Tactile sensitivity in Asperger syndrome

Temporal resolution relates to sensory hyperreactivity independently of stimulus detection sensitivity in individuals with autism spectrum disorder

Researchers have been focusing on perceptual characteristics of autism spectrum disorder (ASD) in terms of sensory hyperreactivity. Previously, we demonstrated that temporal resolution, which is the accuracy to differentiate the order of two successive vibrotactile stimuli, is associated with the severity of sensory hyperreactivity. We currently examined whether an increase in the perceptual intensity of a tactile stimulus, despite its short duration, is derived from high temporal resolution and high frequency of sensory temporal summation. Twenty ASD and 22 typically developing (TD) participants conducted two psychophysical experimental tasks to evaluate detectable duration of vibrotactile stimulus with same amplitude and to evaluate temporal resolution. The sensory hyperreactivity was estimated using self-reported questionnaire. There was no relationship between the temporal resolution and the duration of detectable stimuli in both groups. However, the ASD group showed severe sensory hyperreactivity in daily life than TD group, and the ASD participants with severe sensory hyperreactivity tended to have high temporal resolution, not high sensitivity of detectable duration. Contrary to the hypothesis, there might be different processing between temporal resolution and sensitivity for stimulus detection. We suggested that the atypical temporal processing would affect to sensory reactivity in ASD.

The cerebellum and the Mirror Neuron System: A matter of inhibition? From neurophysiological evidence to neuromodulatory implications. A narrative review

Mirror neurons show activity during both the execution (AE) and observation of actions (AO). The Mirror Neuron System (MNS) could be involved during motor imagery (MI) as well. Extensive research suggests that the cerebellum is interconnected with the MNS and may be critically involved in its activities. We gathered evidence on the cerebellum's role in MNS functions, both theoretically and experimentally. Evidence shows that the cerebellum plays a major role during AO and MI and that its lesions impair MNS functions likely because, by modulating the activity of cortical inhibitory interneurons with mirror properties, the cerebellum may contribute to visuomotor matching, which is fundamental for shaping mirror properties. Indeed, the cerebellum may strengthen sensory-motor patterns that minimise the discrepancy between predicted and actual outcome, both during AE and AO. Furthermore, through its connections with the hippocampus, the cerebellum might be involved in internal simulations of motor programs during MI. Finally, as cerebellar neuromodulation might improve its impact on MNS activity, we explored its potential neurophysiological and neurorehabilitation implications.

Somatosensory temporal sensitivity in adults on the autism spectrum: A high-density electrophysiological mapping study using the mismatch negativity (MMN) sensory memory paradigm

Atypical reactivity to somatosensory inputs is common in autism spectrum disorder and carries considerable impact on downstream social communication and quality of life. While behavioral and survey work have established differences in the perception of somatosensory information, little has been done to elucidate the underlying neurophysiological processes that drive these characteristics. Here, we implemented a duration-based somatosensory mismatch negativity (MMN) paradigm to examine the role of temporal sensitivity and sensory memory in the processing of vibrotactile information in autistic (n = 30) and neurotypical (n = 30) adults. To capture the variability in responses between groups across a range of duration discrepancies, we compared the electrophysiological responses to frequent standard vibrations (100 ms) and four infrequent deviant vibrations (115, 130, 145, and 160 ms). The same stimuli were used in a follow-up behavioral task to determine active detection of the infrequent vibrations. We found no differences between the two groups with regard to discrimination between standard and deviant vibrations, demonstrating comparable neurologic and behavioral temporal somatosensory perception. However, exploratory analyses yielded subtle differences in amplitude at the N1 and P220 time points. Together, these results indicate that the temporal mechanisms of somatosensory discrimination are conserved in adults on the autism spectrum, though more general somatosensory processing may be affected. We discuss these findings in the broader context of the MMN literature in autism, as well as the potential role of cortical maturity in somatosensory mechanisms.

Brain circuits in autonomous sensory meridian response and related phenomena

Autonomous sensory meridian response (ASMR) is characterized by a tingling sensation with a feeling of relaxation and a state of flow. We explore the neural underpinnings and comorbidities of ASMR and related phenomena with altered sensory processing. These phenomena include sensory processing sensitivity (SPS), synaesthesia, Alice in Wonderland syndrome and misophonia. The objective of this article is to uncover the shared neural substrates and distinctive features of ASMR and its counterparts. ASMR, SPS and misophonia exhibit common activations in the brain regions associated with social cognition, emotion regulation and empathy. Nevertheless, ASMR responders display reduced connectivity in the salience network (SN), while individuals with SPS exhibit increased connectivity in the SN. Furthermore, ASMR induces relaxation and temporarily reduces symptoms of depression, in contrast to SPS and misophonia, which are linked to depression. These observations lead us to propose that ASMR is a distinct phenomenon owing to its attention dispatch mechanism and its connection with emotion regulation. We suggest that increased activations in the insula, along with reduction in connectivity within the salience and default mode networks in ASMR responders, may account for their experiences of relaxation and flow states. This article is part of the theme issue 'Sensing and feeling: an integrative approach to sensory processing and emotional experience'.

Differentiating early sensory profiles in toddlers at elevated likelihood of autism and association with later clinical outcome and diagnosis

LAY ABSTRACT

Early sensory responsiveness may produce cascading effects on later development, but the relation between sensory profiles and autistic diagnosis remains unclear. In a longitudinal sample of toddlers at elevated likelihood for autism, we aimed to characterize sensory subgroups and their association with clinical outcomes later on. Three sensory subgroups were described and early sensory sensitivity plays a significant role in later development and diagnosis. This study supported the importance of examining different levels of sensory patterns to dissect the phenotypic heterogeneity in sensory processing. As sensory differences are associated with later developmental outcomes, these results may be critical when designing intervention needs and support for children at increased likelihood for neurodevelopmental disorders.

Impaired cerebellar plasticity hypersensitizes sensory reflexes in SCN2A-associated ASD

Children diagnosed with autism spectrum disorder (ASD) commonly present with sensory hypersensitivity or abnormally strong reactions to sensory stimuli. Such hypersensitivity can be overwhelming, causing high levels of distress that contribute markedly to the negative aspects of the disorder. Here, we identify a mechanism that underlies hypersensitivity in a sensorimotor reflex found to be altered in humans and in mice with loss of function in the ASD risk-factor gene SCN2A. The cerebellum-dependent vestibulo-ocular reflex (VOR), which helps maintain one's gaze during movement, was hypersensitized due to deficits in cerebellar synaptic plasticity. Heterozygous loss of SCN2A-encoded NaV1.2 sodium channels in granule cells impaired high-frequency transmission to Purkinje cells and long-term potentiation, a form of synaptic plasticity important for modulating VOR gain. VOR plasticity could be rescued in mice via a CRISPR-activator approach that increases Scn2a expression, demonstrating that evaluation of a simple reflex can be used to assess and quantify successful therapeutic intervention.

Brain Signatures of Early and Late Neural Measures of Auditory Habituation and Discrimination in Autism and Their Relationship to Autistic Traits and Sensory Overresponsivity

Sensory differences are included in the DSM-5 criteria of autism for the first time, yet it is unclear how they relate to neural indicators of perception. We studied early brain signatures of perception and examined their relationship to sensory behaviors and autistic traits. Thirteen autistic children and 13 Typically Developing (TD) children matched on age and nonverbal IQ participated in a passive oddball task, during which P1 habituation and P1 and MMN discrimination were evoked by pure tones. Autistic children had less neural habituation than the TD comparison group, and the MMN, but not P1, mapped on to sensory overresponsivity. Findings highlight the significance of temporal and contextual factors in neural information processing as it relates to autistic traits and sensory behaviors.

