Reduced Sensory Habituation in Autism and Its Correlation with Behavioral Measures

Sensory-movement underpinnings of lifelong neurodivergence: getting a grip on autism

While the autism diagnosis emphasizes "deficits" in social communication, the article advances that sensory-movement differences underpin autism through a review of the following sources of evidence. This account critically challenges "autistic regression", with evidence that sensory-movement features appear by birth as the earliest signs of autism and underlie the behavioral differences used for diagnosis, which may reflect adaptations to inherent differences and misunderstandings from others. Sensory and motor differences are salient to autistic people, but they often go underrecognized by others. They cause cascading effects in infancy on behavior and communication through differences in sensorimotor learning, automatic imitation, eye contact, sensory perception, and interests. The article then explains how sensory processing differences may influence reduced perceptual narrowing, which involves a bottom-up information processing style grounded in the surrounding environment. Furthermore, this bottom-up processing may grow from reduced sensory integration in feedback loops potentially involving the cerebellum of the brain. The article then moves into implications for the widespread consequences of these inherent differences on quality of life. The article closes with implications for autism as a construct (including underestimated empathy and pain), testing the theory, providing sensory-sensitive support and acceptance of autistic people, and applications to diverse autistic people. The theory may apply particularly well to autistic women and girls, autistic people with speech divergence, autistic people with ADHD, and autistic people with co-occurring sensory and motor-related neurodivergences. Throughout the article, the theory also provides clinical, neurological, and experiential evidence for sensory and motor differences as lifelong, challenging the notion of "losing" (an) autism (diagnosis) as instead reflecting (risky and not necessarily "successful") camouflaging.

Predictive filtering of sensory response via orbitofrontal top-down input

Habituation is a crucial sensory filtering mechanism whose dysregulation can lead to a continuously intense world in disorders with sensory overload. While habituation is considered to require top-down predictive signaling to suppress irrelevant inputs, the exact brain loci storing the internal predictive model and the circuit mechanisms of sensory filtering remain unclear. We found that daily neural habituation in the primary auditory cortex (A1) was reversed by inactivation of the orbitofrontal cortex (OFC). Top-down projections from the ventrolateral OFC, but not other frontal areas, carried predictive signals that grew with daily sound experience and suppressed A1 via somatostatin-expressing inhibitory neurons. Thus, prediction signals from the OFC cancel out behaviorally irrelevant anticipated stimuli by generating their "negative images" in sensory cortices.

Measuring habituation to stimuli: The Italian version of the Sensory Habituation Questionnaire

Sensory habituation allows us to decrease responsiveness to repetitive or prolonged stimuli over time, making them easy to filter out and not interfere with ongoing activities. As such, habituation could be an important aspect to be evaluated within a sensory and cognitive assessment. The main aim of the present study was to validate an Italian version of the Sensory Habituation Questionnaire (S-Hab-Q), a self-report tool assessing how long an adult individual takes to adapt to daily sensory stimuli. We examined the relationship between sensory habituation and sensory sensitivity by administering the Sensory Perception Quotient questionnaire (SPQ) and tested a factor model based on a sensory modality categorization of items. In addition, given the high probability of altered sensory processing in autism, we explored the relationship between sensory habituation and autistic traits by administering the Autism Quotient questionnaire (AQ). A total of 262 participants, aged 18 to 67 years, completed the S-Hab-Q, the SPQ, and the AQ questionnaires. The results showed that, as the original version of the S-Hab-Q, the Italian version had a high internal consistency and a significant correlation with the SPQ score. A confirmatory factor analysis, based on a two-factor model (i.e., vision and hearing vs. touch, smell, and taste), showed a good fit of the S-Hab-Q data. As expected, a significant correlation between the S-Hab-Q and the AQ score was found. Interestingly, mediation analysis revealed that the S-Hab-Q score mediated the relationship between SPQ and AQ scores. Overall, the results confirm that a questionnaire assessing habituation can be a feasible tool to profile individual habituation in daily life. Moreover, they suggest that sensory habituation contributes to explaining the link between sensory sensitivity and autistic traits.

The impact of noise exposure, time pressure, and cognitive load on objective task performance and subjective sensory overload and fatigue

INTRODUCTION

Sensory hypersensitivity (SHS) refers to an increased sensitivity to sensory stimuli, often leading to sensory overload and adversely affecting daily functioning and well-being. This study examined the effects of three situational triggers - noise, time pressure, and cognitive load - on task performance, sensory overload, and fatigue. Additionally, we sought to explore the associations between these effects and SHS, while accounting for other influencing factors such as personality, coping mechanisms, and anxiety.

