Individual differences in sensory sensitivity: A synthesizing framework and evidence from normal variation and developmental conditions

Sensory Processing and Executive Functioning in Autistic Adults

PURPOSE

One of the core features that can be experienced by adults on the autism spectrum is hyper- and hyporeactivity to sensory stimuli. Research suggests that executive functioning (EF) impairments are related to sensory issues. In this study the relationship between sensory processing issues and EF was investigated. We expected sensory processing issues to predict EF impairments.

METHODS

Thirty men and 30 women on the autism spectrum, 20 men and 24 women without autism were included and matched on intelligence and age. Group comparisons were conducted to determine if groups differed regarding self-reported sensory processing issues (GSQ-NL) and self-reports on EF (BRIEF-A). Correlational and regression analyses were carried out to investigate the relationship between self-reports on GSQ-NL and BRIEF-A.

RESULTS

We found significant differences between men and women on the spectrum with regard to sensory processing issues and EF. Hyporeactivity to sensory information explained most of the EF problems.

CONCLUSION

Clinicians should be aware of differences in sensory experiences between adults on the spectrum and non-autistic adults and differences between men and women during assessment and subsequent counselling.

Neural gating of respiratory sensations as a potential mechanism of dyspnea perception: State-of-the-art and future directions

CONTEXT

Dyspnea - the subjective experience of breathing discomfort - is a prevalent and debilitating symptom in various chronic conditions, featuring a complex interplay of sensory, cognitive, and emotional factors contributing to its perception. In recent years, growing evidence emerged for the importance of neural processing in shaping symptom experiences such as dyspnea.

OBJECTIVE

This frontiers review focuses on the neural gating of respiratory sensations (NGRS), as a potential neural mechanism underlying dyspnea perception. NGRS is measured by the repetition suppression of respiratory-related evoked potentials (RREP) elicited by paired inspiratory occlusions. NGRS may reflect the brain's capacity to filter redundant respiratory input, and reduced NGRS may constitute a biomarker for aversive dyspnea experience.

REVIEW

We summarize the current state-of-the-art on the relationships between NGRS and dyspnea, noting the inconsistent findings in healthy individuals along with promising evidence from clinical populations, such as chronic obstructive pulmonary disease (COPD). The inconsistent findings may be attributed to methodological limitations, including the significant variability in experimental designs and analytical choices hampering NGRS reliability, and the influence of top-down attention and expectations. In the final part of the review, we suggest future directions for the investigation of the NGRS-dyspnea relationship, including mechanistic research using advanced EEG analysis, mobile neuroimaging, and brain stimulation techniques to delineate the contributions of top-down and bottom-up mechanisms to NGRS.

CONCLUSIONS

By addressing the current knowledge gaps, this review forms a part of the concentrated effort to promote brain-based interventions for alleviating the distressing experience of chronic dyspnea.

Low correlation between visual discomfort image ratings and hypersensitivity questions is improved with functional questions

To assess visual discomfort, researchers can use questionnaires that require people to self-reflect on their real-world experiences, or researchers can present images and ask for ratings of discomfort while they are viewed. These two methods are conceptualised to measure a similar construct, but they tend to show surprisingly low correlation. A possible reason is that, when viewing the images, people do not know how to calibrate their answers on a standard discomfort scale, because it requires implicit comparison of one's own perception with others (e.g., is my perception unusually uncomfortable?). Here we compared standard discomfort ratings with functional questions that aimed to aid calibration (e.g. I would need to immediately look away; I could tolerate it as a poster; I could live with it as wallpaper). We found correlation with questionnaire questions about stripes and patterns improved with the functional style of question. We conclude that functional questions are helpful for assessing visual discomfort.

The effect of individual visual sensitivity on time perception

The human mind, trying to perceive events coherently, creates the illusion of continuous time passage. Empirical evidence suggests distortions in subjectively perceived time flow associated with well-studied neural responses to sensory stimuli. This study aimed to investigate whether visually uncomfortable patterns, causing exceptionally strong brain activation, affect short time estimates and whether these estimates vary based on the overall reported sensory sensitivity and cortical excitability of individuals. Two experiments in virtual reality testing our assumptions at different levels of complexity of timed stimuli provided initial insight into the studied processes in highly controlled and realistic conditions. Data analysis results did not support our hypotheses, but showed that subjectively most visually uncomfortable simple patterns, i.e., achromatic gratings, cause more variable temporal judgments. Supposedly, this inaccuracy depends on the currently perceived visual comfort and thus the current visual system sensitivity, which cannot be satisfactorily derived from trait-based measures. The exploration of the effect of complex stimuli, i.e., virtual exteriors, suggested that their visual comfort does not affect time perception at all. Biological sex was an important variable across experiments, as males experienced temporal compression of stimuli compared to females. Neuroimaging research is needed for a deeper investigation of the origin of these results.Protocol registration: The Stage 1 manuscript associated with this Registered Report was in-principle accepted on 4 March 2024 prior to data collection for hypothesis testing. The accepted version of the manuscript can be found in the publicly available OSF repository at https://doi.org/ https://doi.org/10.17605/OSF.IO/K3YZE .

Working memory capacity modulates Serial dependence in facial Identity: Evidence from behavioral and EEG data

Serial dependence (SD) is said to occur when the judgment of a current stimulus is drawn toward a no longer relevant stimulus from the recent past. Working memory (WM) contributes to the ability to discriminate between irrelevant and relevant sensory impressions. How WM contributes to SD in facial identity remains to be fully understood. In the present study, we used a WM task with varying load interleaved with a facial matching task to investigate the relations between SD in facial identity and WM. EEG was recorded to capture perceptual face processing and WM maintenance. Overall, statistically significant SD effects were obtained only at high WM load. In addition, individual differences in WM capacity predicted SD. Participants with low WM capacity showed significant SD effects regardless of changes in WM load, while participants with high WM capacity showed significant SD only at high WM load. EEG results showed significant differences in perceptual and WM processing for participants with high WM capacity, while no significant differences were obtained for participants with low WM capacity. Neural correlates of WM maintenance, and perceptual processing of a previous face were directly related to SD. The results suggest that WM capacity contributes to SD in facial identity, in terms of selective suppression of task-irrelevant and selective maintenance of task-relevant information.

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.

