Molecular Autism

Genetic variants linked to autism are thought to change cognition and behaviour by altering the structure and function of the brain. Although a substantial body of literature has identified structural brain differences in autism, it is unknown whether autism-associated common genetic variants are linked to changes in cortical macro- and micro-structure. We investigated this using neuroimaging and genetic data from adults (UK Biobank, N = 31,748) and children (ABCD, N = 4,928). Using polygenic scores and genetic correlations we observe a robust negative association between common variants for autism and a magnetic resonance imaging derived phenotype for neurite density (intracellular volume fraction) in the general population. This result is consistent across both children and adults, in both the cortex and in white matter tracts, and confirmed using polygenic scores and genetic correlations. There were no sex differences in this association. Mendelian randomisation analyses provide no evidence for a causal relationship between autism and intracellular volume fraction, although this should be revisited using better powered instruments. Overall, this study provides evidence for shared common variant genetics between autism and cortical neurite density.

Functional brain networks are altered in Autism Spectrum Disorder (ASD), with differences in thalamocortical connectivity detectable as early as infancy. ASD shows distinct sex differences, not only in diagnostic rates, but also in brain and behavioral manifestations of the condition. Although common variants account for much of the genetic liability for ASD, little is known about the impact of ASD-associated genetic variation on functional brain connectivity and behavioral outcomes in early life or how this may differ between males and females. Here, we utilize functional MRI (fMRI), genetic, and behavioral data from the Developing Human Connectome Project (dHCP) to investigate sex differences in the association between ASD polygenic scores (PGS), thalamocortical functional connectivity (37-44 weeks postmenstrual age), and behavioral outcomes (18 months) in European term-born infants. We show that across the full sample, higher ASD PGS is associated with weaker thalamic connectivity with posterior parietal cortex, as well as greater ASD-related and ADHD symptoms and slower motor development. Sex differences in the relationship between ASD PGS and thalamic connectivity largely encompassed sensorimotor, posterior parietal, temporal, and insular cortices. Further, in female infants, thalamic connectivity patterns associated with greater genetic liability for ASD were related to poorer motor development. These findings suggest genetic predisposition for ASD shapes early thalamocortical functional connectivity in a sex-specific manner and negatively impacts behavioral development in early toddlerhood.

Autism is a highly heterogeneous neurodevelopmental condition, currently diagnosed based on behavioural characteristics. Candidate early intermediate phenotypes, such as the Pupillary Light Reflex (PLR), a reflexive constriction of the pupil in response to increased optical luminance, may provide insights into etiological factors and potential biomarkers, such as DNA methylation (DNAm), involved in the emergence of autism. We conducted epigenome-wide DNAm association analyses of 9-, 14-, 24-month PLR onset latency and constriction amplitude in a sample of 51 infants enriched for autism family history, using buccal DNA collected at 9-months. Our epigenome-wide analysis (EWAS) identified four stringently significant differentially methylated probes (p < 2.4 x 10-7) associated with cross-section PLR latency measurements at 14- and 24-months, and with 14-to 24-month PLR latency developmental change. Differentially methylated probes associated with PLR amplitude were identified, but at a less stringent discovery threshold (p < 5 x 10-5). Our region analyses identified several significant differentially methylated regions associated with both PLR latency and amplitude Downstream exploratory pathway analysis identified enrichment for multiple developmental biological processes, as well as several susceptibility genes to autism and related neurodevelopmental conditions including NR4A2, HNRNPU and NAV2. Our findings provide novel insight into the role of DNAm in PLR development and illuminate biological mechanisms underpinning altered PLR in infancy in emerging autism.

