited from Autism Brain Image Data Exchange-I datasets. Spatial reference-based independent component analysis was used to identify the anterior and posterior part of default-mode network (aDMN and pDMN), salience network (SN), and bilateral executive-control network (ECN) from resting-state functional magnetic resonance imaging data. Spectral dynamic causal model and parametric empirical Bayes with Bayesian model reduction/average were adopted to explore the effective connectivity (EC) within triple-network and the relationship between EC and autism diagnostic observation schedule (ADOS) scores. After adjusting for age and site effect, ASD and TDC groups both showed inhibition patterns. Compared with TDC, ASD group showed weaker self-inhibition in aDMN and pDMN, stronger inhibition in pDMN→aDMN, weaker inhibition in aDMN→LECN, pDMN→SN, LECN→SN, and LECN→RECN. Furthermore, negative relationships between ADOS scores and pDMN self-inhibition strength, as well as with the EC of pDMN→aDMN were observed in ASD group. The present study reveals imbalanced effective connections within triple-networks in ASD children. More attentions should be focused at the pDMN, which modulates the core symptoms of ASD and may serve as an important region for ASD diagnosis and the target region for ASD treatments.

To touch or to be touched? comparing appraisal of vicarious execution and reception of interpersonal touch

Unmyelinated C-Tactile (CT) fibres are activated by caress-like touch, eliciting a pleasant feeling that decreases for static and faster stroking. Previous studies documented this effect also for vicarious touch, hypothesising simulation mechanisms driving the perception and appreciation of observed interpersonal touch. Notably, less is known about appreciation of vicarious execution of touch, that is as referred to the one giving gentle touch. To address this issue, 53 healthy participants were asked to view and rate a series of videoclips displaying an individual being touched by another on hairy (i.e., hand dorsum) or glabrous (i.e., palm) skin sites, with touch being delivered at CT-optimal (5 cm/s) or non-CT optimal velocities (0 cm/s or 30 cm/s). Following the observation of each clip, participants were asked to rate self-referred desirability and model-referred pleasantness of vicarious touch for both executer (toucher-referred) and receiver (touchee-referred). Consistent with the CT fibres properties, for both self-referred desirability and model-referred pleasantness judgements of vicarious touch execution and reception, participants provided higher ratings for vicarious touch delivered at CT-optimal than other velocities, and when observed CT-optimal touch was delivered to the hand-dorsum compared to the palm. However, higher ratings were attributed to vicarious reception compared to execution of CT-optimal touch. Notably, individual differences in interoceptive trusting and attitude to interpersonal touch were positively correlated with, respectively, toucher- and touchee-related overall appraisal ratings of touch. These findings suggest that the appreciation of both toucher- and touchee-referred vicarious touch is specifically attuned to CT-optimal touch, even though they might rely on different neurocognitive mechanisms to understand affective information conveyed by interpersonal tactile interactions.

Rapid Processing of Observed Touch through Social Perceptual Brain Regions: An EEG-fMRI Fusion Study

Seeing social touch triggers a strong social-affective response that involves multiple brain networks, including visual, social perceptual, and somatosensory systems. Previous studies have identified the specific functional role of each system, but little is known about the speed and directionality of the information flow. Is this information extracted via the social perceptual system or from simulation from somatosensory cortex? To address this, we examined the spatiotemporal neural processing of observed touch. Twenty-one human participants (seven males) watched 500-ms video clips showing social and nonsocial touch during electroencephalogram (EEG) recording. Visual and social-affective features were rapidly extracted in the brain, beginning at 90 and 150 ms after video onset, respectively. Combining the EEG data with functional magnetic resonance imaging (fMRI) data from our prior study with the same stimuli reveals that neural information first arises in early visual cortex (EVC), then in the temporoparietal junction and posterior superior temporal sulcus (TPJ/pSTS), and finally in the somatosensory cortex. EVC and TPJ/pSTS uniquely explain EEG neural patterns, while somatosensory cortex does not contribute to EEG patterns alone, suggesting that social-affective information may flow from TPJ/pSTS to somatosensory cortex. Together, these findings show that social touch is processed quickly, within the timeframe of feedforward visual processes, and that the social-affective meaning of touch is first extracted by a social perceptual pathway. Such rapid processing of social touch may be vital to its effective use during social interaction.SIGNIFICANCE STATEMENT Seeing physical contact between people evokes a strong social-emotional response. Previous research has identified the brain systems responsible for this response, but little is known about how quickly and in what direction the information flows. We demonstrated that the brain processes the social-emotional meaning of observed touch quickly, starting as early as 150 ms after the stimulus onset. By combining electroencephalogram (EEG) data with functional magnetic resonance imaging (fMRI) data, we show for the first time that the social-affective meaning of touch is first extracted by a social perceptual pathway and followed by the later involvement of somatosensory simulation. This rapid processing of touch through the social perceptual route may play a pivotal role in effective usage of touch in social communication and interaction.