Traits of Developmental Disorders in Adults With Listening Difficulties Without Diagnosis of Autism Spectrum Disorder And/or Attention-Deficit/Hyperactivity Disorder

Background: Some individuals have a normal audiogram but have listening difficulties (LiD). As many studies have investigated the relationship between listening and developmental disorders, the traits of developmental disorders might explain the symptoms of LiD. In this study, we examined the traits of developmental disorders of adults with LiD to help clarify the cause of LiD symptoms. Methods: In total, 60 adults with LiD and 57 adults without LiD were included. Participants completed a questionnaire for the autism spectrum quotient (AQ) test, the Adult Attention-Deficit Hyperactivity Disorder Self-Rating Scale (A-ADHD), the Adolescent/Adult Sensory Profile (SP), and the severity of subjective LiD in daily life. Results: Before analysis, we excluded participants with LiD who were already diagnosed or met the criteria for autism spectrum disorder (ASD) or ADHD, and the results of the remaining 30 participants (50.0%) with LiD were analyzed. Adults with LiD showed higher scores than those without LiD in the AQ. Attention switching in the AQ and attention ability in the A-ADHD scale were correlated with the severity of LiD symptoms in everyday life. The AQ scores were also significantly correlated with subscales of the SP. Conclusions: Adults with LiD showed greater autistic traits than those without LiD; therefore, LiD symptoms are possibly related to autistic symptoms. Furthermore, adults with LiD might have attention disorder traits of both ASD and ADHD and sensory processing problems. These findings suggest that the attention problems in adults with LiD noted in previous studies might be related to these traits of developmental disorders.

An introduction to the HEALthy Brain and Child Development Study (HBCD) study

The fundamental organization of the human brain is established before birth, with rapid growth continuing over the first postnatal years. Children exposed before or after birth to various biological (e.g., substance exposure) or psychosocial hazards (e.g., maltreatment) are at elevated likelihood of deviating from a typical developmental trajectory, which in turn can be associated with psychological, behavioral, and physical health sequelae. In the HEALthy Brain and Child Development (HBCD) Study, a multi-site prospective longitudinal cohort study, brain, physical, biological, cognitive, behavioral, social, and emotional development is being examined starting in pregnancy and planned through age 10 (data are sampled at varying degrees of granularity depending on age, with more dense sampling earlier in life). HBCD aims to determine the short- and long-term impacts of a variety of both harmful and protective factors, including prenatal substance use, on developmental trajectories through early childhood. Organized as a nationwide consortium across 27 sites, the HBCD Study will collect multimodal data that will be made publicly available on a yearly basis, through a data use application and approval process. Here we provide an overview of the HBCD Study design, sampling, protocol development, and data management. Data collected through HBCD will be fundamental to informing future prenatal and early childhood interventions and policies to promote wellbeing and resilience in all children.

Subjective visual sensitivity in neurotypical adults: insights from a magnetic resonance spectroscopy study

Introduction

Altered subjective visual sensitivity manifests as feelings of discomfort or overload elicited by intense and irritative visual stimuli. This can result in a host of visual aberrations including visual distortions, elementary visual hallucinations and visceral responses like dizziness and nausea, collectively referred to as "pattern glare." Current knowledge of the underlying neural mechanisms has focused on overall excitability of the visual cortex, but the individual contribution of excitatory and inhibitory systems has not yet been quantified.

Methods

In this study, we focus on the role of glutamate and γ-aminobutyric acid (GABA) as potential mediators of individual differences in subjective visual sensitivity, measured by a computerized Pattern Glare Test-a series of monochromatic square-wave gratings with three different spatial frequencies, while controlling for psychological variables related to sensory sensitivity with multiple questionnaires. Resting neurotransmitter concentrations in primary visual cortex (V1) and right anterior insula were studied in 160 healthy participants using magnetic resonance spectroscopy.

Results

Data showed significant differences in the perception of visual distortions (VD) and comfort scores between men and women, with women generally reporting more VD, and therefore the modulatory effect of sex was considered in a further examination. A general linear model analysis showed a negative effect of occipital glutamate on a number of reported visual distortions, but also a significant role of several background psychological traits. When assessing comfort scores in women, an important intervening variable was the menstrual cycle.

Discussion

Our findings do not support that baseline neurotransmitter levels have a significant role in overreactivity to aversive stimuli in neurotypical population. However, we demonstrated that biological sex can have a significant impact on subjective responses. Based on this additional finding, we suggest that future studies investigate aversive visual stimuli while examining the role of biological sex.

Hyper-focus, sticky attention, and springy attention in young autistic children: Associations with sensory behaviors and cognitive ability

The autistic-developed monotropism account suggests that atypical, domain-general attentional hyper-focus on interests is a central aspect of autism, but domain-general attention differences in autism can manifest differently. Prior research suggests autistic children are often slow to disengage attention from stimuli-a pattern often called "sticky attention"-and that they can show reduced novelty preference. These attentional patterns could influence sensory experiences and learning. We used eye-tracking to investigate novelty preference and "sticky attention" in young autistic children; we also examined whether attentional patterns were related to cognitive abilities and caregiver-reported sensory responsiveness. A total of 46 autistic and 28 nonautistic participants, aged between 2 and 4 years, provided usable data. We found no evidence that autistic children exhibited greater "sticky attention" than nonautistics, but "sticky attention" in autism was associated with more caregiver-reported sensory hyper-responsiveness, seeking/interests, and enhanced perception. Autistic children also nonsignificantly trended toward exhibiting reduced novelty preference. Unexpectedly, the time-course of this trending novelty preference difference implied it was not driven by reduced orienting to novelty, but increased returning to already-familiarized stimuli: what we call "springy attention." Exploratory analyses of data from the attentional disengagement task suggest autistic participants may have exhibited greater "springy attention," though further research with paradigms optimized for measuring this construct should confirm this. Importantly, "springy attention" was robustly related to reduced cognitive abilities and greater caregiver-reported hypo-responsiveness. Thus, this study illuminates two distinct domain-general attentional patterns, each with distinct correlates in young autistic children, which could have important implications for understanding autistic children's learning, development, and experiences.

Individual-specific postural discomfort prediction using decision tree models

The objective of the current study was to explore the utilization of the decision tree (DT) algorithm to model posture-discomfort relationships at the individual level. The DT algorithm has the advantage that it makes no assumptions about the distribution of data, is robust in representing non-linear data with noise, and produces white-box models that are interpretable. Individual-level modelling is essential for examining individual-specific postural discomfort perception processes and understanding the inter-individual variability. It also has practical applications, including the development of individual-specific digital human models and more precise and informative population accommodation analysis. Individual-specific DT models were generated using postural discomfort rating data for various seated upper body postures to predict discomfort based on postural and task variables. The individual-specific DT models accurately predicted postural discomfort and revealed large inter-individual variability in the modelling results. DT modelling is expected to greatly facilitate investigating the human discomfort perception process.