Mechanisms of pain in aging and age-related conditions: Focus on caregivers

Pain is a complex, subjective experience that can significantly impact quality of life, particularly in aging individuals, by adversely affecting physical and emotional well-being. Whereas acute pain usually serves a protective function, chronic pain is a persistent pathological condition that contributes to functional deficits, cognitive decline, and emotional disturbances in the elderly. Despite substantial progress that has been made in characterizing age-related changes in pain, complete mechanistic details of pain processing mechanisms in the aging patient remain unknown. Pain is particularly under-recognized and under-managed in the elderly, especially among patients with Alzheimer's disease (AD), Alzheimer's disease-related dementias (ADRD), and other age-related conditions. Furthermore, difficulties in assessing pain in patients with AD/ADRD and other age-related conditions may contribute to the familial caregiver burden. The purpose of this article is to discuss the mechanisms and risk factors for chronic pain development and persistence, with a particular focus on age-related changes. Our article also highlights the importance of caregivers working with aging chronic pain patients, and emphasizes the urgent need for increased legislative awareness and improved pain management in these populations to substantially alleviate caregiver burden.

Intact Somatosensory Temporal Sensitivity in Adults on the Autism Spectrum: A High-Density Electrophysiological Mapping Study Using the Mismatch Negativity (MMN) Sensory Memory Paradigm

Atypical reactivity to somatosensory inputs is common in autism spectrum disorder and carries considerable impact on downstream social communication and quality of life. While behavioral and survey work have established differences in the perception of somatosensory information, little has been done to elucidate the underlying neurophysiological processes that drive these characteristics. Here, we implemented a duration-based somatosensory mismatch negativity paradigm to examine the role of temporal sensitivity and sensory memory in the processing of vibrotactile information in autistic (n=30) and neurotypical (n=30) adults. To capture the variability in responses between groups across a range of duration discrepancies, we compared the electrophysiological responses to frequent standard vibrations (100 ms) and four infrequent deviant vibrations (115, 130, 145, and 160 ms). The same stimuli were used in a follow-up behavioral task to determine active detection of the infrequent vibrations. We found no differences between the two groups with regard to discrimination between standard and deviant vibrations, demonstrating comparable neurologic and behavioral temporal somatosensory perception. However, exploratory analyses yielded subtle differences in amplitude at the N1 and P220 time points. Together, these results indicate that the temporal mechanisms of somatosensory discrimination are conserved in adults on the autism spectrum, though more general somatosensory processing may be affected. We discuss these findings in the broader context of the MMN literature in autism, as well as the potential role of cortical maturity in somatosensory mechanisms.

Cyfip2 controls the acoustic startle threshold through FMRP, actin polymerization, and GABAB receptor function

Animals process a constant stream of sensory input, and to survive they must detect and respond to dangerous stimuli while ignoring innocuous or irrelevant ones. Behavioral responses are elicited when certain properties of a stimulus such as its intensity or size reach a critical value, and such behavioral thresholds can be a simple and effective mechanism to filter sensory information. For example, the acoustic startle response is a conserved and stereotyped defensive behavior induced by sudden loud sounds, but dysregulation of the threshold to initiate this behavior can result in startle hypersensitivity that is associated with sensory processing disorders including schizophrenia and autism. Through a previous forward genetic screen for regulators of the startle threshold a nonsense mutation in Cytoplasmic Fragile X Messenger Ribonucleoprotein (FMRP)-interacting protein 2 (cyfip2) was found that causes startle hypersensitivity in zebrafish larvae, but the molecular mechanisms by which Cyfip2 establishes the acoustic startle threshold are unknown. Here we used conditional transgenic rescue and CRISPR/Cas9 to determine that Cyfip2 acts though both Rac1 and FMRP pathways, but not the closely related FXR1 or FXR2, to establish the acoustic startle threshold during early neurodevelopment. To identify proteins and pathways that may be downstream effectors of Rac1 and FMRP, we performed a candidate-based drug screen that indicated that Cyfip2 can also act acutely to maintain the startle threshold branched actin polymerization and N-methyl D-aspartate receptors (NMDARs). To complement this approach, we used unbiased discovery proteomics to determine that loss of Cyfip2 alters cytoskeletal and extracellular matrix components while also disrupting oxidative phosphorylation and GABA receptor signaling. Finally, we functionally validated our proteomics findings by showing that activating GABAB receptors, which like NMDARs are also FMRP targets, restores normal startle sensitivity in cyfip2 mutants. Together, these data reveal multiple mechanisms by which Cyfip2 regulates excitatory/inhibitory balance in the startle circuit to control the processing of acoustic information.

Disentangling sensory precision and prior expectation of change in autism during tactile discrimination

Predictive coding theories suggest that core symptoms in autism spectrum disorders (ASD) may stem from atypical mechanisms of perceptual inference (i.e., inferring the hidden causes of sensations). Specifically, there would be an imbalance in the precision or weight ascribed to sensory inputs relative to prior expectations. Using three tactile behavioral tasks and computational modeling, we specifically targeted the implicit dynamics of sensory adaptation and perceptual learning in ASD. Participants were neurotypical and autistic adults without intellectual disability. In Experiment I, tactile detection thresholds and adaptation effects were measured to assess sensory precision. Experiments II and III relied on two-alternative forced choice tasks designed to elicit a time-order effect, where prior knowledge biases perceptual decisions. Our results suggest a subtler explanation than a simple imbalance in the prior/sensory weights, having to do with the dynamic nature of perception, that is the adjustment of precision weights to context. Compared to neurotypicals, autistic adults showed no difference in average performance and sensory sensitivity. Both groups managed to implicitly learn and adjust a prior that biased their perception. However, depending on the context, autistic participants showed no, normal or slower adaptation, a phenomenon that computational modeling of trial-to-trial responses helped us to associate with a higher expectation for sameness in ASD, and to dissociate from another observed robust difference in terms of response bias. These results point to atypical perceptual learning rather than altered perceptual inference per se, calling for further empirical and computational studies to refine the current predictive coding theories of ASD.

Relationships between GABA, glutamate, and GABA/glutamate and social and olfactory processing in children with autism spectrum disorder

Theories of altered inhibitory/excitatory signaling in autism spectrum disorder (ASD) suggest that gamma amino butyric acid (GABA) and glutamate (Glu) abnormalities may underlie social and sensory challenges in ASD. Magnetic resonance spectroscopy was used to measure Glu and GABA+ levels in the amygdala-hippocampus region and cerebellum in autistic children (n = 30), a clinical control group with sensory abnormalities (SA) but not ASD (n = 30), and children with typical development (n = 37). All participants were clinically assessed using the Autism Diagnostic Interview-Revised, the Autism Diagnostic Observation Scale-2, and the Child Sensory Profile-2. The Social Responsiveness Scale-2, Sniffin Sticks Threshold Test, and the University of Pennsylvania Smell Identification Test were administered to assess social impairment and olfactory processing. Overall, autistic children showed increased cerebellar Glu levels compared to TYP children. Evidence for altered excitatory/inhibitory signaling in the cerebellum was more clear-cut when analyses were restricted to male participants. Further, lower cerebellar GABA+/Glu ratios were correlated to more severe social impairment in both autistic and SA males, suggesting that the cerebellum may play a transdiagnostic role in social impairment. Future studies of inhibitory/excitatory neural markers, powered to investigate the role of sex, may aid in parsing out disorder-specific neurochemical profiles.

