Somatosensory Temporal Discrimination in Autism Spectrum Disorder

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.

Characterizing Sensory Phenotypes of Subgroups with a Known Genetic Etiology Pertaining to Diagnoses of Autism Spectrum Disorder and Intellectual Disability

We aimed to identify unique constellations of sensory phenotypes for genetic etiologies associated with diagnoses of autism spectrum disorder (ASD) and intellectual disability (ID). Caregivers reported on sensory behaviors via the Sensory Profile for 290 participants (younger than 25 years of age) with ASD and/or ID diagnoses, of which ~ 70% have a known pathogenic genetic etiology. Caregivers endorsed poor registration (i.e., high sensory threshold, passive behaviors) for all genetic subgroups relative to an "idiopathic" comparison group with an ASD diagnosis and without a known genetic etiology. Genetic profiles indicated prominent sensory seeking in ADNP, CHD8, and DYRK1A, prominent sensory sensitivities in SCN2A, and fewer sensation avoidance behaviors in GRIN2B (relative to the idiopathic ASD comparison group).

Assessment of Temporal Somatosensory Discrimination in Females with Fibromyalgia: Reliability and Discriminative Ability of a New Assessment Tool

We assessed the test-retest reliability and discriminative ability of a somatosensory temporal discrimination (SSTD) assessment tool for fibromyalgia syndrome (FMS) and determined if pain-related variables were associated with SSTD performance. Twenty-five women with FMS and twenty-five asymptomatic women were assessed during two sessions 7 to 10 days apart. The proportion of correct responses (range 0-100) was calculated. Sociodemographic information was collected for both groups. The participants with FMS also completed the widespread pain index and the Brief Pain Inventory. Test-retest reliability was verified by calculating intraclass correlation coefficients. Discriminative ability was verified by a between-group comparison of scores using a t-test. Associations between SSTD score and pain variables were tested using Pearson or Spearman correlation coefficients. The test-retest reliability of the SSTD score was excellent (ICC > 0.9, CI: 0.79-0.96) for the asymptomatic group and good for the FMS group (ICC: 0.81, 95% CI: 0.62-0.91). The median (Q1-Q3) test session SSTD score differed significantly between the FMS 84.1 (71-88) and the asymptomatic 91.6 (83.4-96.1) groups (p < 0.001). Only pain duration was associated with the SSTD score. In conclusion, the new SSTD test seems reliable for people with FMS and is discriminative. Further studies should examine its sensitivity to change and correlations with other SSTD tests.

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.

The neural basis of somatosensory temporal discrimination threshold as a paradigm for time processing in the sub-second range: An updated review

BACKGROUND AND OBJECTIVE

The temporal aspect of somesthesia is a feature of any somatosensory process and a pre-requisite for the elaboration of proper behavior. Time processing in the milliseconds range is crucial for most of behaviors in everyday life. The somatosensory temporal discrimination threshold (STDT) is the ability to perceive two successive stimuli as separate in time, and deals with time processing in this temporal range. Herein, we focus on the physiology of STDT, on a background of the anatomophysiology of somesthesia and the neurobiological substrates of timing.

METHODS

A review of the literature through PubMed & Cochrane databases until March 2023 was performed with inclusion and exclusion criteria following PRISMA recommendations.

RESULTS

1151 abstracts were identified. 4 duplicate records were discarded before screening. 957 abstracts were excluded because of redundancy, less relevant content or not English-written. 4 were added after revision. Eventually, 194 articles were included.

CONCLUSIONS

STDT encoding relies on intracortical inhibitory S1 function and is modulated by the basal ganglia-thalamic-cortical interplay through circuits involving the nigrostriatal dopaminergic pathway and probably the superior colliculus.

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

Introduction

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

Methods

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

Results

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

Discussion

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

Sensory Processing in Children and Adolescents with Neurofibromatosis Type 1

Despite the evidence of elevated autistic behaviors and co-occurring neurodevelopmental difficulties in many children with neurofibromatosis type 1 (NF1), we have a limited understanding of the sensory processing challenges that may occur with the condition. This study examined the sensory profile of children and adolescents with NF1 and investigated the relationships between the sensory profiles and patient characteristics and neuropsychological functioning. The parent/caregivers of 152 children with NF1 and 96 typically developing children completed the Sensory Profile 2 (SP2), along with standardized questionnaires assessing autistic behaviors, ADHD symptoms, internalizing symptoms, adaptive functioning, and social skills. Intellectual functioning was also assessed. The SP2 data indicated elevated sensory processing problems in children with NF1 compared to typically developing children. Over 40% of children with NF1 displayed differences in sensory registration (missing sensory input) and were unusually sensitive to and unusually avoidant of sensory stimuli. Sixty percent of children with NF1 displayed difficulties in one or more sensory modalities. Elevated autistic behaviors and ADHD symptoms were associated with more severe sensory processing difficulties. This first detailed assessment of sensory processing, alongside other clinical features, in a relatively large cohort of children and adolescents with NF1 demonstrates the relationships between sensory processing differences and adaptive skills and behavior, as well as psychological well-being. Our characterization of the sensory profile within a genetic syndrome may help facilitate more targeted interventions to support overall functioning.

