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.

Probing the Neurophysiology of Temporal Sensitivity in the Somatosensory System Using the Mismatch Negativity (MMN) Sensory Memory Paradigm.

Duration is an amodal feature common to all sensory experiences, but low-level processing of the temporal qualities of somatosensation remains poorly understood. The goal of the present study was to evaluate electrophysiological discrimination of parametric somatosensory stimuli to better understand how the brain processes the duration of tactile information. This research used a somatosensory mismatch negativity (sMMN) paradigm to evaluate electrophysiological sensitivity to differences in the duration of vibrotactile stimuli in healthy young adults. Specifically, a 100 ms standard vibration was presented 80% of the time while the remaining 20% of presentations were made up of deviant stimuli with one of the following durations: 115, 130, 145, or 160 ms. When a deviation from the anticipated tactile input is detected, the distinct electrophysiological signature of the sMMN is present. A companion behavioral task assessed individual thresholds for cognizant awareness of the standard and deviant vibrotactile stimuli. The results of the present study demonstrated a sMMN response when deviant stimuli were 130, 145, and 160 ms, but not when they were 115 ms. This suggests that on average the participants did not electrophysiologically discriminate between the 100 and 115 ms. Future work may apply this paradigm to better understand atypical tactile sensitivity in various clinical conditions.

Electrophysiological Studies of Reception of Facial Communication in Autism Spectrum Disorder and Schizophrenia.

Autism spectrum disorder (ASD) and schizophrenia spectrum disorders (SZ) are characterized by difficulty with social cognition and atypical reception of facial communication - a key area in the Research Domain Criteria framework. To identify areas of overlap and dissociation between ASD and SZ, we review studies of event-related potentials (ERP) to faces across ASD and SZ populations, focusing on ERPs implicated in social perception: P100, N170, N250, and P300. There were many inconsistent findings across studies; however, replication was strongest for delayed N170 latency in ASD and attenuated N170 amplitude in SZ. These results highlight the challenges of replicating research findings in heterogeneous clinical populations and the need for transdiagnostic research that continuously quantifies behavior and neural activity across neurodevelopmental disorders.

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

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

Investigating Motor Preparation in Autism Spectrum Disorder With and Without Attention Deficit/Hyperactivity Disorder.

This study investigated motor preparation and action-consequence prediction using the lateralized readiness potential (LRP). Motor impairments are common in autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD), which commonly co-occur. Alterations in predictive processes may impact motor planning. Whether motor planning deficits are characteristic of ASD broadly or magnified in the context of co-morbid ADHD is unclear. ASD children with (ASD + ADHD; n = 12) and without (ASD - ADHD; n = 9) comorbid ADHD and typical controls (n = 29) performed voluntary motor actions that either did or did not result in auditory consequences. ASD - ADHD children demonstrated LRP enhancement when their action produced an effect while ASD + ADHD children had attenuated responses regardless of action-effect pairings. Findings suggest influence of ADHD comorbidity on motor preparation and prediction in ASD.

Social visual attentional engagement and memory in Phelan-McDermid syndrome and autism spectrum disorder: a pilot eye tracking study.

BACKGROUND: The current study used eye tracking to investigate attention and recognition memory in Phelan-McDermid syndrome (PMS), a rare genetic disorder characterized by intellectual disability, motor delays, and a high likelihood of comorbid autism spectrum disorder (ASD). Social deficits represent a core feature of ASD, including decreased propensity to orient to or show preference for social stimuli. METHODS: We used a visual paired-comparison task with both social and non-social images, assessing looking behavior to a novel image versus a previously viewed familiar image to characterize social attention and recognition memory in PMS (n = 22), idiopathic ASD (iASD, n = 38), and typically developing (TD) controls (n = 26). The idiopathic ASD cohort was divided into subgroups with intellectual disabilities (ID; developmental quotient < 70) and without (developmental quotient > 70) and the PMS group into those with and without a co-morbid ASD diagnosis. RESULTS: On measures of attention, the PMS group with a comorbid ASD diagnosis spent less time viewing the social images compared to non-social images; the rate of looking back and forth between images was lowest in the iASD with ID group. Furthermore, while all groups demonstrated intact recognition memory when novel non-social stimuli were initially presented (pre-switch), participants with PMS showed no preference during the post-switch memory presentation. In iASD, the group without ID, but not the group with ID, showed a novelty preference for social stimuli. Across indices, individuals with PMS and ASD performed more similarly to PMS without ASD and less similarly to the iASD group. CONCLUSION: These findings demonstrate further evidence of differences in attention and memory for social stimuli in ASD and provide contrasts between iASD and PMS.