A Novel Head-Fixed Assay for Social Touch in Mice Uncovers Aversive Responses in Two Autism Models

Social touch, an important aspect of social interaction and communication, is essential to kinship across animal species. How animals experience and respond to social touch has not been thoroughly investigated, in part because of the lack of appropriate assays. Previous studies that examined social touch in freely moving rodents lacked the necessary temporal and spatial control over individual touch interactions. We designed a novel head-fixed assay for social touch in mice, in which the experimenter has complete control to elicit highly stereotyped bouts of social touch between two animals. The user determines the number, duration, context, and type of social touch interactions, while monitoring an array of complex behavioral responses with high resolution cameras. We focused on social touch to the face because of its high translational relevance to humans. We validated this assay in two different models of autism spectrum disorder (ASD), the Fmr1 knock-out (KO) model of Fragile X syndrome (FXS) and maternal immune activation (MIA) mice. We observed higher rates of avoidance running, hyperarousal, and aversive facial expressions (AFEs) to social touch than to object touch, in both ASD models compared with controls. Fmr1 KO mice showed more AFEs to mice of the same sex but whether they were stranger or familiar mice mattered less. Because this new social touch assay for head-fixed mice can be used to record neural activity during repeated bouts of social touch it could be used to uncover underlying circuit differences.SIGNIFICANCE STATEMENT Social touch is important for communication in animals and humans. However, it has not been extensively studied and current assays to measure animals' responses to social touch have limitations. We present a novel head-fixed assay to quantify how mice respond to social facial touch with another mouse. We validated this assay in autism mouse models since autistic individuals exhibit differences in social interaction and touch sensitivity. We find that mouse models of autism exhibit more avoidance, hyperarousal, and aversive facial expressions (AFEs) to social touch compared with controls. Thus, this novel assay can be used to investigate behavioral responses to social touch and the underlying brain mechanisms in rodent models of neurodevelopmental conditions, and to evaluate therapeutic responses in preclinical studies.

A multidimensional investigation of the relationship between skin-mediated somatosensory signals, emotion regulation and behavior problems in autistic children

Introduction

Autistic children may have abnormal sensory perception, emotion dysregulation and behavior problems. The aim of this cross-sectional study was to explore the relationship between skin-mediated somatosensory signals and emotion/behavior difficulties in autistic children and adolescents, in comparison typically developing peers (TDP).

Methods

Thirty-eight autistic children and adolescents and 34 TDP completed a multidimensional assessment consisting of the measurement of somatosensory thresholds of touch, pain and temperature, a task on emotion knowledge and parent-reported questionnaires on sensory reactivity, emotion regulation and behavior.

Results

Autistic children had higher pain sensitivity, less sensory reactive behaviors and more behavior problems than their TDP. In contrast to TDP, several somatosensory thresholds of autistic children correlated with emotion regulation and behavior problems.

Discussion

Sensory dysfunction may affect the development of emotional processing and behavior in autistic children and adolescents. This knowledge can lay the foundation for future studies on co-occurring alterations in corresponding neural networks and for the implementation of early interventions, including sensory rehabilitation therapy, for promoting regulated behaviors in autistic children and adolescents.

A novel head-fixed assay for social touch in mice uncovers aversive responses in two autism models

Social touch, an important aspect of social interaction and communication, is essential to kinship across animal species. How animals experience and respond to social touch has not been thoroughly investigated, in part due to the lack of appropriate assays. Previous studies that examined social touch in freely moving rodents lacked the necessary temporal and spatial control over individual touch interactions. We designed a novel head-fixed assay for social touch in mice, in which the experimenter has complete control to elicit highly stereotyped bouts of social touch between two animals. The user determines the number, duration, context, and type of social touch interactions, while monitoring with high frame rate cameras an array of complex behavioral responses. We focused on social touch to the face because of their high translational relevance to humans. We validated this assay in two different models of autism spectrum disorder (ASD), the Fmr1 knockout model of Fragile X Syndrome and maternal immune activation mice. We observed increased avoidance, hyperarousal, and more aversive facial expressions to social touch, but not to object touch, in both ASD models compared to controls. Because this new social touch assay for head-fixed mice can be used to record neural activity during repeated bouts of social touch it should be of interest to neuroscientists interested in uncovering the underlying circuits.

Do sparse brain activity patterns underlie human cognition?