Language impairment is the most frequently reported co-occurring condition in autism; however, its neural mechanisms are not well understood. A potential neural biomarker associated with language in autism can be a 40Hz Auditory Steady-State Response (ASSR) triggered by periodic click trains which in electroencephalogram (EEG) evokes two types of responses - 40Hz steady-state gamma response (or ASSR) and sustained potential (SP). Although these responses represent low-level auditory processing, they correspond to different stages of sound perception/analysis and are essential in processing of spectrally/temporally complex sounds, including speech. However, until now there were no studies focusing on the potential of these responses to serve as objective measures in clinical trials. This open-label clinical trial evaluated the effects of the probiotic beverage supplement Bio-K+ in children with autism. Participants were assessed at three timepoints: T0 (baseline), T14 (14 weeks after treatment initiation), and T22 (8 weeks post-treatment, during the wash-out phase), including EEG 40Hz ASSR and behavioral phenotyping. First, at T0 we showed a reduction of SP amplitude in children with autism compared to typically-developing (TD) controls, and this reduction was associated with lower language skills. Second, the amplitude of SP significantly changed during the treatment period: by T14 it became similar to that of TD children. Finally, these changes in the amplitude of SP were associated with improvement in language skills. Importantly, we showed that this biomarker as well as its change was related specifically to language, but not to other behavioral measures.

Sensory processing differences are a core feature of autism, affecting 60-95% of individuals, yet the associated neural mechanisms remain unclear. An excitation-inhibition (E/I) imbalance in brain circuits has been proposed, but in vivo evidence linking genetic variation in E/I pathways, regional neurochemistry, neural circuit function, and sensory behaviour has been lacking. Here we performed a multimodal investigation in 206 individuals (130 autistic), integrating gene-set polygenic scores for excitatory glutamatergic and inhibitory gamma-aminobutyric acid (GABA)-ergic pathways, magnetic resonance spectroscopy (MRS) measures of regional GABA and Glx (glutamate + glutamine) levels, vibrotactile psychophysical measures of tactile perception, and questionnaire measures of behavioural sensory reactivity. We found that glutamatergic polygenic scores predicted thalamic glutamate levels in neurotypical but not autistic individuals, suggesting altered genotype-neurochemistry coupling in autism. Thalamic Glx:GABA levels associated with tactile perception in both groups, but with opposing directions of effect, indicating that autistic and neurotypical individuals achieve similar perceptual outcomes with potentially differing thalamocortical circuit mechanisms. Within autistic individuals, tactile perceptual differences further related to behavioural sensory reactivity. Together, these findings suggest that autistic sensory processing potentially relies on distinct circuit mechanisms linking genetic variation, neurochemistry and perception. This work thus has important implications for how sensory differences are conceptualised, studied, and interpreted, and ultimately for how interventions and support are developed.

Suppressing responses to repetitive sounds, while staying vigilant to rare sounds, is a cross-species trait vital for survival, which is altered in autism spectrum disorder (ASD). Preclinical models implicate {Upsilon}-aminobutyric acid (GABA) in this process. Although differences in GABA genes, post-mortem markers and bulk tissue GABA levels have been observed in ASD, the link between GABA and auditory processing in humans (with or without ASD) is largely correlational. Here, we directly evaluated the role of GABA in auditory repetition suppression in 66 adults (n = 28 with ASD). Neurophysiological responses (temporal and frequency domains) to repetitive standard tones and novel deviants presented in an oddball paradigm were compared after double-blind, randomized administration of placebo, 15 or 30 mg of arbaclofen (STX209), a GABA type B (GABAB) receptor agonist. We first established that temporal mismatch negativity was comparable between control participants and those with ASD. Next, we showed that temporal and spectral responses to repetitive standards were suppressed relative to responses to deviants in the two groups, but suppression was significantly weaker in individuals with ASD at baseline. Arbaclofen reversed weaker suppression of spectral responses in ASD but disrupted suppression in controls. An individual sensitivity index of arbaclofen-elicited shift in suppression strongly correlated with autistic symptomatology measured using the Autism Quotient. Thus, our results confirm: GABAergic dysfunction is fundamental to the neurophysiology of auditory sensory processing alterations in ASD, which can be modulated by targeting GABAB activity; and these GABA-dependent sensory differences may be upstream of more complex autistic phenotypes. One Sentence SummaryDifferences in GABAergic function are fundamental to autistic (auditory) sensory neurobiology; but are modulated by targeting GABAB.