METHOD

We experimentally tested 105 university students, employing a visuospatial task (the Paper Folding Test, PFT) under eight different conditions, manipulating the three situational triggers. The measured outcomes included task accuracy, average response time, sensory overload, and fatigue. Participants also completed several questionnaires: Highly Sensitive Person Scale (HSPS), Multi-Modal Evaluation of Sensory Sensitivity (MESSY), State and Trait Anxiety Index, Big Five Inventory, and COPE Easy.

RESULTS

Our findings indicated that sensory overload increased as more situational triggers were introduced, with noise having the most significant impact. However, this increase in sensory overload did not correspond to changes in objective performance measures, such as accuracy and average response time on the PFT, which were primarily influenced by cognitive load (i.e. easy versus difficult items). Additionally, individuals with higher levels of SHS (HSPS and MESSY) reported greater overall sensory overload and fatigue. Nonetheless, the impact of the triggers on sensory overload and fatigue was not exclusive to those with high SHS, and neuroticism, conscientiousness, openness, and trait anxiety were significant predictors of SHS, more so than task-related outcomes.

CONCLUSIONS

Feelings of sensory overload may not necessarily impair cognitive performance, and the impact of situational triggers can be similar for individuals with and without SHS. This implies that the burden of SHS and overall sensory overload may be influenced by other underlying factors leading to an elevation of baseline sensory overload, warranting further investigation.

How auditory processing influences the autistic profile: A review

We need to combine sensory data from various sources to make sense of the world around us. This sensory data helps us understand our surroundings, influencing our experiences and interactions within our everyday environments. Recent interest in sensory-focused approaches to supporting autistic people has fixed on auditory processing-the sense of hearing and the act of listening-and its crucial role in language, communications, and social domains, as well as non-social autism-specific attributes, to understand better how sensory processing might differ in autistic people. In this narrative review, we synthesize published research into auditory processing in autistic people and the relationship between auditory processing and autistic attributes in a contextually novel way. The purpose is to understand the relationship between these domains more fully, drawing on evidence gleaned from experiential perspectives through to neurological investigations. We also examine the relationship between auditory processing and diagnosable auditory conditions, such as hyperacusis, misophonia, phonophobia, and intolerance to loud sounds, as well as its relation to sleep, anxiety, and sensory overload. Through reviewing experiential, behavioral and neurological literature, we demonstrate that auditory processes interact with and shape the broader autistic profile-something not previously considered. Through a better understanding of the potential impact of auditory experiences, our review aims to inform future research on investigating the relationship between auditory processing and autistic traits through quantitative measures or using qualitative experiential inquiry to examine this relationship more holistically.

Neurodivergence, intersectionality, and eating disorders: a lived experience-led narrative review

Autistic people and those with attention deficit hyperactivity disorder are at a high risk of developing an eating disorder. While there is limited evidence on the relationship between other forms of neurodivergence and eating disorders, research suggests associations between giftedness, intellectual disability, obsessive-compulsive disorder, psychosis, Tourette's syndrome, and disordered eating. Factors underlying disordered eating and/or eating disorder risk for neurodivergent people are multifaceted and complex, encompassing a wide range of intertwined psychosocial, environmental, and biological processes. Moreover, research shows that neurodivergent individuals experience poorer treatment outcomes compared to neurotypical individuals. However, there is a paucity of research in this area overall. More specifically, lived experience-led research remains rare, despite its critical role for improving individualised eating disorder care, as well as mental healthcare more broadly. Indeed, the importance of eating disorder care individuation is increasingly being recognised, particularly within the context of neurodivergence, given the heterogeneous experiences and support needs of neurodivergent people affected by disordered eating and/or eating disorders. Furthermore, despite documented overlaps between various forms of neurodivergence (e.g., co-occurring autism and attention deficit hyperactivity disorder), research looking at eating disorders in the context of neurodivergence through a transdiagnostic perspective is scarce. This lived experience-led narrative review aims to shed light on the intersectional factors underlying elevated disordered eating and/or eating disorder risk for neurodivergent individuals. First, an overview of prevalence data is provided, followed by a thematic framework identifying factors underlying disordered eating and/or eating disorder risk in relation to neurodivergence. A critical appraisal of current eating disorder research and care is then offered before suggestions for neurodiversity-affirming eating disorder care are made. In this view, this paper offers a foundation for future empirical work in this nascent field of inquiry by providing a lived experience-led, transdiagnostic, and intersectional account of eating disorders in the context of neurodivergence.

Reduced precision of motor and perceptual rhythmic timing in autistic adults

Recent results suggest that autistic individuals exhibit reduced accuracy compared to non-autistic peers in temporally coordinating their actions with predictable external cues, e.g., synchronizing finger taps to an auditory metronome. However, it is not yet clear whether these difficulties are driven primarily by motor differences or extend into perceptual rhythmic timing tasks. We recruited autistic and non-autistic participants for an online study testing both finger tapping synchronization and continuation as well as rhythmic time perception (anisochrony detection). We fractionated each participant's synchronization results into parameters representing error correction, motor noise, and internal time-keeper noise, and also investigated error-correcting responses to small metronome timing perturbations. Contrary to previous work, we did not find strong evidence for reduced synchronization error correction. However, we found compelling evidence for noisier internal rhythmic timekeeping in the synchronization, continuation, and perceptual components of the experiment. These results suggest that noisier internal rhythmic timing processes underlie some sensorimotor coordination challenges in autism.