Qualitative data on triggers and coping of sensory hypersensitivity in acquired brain injury patients: A proposed model

Sensory hypersensitivity (SHS) is a frequently heard complaint after acquired brain injury (ABI) and is related to reduced quality of life and physical and mental health. This study aimed to identify triggers for SHS after ABI and investigate how individuals cope with SHS. Nineteen adults with ABI took part in 45-min individual interviews. Data were audio-recorded and transcribed verbatim. Inductive thematic analysis revealed five themes: (1) A mismatch between resources and demands, (2) Altered experience of ordinary stimuli, (3) It affects all aspects of living, (4) Avoid, approach, accept, (5) It's highly heterogeneous. A model explaining the impact of triggers on subjective SHS after ABI is proposed, which states that SHS arises from a mismatch between the demands of a sensory environment (triggers) and the available biopsychosocial resources of an individual to meet these demands. The elicited SHS can affect and be affected by levels of fatigue, which limits the resources and creates a loop. Coping strategies can act on various stages of this model, i.e., to reduce the mismatch and potentially alter the loop. This model can contribute to the identification of mechanisms behind SHS in ABI patients and other populations, ultimately leading to evidence-based treatments.

Why am I overwhelmed by bright lights? The behavioural mechanisms of post-stroke visual hypersensitivity

After stroke, patients can experience visual hypersensitivity, an increase in their sensitivity for visual stimuli as compared to their state prior to the stroke. Candidate behavioural mechanisms for these subjective symptoms are atypical bottom-up sensory processing and impaired selective attention, but empirical evidence is currently lacking. In the current study, we aimed to investigate the relationship between post-stroke visual hypersensitivity and sensory thresholds, sensory processing speed, and selective attention using computational modelling of behavioural data. During a whole/partial report task, participants (51 stroke patients, 76 orthopedic patients, and 77 neurotypical adults) had to correctly identify a single target letter that was presented alone (for 17-100 ms) or along a distractor (for 83ms). Performance on this task was used to estimate the sensory threshold, sensory processing speed, and selective attention abilities of each participant. In the stroke population, both on a group and individual level, there was evidence for impaired selective attention and -to a lesser extent- lower sensory thresholds in patients with post-stroke visual hypersensitivity as compared to neurotypical adults, orthopedic patients, or stroke patients without post-stroke sensory hypersensitivity. These results provide a significant advancement in our comprehension of post-stroke visual hypersensitivity and can serve as a catalyst for further investigations into the underlying mechanisms of sensory hypersensitivity after other types of acquired brain injury as well as post-injury hypersensitivity for other sensory modalities.

A transdiagnostic approach to neurodiversity in a representative population sample: The N+ 4 model

Background

The concept of neurodiversity draws upon scientific research, and lessons from practice and lived experience to suggest new ways of thinking about neurodevelopmental conditions. Among the formative observations are that characteristics associated with neurodevelopmental conditions are part of a "broader phenotype" of variation across the whole population, and that there appear to be "transdiagnostic" similarities as well as differences in these characteristics. These observations raise important questions that have implications for understanding diversity in neurodevelopmental conditions and in neurocognitive phenotypes across the whole population.

Method

The present work examines broader phenotypes using seven widely used self-report assessments of traits associated with autism, ADHD, dyslexia, Developmental Coordination Disorder/dyspraxia, tic disorders/Tourette's, cortical hyperexcitability associated with subclinical epilepsy, and sensory sensitivities. A representative sample of 995 adults (aged 17-77) in the UK completed self-report measures of neurodiversity, wellbeing, generalized anxiety, and depression, and cognitive abilities (nonverbal intelligence and executive functioning).

Results

We used confirmatory factor analysis to test whether variation and covariation was better characterized (1) by traditional diagnostic labels, or (2) transdiagnostically according to similarities in functions, behaviours, or phenomena. Results indicated that neurodiversity characteristics were best explained using a bifactor model with one general "N" factor and four condition-specific factors.

Conclusion

This was the largest examination to date of the factor structure of broader phenotypes relevant to neurodevelopmental conditions. It provides critical benchmark data, and a framework approach for asking systematic questions about the structure of neurocognitive diversities seen in the whole population and in people with one or more diagnoses.

Fibromyalgia is linked to increased subjective sensory sensitivity across multiple senses

Changes in subjective sensory sensitivity - reporting sensory stimuli as being atypically intense or weak - are a transdiagnostic symptom of several disorders. The present study documents for the first time the sensory sensitivity profile of fibromyalgia, taking a questionnaire measure that asks about different sensory modalities and both hyper- and hyposensitivity (the Glasgow Sensory Questionnaire, GSQ). The fibromyalgia group had higher overall scores on this measure. This was linked more strongly to sensory hypersensitivity and was pervasive across all senses that were surveyed. Although differences in hyposensitivity were found, these were sporadic (perhaps linked to the symptoms of fibromyalgia itself) and did not resemble the pattern documented for autism (e.g., self-stimulating and repetitive behaviours were not a feature of fibromyalgia). We suggest that individual differences in subjective sensory hypersensitivity may be a multisensory dispositional trait linked to fibromyalgia which ultimately becomes most pronounced for pain.

"Neural Noise" in Auditory Responses in Young Autistic and Neurotypical Children

Elevated "neural noise" has been advanced as an explanation of autism and autistic sensory experiences. However, functional neuroimaging measures of neural noise may be vulnerable to contamination by recording noise. This study explored variability of electrophysiological responses to tones of different intensities in 127 autistic and 79 typically-developing children aged 2-5 years old. A rigorous data processing pipeline, including advanced visualizations of different signal sources that were maximally independent across different time lags, was used to identify and eliminate putative recording noise. Inter-trial variability was measured using median absolute deviations (MADs) of EEG amplitudes across trials and inter-trial phase coherence (ITPC). ITPC was elevated in autism in the 50 and 60 dB intensity conditions, suggesting diminished (rather than elevated) neural noise in autism, although reduced ITPC to soft 50 dB sounds was associated with increased loudness discomfort. Autistic and non-autistic participants did not differ in MADs, and indeed, the vast majority of the statistical tests examined in this study yielded no significant effects. These results appear inconsistent with the neural noise account.

Higher Sensory Sensitivity is Linked to Greater Expansion Amongst Functional Connectivity Gradients

Insofar as the autistic-like phenotype presents in the general population, it consists of partially dissociable traits, such as social and sensory issues. Here, we investigate individual differences in cortical organisation related to autistic-like traits. Connectome gradient decomposition based on resting state fMRI data reliably reveals a principal gradient spanning from unimodal to transmodal regions, reflecting the transition from perception to abstract cognition. In our non-clinical sample, this gradient's expansion, indicating less integration between visual and default mode networks, correlates with subjective sensory sensitivity (measured using the Glasgow Sensory Questionnaire, GSQ), but not other autistic-like traits (measured using the Autism Spectrum Quotient, AQ). This novel brain-based correlate of the GSQ demonstrates sensory issues can be disentangled from the wider autistic-like phenotype.