Autistic Traits Related to the Importance of Interpersonal Touch and Appreciation of Observed Touch during COVID-19 Social Distancing

Studies have confirmed the significance of touch for psychological wellbeing. Social distancing regulations during the COVID-19 pandemic reduced people's ability to engage in interpersonal touch and caused increased an appreciation for observed touch, as well as a longing for touch within the neurotypical population. Yet, while the impact of social distancing and the importance of touch are evident in neurotypical individuals, it remains unclear how these factors manifest in autistic individuals. Previous research has related high levels of autistic traits to reduced levels of perceived pleasantness of touch and a reduced interest in interpersonal touch. Our study aimed to examine the differences in the appreciation of observed touch and longing for touch during social distancing between individuals with low and high levels of autistic traits. We conducted an online survey on autistic traits, the appreciation of observed CT-optimal touch and longing for touch. Consistent with our predictions, our results confirmed that individuals with high levels of autistic traits evaluated videos depicting CT-optimal touch less favorably compared to those with lower scores on autistic traits. Additionally, only the group with low levels of autistic traits exhibited a longing for touch during social distancing, whereas the group with high levels of autistic traits did not. The results provide insights in the appreciation of touch in relation to autistic traits during the unique circumstances of the COVID-19 pandemic.

Circuit-level theories for sensory dysfunction in autism: convergence across mouse models

Individuals with autism spectrum disorder (ASD) exhibit a diverse range of behavioral features and genetic backgrounds, but whether different genetic forms of autism involve convergent pathophysiology of brain function is unknown. Here, we analyze evidence for convergent deficits in neural circuit function across multiple transgenic mouse models of ASD. We focus on sensory areas of neocortex, where circuit differences may underlie atypical sensory processing, a central feature of autism. Many distinct circuit-level theories for ASD have been proposed, including increased excitation-inhibition (E-I) ratio and hyperexcitability, hypofunction of parvalbumin (PV) interneuron circuits, impaired homeostatic plasticity, degraded sensory coding, and others. We review these theories and assess the degree of convergence across ASD mouse models for each. Behaviorally, our analysis reveals that innate sensory detection behavior is heightened and sensory discrimination behavior is impaired across many ASD models. Neurophysiologically, PV hypofunction and increased E-I ratio are prevalent but only rarely generate hyperexcitability and excess spiking. Instead, sensory tuning and other aspects of neural coding are commonly degraded and may explain impaired discrimination behavior. Two distinct phenotypic clusters with opposing neural circuit signatures are evident across mouse models. Such clustering could suggest physiological subtypes of autism, which may facilitate the development of tailored therapeutic approaches.

Functional and structural synaptic remodeling mechanisms underlying somatotopic organization and reorganization in the thalamus

The somatosensory system organizes the topographic representation of body maps, termed somatotopy, at all levels of an ascending hierarchy. Postnatal maturation of somatotopy establishes optimal somatosensation, whereas deafferentation in adults reorganizes somatotopy, which underlies pathological somatosensation, such as phantom pain and complex regional pain syndrome. Here, we focus on the mouse whisker somatosensory thalamus to study how sensory experience shapes the fine topography of afferent connectivity during the critical period and what mechanisms remodel it and drive a large-scale somatotopic reorganization after peripheral nerve injury. We will review our findings that, following peripheral nerve injury in adults, lemniscal afferent synapses onto thalamic neurons are remodeled back to immature configuration, as if the critical period reopens. The remodeling process is initiated with local activation of microglia in the brainstem somatosensory nucleus downstream to injured nerves and heterosynaptically controlled by input from GABAergic and cortical neurons to thalamic neurons. These fruits of thalamic studies complement well-studied cortical mechanisms of somatotopic organization and reorganization and unveil potential intervention points in treating pathological somatosensation.

No differences in implicit hand maps among different degrees of autistic traits

People with autism spectrum disorder (ASD) or higher levels of autistic traits have atypical characteristics in sensory processing. Atypicalities have been reported for proprioceptive judgments, which are tightly related to internal bodily representations underlying position sense. However, no research has directly investigated whether self-bodily representations are different in individuals with ASD. Implicit hand maps, estimated based on participants' proprioceptive sensations without sight of their hand, are known to be distorted such that the shape is stretched along the medio-lateral hand axis even for neurotypical participants. Here, with the view of ASD as falling on a continuous distribution among the general population, we explored differences in implicit body representations along with autistic traits by focusing on relationships between autistic traits and the magnitudes of the distortions in implicit hand maps (N ~ 100). We estimated the magnitudes of distortions in implicit hand maps both for fingers and hand surfaces on the dorsal and palmar sides of the hand. Autistic traits were measured by questionnaires (Autism Spectrum [AQ] and Empathy/Systemizing [EQ-SQ] Quotients). The distortions in implicit hand maps were replicated in our experimental situations. However, there were no significant relationships between autistic traits and the magnitudes of the distortions as well as within-individual variabilities in the maps and localization performances. Consistent results were observed from comparisons between IQ-matched samples of people with and without a diagnosis of ASD. Our findings suggest that there exist perceptual and neural processes for implicit body representations underlying position sense consistent across levels of autistic traits.

Stretch marks: a visible expression of connective's involvement in autism spectrum disorders

In autism spectrum disorders (ASDs) in the pediatric population, skin manifestations are generally attributable to the concomitance of allergic forms or to accidental, self-inflicted or abusive lesions. However, clinical evidence has highlighted the presence of an increasing number of abdominal stretch marks, probably caused by the increase in the number of obesity cases in the pediatric population, in general, and therefore also among children with ASD. Stretch marks are often attributed to obesity, as they have an incidence of more than 50% in obese individuals. In the first part of this article we hypothesized that in addition to obesity there are other factors, such as a structural alteration on the skin in people with ASD, which can contribute/aggravate the phenomenon of stretch marks. Despite the high frequency with which stretch marks are found in children with ASD, this aspect has never been studied, the structure of the skin of children with ASD is not known. Furthermore, it is not known whether this structure is different from that of subjects without ASD. In the second part of the article, we hypothesized the mechanisms of the negative impact of simple abdominal stretch marks on the symptomatic picture of children with ASD. The presence of stretch marks, altered tactile perception, altered sensitivity to clothing fabrics can be a combination that influences development and determines negative consequences in the neurological picture of a child with ASD, as it is already known that the altered sensory perception in children with ASD contributes to the deterioration of social behavior. Furthermore, the presence of stretch marks may play a role in the postural and motor defects of children with ASD.