Oculomotor corollary discharge signaling is related to repetitive behavior in children with autism spectrum disorder.

Corollary discharge (CD) signals are "copies" of motor signals sent to sensory regions that allow animals to adjust sensory consequences of self-generated actions. Autism spectrum disorder (ASD) is characterized by sensory and motor deficits, which may be underpinned by altered CD signaling. We evaluated oculomotor CD using the blanking task, which measures the influence of saccades on visual perception, in 30 children with ASD and 35 typically developing (TD) children. Participants were instructed to make a saccade to a visual target. Upon saccade initiation, the presaccadic target disappeared and reappeared to the left or right of the original position. Participants indicated the direction of the jump. With intact CD, participants can make accurate perceptual judgements. Otherwise, participants may use saccade landing site as a proxy of the presaccadic target and use it to inform perception. We used multilevel modeling to examine the influence of saccade landing site on trans-saccadic perceptual judgements. We found that, compared with TD participants, children with ASD were more sensitive to target displacement and less reliant on saccade landing site when spatial uncertainty of the post-saccadic target was high. This pattern was driven by ASD participants with less severe restricted and repetitive behaviors. These results suggest a relationship between altered CD signaling and core ASD symptoms.

Atypical and inflexible visual encoding in autism spectrum disorder.

Encoding, which involves translating sensory information into neural representations, is a critical first step in the sensory-perceptual pathway. Using a visual orientation task, a new study found both lower encoding capacity and less flexible adaptation in people with autism spectrum disorder.

Reduced engagement of visual attention in children with autism spectrum disorder.

LAY ABSTRACT: Limited eye contact and difficulty tracking where others are looking are common in people with autism spectrum disorder. It is unclear, however, whether these are specifically social differences; it is possible that they are a result of broader alterations in engaging and disengaging visual attention. We used eye-tracking technology with children with autism spectrum disorder (n = 35) and typical development (n = 32), showing them both social and nonsocial imaging to test their visual attention. Children with autism spectrum disorder had a significant difference in how long it took them to look from an image in the middle to one on the side, depending on whether the middle image stayed on the screen or flashed off before the one on the side appeared. This difference was present for both social and nonsocial images, and was related to cognitive ability for only the children with autism spectrum disorder. Our findings suggest that children with autism spectrum disorder have differences in general processes of engaging visual attention that are not specifically social in nature, and that these processes may relate to cognitive ability in autism spectrum disorder. Affected processes of visual engagement in autism spectrum disorder may contribute to symptoms like reduced eye contact, but social-specific symptoms of autism spectrum disorder likely do not stem from reduced visual engagement alone.

Brief Report: A Job-Based Social Skills Program (JOBSS) for Adults with Autism Spectrum Disorder: A Pilot Randomized Controlled Trial.

Adults with autism spectrum disorder (ASD) have low employment rates; even those who are employed have low wages and limited hours. This study evaluated the effectiveness of the Job-Based Social Skills (JOBSS) curriculum, a manualized, 15-week, group-delivered intervention for adults with ASD. The intervention aimed to increase social-pragmatic skills necessary to obtain and maintain employment. Twenty-two adults were randomly assigned to either JOBSS intervention or wait-list control groups. Results showed significant improvement in social cognition, as reported by caregivers, among JOBSS group participants compared to wait-list control participants. Forty-five percent of intervention participants gained employment in the six months following participation. This curriculum has potential to improve social skills of adults with ASD, thereby increasing successful employment.