Assessing Trial-to-Trial Variability in Auditory ERPs in Autism and Schizophrenia

Sensory abnormalities are characteristic of autism and schizophrenia. In autism, greater trial-to-trial variability (TTV) in sensory neural responses suggest that the system is more unstable. However, these findings have only been identified in the amplitude and not in the timing of neural responses, and have not been fully explored in schizophrenia. TTV in event-related potential amplitudes and inter-trial coherence (ITC) were assessed in the auditory mismatch negativity (MMN) in autism, schizophrenia, and controls. MMN was largest in autism and smallest in schizophrenia, and TTV was greater in autism and schizophrenia compared to controls. There were no differences in ITC. Greater TTV appears to be characteristic of both autism and schizophrenia, implicating several neural mechanisms that could underlie sensory instability.

Endogenous noise of neocortical neurons correlates with atypical sensory response variability in the Fmr1-/y mouse model of autism

Excessive neural variability of sensory responses is a hallmark of atypical sensory processing in autistic individuals with cascading effects on other core autism symptoms but unknown neurobiological substrate. Here, by recording neocortical single neuron activity in a well-established mouse model of Fragile X syndrome and autism, we characterized atypical sensory processing and probed the role of endogenous noise sources in exaggerated response variability in males. The analysis of sensory stimulus evoked activity and spontaneous dynamics, as well as neuronal features, reveals a complex cellular and network phenotype. Neocortical sensory information processing is more variable and temporally imprecise. Increased trial-by-trial and inter-neuronal response variability is strongly related to key endogenous noise features, and may give rise to behavioural sensory responsiveness variability in autism. We provide a novel preclinical framework for understanding the sources of endogenous noise and its contribution to core autism symptoms, and for testing the functional consequences for mechanism-based manipulation of noise.

Examining the latent structure and correlates of sensory reactivity in autism: a multi-site integrative data analysis by the autism sensory research consortium

BACKGROUND

Differences in responding to sensory stimuli, including sensory hyperreactivity (HYPER), hyporeactivity (HYPO), and sensory seeking (SEEK) have been observed in autistic individuals across sensory modalities, but few studies have examined the structure of these "supra-modal" traits in the autistic population.

METHODS

Leveraging a combined sample of 3868 autistic youth drawn from 12 distinct data sources (ages 3-18 years and representing the full range of cognitive ability), the current study used modern psychometric and meta-analytic techniques to interrogate the latent structure and correlates of caregiver-reported HYPER, HYPO, and SEEK within and across sensory modalities. Bifactor statistical indices were used to both evaluate the strength of a "general response pattern" factor for each supra-modal construct and determine the added value of "modality-specific response pattern" scores (e.g., Visual HYPER). Bayesian random-effects integrative data analysis models were used to examine the clinical and demographic correlates of all interpretable HYPER, HYPO, and SEEK (sub)constructs.

RESULTS

All modality-specific HYPER subconstructs could be reliably and validly measured, whereas certain modality-specific HYPO and SEEK subconstructs were psychometrically inadequate when measured using existing items. Bifactor analyses supported the validity of a supra-modal HYPER construct (ωH = .800) but not a supra-modal HYPO construct (ωH = .653), and supra-modal SEEK models suggested a more limited version of the construct that excluded some sensory modalities (ωH = .800; 4/7 modalities). Modality-specific subscales demonstrated significant added value for all response patterns. Meta-analytic correlations varied by construct, although sensory features tended to correlate most with other domains of core autism features and co-occurring psychiatric symptoms (with general HYPER and speech HYPO demonstrating the largest numbers of practically significant correlations).

LIMITATIONS

Conclusions may not be generalizable beyond the specific pool of items used in the current study, which was limited to caregiver report of observable behaviors and excluded multisensory items that reflect many "real-world" sensory experiences.

CONCLUSION

Of the three sensory response patterns, only HYPER demonstrated sufficient evidence for valid interpretation at the supra-modal level, whereas supra-modal HYPO/SEEK constructs demonstrated substantial psychometric limitations. For clinicians and researchers seeking to characterize sensory reactivity in autism, modality-specific response pattern scores may represent viable alternatives that overcome many of these limitations.

A multilevel investigation of sensory sensitivity and responsivity in autistic adults

Atypical sensory processing is a core symptom of autism spectrum disorders (ASD). We aimed at better characterizing visual sensitivity and responsivity in ASD at the self-reported, behavioral and neural levels, and at describing the relationships between these levels. We refer to sensory sensitivity as the ability to detect sensory stimuli and to sensory responsivity as an affective response to sensory stimuli. Participants were 25 neurotypical and 24 autistic adults. At the self-reported level, autistic participants had higher scores of sensory sensitivity and responsivity than neurotypicals. The behavioral and neural tasks involved contrast-reversing gratings which became progressively (in)visible as their contrast or spatial frequency evolved. At the behavioral level, autistic participants had higher detection and responsivity thresholds when gratings varied in spatial frequency, but their thresholds did not differ from neurotypicals when gratings varied in contrast. At the neural level, we used fast periodic visual stimulations and electroencephalography to implicitly assess detection thresholds for contrast and spatial frequency, and did not reveal any group difference. Higher self-reported responsivity was associated with higher behavioral responsivity, more intolerance of uncertainty and anxiety, in particular in ASD. At the self-reported level, higher sensitivity was associated with more responsivity in both groups, contrary to the behavioral level where these relationships were not found. These heterogeneous results suggest that sensitivity and responsivity per se are not simply increased in ASD, but may be modulated by other factors such as environmental predictability. Multi-level approaches can shed light on the mechanisms underlying sensory issues in ASD.

The Neuroanatomy of Poststroke Subjective Sensory Hypersensitivity

BACKGROUND

Although subjective sensory hypersensitivity is prevalent after stroke, it is rarely recognized by health care providers, and its neural mechanisms are largely unknown.

OBJECTIVE

To investigate the neuroanatomy of poststroke subjective sensory hypersensitivity as well as the sensory modalities in which subjective sensory hypersensitivity can occur by conducting both a systematic literature review and a multiple case study of patients with subjective sensory hypersensitivity.

METHOD

For the systematic review, we searched three databases (Web of Science, PubMed, and Scopus) for empirical articles discussing the neuroanatomy of poststroke subjective sensory hypersensitivity in humans. We assessed the methodological quality of the included studies using the case reports critical appraisal tool and summarized the results using a qualitative synthesis. For the multiple case study, we administered a patient-friendly sensory sensitivity questionnaire to three individuals with a subacute right-hemispheric stroke and a matched control group and delineated brain lesions on a clinical brain scan.

RESULTS

Our systematic literature search resulted in four studies (describing eight stroke patients), all of which linked poststroke subjective sensory hypersensitivity to insular lesions. The results of our multiple case study indicated that all three stroke patients reported an atypically high sensitivity to different sensory modalities. These patients' lesions overlapped with the right anterior insula, the claustrum, and the Rolandic operculum.