Impaired cerebellar plasticity hypersensitizes sensory reflexes in SCN2A-associated ASD

Children diagnosed with autism spectrum disorder (ASD) commonly present with sensory hypersensitivity, or abnormally strong reactions to sensory stimuli. Such hypersensitivity can be overwhelming, causing high levels of distress that contribute markedly to the negative aspects of the disorder. Here, we identify the mechanisms that underlie hypersensitivity in a sensorimotor reflex found to be altered in humans and in mice with loss-of-function in the ASD risk-factor gene SCN2A. The cerebellum-dependent vestibulo-ocular reflex (VOR), which helps maintain one's gaze during movement, was hypersensitized due to deficits in cerebellar synaptic plasticity. Heterozygous loss of SCN2A-encoded NaV1.2 sodium channels in granule cells impaired high-frequency transmission to Purkinje cells and long-term potentiation, a form of synaptic plasticity important for modulating VOR gain. VOR plasticity could be rescued in adolescent mice via a CRISPR-activator approach that increases Scn2a expression, highlighting how evaluation of simple reflexes can be used as quantitative readout of therapeutic interventions.

A working taxonomy for describing the sensory differences of autism

BACKGROUND

Individuals on the autism spectrum have been long described to process sensory information differently than neurotypical individuals. While much effort has been leveraged towards characterizing and investigating the neurobiology underlying the sensory differences of autism, there has been a notable lack of consistency in the terms being used to describe the nature of those differences.

MAIN BODY

We argue that inconsistent and interchangeable terminology-use when describing the sensory differences of autism has become problematic beyond mere pedantry and inconvenience. We begin by highlighting popular terms that are currently being used to describe the sensory differences of autism (e.g. "sensitivity", "reactivity" and "responsivity") and discuss why poor nomenclature may hamper efforts towards understanding the aetiology of sensory differences in autism. We then provide a solution to poor terminology-use by proposing a hierarchical taxonomy for describing and referring to various sensory features.

CONCLUSION

Inconsistent terminology-use when describing the sensory features of autism has stifled discussion and scientific understanding of the sensory differences of autism. The hierarchical taxonomy proposed was developed to help resolve lack of clarity when discussing the sensory differences of autism and to place future research targets at appropriate levels of analysis.

Clothes, Sensory Experiences and Autism: Is Wearing the Right Fabric Important?

Tactile defensiveness in autistic individuals is the least investigated sensory modality. The current multi-component, explorative study aimed to understand the experiences of ten autistic adults regarding tactile defensiveness and fabrics, using semi-structured, one-to-one interviews. Participants were asked to discuss the effects of seven provided samples of fabrics and were also asked to bring their 'favourite' fabric (s) and express their thoughts about their choices. Using Interpretative Phenomenological Analysis and Content Analysis, the findings showed that some fabrics can impact individuals' reported wellbeing. Participants' experiences with several stimuli appeared to have helped them implement coping strategies. By understanding tactile defensiveness, society could move towards increasing autism-friendly approaches with appropriate fabrics. Recommendations for future research, policy and practice are also discussed.

Qualitative and quantitative analysis of self-reported sensory issues in individuals with neurodevelopmental disorders

INTRODUCTION

Individuals with neurodevelopmental disorders, such as autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), and specific learning disorders (SLD) have various types of sensory characteristics.

METHODS

This study investigated sensory issues in individuals with neurodevelopmental disorders using a web-based questionnaire for qualitative and quantitative analysis, categorized the contents of their three most distressful sensory issues, and evaluated their order of priority.

RESULTS

Auditory problems were reported as the most distressing sensory issue among the participants. In addition to auditory problems, individuals with ASD frequently reported more tactile problems, and individuals with SLD reported more visual problems. Among the individual sensory issues, in addition to aversion to sudden, strong, or specific stimuli, some participants reported confusions regarding multiple stimuli presenting concurrently. Additionally, the sensory issues related to foods (i.e., taste) was relatively more common in the minor group.

CONCLUSION

These results suggest that the diversity of sensory issues experienced should be carefully considered when aiding persons with neurodevelopmental disorders.

Atypical Response to Affective Touch in Children with Autism: Multi-Parametric Exploration of the Autonomic System

This study aimed at evaluating the autonomic response to pleasant affective touch in children with Autism Spectrum Disorders (ASD) and age-matched typically developing (TD) peers, thanks to multiple autonomic nervous system (ANS) parameters and by contrasting CT (C-tactile fibers) high- vs. low-density territory stimulations. We measured pupil diameter, skin conductance, and heart rate during gentle stroking of two skin territories (CT high- and low-density, respectively, forearm and palm of the hand) in thirty 6-12-year-old TD children and twenty ASD children. TD children showed an increase in pupil diameter and skin conductance associated with a heart rate deceleration in response to tactile stimulations at the two locations. Only the pupil was influenced by the stimulated location, with a later dilation peak following CT low-density territory stimulation. Globally, ASD children exhibited reduced autonomic responses, as well as different ANS baseline values compared to TD children. These atypical ANS responses to pleasant touch in ASD children were not specific to CT-fiber stimulation. Overall, these results point towards both basal autonomic dysregulation and lower tactile autonomic evoked responses in ASD, possibly reflecting lower arousal and related to social disengagement.

Neural processing of self-touch and other-touch in anorexia nervosa and autism spectrum condition

INTRODUCTION

The tactile sense plays a crucial role in the development and maintenance of a functional bodily self. The ability to differentiate between self- and nonself-generated touch contributes to the perception of the bodies' boundaries and more generally to self-other-distinction, both of which are thought be altered in anorexia nervosa (AN) and autism spectrum condition (AS). While it has been suggested that AN and AS are characterized by overlapping symptomatology, they might differ regarding body perception and self-other-distinction.

METHODS

Participants with a diagnosis of AN (n = 25), AS (n = 29), and a comparison group without diagnoses (n = 57) performed a self-other-touch task during functional brain imaging. In the experimental conditions, they stroked their own arm or were stroked on the arm by an experimenter.

RESULTS

As shown previously, the CG group showed lower activation or deactivation in response to self-touch compared to social touch from someone else. A main group effect was found in areas including somatosensory cortex, frontal and temporal gyri, insula, and subcortical regions. This was driven by increased activations in participants with AN, while participants in the AS group showed mostly comparable activations to the comparison group.

CONCLUSIONS

AN diagnosis was associated with an increased neural activity in response to both self-touch and social touch. Failure to attenuate self-touch might relate to altered predictions regarding the own body and reduced perception of bodily boundaries. Participants with an AS diagnosis were mostly comparable to the comparison group, potentially indicating unaltered tactile self-other-distinction.

Family life and autistic children with sensory processing differences: A qualitative evidence synthesis of occupational participation

Autistic children with sensory processing differences successfully navigate and engage in meaningful family daily occupations within home and community environments through the support of their family. To date however, much of the research on autistic children with sensory processing differences, has primarily been deficit focused, while much of the caregiver research has focused on issues of distress, burden, effort, and emotional trauma in coping with their child's diagnosis. This study aimed to conduct a qualitative evidence synthesis, using a meta-ethnographic approach to explore the gap identified in understanding successful occupational experiences of family participation and daily family routines when supporting an autistic child with sensory processing differences and to offer an alternative strengths-based perspective. Inclusion criteria were studies which were peer-reviewed qualitative design, published from 2000 to 2021, and that concerned parents/caregivers' perspectives of family occupations of children diagnosed with autism spectrum disorder. Studies were electronically searched in eight databases from October to December 2021 and 23 studies were identified which met the inclusion criteria. Noblit and Hare's seven step approach for conducting analysis in meta-ethnography was used, and three themes identified: (1) sensory processing differences in daily life, (2) what is hard about hard, and (3) orchestrating family life. Results identified the centrality of sensory experiences in understanding family life. Living with unpredictability while orchestrating certainty through routines was core to successful participation. This review provides insights into how parents negotiate the complexities of constructing family life when living with an autistic child. The results can inform the design of future interventions that specifically address the relationship between meaningful participation in family occupations and daily routines and sensory processing in autistic children.