Accumulating multivariate pattern analysis (MVPA) results from fMRI studies suggest that information is represented in fingerprint patterns of activations and deactivations during perception, emotions, and cognition. We postulate that these fingerprint patterns might reflect neuronal-population level sparse code documented in two-photon calcium imaging studies in animal models, i.e., information represented in specific and reproducible ensembles of a few percent of active neurons amidst widespread inhibition in neural populations. We suggest that such representations constitute a fundamental organizational principle via interacting across multiple levels of brain hierarchy, thus giving rise to perception, emotions, and cognition.

The Current View on the Paradox of Pain in Autism Spectrum Disorders

Autism spectrum disorder (ASD) is a neurodevelopmental disorder, which affects 1 in 44 children and may cause severe disabilities. Besides socio-communicational difficulties and repetitive behaviors, ASD also presents as atypical sensorimotor function and pain reactivity. While chronic pain is a frequent co-morbidity in autism, pain management in this population is often insufficient because of difficulties in pain evaluation, worsening their prognosis and perhaps driving higher mortality rates. Previous observations have tended to oversimplify the experience of pain in autism as being insensitive to painful stimuli. Various findings in the past 15 years have challenged and complicated this dogma. However, a relatively small number of studies investigates the physiological correlates of pain reactivity in ASD. We explore the possibility that atypical pain perception in people with ASD is mediated by alterations in pain perception, transmission, expression and modulation, and through interactions between these processes. These complex interactions may account for the great variability and sometimes contradictory findings from the studies. A growing body of evidence is challenging the idea of alterations in pain processing in ASD due to a single factor, and calls for an integrative view. We propose a model of the pain cycle that includes the interplay between the molecular and neurophysiological pathways of pain processing and it conscious appraisal that may interfere with pain reactivity and coping in autism. The role of social factors in pain-induced response is also discussed. Pain assessment in clinical care is mostly based on subjective rather than objective measures. This review clarifies the strong need for a consistent methodology, and describes innovative tools to cope with the heterogeneity of pain expression in ASD, enabling individualized assessment. Multiple measures, including self-reporting, informant reporting, clinician-assessed, and purely physiological metrics may provide more consistent results. An integrative view on the regulation of the pain cycle offers a more robust framework to characterize the experience of pain in autism.

The Embodied-Enactive-Interactive Brain: Bridging Neuroscience and Creative Arts Therapies

The recognition and incorporation of evidence-based neuroscientific concepts into creative arts therapeutic knowledge and practice seem valuable and advantageous for the purpose of integration and professional development. Moreover, exhilarating insights from the field of neuroscience coincide with the nature, conceptualization, goals, and methods of Creative Arts Therapies (CATs), enabling comprehensive understandings of the clinical landscape, from a translational perspective. This paper contextualizes and discusses dynamic brain functions that have been suggested to lie at the heart of intra- and inter-personal processes. Touching upon fundamental aspects of the self and self-other interaction, the state-of-the-art neuroscientific-informed views will shed light on mechanisms of the embodied, predictive and relational brain. The conceptual analysis introduces and interweaves the following contemporary perspectives of brain function: firstly, the grounding of mental activity in the lived, bodily experience will be delineated; secondly, the enactive account of internal models, or generative predictive representations, shaped by experience, will be defined and extensively deliberated; and thirdly, the interpersonal simulation and synchronization mechanisms that support empathy and mentalization will be thoroughly considered. Throughout the paper, the cross-talks between the brain and the body, within the brain through functionally connected neural networks and in the context of agent-environment dynamics, will be addressed. These communicative patterns will be elaborated on to unfold psychophysiological linkage, as well as psychopathological shifts, concluding with the neuroplastic change associated with the formulation of CATs. The manuscript suggests an integrative view of the brain-body-mind in contexts relevant to the therapeutic potential of the expressive creative arts and the main avenues by which neuroscience may ground, enlighten and enrich the clinical psychotherapeutic practice.

Altered relationship between subjective perception and central representation of touch hedonics in adolescents with autism-spectrum disorder

An impairment of social communication is a core symptom of autism-spectrum disorder (ASD). Affective touch is an important means of social interaction, and C-Tactile (CT) afferents are thought to play a key role in the peripheral detection and encoding of these stimuli. Exploring the neural and behavioral mechanisms for processing CT-optimal touch (~3 cm/s) may therefore provide useful insights into the pathophysiology of ASD. We examined the relationship between touch hedonics (i.e. the subjective pleasantness with which affective touch stimuli are perceived) and neural processing in the posterior superior temporal sulcus (pSTS). This region is less activated to affective touch in individuals with ASD, and, in typically developing individuals (TD), is correlated positively with touch pleasantness. TD and ASD participants received brushing stimuli at CT-optimal, and CT-non-optimal speeds during fMRI. Touch pleasantness and intensity ratings were collected, and affective touch awareness, a measure of general touch hedonics was calculated. As expected, slow touch was perceived as more pleasant and less intense than fast touch in both groups, whereas affective touch awareness was moderately higher in TD compared to ASD. There was a strong, positive correlation between right pSTS activation and affective touch awareness in TD, but not in ASD. Our findings suggest that altered neural coupling between right pSTS and touch hedonics in ASD may be associated with social touch avoidance in ASD.