Evidence of mutual non-verbal synchrony in learners with severe learning disability and autism, and their support workers: a motion energy analysis study

Introduction

Some research indicates that neurodivergent people are less likely than "neurotypical" people to adapt their movements to a partner's movements to facilitate interpersonal motor synchrony. Researchers therefore suggest synchrony deficits underlie the social differences associated with autism and other neurodivergences. Intensive Interaction (II) is a client-led approach, where Learning Support Workers (LSW) follow the lead of learners to create balanced and reciprocal interactions.

Methods

We aimed to examine the balance of synchrony in learners with autism and Severe Learning Disabilities and their LSWs in a special education college where learners had prior experience with II. Using Motion Energy Analysis, we assessed the degree to which each partner acted as a leader, and hence which partner acted as a follower, during moments of close synchrony.

Results

Overall, learners and LSWs showed higher than chance synchrony. There were no differences in the degree to which each partner led the moments of synchrony, or the amount pairs synchronized with zero-lag, where there was no delay between each partners' movements.

Discussion

The equal balance of leading and following in the learner and LSW pairs demonstrates that both partners consistently adapted their movements to their partner's movements to facilitate synchrony. The findings tentatively challenge the notion of a synchrony deficit in autism and suggest synchrony can be present in cross-neurotype pairs in comfortable and engaging conditions. We discuss the potential for client-led, movement-based approaches to support smooth interactions across neurotypes.

No Differences in Auditory Steady-State Responses in Children with Autism Spectrum Disorder and Typically Developing Children

Auditory steady-state response (ASSR) has been studied as a potential biomarker for abnormal auditory sensory processing in autism spectrum disorder (ASD), with mixed results. Motivated by prior somatosensory findings of group differences in inter-trial coherence (ITC) between ASD and typically developing (TD) individuals at twice the steady-state stimulation frequency, we examined ASSR at 25 and 50 as well as 43 and 86 Hz in response to 25-Hz and 43-Hz auditory stimuli, respectively, using magnetoencephalography. Data were recorded from 22 ASD and 31 TD children, ages 6-17 years. ITC measures showed prominent ASSRs at the stimulation and double frequencies, without significant group differences. These results do not support ASSR as a robust ASD biomarker of abnormal auditory processing in ASD. Furthermore, the previously observed atypical double-frequency somatosensory response in ASD did not generalize to the auditory modality. Thus, the hypothesis about modality-independent abnormal local connectivity in ASD was not supported.

The developmental timing of spinal touch processing alterations predicts behavioral changes in genetic mouse models of autism spectrum disorders

Altered somatosensory reactivity is frequently observed among individuals with autism spectrum disorders (ASDs). Here, we report that although multiple mouse models of ASD exhibit aberrant somatosensory behaviors in adulthood, some models exhibit altered tactile reactivity as early as embryonic development, whereas in others, altered reactivity emerges later in life. Additionally, tactile overreactivity during neonatal development is associated with anxiety-like behaviors and social behavior deficits in adulthood, whereas tactile overreactivity that emerges later in life is not. The locus of circuit disruption dictates the timing of aberrant tactile behaviors, as altered feedback or presynaptic inhibition of peripheral mechanosensory neurons leads to abnormal tactile reactivity during neonatal development, whereas disruptions in feedforward inhibition in the spinal cord lead to touch reactivity alterations that manifest later in life. Thus, the developmental timing of aberrant touch processing can predict the manifestation of ASD-associated behaviors in mouse models, and differential timing of sensory disturbance onset may contribute to phenotypic diversity across individuals with ASD.

Effects of background noise on autonomic arousal (skin conductance level)

This study was designed to investigate the relationship between sound level and autonomic arousal using acoustic signals similar in level and acoustic properties to common sounds in the built environment. Thirty-three young adults were exposed to background sound modeled on ventilation equipment noise presented at levels ranging from 35 to 75 dBA sound pressure level (SPL) in 2 min blocks while they sat and read quietly. Autonomic arousal was measured in terms of skin conductance level. Results suggest that there is a direct relationship between sound level and arousal, even at these realistic levels. However, the effect of habituation appears to be more important overall.

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.

Sensory Integration Approaches for Children and Youth in Occupational Therapy Practice

This AOTA Position Statement describes the role of occupational therapy practitioners in providing services to children and youth with a variety of sensory processing patterns and sensory integrative dysfunction. It also serves as a resource for policymakers, funding and reimbursement sources, and caregivers.