Emergence of sensory attenuation based upon the free-energy principle

The brain attenuates its responses to self-produced exteroceptions (e.g., we cannot tickle ourselves). Is this phenomenon, known as sensory attenuation, enabled innately, or acquired through learning? Here, our simulation study using a multimodal hierarchical recurrent neural network model, based on variational free-energy minimization, shows that a mechanism for sensory attenuation can develop through learning of two distinct types of sensorimotor experience, involving self-produced or externally produced exteroceptions. For each sensorimotor context, a particular free-energy state emerged through interaction between top-down prediction with precision and bottom-up sensory prediction error from each sensory area. The executive area in the network served as an information hub. Consequently, shifts between the two sensorimotor contexts triggered transitions from one free-energy state to another in the network via executive control, which caused shifts between attenuating and amplifying prediction-error-induced responses in the sensory areas. This study situates emergence of sensory attenuation (or self-other distinction) in development of distinct free-energy states in the dynamic hierarchical neural system.

Prenatal exposure to valproic acid causes allodynia associated with spinal microglial activation

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by deficits in social communication and social interaction and the presence of restricted, repetitive behaviors. Additionally, difficulties in sensory processing commonly occur in ASD. Sensory abnormalities include heightened or reduced sensitivity to pain, but the mechanism underlying sensory phenotypes in ASD remain unknown. Emerging evidence suggests that microglia play an important role in forming and refining neuronal circuitry, and thus contribute to neuronal plasticity and nociceptive signaling. In the present study, we investigated the age-dependent tactile sensitivity in an animal model of ASD induced by prenatal exposure to valproic acid (VPA) and subsequently assessed the involvement of microglia in the spinal cord in pain processing. Pregnant ICR (CD1) mice were intraperitoneally injected with either saline or VPA (500 mg/kg) on embryonic day 12.5. Male offspring of VPA-treated mothers showed mechanical allodynia at both 4 and 8 weeks of age. In the spinal cord dorsal horn in prenatally VPA-treated mice, the numbers and staining intensities of ionized calcium-binding adapter molecule 1-positive cells were increased and the cell bodies became enlarged, indicating microglial activation. Treatment with PLX3397, a colony-stimulating factor 1 receptor inhibitor, for 10 days resulted in a decreased number of spinal microglia and attenuated mechanical allodynia in adult mice prenatally exposed to VPA. Additionally, intrathecal injection of Mac-1-saporin, a saporin-conjugated anti-CD11b antibody to deplete microglia, abolished mechanical allodynia. These findings suggest that prenatal VPA treatment causes allodynia and that spinal microglia contribute to the increased nociceptive responses.

Sensory Perception in Autism: What Can We Learn?

Autism is a neurodevelopmental disorder of unknown etiology. Recently, there has been a growing interest in sensory processing in autism as a core phenotype. However, basic questions remain unanswered. Here, we review the major findings and models of perception in autism and point to methodological issues that have led to conflicting results. We show that popular models of perception in autism, such as the reduced prior hypothesis, cannot explain the many and varied findings. To resolve these issues, we point to the benefits of using rigorous psychophysical methods to study perception in autism. We advocate for perceptual models that provide a detailed explanation of behavior while also taking into account factors such as context, learning, and attention. Furthermore, we demonstrate the importance of tracking changes over the course of development to reveal the causal pathways and compensatory mechanisms. Finally, we propose a developmental perceptual narrowing account of the condition. Expected final online publication date for the Annual Review of Vision Science, Volume 8 is September 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

A Multidimensional Investigation of Sensory Processing in Autism: Parent- and Self-Report Questionnaires, Psychophysical Thresholds, and Event-Related Potentials in the Auditory and Somatosensory Modalities

Background

Reconciling results obtained using different types of sensory measures is a challenge for autism sensory research. The present study used questionnaire, psychophysical, and neurophysiological measures to characterize autistic sensory processing in different measurement modalities.

Methods

Participants were 46 autistic and 21 typically developing 11- to 14-year-olds. Participants and their caregivers completed questionnaires regarding sensory experiences and behaviors. Auditory and somatosensory event-related potentials (ERPs) were recorded as part of a multisensory ERP task. Auditory detection, tactile static detection, and tactile spatial resolution psychophysical thresholds were measured.

Results

Sensory questionnaires strongly differentiated between autistic and typically developing individuals, while little evidence of group differences was observed in psychophysical thresholds. Crucially, the different types of measures (neurophysiological, psychophysical, questionnaire) appeared to be largely independent of one another. However, we unexpectedly found autistic participants with larger auditory Tb ERP amplitudes had reduced hearing acuity, even though all participants had hearing acuity in the non-clinical range.

Limitations

The autistic and typically developing groups were not matched on cognitive ability, although this limitation does not affect our main analyses regarding convergence of measures within autism.

Conclusion

Overall, based on these results, measures in different sensory modalities appear to capture distinct aspects of sensory processing in autism, with relatively limited convergence between questionnaires and laboratory-based tasks. Generally, this might reflect the reality that laboratory tasks are often carried out in controlled environments without background stimuli to compete for attention, a context which may not closely resemble the busier and more complex environments in which autistic people's atypical sensory experiences commonly occur. Sensory questionnaires and more naturalistic laboratory tasks may be better suited to explore autistic people's real-world sensory challenges. Further research is needed to replicate and investigate the drivers of the unexpected association we observed between auditory Tb ERP amplitudes and hearing acuity, which could represent an important confound for ERP researchers to consider in their studies.

The acquisition of mechanoreceptive competence by human digital Merkel cells and sensory corpuscles during development: an immunohistochemical study of PIEZO2

BACKGROUND

PIEZO2 is a transmembrane protein forming part of an ion channel required for mechanotransduction. In humans, PIEZO2 is present in axon terminals of adult Meissner and Pacinian corpuscles, as well as Merkel cells in Merkel cell-neurite complexes.

METHODS

To study the acquisition of functional capability for mechanotransduction of developing type I slowly adapting low-threshold mechanoreceptors, i.e., Merkel cell-neurite complexes, a battery of immunohistochemical and immunofluorescence techniques was performed on human skin specimens covering the whole development and growth, from 11 weeks of estimated gestational age to 20 years of life. In addition, developmental expression of PIEZO2 type I (Meissner's corpuscles) and type II (Pacinian corpuscles) rapidly adapting mechanoreceptors was studied in parallel.

RESULTS

The first evidence of Merkel cells showing the typical morphology and placement was at 13 weeks of estimated gestation age, and at this time positive immunoreactivity for PIEZO2 was achieved. PIEZO2 expression in axons terminals started at 23 WEGA in Pacinian corpuscles and at 36 WEGA in the case of Meissner corpuscles. The occurrence of PIEZO2 in Merkel cells, Meissner and Pacinian corpuscles was maintained for all the time investigated. Interestingly PIEZO2 was absent in most Aβ type I slowly adapting low-threshold mechanoreceptors that innervate MC while it was regularly present in most Aβ type I and type II rapidly adapting low-threshold mechanoreceptors that supplies Meissner and Pacinian corpuscles.