Bliss in and Out of the Body: The (Extra)Corporeal Space Is Impervious to Social Pleasant Touch

Slow, gentle stimulation of hairy skin is generally accompanied by hedonic sensations. This phenomenon, also known as (positive) affective touch, is likely to be the basis of affiliative interactions with conspecifics by promoting inter-individual bindings. Previous studies on healthy humans have demonstrated that affective touch can remarkably impact behavior. For instance, by administering the Rubber Hand Illusion (RHI) paradigm, the embodiment of a fake hand enhances after a slow, affective touch compared to a fast, neutral touch. However, results coming from this area are not univocal. In addition, there are no clues in the existing literature on the relationship between affective touch and the space around our body. To overcome these lacks, we carried out two separate experiments where participants underwent a RHI paradigm (Experiment 1) and a Visuo-Tactile Interaction task (Experiment 2), designed to tap into body representation and peripersonal space processing, respectively. In both experiments, an affective touch (CT-optimal, 3 cm/s) and neutral touch (CT-suboptimal, 18 cm/s) were delivered by the experimenter on the dorsal side of participants’ hand through a “skin to skin” contact. In Experiment 1, we did not find any modulation of body representation—not at behavioral nor at a physiological level—by affective touch. In Experiment 2, no visuo-tactile spatial modulation emerged depending upon the pleasantness of the touch received. These null findings are interpreted in the light of the current scientific context where the real nature of affective touch is often misguided, and they offer the possibility to pave the way for understanding the real effects of affective touch on body/space representation.

Neural processing of facial identity and expression in adults with and without autism: A multi-method approach

The ability to recognize faces and facial expressions is a common human talent. It has, however, been suggested to be impaired in individuals with autism spectrum disorder (ASD). The goal of this study was to compare the processing of facial identity and emotion between individuals with ASD and neurotypicals (NTs). Behavioural and functional magnetic resonance imaging (fMRI) data from 46 young adults (aged 17-23 years, N_ASD = 22, N_NT = 24) was analysed. During fMRI data acquisition, participants discriminated between short clips of a face transitioning from a neutral to an emotional expression. Stimuli included four identities and six emotions. We performed behavioural, univariate, multi-voxel, adaptation and functional connectivity analyses to investigate potential group differences. The ASD-group did not differ from the NT-group on behavioural identity and expression processing tasks. At the neural level, we found no differences in average neural activation, neural activation patterns and neural adaptation to faces in face-related brain regions. In terms of functional connectivity, we found that amygdala seems to be more strongly connected to inferior occipital cortex and V1 in individuals with ASD. Overall, the findings indicate that neural representations of facial identity and expression have a similar quality in individuals with and without ASD, but some regions containing these representations are connected differently in the extended face processing network.

Reduced task-dependent modulation of functional network architecture for positive versus negative affective touch processing in autism spectrum disorders

Individuals with autism spectrum disorders (ASD) experience impairments in social communication and interaction, and often show difficulties with receiving and offering touch. Despite the high prevalence of abnormal reactions to touch in ASD, and the importance of touch communication in human relationships, the neural mechanisms underlying atypical touch processing in ASD remain largely unknown. To answer this question, we provided both pleasant and unpleasant touch stimulation to male adults with and without ASD during functional neuroimaging. By employing generalized psychophysiological interaction analysis combined with an independent component analysis approach, we characterize stimulus-dependent changes in functional connectivity patterns for processing two tactile stimuli that evoke different emotions (i.e., pleasant vs. unpleasant touch). Results reveal that neurotypical male adults showed extensive stimulus-sensitive modulations of the functional network architecture in response to the different types of touch, both at the level of brain regions and large-scale networks. Conversely, far fewer stimulus-sensitive modulations were observed in the ASD group. These aberrant functional connectivity profiles in the ASD group were marked by hypo-connectivity of the parietal operculum and major pain networks and hyper-connectivity between the semantic and limbic networks. Lastly, individuals presenting more social deficits and a more negative attitude towards social touch showed greater hyper-connectivity between the limbic and semantic networks. These findings suggest that reduced stimulus-related modulation of this functional network architecture is associated with abnormal processing of touch in ASD.