BackgroundGenes associated with Intellectual disability (ID) can be grouped into networks according to gene function. This study asked whether individuals with ID show differences in autism spectrum characteristics (ASC), depending on the functional network membership of their rare, pathogenic de novo genetic variants. MethodsChildren and young people with ID of known genetic origin were allocated to two broad functional network groups: synaptic physiology (n=29) or chromatin regulation (n=23). We applied principle components analysis to the Social Responsiveness Scale to map the structure of ASC in this population, and identified three components - Inflexibility, Social Understanding and Social Motivation. We then used Akaike Information Criterion (AIC) to test the best fitting models for predicting ASC components, including demographic factors (age, gender), non-ASC behavioural factors (global adaptive function, anxiety, hyperactivity, inattention) and gene functional networks. ResultsWe found that, when other factors are accounted for, the chromatin regulation group showed higher levels of Inflexibility. We also observed contrasting predictors of ASC within each network group. Within the chromatin regulation group, Social Understanding was associated with inattention, and Social Motivation was predicted by hyperactivity. Within the synaptic group, Social Understanding was associated with hyperactivity, and Social Motivation was linked to anxiety. ConclusionWe report that gene functional networks can predict Inflexibility, but not other ASC dimensions. Contrasting behavioural associations within each group suggests network-specific developmental pathways from genomic variation to autism. Simple classification of neurodevelopmental disorder genes as high risk or low risk for autism is unlikely to be valid or useful.

The genetic heterogeneity of autism has stymied the search for causes and cures. Even whole-genomic studies on large numbers of families have yielded results of relatively little impact. In the present work, we analyze two genomic databases using a novel strategy that takes prior knowledge of genetic relationships into account and that was designed to boost signal important to our understanding of the molecular basis of autism. Our strategy was designed to identify significant genomic variation within a priori defined biological concepts and improves signal detection while lessening the severity of multiple test correction seen in standard analysis of genome-wide association data. Upon application of our approach using 3,244 biological concepts, we detected genomic variation in 68 biological concepts with significant association to autism in comparison to family-based controls. These concepts clustered naturally into a total of 19 classes, principally including cell adhesion, cancer, and immune response. The top-ranking concepts contained high percentages of genes already suspected to play roles in autism or in a related neurological disorder. In addition, many of the sets associated with autism at the DNA level also proved to be predictive of changes in gene expression within a separate population of autistic cases, suggesting that the signature of genomic variation may also be detectable in blood-based transcriptional profiles. This robust cross-validation with gene expression data from individuals with autism coupled with the enrichment within autism-related neurological disorders supported the possibility that the mutations play important roles in the onset of autism and should be given priority for further study. In sum, our work provides new leads into the genetic underpinnings of autism and highlights the importance of reanalysis of genomic studies of complex disease using prior knowledge of genetic organization. Author SummaryThe genetic heterogeneity of autism has stymied the search for causes and cures. Even whole-genomic studies on large numbers of families have yielded results of relatively little impact. In the present work, we reanalyze two of the most influential whole-genomic studies using a novel strategy that takes prior knowledge of genetic relationships into account in an effort to boost signal important to our understanding of the molecular structure of autism. Our approach demonstrates that these genome wide association studies contain more information relevant to autism than previously realized. We detected 68 highly significant collections of mutations that map to genes with measurable and significant changes in gene expression in autistic individuals, and that have been implicated in other neurological disorders believed to be closely related, and genetically linked, to autism. Our work provides leads into the genetic underpinnings of autism and highlights the importance of reanalysis of genomic studies of disease using prior knowledge of genetic organization.