In Context: A Developmental Model of Reward Processing, With Implications for Autism and Sensitive Periods

OBJECTIVE

Differences in reward processing have been associated with numerous psychiatric disorders, including autism and attention-deficit/hyperactivity disorder (ADHD). Many attempts to understand reward processing characterize differences in clinical populations after disorder onset; however, divergence may begin much earlier. In fact, the typical developmental progression of reward processing in infancy and early childhood is poorly understood. We re-conceptualize classic infant developmental constructs such as preferential looking into a Six-Component Developmental Model of Reward Processing: an infant- and young child-focused framework to guide research and assessment of reward processing across development.

METHOD

The extant developmental literature including recent textbooks, systematic reviews, and meta-analyses was reviewed to build a conceptual framework. We describe experimental paradigms to assess each developmental component of reward processing longitudinally from infancy. A timeline of each component's emergence was estimated.

RESULTS

Six components of reward processing were identified-association, discrimination, preference/valuation, effort, anticipation, and response. Selected evidence suggests emergence between birth and 6 months. Application of this model to autism led to a reinterpretation of existing disparate results, and illuminated a path to study the developmental processes underlying a popular hypothesis of autism, the motivation hypothesis. Current evidence further suggests that a sensitive period may exist for the emergence of reward processing.

CONCLUSION

The proposed framework offers a useful reconceptualization of the extant literature. Future longitudinal work using the suggested experimental paradigms with high-risk populations could elucidate the developmental trajectory of the components and timing of potential sensitive period(s) for each component.

Probabilistic Learning of Cue-Outcome Associations is not Influenced by Autistic Traits

According to Bayesian/predictive coding models of autism, autistic individuals may have difficulties learning probabilistic cue-outcome associations, but empirical evidence has been mixed. The target cues used in previous studies were often straightforward and might not reflect real-life learning of such associations which requires learners to infer which cue(s) among many to track. Across two experiments, we compared adult learners with varying levels of autistic traits on their ability to infer the correct cue to learn probabilistic cue-outcome associations when explicitly instructed to do so or when exposed implicitly. We found no evidence for the effect of autistic traits on probabilistic learning accuracy, contrary to the predictions of Bayesian/predictive coding models. Implications for the current Bayesian/predictive coding models are discussed.

Sensory Processing Differences in Individuals With Autism Spectrum Disorder: A Narrative Review of Underlying Mechanisms and Sensory-Based Interventions

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by difficulties with social interaction and restricted, repetitive patterns of behavior. Altered sensory processing and perception are considered characteristics of ASD. Sensory processing differences (SPDs) are commonly observed in individuals with ASD, leading to atypical responses to sensory stimuli. SPDs refer to the way in which individuals receive, process, and respond to sensory information from the environment. People with SPDs may be hypersensitive (over-reactive) or hyposensitive (under-reactive) to sensory input, or they may experience fragmented or distorted perceptions. These differences can make it difficult for individuals with SPDs to filter out irrelevant sensory information, and to integrate sensory information from different sources. This study intends to investigate the underlying mechanisms contributing to SPDs in individuals with autism and determine the effectiveness of sensory-based therapies in addressing these challenges. The literature suggests that altered neural pathways, sensory gating dysfunction, and atypical sensory modulation contribute to SPDs in individuals with ASD. Assistive technology, environmental changes, and sensory-based interventions like sensory integration therapy (SIT) have all shown promise in improving sensory functioning and reducing associated behavioral issues. However, further research is needed to improve our understanding of sensory processing in autism and to optimize interventions for individuals with ASD.

Habituation of auditory responses in young autistic and neurotypical children

Prior studies suggest that habituation of sensory responses is reduced in autism and that diminished habituation could be related to atypical autistic sensory experiences, for example, by causing brain responses to aversive stimuli to remain strong over time instead of being suppressed. While many prior studies exploring habituation in autism have repeatedly presented identical stimuli, other studies suggest group differences can still be observed in habituation to intermittent stimuli. The present study explored habituation of electrophysiological responses to auditory complex tones of varying intensities (50-80 dB SPL), presented passively in an interleaved manner, in a well-characterized sample of 127 autistic (MDQ  = 65.41, SD = 20.54) and 79 typically developing (MDQ  = 106.02, SD = 11.50) children between 2 and 5 years old. Habituation was quantified as changes in the amplitudes of single-trial responses to tones of each intensity over the course of the experiment. Habituation of the auditory N2 response was substantially reduced in autistic participants as compared to typically developing controls, although diagnostic groups did not clearly differ in habituation of the P1 response. Interestingly, the P1 habituated less to loud 80 dB sounds than softer sounds, whereas the N2 habituated less to soft 50 dB sounds than louder sounds. No associations were found between electrophysiological habituation and cognitive ability or participants' caregiver-reported sound tolerance (Sensory Profile Hyperacusis Index). The results present study results extend prior research suggesting habituation of certain sensory responses is reduced in autism; however, they also suggest that habituation differences observed using this study's paradigm might not be a primary driver of autistic participants' real-world sound intolerance.