Modulation of the thermosensory system by oxytocin

Oxytocin (OT) is a neurohormone involved early in neurodevelopment and is implicated in multiple functions, including sensory modulation. Evidence of such modulation has been observed for different sensory modalities in both healthy and pathological conditions. This review summarizes the pleiotropic modulation that OT can exercise on an often overlooked sensory system: thermosensation. This system allows us to sense temperature variations and compensate for the variation to maintain a stable core body temperature. Oxytocin modulates autonomic and behavioral mechanisms underlying thermoregulation at both central and peripheral levels. Hyposensitivity or hypersensitivity for different sensory modalities, including thermosensitivity, is a common feature in autism spectrum disorder (ASD), recapitulated in several ASD mouse models. These sensory dysregulations occur early in post-natal development and are correlated with dysregulation of the oxytocinergic system. In this study, we discussed the potential link between thermosensory atypia and the dysregulation of the oxytocinergic system in ASD.

Effect of vibrostimulatory wearable technology on stereotyped behaviour in a child with autism and intellectual disability

The aim of the work has been to report on the effects of vibrostimulation, administered through wearable technology, on stereotyped behaviour of a child in middle childhood, with autism, intellectual disability and severe behaviour in the 'stereotypic behaviour' subscale of the Restricted and Repetitive Behaviour Revised Scale. He received vibrostimulation (210 Hz, 2.8 µm), with a continuous pattern of vibration: three vibrations of 700 ms, each separated by a rest period of 500 ms and a pause of 8000 ms. Vibration was delivered bilaterally by two devices, repeating the vibration pattern for 3 min. The measures were repeated four times alternately, with the device turned off and on. The outcome measure was frequency of stereotyed behaviour, which was evaluated for 3 min with and without vibrostimulation. The results and observations, over 3 min of stimulation, showed the disappearance of stereotyped movements during vibrostimulation and better precision in intentional hand movements. Subjectively, the child enjoyed vibrostimulation.

Sensory processing difficulties in psychiatric disorders: A meta-analysis

In clinical practice, many individuals with psychiatric disorders report difficulties in sensory processing, including increased awareness or sensitivity to external stimuli. In this meta-analysis, we examined the sensory processing patterns of adolescent and adult individuals with a broad spectrum of different psychiatric conditions. A systematic search in various databases resulted in the inclusion of 33 studies (N=2008), all using the Adolescent/Adult Sensory Profile (AASP). By comparing diagnostic subgroups to the corresponding reference group of the AASP, we detected a general pattern of sensory processing, indicating elevated levels of low registration, sensory sensitivity and sensory avoiding and lowered sensory seeking behavior in patients with different types of psychiatric disorders. The majority of effect sizes were large to very large. In conclusion, sensory processing difficulties can be considered as a non-specific transdiagnostic phenotype associated with a broad spectrum of psychiatric conditions. Further research into the relevance and role of sensory processing difficulties in psychiatric disorders may improve long-term prognosis and treatment.

Magnetoencephalography and electroencephalography can both detect differences in cortical responses to vibrotactile stimuli in individuals on the autism spectrum

Autism Spectrum (AS) is defined primarily by differences in social interactions, with impairments in sensory processing also characterizing the condition. In the search for neurophysiological biomarkers associated with traits relevant to the condition, focusing on sensory processing offers a path that is likely to be translatable across populations with different degrees of ability, as well as into animal models and across imaging modalities. In a prior study, a somatosensory neurophysiological signature of AS was identified using magnetoencephalography (MEG). Specifically, source estimation results showed differences between AS and neurotypically developing (NTD) subjects in the brain response to 25-Hz vibrotactile stimulation of the right fingertips, with lower inter-trial coherence (ITC) observed in the AS group. Here, we examined whether these group differences can be detected without source estimation using scalp electroencephalography (EEG), which is more commonly available in clinical settings than MEG, and therefore offers a greater potential for clinical translation. To that end, we recorded simultaneous whole-head MEG and EEG in 14 AS and 10 NTD subjects (age 15-28 years) using the same vibrotactile paradigm. Based on the scalp topographies, small sets of left hemisphere MEG and EEG sensors showing the maximum overall ITC were selected for group comparisons. Significant differences between the AS and NTD groups in ITC at 25 Hz as well as at 50 Hz were recorded in both MEG and EEG sensor data. For each measure, the mean ITC was lower in the AS than in the NTD group. EEG ITC values correlated with behaviorally assessed somatosensory sensation avoiding scores. The results show that information about ITC from MEG and EEG signals have substantial overlap, and thus EEG sensor-based ITC measures of the AS somatosensory processing biomarker previously identified using source localized MEG data have a potential to be developed into clinical use in AS, thanks to the higher accessibility to EEG in clinical settings.

Implications of Sensory Processing and Attentional Differences Associated With Autism in Academic Settings: An Integrative Review

The impact of classroom environments on student engagement and academic performance is well-documented. Autism spectrum disorder (ASD) is associated with atypical sensory processing and attentional impairments, which may lead to challenges in successfully accessing educational material within these settings. These symptoms may help explain why students with ASD show discrepancies between intellectual ability and academic performance. Given the increasing number of students with ASD present in classrooms, understanding strengths and weaknesses in sensory processing and attention is necessary in order to design better classroom environments and develop more efficacious accommodations and interventions to support optimal student success. Therefore, the objectives of this review are to provide a brief review of the current literature on sensory processing and attention in ASD, survey how sensory and attentional functions affect academic outcomes in both neurotypical and ASD learners, and suggest potential accommodations/interventions for students with ASD based on these findings.