CONCLUSION

The present results provide evidence that human cutaneous mechanoreceptors could perform mechanotransduction already during embryonic development.

Atypical Tactile Perception in Early Childhood Autism

We assessed different aspects of tactile perception in young children (3-6 years) with autism. Autistic and neurotypical children completed vibrotactile tasks assessing reaction time, amplitude discrimination (sequential and simultaneous) and temporal discrimination (temporal order judgment and duration discrimination). Autistic children had elevated and more variable reaction times, suggesting slower perceptual-motor processing speed and/or greater distractibility. Children with autism also showed higher amplitude discrimination and temporal order judgement thresholds compared to neurotypical children. Tactile perceptual metrics did not associate with social or tactile sensitivities measured by parent-reports. Altered tactile behavioral responses appear in early childhood, can be quantified but appear dissociated from sensitivity. This implies these measures are complementary, but not necessarily related, phenomena of atypical tactile perception in autism.

Behavioural and neural indices of perceptual decision-making in autistic children during visual motion tasks

Many studies report atypical responses to sensory information in autistic individuals, yet it is not clear which stages of processing are affected, with little consideration given to decision-making processes. We combined diffusion modelling with high-density EEG to identify which processing stages differ between 50 autistic and 50 typically developing children aged 6-14 years during two visual motion tasks. Our pre-registered hypotheses were that autistic children would show task-dependent differences in sensory evidence accumulation, alongside a more cautious decision-making style and longer non-decision time across tasks. We tested these hypotheses using hierarchical Bayesian diffusion models with a rigorous blind modelling approach, finding no conclusive evidence for our hypotheses. Using a data-driven method, we identified a response-locked centro-parietal component previously linked to the decision-making process. The build-up in this component did not consistently relate to evidence accumulation in autistic children. This suggests that the relationship between the EEG measure and diffusion-modelling is not straightforward in autistic children. Compared to a related study of children with dyslexia, motion processing differences appear less pronounced in autistic children. Exploratory analyses also suggest weak evidence that ADHD symptoms moderate perceptual decision-making in autistic children.

Electrophysiological Measures of Tactile and Auditory Processing in Children With Autism Spectrum Disorder

Behavioral differences in responding to tactile and auditory stimuli are widely reported in individuals with autism spectrum disorder (ASD). However, the neural mechanisms underlying distinct tactile and auditory reactivity patterns in ASD remain unclear with theories implicating differences in both perceptual and attentional processes. The current study sought to investigate (1) the neural indices of early perceptual and later attentional factors underlying tactile and auditory processing in children with and without ASD, and (2) the relationship between neural indices of tactile and auditory processing and ASD symptomatology. Participants included 14, 6–12-year-olds with ASD and 14 age- and non-verbal IQ matched typically developing (TD) children. Children participated in an event-related potential (ERP) oddball paradigm during which they watched a silent video while being presented with tactile and auditory stimuli (i.e., 80% standard speech sound/a/; 10% oddball speech sound/i/; 10% novel vibrotactile stimuli on the fingertip with standard speech sound/a/). Children’s early and later ERP responses to tactile (P1 and N2) and auditory stimuli (P1, P3a, and P3b) were examined. Non-parametric analyses showed that children with ASD displayed differences in early perceptual processing of auditory (i.e., lower amplitudes at central region of interest), but not tactile, stimuli. Analysis of later attentional components did not show differences in response to tactile and auditory stimuli in the ASD and TD groups. Together, these results suggest that differences in auditory responsivity patterns could be related to perceptual factors in children with ASD. However, despite differences in caregiver-reported sensory measures, children with ASD did not differ in their neural reactivity to infrequent touch-speech stimuli compared to TD children. Nevertheless, correlational analyses confirmed that inter-individual differences in neural responsivity to tactile and auditory stimuli were related to social skills in all children. Finally, we discuss how the paradigm and stimulus type used in the current study may have impacted our results. These findings have implications for everyday life, where individual differences in responding to tactile and auditory stimuli may impact social functioning.

Cortico-Cerebellar Hyper-Connections and Reduced Purkinje Cells Behind Abnormal Eyeblink Conditioning in a Computational Model of Autism Spectrum Disorder

Empirical evidence suggests that children with autism spectrum disorder (ASD) show abnormal behavior during delay eyeblink conditioning. They show a higher conditioned response learning rate and earlier peak latency of the conditioned response signal. The neuronal mechanisms underlying this autistic behavioral phenotype are still unclear. Here, we use a physiologically constrained spiking neuron model of the cerebellar-cortical system to investigate which features are critical to explaining atypical learning in ASD. Significantly, the computer simulations run with the model suggest that the higher conditioned responses learning rate mainly depends on the reduced number of Purkinje cells. In contrast, the earlier peak latency mainly depends on the hyper-connections of the cerebellum with sensory and motor cortex. Notably, the model has been validated by reproducing the behavioral data collected from studies with real children. Overall, this article is a starting point to understanding the link between the behavioral and neurobiological basis in ASD learning. At the end of the paper, we discuss how this knowledge could be critical for devising new treatments.

Behavioural evidence of altered sensory attenuation in obesity

Body ownership (i.e., the conscious belief of owning a body) and sense of agency (i.e., being the agent of one's own movements) are part of a pre-reflective experience of bodily self, which grounds on low-level complex sensory-motor processes. Although previous literature had already investigated body ownership in obesity, sense of agency was never explored. Here, we exploited the sensory attenuation effect (i.e., an implicit marker of the sense of agency; SA effect) to investigate whether the sense of agency was altered in a sample of 18 individuals affected by obesity as compared with 18 healthy-weight individuals. In our experiment, participants were asked to rate the perceived intensity of self-generated and other-generated tactile stimuli. Healthy-weight individuals showed a significantly greater SA effect than participants affected by obesity. Indeed, while healthy-weight participants perceived self-generated stimuli as significantly less intense as compared to externally generated ones, this difference between stimuli was not reported by affected participants. Our results relative to the SA effect pinpointed an altered sense of agency in obesity. We discussed this finding within the motor control framework with reference to obesity. We encouraged future research to further explore such effect and its role in shaping the clinical features of obesity.

Altered nociceptive behavior and emotional contagion of pain in mouse models of autism

Individuals with autism spectrum disorder (ASD) have altered sensory processing but may ineffectively communicate their experiences. Here, we used a battery of nociceptive behavioral tests to assess sensory alterations in two commonly used mouse models of ASD, BTBR T⁺ Itpr3^tf /J (BTBR), and fragile-X mental retardation-1 knockout (Fmr1-KO) mice. We also asked whether emotional contagion, a primitive form of empathy, was altered in BTBR and Fmr1 KO mice when experiencing pain with a social partner. BTBR mice demonstrated mixed nociceptive responses with hyporesponsivity to mechanical/thermal stimuli and intraplantar injections of formalin and capsaicin while displaying hypersensitivity on the acetic acid test. Fmr1-KO mice were hyposensitive to mechanical stimuli and intraplantar injections of capsaicin and formalin. BTBR and Fmr1-KO mice developed significantly less mechanical allodynia following intraplantar injections of complete Freund's adjuvant, while BTBR mice developed slightly more thermal hyperalgesia. Finally, as measured by the formalin and acetic acid writhing tests, BTBR and Fmr1-KO mice did not show emotional contagion of pain. In sum, our findings indicate that depending on the sensation, pain responses may be mixed, which reflects findings in ASD individuals.