Olfactive short-term habituation in children and young people with profound intellectual and multiple disabilities

BACKGROUND

Despite its importance for learning, the existence of the habituation process and its characteristics in people with profound intellectual and multiple disabilities (PIMD) remains understudied. Habituation is, however, considered the simplest form of learning, and a significant neuroadaptive mechanism. Even though habituation occurs in all sensory modalities, the olfactory system is where it manifests itself very visibly.

AIM

This study explores the olfactory short-term habituation abilities of children and young people with PIMD.

METHOD

Twenty children and young people with PIMD (7-18 years) were presented six times successively with a 30-second habituating olfactory stimulus. The interstimulus interval was 15 s. A new odour was presented on the seventh trial. The scenario was carried out two times with two pairs of stimuli. The participants' head alignment duration on the odour was measured.

RESULTS

Seventeen participants out of 20 manifested a decline in response, which reached about 50 % between the first and sixth presentation of the habituation odour. All habituators also showed a distinctive response when exposed to a novel odour. The participants who did not habituate showed a strong, non-fluctuating response to the stimulus throughout the presentations. Three participants only habituated to one of the two habituation stimuli.

CONCLUSION AND IMPLICATIONS

The results raise theoretical, scientific, and practical issues. They question the factors explaining olfactory habituation mechanisms, namely the stimulus properties and the severity of impairment, reveal the need for points of comparison for interpreting this population's responses, and point to the consequences of stimuli repetition and or variety in therapeutic or educational settings for these individuals' learning and cognitive functioning.

Habituation, Adaptation and Prediction Processes in Neurodevelopmental Disorders: A Comprehensive Review

Habituation, the simplest form of learning preserved across species and evolution, is characterized by a response decrease as a stimulus is repeated. This adaptive function has been shown to be altered in some psychiatric and neurodevelopmental disorders such as autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD) or schizophrenia. At the brain level, habituation is characterized by a decrease in neural activity as a stimulation is repeated, referred to as neural adaptation. This phenomenon influences the ability to make predictions and to detect change, two processes altered in some neurodevelopmental and psychiatric disorders. In this comprehensive review, the objectives are to characterize habituation, neural adaptation, and prediction throughout typical development and in neurodevelopmental disorders; and to evaluate their implication in symptomatology, specifically in sensitivity to change or need for sameness. A summary of the different approaches to investigate adaptation will be proposed, in which we report the contribution of animal studies as well as electrophysiological studies in humans to understanding of underlying neuronal mechanisms.

Sensory Gating in Neurodevelopmental Disorders: A Scoping Review

This review aimed to explore the current understanding of sensory gating in neurodevelopmental disorders as a possible transdiagnostic mechanism. We applied methods according to the Joanna Briggs Institute Manual for Evidence Synthesis, following the population, concept, and context scoping review eligibility criteria. Using a comprehensive search strategy in five relevant research databases (Medline, EMBASE, CINAHL, PsychInfo, and Scopus), we searched for relevant peer-reviewed, primary research articles and unpublished data. Two independent reviewers screened the titles and abstracts, full-texts, and completed data extraction. We identified a total of 81 relevant articles and used descriptive analyses to summarize the characteristics and outcomes of all identified studies. Literature regarding sensory gating was most common in autistic populations with relatively fewer studies examining attention-deficit/hyperactivity disorder, tic disorders, and childhood-onset fluency disorder (COFD). The methods to assess sensory gating varied widely both within and between groups and included measures such as habituation, prepulse inhibition, affect-modulated inhibition, medication and other intervention trials. Most consistently, when participants complete questionnaires about their sensory experiences, those who have neurodevelopmental disorders report differences in their sensory gating. Affect-modulated inhibition appears to be discrepant between samples with and without neurodevelopmental disorder diagnoses. Habituation was the most commonly reported phenomenon and many differences in habituation have been found in autistic individuals and individuals with tic disorders whereas concerns with inhibition seemed more common in COFD. Overall, the evidence is inconsistent within and between disorders suggesting there is still much to learn about sensory gating in neurodevelopmental disorders.