CONCLUSION

Both our systematic literature review and our multiple case study provide preliminary evidence for a role of the insula in poststroke subjective sensory hypersensitivity and suggest that poststroke subjective sensory hypersensitivity can occur in different sensory modalities.

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.

Sensory emotion regulation

Decades of evidence reveal intimate links between sensation and emotion. Yet, discussion of sensory experiences as tools that promote emotion regulation is largely absent from current theorizing on this topic. Here, we address this gap by integrating evidence from social-personality, clinical, cognitive-neuroscience, and animal research to highlight the role of sensation as a tool that can be harnessed to up- or downregulate emotion. Further, we review evidence implicating sensation as a rapid and relatively effortless emotion regulation modality and highlight future research directions. Notably, we emphasize the need to examine the duration of sensory emotion regulation effects, the moderating role of individual and cultural differences, and how sensory strategies interact with other strategies.

Sensory sensitivity after acquired brain injury: A systematic review

Patients with acquired brain injury frequently report experiencing sensory stimuli as abnormally under- (sensory hyposensitivity) or overwhelming (sensory hypersensitivity). Although they can negatively impact daily functioning, these symptoms are poorly understood. To provide an overview of the current evidence on atypical sensory sensitivity after acquired brain injury, we conducted a systematic literature review. The primary aim of the review was to investigate the behavioural and neural mechanisms that are associated with self-reported sensory sensitivity. Studies were included when they studied sensory sensitivity in acquired brain injury populations, and excluded when they were not written in English, consisted of non-empirical research, did not study human subjects, studied pain, related sensory sensitivity to peripheral injury or studied patients with a neurodegenerative disorder, meningitis, encephalitis or a brain tumour. The Web of Science, PubMed and Scopus databases were searched for appropriate studies. A qualitative synthesis of the results of the 81 studies that were included suggests that abnormal sensory thresholds and a reduced information processing speed are candidate behavioural mechanisms of atypical subjective sensory sensitivity after acquired brain injury. Furthermore, there was evidence for an association between subjective sensory sensitivity and structural grey or white matter abnormalities, and to functional abnormalities in sensory cortices. However, further research is needed to explore the causation of atypical sensory sensitivity. In addition, there is a need for the development of adequate diagnostic tools. This can significantly advance the quantity and quality of research on the prevalence, aetiology, prognosis and treatment of these symptoms.

Tackling hypo and hyper sensory processing heterogeneity in autism: From clinical stratification to genetic pathways

As an integral part of autism spectrum symptoms, sensory processing issues including both hypo and hyper sensory sensitivities. These sensory specificities may result from an excitation/inhibition imbalance with a poorly understood of their level of convergence with genetic alterations in GABA-ergic and glutamatergic pathways. In our study, we aimed to characterize the hypo/hyper-sensory profile among autistic individuals. We then explored its link with the burden of deleterious mutations in a subset of individuals with available whole-genome sequencing data. To characterize the hypo/hyper-sensory profile, the differential Short Sensory Profile (dSSP) was defined as a normalized and centralized hypo/hypersensitivity ratio from the Short Sensory Profile (SSP). Including 1136 participants (533 autistic individuals, 210 first-degree relatives, and 267 controls) from two independent study samples (PARIS and LEAP), we observed a statistically significant dSSP mean difference between autistic individuals and controls, driven mostly by a high dSSP variability, with an intermediated profile represented by relatives. Our genetic analysis tended to associate the dSSP and the hyposensitivity with mutations of the GABAergic pathway. The major limitation was the dSSP difficulty to discriminate subjects with a similar quantum of hypo- and hyper-sensory symptoms to those with no such symptoms, resulting both in a similar ratio score of 0. However, the dSSP could be a relevant clinical score, and combined with additional sensory descriptions, genetics and endophenotypic substrates, will improve the exploration of the underlying neurobiological mechanisms of sensory processing differences in autism spectrum.

Associations among perceived taste and smell sensitivity, gastrointestinal symptoms, and restrictive eating in a community sample of adults

Restrictive eating is associated with several poor health outcomes. Exteroceptive sensory modalities, including taste and smell, are employed while eating and disturbances in exteroceptive sensitivity may influence eating behavior. Meal-related gastrointestinal disturbances, such as early satiety and postprandial fullness, are well-documented in eating disorders and may influence eating behavior. This study examined the relationships of perceived sensitivity to taste or smell and gastrointestinal symptoms with restrictive eating, and potential interactions between gastrointestinal symptoms and perceived sensitivity to taste or smell. Adults aged 18-65 were recruited via ResearchMatch.org (N = 420) and completed questionnaires assessing restrictive eating, perceived sensitivity to taste and smell, and gastrointestinal symptom severity. There was a weak relationship between restrictive eating and perceived sensitivity to taste (r = -0.115, p = .022) and smell (r = -0.101, p = .039). There was a strong relationship between gastrointestinal symptom severity and restrictive eating (r = 0.583, p < .001). Gastrointestinal symptom severity moderated the relationship between perceived sensitivity to taste and restrictive eating, such that this relationship was strongest at lower levels of gastrointestinal symptom severity (Estimate = -0.136, p = .014). There was no observed interaction between perceived sensitivity to smell and gastrointestinal symptoms (Estimate = 0.001, p = .156). Results indicate that increased perceived sensitivity to taste, smell, and gastrointestinal symptom severity were each associated with greater restrictive eating. The relationship between perceived sensitivity to taste and restrictive eating is strongest at lower gastrointestinal symptom severity. Future research should examine whether tailoring treatments for individuals who present with elevated perceived sensitivity to taste or smell, gastrointestinal symptoms, or both is effective in reducing restrictive eating.

Hyper-Sensitivity to Pitch and Poorer Prosody Processing in Adults With Autism: An ERP Study

Individuals with autism typically experience a range of symptoms, including abnormal sensory sensitivities. However, there are conflicting reports on the sensory profiles that characterize the sensory experience in autism that often depend on the type of stimulus. Here, we examine early auditory processing to simple changes in pitch and later auditory processing of more complex emotional utterances. We measured electroencephalography in 24 adults with autism and 28 controls. First, tones (1046.5Hz/C6, 1108.7Hz/C#6, or 1244.5Hz/D#6) were repeated three times or nine times before the pitch changed. Second, utterances of delight or frustration were repeated three or six times before the emotion changed. In response to the simple pitched tones, the autism group exhibited larger mismatch negativity (MMN) after nine standards compared to controls and produced greater trial-to-trial variability (TTV). In response to the prosodic utterances, the autism group showed smaller P3 responses when delight changed to frustration compared to controls. There was no significant correlation between ERPs to pitch and ERPs to prosody. Together, this suggests that early auditory processing is hyper-sensitive in autism whereas later processing of prosodic information is hypo-sensitive. The impact the different sensory profiles have on perceptual experience in autism may be key to identifying behavioral treatments to reduce symptoms.