Working on Cognitive Functions in a Fully Digitalized Multisensory Interactive Room: A New Approach for Intervention in Autism Spectrum Disorders

The feasibility of working on cognitive functions with children and adults with Autism Spectrum Disorders (ASD) inside Multisensory Interactive Rooms (MIRs) has been poorly investigated, even if sensory atypicalities are common in ASD and usual intervention rooms could represent a challenging sensory setting for patients with ASD. We hypothesized that the possibility to calibrate the sensory stimulation offered by this type of environment, able to promote a positive emotional state in patients with ASD, can consequently favor the interaction with the therapist and the motivation towards activities targeting cognitive functions. High- and low-functioning children and low-functioning adolescents/adults underwent five sessions in a fully digitalized MIR, working on sustained attention, selective attention, association, single inhibition, receptive communication, verbalization, and turn. We developed specific protocols calibrated for sensory stimulation and difficulty level based on the characteristics of the participants. We found statistically significant improvements in all functions, except association, in the children's group. Therefore, a fully digitalized MIR seems suitable for intervention on cognitive functions in ASDs, but further investigations are needed to better address possible differences related to age and functioning level.

Atypical interoception as a common risk factor for psychopathology: A review

The inadequacy of a categorial approach to mental health diagnosis is now well-recognised, with many authors, diagnostic manuals and funding bodies advocating a dimensional, trans-diagnostic approach to mental health research. Variance in interoception, the ability to perceive one's internal bodily state, is reported across diagnostic boundaries, and is associated with atypical functioning across symptom categories. Drawing on behavioural and neuroscientific evidence, we outline current research on the contribution of interoception to numerous cognitive and affective abilities (in both typical and clinical populations), and describe the interoceptive atypicalities seen in a range of psychiatric conditions. We discuss the role that interoception may play in the development and maintenance of psychopathology, as well as the ways in which interoception may differ across clinical presentations. A number of important areas for further research on the role of interoception in psychopathology are highlighted.

Quantifying the Generation Process of Multi-Level Tactile Sensations via ERP Component Investigation

Humans obtain characteristic information such as texture and weight of external objects, relying on the brain's integration and classification of tactile information; however, the decoding mechanism of multi-level tactile information is relatively elusive from the temporal sequence. In this paper, nonvariant frequency, along with the variant pulse width of electrotactile stimulus, was performed to generate multi-level pressure sensation. Event-related potentials (ERPs) were measured to investigate the mechanism of whole temporal tactile processing. Five ERP components, containing P100-N140-P200-N200-P300, were observed. By establishing the relationship between stimulation parameters and ERP component amplitudes, we found the following: (1) P200 is the most significant component for distinguishing multi-level tactile sensations; (2) P300 is correlated well with the subjective judgment of tactile sensation. The temporal sequence of brain topographies was implemented to clarify the spatiotemporal characteristics of the tactile process, which conformed to the serial processing model in neurophysiology and cortical network response area described by fMRI. Our results can help further clarify the mechanism of tactile sequential processing, which can be applied to improve the tactile BCI performance, sensory enhancement, and clinical diagnosis for doctors to evaluate the tactile process disorders by examining the temporal ERP components.

A huggable device can reduce the stress of calling an unfamiliar person on the phone for individuals with ASD

Individuals with autism spectrum disorders (ASD) are often not comfortable during mobile-phone conversations with unfamiliar people. “Hugvie” is a pillow with a human-like shape that has been designed to provide users with the tactile sensation of hugging another person during phone conversations to promote feelings of comfort and trust in the speaker toward their conversation partners. Our primary aim was to examine whether physical contact by hugging a Hugvie could reduce the stress of speaking with an unfamiliar person on the phone in individuals with ASD. We enrolled 24 individuals and requested them to carry out phone conversations either using only a mobile phone or using a mobile phone along with the Hugvie. All participants in both groups completed questionnaires designed to evaluate their self-confidence while talking on the phone, and also provided salivary cortisol samples four times each day. Our analysis revealed that the medium of communication was a significant factor, indicating that individuals with ASD who spoke with an unfamiliar person on the phone while hugging a Hugvie had stronger self-confidence and lower stress levels than those who did not use Hugvie. Hence, we recommend that huggable devices be used as adjunctive tools to support individuals with ASD during telephonic conversations with unfamiliar people.

Clothes, Sensory Experiences and Autism: Is Wearing the Right Fabric Important?

Tactile defensiveness in autistic individuals is the least investigated sensory modality. The current multi-component, explorative study aimed to understand the experiences of ten autistic adults regarding tactile defensiveness and fabrics, using semi-structured, one-to-one interviews. Participants were asked to discuss the effects of seven provided samples of fabrics and were also asked to bring their 'favourite' fabric (s) and express their thoughts about their choices. Using Interpretative Phenomenological Analysis and Content Analysis, the findings showed that some fabrics can impact individuals' reported wellbeing. Participants' experiences with several stimuli appeared to have helped them implement coping strategies. By understanding tactile defensiveness, society could move towards increasing autism-friendly approaches with appropriate fabrics. Recommendations for future research, policy and practice are also discussed.

A Neuro-Phenomenological Perspective on the Autism Phenotype

In the current paper, we present a view of autism spectrum disorder (ASD) which avoids the typical relational issues, instead drawing on philosophy, in particular Husserlian phenomenology. We begin by following the recent etiological perspectives that suggest a natural predisposition of a part of individuals with ASD towards hypersensitivity and the reduced influence of cognitive priors (i.e., event schemas). Following this perspective, these two characteristics should be considered as a sort of phenomenological a priori that, importantly, could predispose people with ASD towards a spiritual experience, not intended in its religious meaning, but as an attribute of consciousness that consists of being aware of and attentive to what is occurring in the present moment. Potential clinical implications are discussed.

Visuomotor adaptation and its relationship with motor ability in children with and without autism spectrum disorder

The high prevalence rates of motor impairments among individuals with autism spectrum disorder (ASD) lead to increased attention to motor learning. The current study examined the visuomotor adaptability in children with and without ASD using a computerized visuomotor adaptation task in which the real-time visual feedback of hand movement was rotated. The relationships between visuomotor adaptability and clinical symptomology were also investigated. Results revealed that the children with ASD showed a slower rate of improvement and smaller after-effects than their peers on the measures of motor planning. Additionally, autistic characteristics significantly moderated the association between individuals' adaptability and fine motor skills. The findings contribute to the growing evidence of compromised visuomotor adaptability, which suggested the importance of addressing these clinical features of ASD.

Sleep Disorders in Children With Autism Spectrum Disorder: Insights From Animal Models, Especially Non-human Primate Model

Autism Spectrum Disorder (ASD) is a heterogeneous neurodevelopmental disorder with deficient social skills, communication deficits and repetitive behaviors. The prevalence of ASD has increased among children in recent years. Children with ASD experience more sleep problems, and sleep appears to be essential for the survival and integrity of most living organisms, especially for typical synaptic development and brain plasticity. Many methods have been used to assess sleep problems over past decades such as sleep diaries and parent-reported questionnaires, electroencephalography, actigraphy and videosomnography. A substantial number of rodent and non-human primate models of ASD have been generated. Many of these animal models exhibited sleep disorders at an early age. The aim of this review is to examine and discuss sleep disorders in children with ASD. Toward this aim, we evaluated the prevalence, clinical characteristics, phenotypic analyses, and pathophysiological brain mechanisms of ASD. We highlight the current state of animal models for ASD and explore their implications and prospects for investigating sleep disorders associated with ASD.