The developmental timing of spinal touch processing alterations and its relation to ASD-associated behaviors in mouse models

Altered somatosensory reactivity is frequently observed among individuals with autism spectrum disorders (ASDs). Here, we report that while multiple mouse models of ASD exhibit aberrant somatosensory behaviors in adulthood, some models exhibit altered tactile reactivity as early as embryonic development, while in others, altered reactivity emerges later in life. Additionally, tactile over-reactivity during neonatal development is associated with anxiety-like behaviors and social interaction deficits in adulthood, whereas tactile over-reactivity that emerges later in life is not. The locus of circuit disruption dictates the timing of aberrant tactile behaviors: altered feedback or presynaptic inhibition of peripheral mechanosensory neurons leads to abnormal tactile reactivity during neonatal development, while disruptions in feedforward inhibition in the spinal cord lead to touch reactivity alterations that manifest later in life. Thus, the developmental timing of aberrant touch processing can predict the manifestation of ASD-associated behaviors in mouse models, and differential timing of sensory disturbance onset may contribute to phenotypic diversity across individuals with ASD.

Sensory profiles, behavioral problems, and auditory findings in children with autism spectrum disorder

Objective

This study examined the relationship between sensory processing (SP) differences and behavioral problems in children with autism spectrum disorder (ASD). We also investigated whether audiological test results could objectively detect auditory processing differences.

Method

Forty-six children with ASD, ages 3-9 years, were enrolled in the study. Problematic behaviors and sensory processing of children were assessed using scales. The otolaryngologist performed a detailed head and neck examination and a formal audiological examination was performed by an audiologist.

Results

Stereotypy, hyperactivity, and irritability were related to sensation seeking. Stereotypy was also associated with visual processing. Touch processing differences was related to irritability and inappropriate speech. Lethargy was associated with auditory processing. There were no differences in SP and behavior problems in the children whose audiological profiles could be measured between those who passed or failed the test.

Conclusion

There was an association between SP differences and behavioral problems in children with ASD, supporting previous studies. Audiological test results did not reveal the SP differences documented in the parent forms.

Diminished Repetition Suppression Reveals Selective and Systems-Level Face Processing Differences in ASD

Repeated exposure to a stimulus results in reduced neural response, or repetition suppression, in brain regions responsible for processing that stimulus. This rapid accommodation to repetition is thought to underlie learning, stimulus selectivity, and strengthening of perceptual expectations. Importantly, reduced sensitivity to repetition has been identified in several neurodevelopmental, learning, and psychiatric disorders, including autism spectrum disorder (ASD), a neurodevelopmental disorder characterized by challenges in social communication and repetitive behaviors and restricted interests. Reduced ability to exploit or learn from repetition in ASD is hypothesized to contribute to sensory hypersensitivities, and parallels several theoretical frameworks claiming that ASD individuals show difficulty using regularities in the environment to facilitate behavior. Using fMRI in autistic and neurotypical human adults (females and males), we assessed the status of repetition suppression across two modalities (vision, audition) and with four stimulus categories (faces, objects, printed words, and spoken words). ASD individuals showed domain-specific reductions in repetition suppression for face stimuli only, but not for objects, printed words, or spoken words. Reduced repetition suppression for faces was associated with greater challenges in social communication in ASD. We also found altered functional connectivity between atypically adapting cortical regions and higher-order face recognition regions, and microstructural differences in related white matter tracts in ASD. These results suggest that fundamental neural mechanisms and system-wide circuits are selectively altered for face processing in ASD and enhance our understanding of how disruptions in the formation of stable face representations may relate to higher-order social communication processes.SIGNIFICANCE STATEMENT A common finding in neuroscience is that repetition results in plasticity in stimulus-specific processing regions, reflecting selectivity and adaptation (repetition suppression [RS]). RS is reduced in several neurodevelopmental and psychiatric conditions including autism spectrum disorder (ASD). Theoretical frameworks of ASD posit that reduced adaptation may contribute to associated challenges in social communication and sensory processing. However, the scope of RS differences in ASD is unknown. We examined RS for multiple categories across visual and auditory domains (faces, objects, printed words, spoken words) in autistic and neurotypical individuals. We found reduced RS in ASD for face stimuli only and altered functional connectivity and white matter microstructure between cortical face-recognition areas. RS magnitude correlated with social communication challenges among autistic individuals.

Autism Spectrum Disorder and auditory sensory alterations: a systematic review on the integrity of cognitive and neuronal functions related to auditory processing

Autism Spectrum Disorder (ASD) is a neurodevelopmental condition with a wide spectrum of symptoms, mainly characterized by social, communication, and cognitive impairments. Latest diagnostic criteria according to DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, 2013) now include sensory issues among the four restricted/repetitive behavior features defined as "hyper- or hypo-reactivity to sensory input or unusual interest in sensory aspects of environment". Here, we review auditory sensory alterations in patients with ASD. Considering the updated diagnostic criteria for ASD, we examined research evidence (2015-2022) of the integrity of the cognitive function in auditory-related tasks, the integrity of the peripheral auditory system, and the integrity of the central nervous system in patients diagnosed with ASD. Taking into account the different approaches and experimental study designs, we reappraise the knowledge on auditory sensory alterations and reflect on how these might be linked with behavior symptomatology in ASD.