Sensory over-responsivity and obsessive-compulsive disorder: Measuring habituation and sensitivity through self-report, physiological and behavioral indices

Individuals with obsessive-compulsive disorder (OCD) may report Sensory Over Responsivity (SOR), but evidence for specific shared mechanism is limited. This study investigated a habituation-sensitivity mechanism in individuals with OCD (n = 30). Sensory habituation and sensitivity were compared with a neurotypical sample, divided to high (n = 30) and low (n = 30) obsessive-compulsive symptoms (HOCS and LOCS). Participants completed self-report sensory questionnaires and a physiological protocol measuring Electro Dermal Activity (EDA) while presenting aversive and neutral sounds in two conditions: Aversive stimuli followed by neutral stimuli (AVfirst), or neutral stimuli followed by aversive stimuli (NEfirst). In addition, participants could shorten the stimulus duration by pressing a key. LOCS differed from HOCS and OCD in most sensory self-report scores, with no significant difference between OCD and HOCS. HOCS had no significant differences in habituation patterns across conditions, while OCD had no differences in habituation patterns in AVfirst (p = .08) but significantly slower habituation patterns to the NEfirst neutral stimuli (p < .001). Condition order determined sensitivity for LOCS (AVfirst p = .017; NEfirst p = .045) but not for OCD and HOCS. HOCS and OCD shortened aversive stimuli by key pressing more than LOCS, with no significant difference between OCD and HOCS. The habituation process of individuals with OCD and HOCS was more influenced by stimulus type than by condition order, which might be due to a cognitive bias of prediction. Individuals with elevated OCS have difficulty relying upon sensory input to respond adaptively to the environment. This process can explain the avoidant behavior and complains of individuals with OCD not being able to ignore and to habituate to the sensory environment. These evidence warrants design of psychoeducation and intervention methods for relying on prior sensory information to improve functioning in individuals with OCD and SOR.

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.

Autism and chronic ill health: an observational study of symptoms and diagnoses of central sensitivity syndromes in autistic adults

BACKGROUND

Autistic adults, particularly women, are more likely to experience chronic ill health than the general population. Central sensitivity syndromes (CSS) are a group of related conditions that are thought to include an underlying sensitisation of the central nervous system; heightened sensory sensitivity is a common feature. Anecdotal evidence suggests autistic adults may be more prone to developing a CSS. This study aimed to investigate the occurrence of CSS diagnoses and symptoms in autistic adults, and to explore whether CSS symptoms were related to autistic traits, mental health, sensory sensitivity, or gender.

METHODS

The full sample of participants included 973 autistic adults (410 men, 563 women, mean age = 44.6) registered at the Netherlands Autism Register, who completed questionnaires assessing autistic traits, sensory sensitivity, CSS, physical and mental health symptoms. The reliability and validity of the Central Sensitization Inventory (CSI) in an autistic sample was established using exploratory and confirmatory factor analyses. Chi2 analyses, independent t-tests, hierarchical regression and path analysis were used to analyse relationships between CSS symptoms, autistic traits, measures of mental health and wellbeing, sensory sensitivity, age and gender.

RESULTS

21% of participants reported one or more CSS diagnosis, and 60% scored at or above the clinical cut-off for a CSS. Autistic women were more likely to report a CSS diagnosis and experienced more CSS symptoms than men. Sensory sensitivity, anxiety, age and gender were significant predictors of CSS symptoms, with sensory sensitivity and anxiety fully mediating the relationship between autistic traits and CSS symptoms.

LIMITATIONS

Although this study included a large sample of autistic adults, we did not have a control group or a CSS only group. We also could not include a non-binary group due to lack of statistical power.

CONCLUSIONS

CSS diagnoses and symptoms appear to be very common in the autistic population. Increased awareness of an association between autism and central sensitisation should inform clinicians and guide diagnostic practice, particularly for women where CSS are common and autism under recognised.

An German Short-Version of the "Sensory Perception Quotient" for Adults With Autism Spectrum Disorder

Sensory features in autism spectrum disorder (ASD) have received increasing interest in clinical work and research during the recent years. With the Sensory Perception Quotient (SPQ), Tavasolli and colleagues have produced a self-rating scale for adults with ASD that measures sensory hyper-sensitivity in different sensory modalities, without also tapping cognitive or motivational aspects that precede or follow autistic sensory experiences. Here, we present the results of a translation of the SPQ to German and its short version as well as their validation in samples of autistic or neuro-typical participants. We, furthermore, present the psychometric properties and validities of Tavasolli's original SPQ-short version as well as an alternative short version based on different psychometric item-selection criteria. We can show here that our alternative SPQ-short version, overlapping with the original short-version in 61% of its items, exhibits superior reliabilities, reasonable concurrent validities with other related measures. It, furthermore, exhibits excellent differentiation between autistic and non-autistic samples, underscoring its utility as a screening instrument in research and a clinical instrument to supplement the ASD diagnostic process.

Subjective touch sensitivity leads to behavioral shifts in oral food texture sensitivity and awareness

Neurotypical individuals have subjective sensitivity differences that may overlap with more heavily studied clinical populations. However, it is not known whether these subjective differences in sensory sensitivity are modality specific, or lead to behavioral shifts. In our experiment, we measured the oral touch sensitivity and food texture awareness differences in two neurotypical groups having either a high or low subjective sensitivity in touch modality. To measure oral touch sensitivity, individuals performed discrimination tasks across three types of stimuli (liquid, semisolid, and solid). Next, they performed two sorting exercises for two texture-centric food products: cookies and crackers. The stimuli that required low oral processing (liquid) were discriminated at higher rates by participants with high subjective sensitivity. Additionally, discrimination strategies between several foods in the same product space were different across the groups, and each group used attributes other than food texture as differentiating characteristics. The results show subjective touch sensitivity influences behavior (sensitivity and awareness). However, we show that the relationship between subjective touch sensitivity and behavior generalizes beyond just touch to other sensory modalities.

Subjective sensory sensitivity and its relationship with anxiety in people with probable migraine

OBJECTIVE

To better characterize differences in interictal sensory experience in adults with migraine and more comprehensively describe the relevance of anxiety to these experiences.

BACKGROUND

Evidence suggests that sensitivity to sensory input may not be limited to migraine attacks but continues between them. However, there is a need to better understand whether this is the case across senses, and to clearly distinguish sensory experience from measured sensory threshold, which are not straightforwardly related. Previous literature also indicates a co-occurrence between sensory sensitivity, migraine, and anxiety, but this relationship remains to be fully elucidated.

METHODS

The present cross-sectional study used online questionnaires to investigate how self-reported sensory experiences relate to migraine in a large community sample including 117 individuals with probable migraine and 827 without. Mediation analyses were also used to determine whether any relationship between migraine and sensory sensitivity was mediated by anxiety.