Equivalent Behavioral Facilitation to Tactile Cues in Children with Autism Spectrum Disorder

The alerting network, a subcomponent of attention, enables humans to respond to novel information. Children with ASD have shown equivalent alerting in response to visual and/or auditory stimuli compared to typically developing (TD) children. However, it is unclear whether children with ASD and TD show equivalent alerting to tactile stimuli. We examined (1) whether tactile cues affect accuracy and reaction times in children with ASD and TD, (2) whether the duration between touch-cues and auditory targets impacts performance, and (3) whether behavioral responses in the tactile cueing task are associated with ASD symptomatology. Six- to 12-year-olds with ASD and TD participated in a tactile-cueing task and were instructed to respond with a button press to a target sound /a/. Tactile cues were presented at 200, 400, and 800 ms (25% each) prior to the auditory target. The remaining trials (25%) were presented without tactile cues. Findings suggested that both groups showed equivalent alerting responses to tactile cues. Additionally, all children were faster to respond to auditory targets at longer cue–target intervals. Finally, there was an association between rate of facilitation and RRB scores in all children, suggesting that patterns of responding to transient phasic cues may be related to ASD symptomatology.

Clustering of Social and Physical Pain Variables and Their Association With Mortality in Two Population-Based Cohorts

OBJECTIVE

Social pain and physical pain are related bidirectionally, but how these variables cluster in the population is unknown.

METHODS

This study included 2833 women from the Study of Women's Health Across the Nation (SWAN), a community-based cohort of middle-aged women, and 3972 women from the Pathways Study, a population-based cohort of women diagnosed with American Joint Committee on Cancer stages I-IV breast cancer diagnosed between 2005 and 2013. Women provided data on measures related to social pain (social network size, social support, loneliness, social well-being) and physical pain (sensitivity to pain, bodily pain) at study baseline. Analyzing each cohort separately, we used latent class analysis to evaluate social-physical pain clusters, logistic regression to evaluate predictors of categorization into clusters, and Cox proportional hazards models to evaluate associations of clusters with all-cause mortality. We also performed a meta-analysis to combine cohort mortality associations.

RESULTS

Each cluster analysis produced a "low social-physical pain" cluster (SWAN, 48.6%; Pathways, 35.2%) characterized by low social and pain symptoms, a "high social-physical pain" cluster (SWAN, 17.9%; Pathways, 17.9%) characterized by high symptoms, and a "low social/high physical pain" cluster of women with high pain and compromised social functioning but otherwise low social symptoms (SWAN, 33.5%; Pathways, 46.9%). In meta-analysis, categorization into the high social-physical pain cluster was associated with elevated mortality (adjusted hazard ratio = 1.34, 95% confidence interval = 1.05-1.71, Q statistic = 0.782), compared with those in the low social-physical pain cluster.

CONCLUSIONS

In two cohorts of women, latent class analysis produced similar sets of social-physical pain clusters, with the same proportion having both high social and pain symptoms; women in this cluster had elevated mortality.

Low-level, prediction-based sensory and motor processes are unimpaired in Autism

A new promising account of human brain function suggests that sensory cortices try to optimise information processing via predictions that are based on prior experiences. The brain is thus likened to a probabilistic prediction machine. There has been a growing - though inconsistent - literature to suggest that features of autism spectrum conditions (ASCs) are associated with a deficit in modelling the world through such prediction-based inference. However empirical evidence for differences in low-level sensorimotor predictions in autism is still lacking. One approach to examining predictive processing in the sensorimotor domain is in the context of self-generated (predictable) as opposed to externally-generated (less predictable) effects. We employed two complementary tasks - forcematching and intentional binding - which examine self-versus externally-generated action effects in terms of sensory attenuation and intentional binding respectively in adults with and without autism. The results show that autism was associated with normal levels of sensory attenuation of internally-generated force and with unaltered temporal attraction of voluntary actions and their outcomes. Thus, our results do not support a general deficit in predictive processing in autism.

Convergent Validity of Behavioural and Subjective Sensitivity in Relation to Autistic Traits

Sensory issues are highly prevalent in autism and previous findings support a relationship between questionnaires of sensitivity and autistic symptoms and traits, whereas studies that examine this relationship through behavioural assessments of sensitivity are less consistent. The current study explores these differences and suggests that behavioural thresholds for sensitivity and subjective sensitivity are distinct constructs. One hundred and eighteen adults completed a visual and auditory detection task and questionnaires on sensory processing and autistic traits. Visual thresholds and subjective visual sensitivity were not correlated, but both were related to autistic traits. Auditory thresholds and subjective auditory sensitivity were also unrelated. Overall, sensitivity is highly associated with autistic traits, however, behavioural and questionnaire assessments lack convergent validity and therefore, likely assess distinct constructs.

Tactile Processing and Quality of Sleep in Autism Spectrum Disorders

Individuals with autism spectrum disorders (ASDs) commonly experience problems with the processing of tactile stimuli and poor quality of sleep. The aim of the present study was to analyze whether tactile stimuli modulation (TSM) disorders might be linked to insomnia prevalence in ASD individuals. We hypothesized that sleep disorders in children with ASD may result from improper tactile under/over responsivity. The study included 27 children diagnosed with ASD, aged 6.8 (±2.9 years) with male dominance (n = 22, 81.5%). To evaluate the pattern of TSM we used a clinical interview with a parent, and guided and spontaneous observation of the patients. Sleep disorders were diagnosed using the Athens Insomnia Scale. Of all the children diagnosed with TSM, 20 patients (74.1%) had an over-responsivity pattern and 7 children (25.9%) had an under-responsivity pattern. Of the patients, 11 children (40.7%) met the diagnostic criteria for insomnia. The data indicated a statistical tendency for higher prevalence of insomnia in individuals diagnosed with tactile under-responsivity (p = 0.051). We concluded that under-responsivity toward tactile stimuli may be partly responsible for poor sleep quality in ASD. There is an urgent need to treat sleep and sensory disruptions which may intensify behavioral difficulties in ASD.

Interpersonal Motor Interactions Shape Multisensory Representations of the Peripersonal Space

This perspective review focuses on the proposal that predictive multisensory integration occurring in one's peripersonal space (PPS) supports individuals' ability to efficiently interact with others, and that integrating sensorimotor signals from the interacting partners leads to the emergence of a shared representation of the PPS. To support this proposal, we first introduce the features of body and PPS representations that are relevant for interpersonal motor interactions. Then, we highlight the role of action planning and execution on the dynamic expansion of the PPS. We continue by presenting evidence of PPS modulations after tool use and review studies suggesting that PPS expansions may be accounted for by Bayesian sensory filtering through predictive coding. In the central section, we describe how this conceptual framework can be used to explain the mechanisms through which the PPS may be modulated by the actions of our interaction partner, in order to facilitate interpersonal coordination. Last, we discuss how this proposal may support recent evidence concerning PPS rigidity in Autism Spectrum Disorder (ASD) and its possible relationship with ASD individuals' difficulties during interpersonal coordination. Future studies will need to clarify the mechanisms and neural underpinning of these dynamic, interpersonal modulations of the PPS.