Prenatal marijuana exposure and visual perception in toddlers: Evidence of a sensory processing deficit

Background

Research has identified a link between prenatal marijuana exposure and multiple outcomes in children, including cognitive development. Several studies have found specific differences in sensory processing and attention, with visual perception especially impacted in school age children. The current study explored whether this effect is evident at an earlier age, and thus our goal was to investigate the relationship between in-utero marijuana exposure and sensory processing capabilities in toddlers. We hypothesized that in-utero marijuana exposure throughout pregnancy would specifically predict visual sensory hyperactivity in children as young as 15 months of age.

Methods

Participants were 225 15-month-old children whose mothers were recruited during pregnancy. Substance exposure was prospectively collected and biochemically verified, with marijuana coded as no exposure, 1st trimester exposure only, or exposure throughout pregnancy. The Infant Toddler Sensory Profile evaluated 5 domains of sensory processing (visual, auditory, tactile, vestibular, oral).

Results

Prenatal marijuana exposure throughout pregnancy, but not when limited to the first trimester, predicted a two-fold increased likelihood of scoring in a range indicating high levels of seeking out and potentially over-attending to visual stimulation after controlling for potentially confounding factors including other prenatal exposures. Marijuana exposure was not significantly related to other processing domains.

Conclusion

Results indicate that links previously identified between prenatal marijuana exposure and visual function and attention may already be evident at 15 months of age, and also suggest an impact related to continuous/later pregnancy exposure. Our findings, as well as those from previous studies, all suggest visual processing differences for exposed children, differences that may predict emerging issues with visual attention and habituation. As legalization of marijuana continues to increase, further research is clearly needed to examine specific teratologic effects associated with use during pregnancy.

Larger pupil dilation to nonsocial sounds in infants with subsequent autism diagnosis

BACKGROUND

Studies of infants with an elevated likelihood of autism spectrum disorder can identify basic developmental processes that are associated with subsequently emerging clinical symptoms. Atypical responsiveness to sounds in infancy is such a potential early marker of autism. Here, we used pupillometry to quantify reactivity to social and nonsocial sounds in infants with a subsequent diagnosis. Previous research suggest that pupil dilation reflects attentional alerting, and link it to the locus coeruleus norepinephrine system.

METHODS

We measured pupil dilation responses to child-directed speech and the sound of running water; sounds infants often hear in their everyday life. The final sample consisted of 99 ten-month-old infants (52 girls), of whom 68 had an elevated likelihood of autism and 31 were typically developing low-likelihood infants. At follow-up (36 months of age), 18 children in the elevated-likelihood group were diagnosed with autism.

RESULTS

Compared to infants without diagnosis, the infants who were subsequently diagnosed with autism had larger pupil dilation when listening to nonsocial sounds, while reactivity to speech was strikingly similar between groups. In the total sample, more pupil dilation to the nonsocial sound was associated with higher levels of autistic symptoms. We also found that on a trial-by-trial basis, across all conditions and groups, more pupil dilation was associated with making fewer gaze shifts.

CONCLUSIONS

This study did not find evidence of atypical pupillary reactivity to child-directed speech early in life in autism. Instead, the results suggest that certain nonsocial sounds elicit atypically strong alerting responses in infants with a subsequent autism diagnosis. These findings may have important theoretical and clinical implications.

Equivalent own name bias in autism: An EEG study of the Attentional Blink

The "Attentional Blink" refers to difficulty in detecting the second of two target stimuli presented in rapid temporal succession. Studies have shown that salient target stimuli, such as one's own name, reduce the magnitude of this effect. Given indications that self-related processing is altered in autism, it is an open question whether this attentional self-bias is reduced in autism. To investigate this, in the current study we utilised an Attentional Blink paradigm involving one's own and others' names, in a group of 24 autistic adults, and 22 neurotypical adults, while measuring EEG. In line with previous studies, the Attentional Blink was reduced when the participant's own name was the second target, with no differences between autistic and neurotypical participants. ERP results show that the effect on the Attentional Blink of one's own name was reflected in increased N2 and P3 amplitudes, for both autistic and nonautistic individuals. This is the first event-related potential study of own-name processing in the context of the Attentional Blink. The results provide evidence of an intact attentional self-bias in autism, both at the behavioural and neural level.