RESULTS

Significant increases in subjective reports of sensory sensitivity (d = 0.80) and sensory avoidance (d = 0.71) were found in participants with migraine. Anxiety symptoms partially mediated the relationship between subjective sensory sensitivity and migraine. Finally, visual, movement, and auditory subscales were found to provide unique explanatory variance in analyses predicting the incidence of migraine (area under the curve = 0.73, 0.69, 0.62 respectively).

CONCLUSION

Subjective sensory sensitivities are present between attacks and across senses in individuals with migraine. Anxiety symptoms are relevant to this relationship; however, sensory sensitivities appear to exist independent of this affective influence. The implications of interictal sensitivities for the daily lives of those with migraine should, therefore, be considered in clinical management wherever appropriate.

What is the Link Between Mental Imagery and Sensory Sensitivity? Insights from Aphantasia

People with aphantasia have impoverished visual imagery so struggle to form mental pictures in the mind's eye. By testing people with and without aphantasia, we investigate the relationship between sensory imagery and sensory sensitivity (i.e., hyper- or hypo-reactivity to incoming signals through the sense organs). In Experiment 1 we first show that people with aphantasia report impaired imagery across multiple domains (e.g., olfactory, gustatory etc.) rather than simply vision. Importantly, we also show that imagery is related to sensory sensitivity: aphantasics reported not only lower imagery, but also lower sensory sensitivity. In Experiment 2, we showed a similar relationship between imagery and sensitivity in the general population. Finally, in Experiment 3 we found behavioural corroboration in a Pattern Glare Task, in which aphantasics experienced less visual discomfort and fewer visual distortions typically associated with sensory sensitivity. Our results suggest for the very first time that sensory imagery and sensory sensitivity are related, and that aphantasics are characterised by both lower imagery, and lower sensitivity. Our results also suggest that aphantasia (absence of visual imagery) may be more accurately defined as a subtype of a broader imagery deficit we name dysikonesia, in which weak or absent imagery occurs across multiple senses.

Visual gamma oscillations predict sensory sensitivity in females as they do in males

Gamma oscillations are driven by local cortical excitatory (E)-inhibitory (I) loops and may help to characterize neural processing involving excitatory-inhibitory interactions. In the visual cortex reliable gamma oscillations can be recorded with magnetoencephalography (MEG) in the majority of individuals, which makes visual gamma an attractive candidate for biomarkers of brain disorders associated with E/I imbalance. Little is known, however, about if/how these oscillations reflect individual differences in neural excitability and associated sensory/perceptual phenomena. The power of visual gamma response (GR) changes nonlinearly with increasing stimulation intensity: it increases with transition from static to slowly drifting high-contrast grating and then attenuates with further increase in the drift rate. In a recent MEG study we found that the GR attenuation predicted sensitivity to sensory stimuli in everyday life in neurotypical adult men and in men with autism spectrum disorders. Here, we replicated these results in neurotypical female participants. The GR enhancement with transition from static to slowly drifting grating did not correlate significantly with the sensory sensitivity measures. These findings suggest that weak velocity-related attenuation of the GR is a reliable neural concomitant of visual hypersensitivity and that the degree of GR attenuation may provide useful information about E/I balance in the visual cortex.

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.

A distinct electrophysiological signature for synaesthesia that is independent of individual differences in sensory sensitivity

People with synaesthesia have been reported to show atypical electrophysiological responses to certain simple sensory stimuli, even if these stimuli are not inducers of synaesthesia. However, it is unclear whether this constitutes a neural marker that is relatively specific to synaesthesia or whether it reflects some other trait that co-occurs with synaesthesia, but is not specific to it. One candidate is atypical sensory sensitivity (e.g., strong aversion to certain lights and sounds, 'sensory overload') which is a feature of both synaesthesia and autism and that varies greatly in the neurotypical population. Using visual evoked-potentials (to stimuli varying in spatial frequency) and auditory-evoked potentials (to stimuli varying in auditory frequency), we found that synaesthetes had a modulated visual evoked-potential around P1/N1 (emanating from fusiform cortex), a greater auditory N1, as well as differences in the time-frequency domain (increased alpha and beta induced power for visual stimuli). This was distinct from that found in non-synaesthetes. By contrast, no significant electrophysiological differences were found that were linked to neurotypical variation in sensory sensitivity.

A review of decreased sound tolerance in autism: Definitions, phenomenology, and potential mechanisms

Atypical behavioral responses to environmental sounds are common in autistic children and adults, with 50-70 % of this population exhibiting decreased sound tolerance (DST) at some point in their lives. This symptom is a source of significant distress and impairment across the lifespan, contributing to anxiety, challenging behaviors, reduced community participation, and school/workplace difficulties. However, relatively little is known about its phenomenology or neurocognitive underpinnings. The present article synthesizes a large body of literature on the phenomenology and pathophysiology of DST-related conditions to generate a comprehensive theoretical account of DST in autism. Notably, we argue against conceptualizing DST as a unified construct, suggesting that it be separated into three phenomenologically distinct conditions: hyperacusis (the perception of everyday sounds as excessively loud or painful), misophonia (an acquired aversive reaction to specific sounds), and phonophobia (a specific phobia of sound), each responsible for a portion of observed DST behaviors. We further elaborate our framework by proposing preliminary neurocognitive models of hyperacusis, misophonia, and phonophobia that incorporate neurophysiologic findings from studies of autism.

Disorder-specific alterations of tactile sensitivity in neurodevelopmental disorders

Alterations of tactile processing have long been identified in autism spectrum disorders (ASD) and attention-deficit/hyperactivity disorder (ADHD). However, the extent to which these alterations are disorder-specific, rather than disorder-general, and how they relate to the core symptoms of each disorder, remains unclear. We measured and compared tactile detection, discrimination, and order judgment thresholds between a large sample of children with ASD, ADHD, ASD + ADHD combined and typically developing controls. The pattern of results suggested that while difficulties with tactile detection and order judgement were more common in children with ADHD, difficulties with tactile discrimination were more common in children with ASD. Interestingly, in our subsequent correlation analyses between tactile perception and disorder-specific clinical symptoms, tactile detection and order judgment correlated exclusively with the core symptoms of ADHD, while tactile discrimination correlated exclusively with the symptoms of ASD. When taken together, these results suggest that disorder-specific alterations of lower-level sensory processes exist and are specifically related to higher-level clinical symptoms of each disorder.

Improvements and Degradation to Spatial Tactile Acuity Among Blind and Deaf Individuals

Cross-modal reorganization takes place for sensory cortices when there is no more primary input. For instance, the visual cortex in blind individuals which receives no visual input starts responding to auditory and tactile stimuli. Reorganization may improve or degrade processing of other modality inputs, via bottom-up compensational processes and top-down updating. In two experiments, we measured the spatial tactile response in a large sample of early- (N = 49) and late-blind (N = 51) individuals with varying levels of Braille proficiencies, and early-deaf (N = 69) with varying levels of hearing devices against separate hearing and sighted controls. Spatial tactile responses were measured using a standard gradient orientation task on two locations, the finger and tongue. Experiments show limited to no advantage in passive tactile response for blind individuals and degradation for deaf individuals at the finger. However, the use of hearing devices decreased the tactile impairment in early-deaf individuals. Also, no differences in age-related decline in both sensory-impaired groups were shown. Results show less tactile acuity differences between blind and sighted than previously reported, but supports recent reports of tactile impairment among the early-deaf.

Greater hippocampal gray matter volume in subjective hyperosmia: a voxel-based morphometry study

Subjective hyperosmia refers to a self-reported olfactory ability that is superior to a normal, intact sense of smell (normosmia), and is associated with olfactory emotional experience. The current study used voxel-based morphometry to investigate the gray matter volume (GMV) in people with self-rated hyperosmia (subjective hyperosmia, SH, N = 18) in comparison to people with self-rated normal olfaction (subjective normosmia, SN, N = 14). Participants’ olfactory function were assessed by the extensive olfactory test battery, the “Sniffin’ Sticks” test. Within the predicted brain regions (regions-of-interest analyses), the SH participants showed larger GMV of the left hippocampus as compared to SN participants (FWE corrected p < 0.05). Further, the whole-brain search indicated that SH had larger GMV of the bilateral hippocampus, the right hypothalamus, the left precuneus, and the left superior frontal gyrus as compared to the SN group. ROI analyses showed positive correlations between the left hippocampal GMV and odor threshold or discrimination scores across all participants. In addition, the whole-brain analysis suggested that the self-rated olfactory ability was positively associated with GMV in the cerebellum, superior frontal gyrus and the precentral gyrus among SH participants. In conclusion, the current results suggest that SH was associated with increased GMV in several brain regions that were previously shown to be involved in the processing of cognitive aspects of odors.

Perceptual category learning in autism spectrum disorder: Truth and consequences

The ability to categorize is fundamental to cognitive development. Some categories emerge effortlessly and rapidly while others can take years of experience to acquire. Children with autism spectrum disorder (ASD) are often able to name and sort objects, suggesting that their categorization abilities are largely intact. However, recent experimental work shows that the categories formed by individuals with ASD may diverge substantially from those that most people learn. This review considers how atypical perceptual category learning can affect cognitive development in children with ASD and how atypical categorization may contribute to many of the socially problematic symptoms associated with this disorder. Theoretical approaches to understanding perceptual processing and category learning at both the behavioral and neural levels are assessed in relation to known alterations in perceptual category learning associated with ASD. Mismatches between the ways in which children learn to organize perceived events relative to their peers and adults can accumulate over time, leading to difficulties in communication, social interactions, academic performance, and behavioral flexibility.

The Dutch Sensory Perception Quotient-Short in adults with and without autism

Sensory symptoms were recently added to the diagnostic criteria of autism spectrum disorder and may be a mechanism underlying the broad phenotype of autism spectrum disorder. To measure sensory symptoms based on perceptual rather than affective, regulative, or attention components, the Sensory Perception Quotient (SPQ) measuring five modalities of sensory sensitivity has been developed. In this study, the Dutch translation of the abridged SPQ-Short was investigated in a large sample of adults with (n = 657) and without autism spectrum disorder (n = 585). Its hypothesized factor structure, combining modality specific and one modality-independent factor, was assessed in a hierarchical model. Results show that modality-specific subscales are indeed present in the short version. Furthermore, its reliability is high and comparable to the original English version. The autism spectrum disorder group reported higher sensory sensitivities than the comparison group, and women with autism spectrum disorder reported higher sensitivities compared with men with autism spectrum disorder. The SPQ-Short correlates with all Autism Quotient (AQ)-Short subscales, except for the “imagination” subscale. The SPQ-Short seems suitable to further explore the relationship between basic sensory sensitivities in autism spectrum disorder and their related symptoms such as over- and under-responsivity to sensory stimulation.

Defining clusters of young autistic and typically developing children based on loudness-dependent auditory electrophysiological responses

BACKGROUND

Autistic individuals exhibit atypical patterns of sensory processing that are known to be related to quality of life, but which are also highly heterogeneous. Previous investigations of this heterogeneity have ordinarily used questionnaires and have rarely investigated sensory processing in typical development (TD) alongside autism spectrum development (ASD).

METHODS

The present study used hierarchical clustering in a large sample to identify subgroups of young autistic and typically developing children based on the normalized global field power (GFP) of their event-related potentials (ERPs) to auditory stimuli of four different loudness intensities (50, 60, 70, 80 dB SPL): that is, based on an index of the relative strengths of their neural responses across these loudness conditions.

RESULTS

Four clusters of participants were defined. Normalized GFP responses to sounds of different intensities differed strongly across clusters. There was considerable overlap in cluster assignments of autistic and typically developing participants, but autistic participants were more likely to display a pattern of relatively linear increases in response strength accompanied by a disproportionately strong response to 70 dB stimuli. Autistic participants displaying this pattern trended towards obtaining higher scores on assessments of cognitive abilities. There was also a trend for typically developing participants to disproportionately fall into a cluster characterized by disproportionately/nonlinearly strong 60 dB responses. Greater auditory distractibility was reported among autistic participants in a cluster characterized by disproportionately strong responses to the loudest (80 dB) sounds, and furthermore, relatively strong responses to loud sounds were correlated with auditory distractibility. This appears to provide evidence of coinciding behavioral and neural sensory atypicalities.

LIMITATIONS

Replication may be needed to verify exploratory results. This analysis does not address variability related to classical ERP latencies and topographies. The sensory questionnaire employed was not specifically designed for use in autism. Hearing acuity was not measured. Variability in sensory responses unrelated to loudness is not addressed, leaving room for additional research.

CONCLUSIONS

Taken together, these data demonstrate the broader benefits of using electrophysiology to explore individual differences. They illuminate different neural response patterns and suggest relationships between sensory neural responses and sensory behaviors, cognitive abilities, and autism diagnostic status.

Synesthesia and the Perception of Unseen Realities

Exceptional experiences (ExE) incorporate a range of phenomena including subjective paranormal and transpersonal experiences. Synesthesia and synesthetic experiences are discussed as important variables in understanding the etiologies of ExE. The neural and psychological correlates of synesthetic experiences (associated with hyperconnectivity) are discussed in relation to ExE. It is argued that synesthetic processes enable both the detection and conscious perception of information from a range of sources that are usually unseen or inaccessible, including abstract, unlanguaged, preconscious, and potentially other nonlocal sources.