Reduced mismatch negativity in children and adolescents with autism spectrum disorder is associated with their impaired adaptive functioning

Children and adolescents on the autism spectrum display sensory disturbances, rigid and repetitive behavior, social communication problems and a high prevalence of impaired adaptive functioning. Autism is associated with slowed behavioral and neural habituation to repeated sensory input and decreased responses to sensory deviations. Mismatch negativity (MMN) reflects a pre‐attentive difference in the neural response to sensory deviations relative to regularities and studies overall suggest that children and adolescents with autism tend to have smaller MMN. However, it remains unclear whether reduced MMN in autism is coupled to severity of specific autistic symptoms or more generally to lower level of adaptive functioning. To address these questions, the present study used electroencephalography (EEG) to assess whether auditory MMN in 59 children and adolescents with autism aged 7–14 years compared to 59 typically developing children and adolescents were related to specific autistic symptoms or level in adaptive functioning. As hypothesized, the autism group had a lower MMN amplitude than controls. Smaller MMN amplitudes were specifically associated with lower adaptive functioning in the autistic subjects but not in controls while no apparent relationships were observed with autistic‐like social interaction and communication problems, atypical language, rigidity, stereotypy or sensory sensitivity symptoms. Our findings indicate that a blunted response to changes in sensory input may underlie or contribute to the generalized difficulties with adapting to daily life circumstances seen in children and adolescents with autism.

Bisphenol A Exposure Induces Sensory Processing Deficits in Larval Zebrafish during Neurodevelopment

Because of their ex utero development, relatively simple nervous system, translucency, and availability of tools to investigate neural function, larval zebrafish are an exceptional model for understanding neurodevelopmental disorders and the consequences of environmental toxins. Furthermore, early in development, zebrafish larvae easily absorb chemicals from water, a significant advantage over methods required to expose developing organisms to chemical agents in utero Bisphenol A (BPA) and BPA analogs are ubiquitous environmental toxins with known molecular consequences. All humans have measurable quantities of BPA in their bodies. Most concerning, the level of BPA exposure is correlated with neurodevelopmental difficulties in people. Given the importance of understanding the health-related effects of this common toxin, we have exploited the experimental advantages of the larval zebrafish model system to investigate the behavioral and anatomic effects of BPA exposure. We discovered that BPA exposure early in development leads to deficits in the processing of sensory information, as indicated by BPA's effects on prepulse inhibition (PPI) and short-term habituation (STH) of the C-start reflex. We observed no changes in locomotion, thigmotaxis, and repetitive behaviors (circling). Despite changes in sensory processing, we detected no regional or whole-brain volume changes. Our results show that early BPA exposure can induce sensory processing deficits, as revealed by alterations in simple behaviors that are mediated by a well-defined neural circuit.

Neural Markers of Auditory Response and Habituation in Phelan-McDermid Syndrome

Phelan-McDermid Syndrome (PMS) is a rare genetic disorder caused by deletion or sequence variation in the SHANK3 gene at terminal chromosome 22 that confers high likelihood of comorbid autism spectrum disorder (ASD). Whereas individuals with idiopathic ASD (iASD) can demonstrate diverse patterns of sensory differences, PMS is mainly characterized by sensory hyporesponsiveness. This study used electrophysiology and a passive auditory habituation paradigm to test for neural markers of hyporesponsiveness. EEG was recorded from 15 individuals with PMS, 15 with iASD, and 16 with neurotypical development (NT) while a series of four consecutive 1,000 Hz tones was repeatedly presented. We found intact N1, P2, and N2 event-related potentials (ERPs) and habituation to simple auditory stimuli, both in individuals with iASD and in those with PMS. Both iASD and PMS groups showed robust responses to the initial tone and decaying responses to each subsequent tone, at levels comparable to the NT control group. However, in PMS greater initial N1 amplitude and habituation were associated with auditory hypersensitivity, and P2 habituation correlated with ASD symptomatology. Additionally, further classification of the PMS cohort into genetic groupings revealed dissociation of initial P2 amplitude and habituation of N1 based on whether the deletions included additional genes beyond solely SHANK3 and those not thought to contribute to phenotype. These results provide preliminary insight into early auditory processing in PMS and suggest that while neural response and habituation is generally preserved in PMS, genotypic and phenotypic characteristics may drive some variability. These initial findings provide early evidence that the robust pattern of behavioral hyporesponsiveness in PMS may be due, at least in audition, to higher order factors.

Parenting Styles, Parenting Stress and Hours Spent Online as Predictors of Child Internet Addiction Among Children with Autism

The current study examined the association between hours spent online (HOS), positive parenting, negative parenting, autism parental stress and Internet addiction among Singapore based boys and girls (aged 6 to 14 years old) with Autism Spectrum Disorder (ASD). The research participants included 59 parents (41 females and 18 males) aged between 28 and 74 years old (mean age 37.95). Results indicated HOS, negative parenting and autism parenting stress predicted 54.8% of the total variance in Child Internet Addiction scores of children with ASD. Autism parental stress was the most significant predictor explaining 25.3% of the total variance with time spent online explaining another 23.5% and negative parenting predicted 6%. Positive parenting was not found to be significant. The findings reinforce the importance of according greater consideration for the role of parents when working with such children.