Autism Spectrum Disorder (ASD) is a large set of neurodevelopmental disorders of complex aetiology. A mix of genetic and environmental factors are likely to cause ASD. Genetic risk for autism comes from common genetic variation. Genomic imprinting refers to genes that have different expression patterns according to the parent of origin - being silenced when imprinted. Paternally active genes increase resource extraction from the mother and reduce resource burden on the father. Children with ASD show consistent overgrowth during their first 1-2 years of life. Recently, it has been shown that children with higher birth weight and length have an increased risk of developing ASD. This overgrowth and apparent larger birth weight and length are consistent with the notion that a paternally biased genome might underlie the risk for ASD. The study compared height, weight, head circumference and thoracic circumference for age-matched (ages 4-8 years old) male children with ASD (n=30) with neurotypical children (n=33). No clinically significant differences were found among the two groups. After weaning, relative paternal contribution to a childs somatic development would increase, thus one would expect paternally active genes to start changing the childs behaviour, so as to make the child less demanding of resources (overall, and thus also on the father), with a counterweight represented by maternally active genes. A relative overabundance of paternally active genes would explain the data presented here, that shows children with ASD being no different from controls. Given the fact presented by other studies, that children with ASD seem to get a head start in growth, the lack of differences found in this 4-8 years old group indicates that children with ASD might actually fall behind in somatic growth, or at least stagnate by middle childhood.

Mental health conditions are difficult to diagnose, requiring expert clinicians and subjective judgements. There has been interest in finding quantitative biomarkers using resting state electroencephalogram (EEG) data. Here, we focus on resting state EEG biomarkers of autism. Although many previous reports have pointed to differences between autistic and neurotypical participants, results have often failed to replicate and sample sizes have typically been small. Taking a big-data, open-science approach, we combined data from 5 studies to create a large sample of autistic and neurotypical individuals (n=776) and used high-power computing to extract 942 variables from each participants data. Using a systematic, preregistered analysis pipeline, we failed to identify even a single EEG-based variable that could serve as a practically useful biomarker of autism clinical diagnosis. Our results highlight that a biomarker for autism drawn from EEG data is an elusive construct that may not exist.

MotivationAltered auditory processing likely contributes to core social and attentional impairments in autism spectrum disorder (ASD). The auditory steady-state response (ASSR)-- a neural measure of auditory processing and cortical excitatory-inhibitory balance--has yielded mixed results in ASD. This study uses high density electroencephalography (EEG) to evaluate ASSR in ASD and unaffected siblings to clarify neural mechanisms underlying auditory deficits in autism. MethodsHigh-density 70-channel EEG was recorded in children (8-12 years, IQ >80) with ASD (n=53), typically developing (TD) peers (n=35), and unaffected biological siblings (n=26) during 500-ms binaural click trains (27- and 40-Hz) in an active oddball task. ResultsNo group differences were observed in frequency-following responses (FFR) to 27- or 40-Hz stimuli, although higher 40-Hz power was associated with older age and better behavioral performance in ASD. The broad-band response from 180-250 ms was reduced in ASD for both stimulation frequencies--particularly in the low-frequency (<8 Hz) range--and significantly correlated with IQ and age. Siblings showed intermediate broad-band responses. DiscussionWhile FFRs appeared intact in ASD, we observed reduced broad-band response in the transition period to the steady state FFR, which was specific to low (<8-Hz) frequencies--potentially reflecting reduced synchronization at timescales that correspond with slower, syllabic rhythms ([~]4-8 Hz) occurring in natural speech. Intermediate responses in first-degree relatives suggest that this is related to genetic vulnerability for ASD and highlights its clinical relevance. These findings suggest intact sensory processing in ASD alongside possible top-down auditory feedback deficits, which may serve as heritable neurophysiological markers. Lay AbstractChildren with autism may process sounds differently, which could contribute to challenges with attention and communication. Here, electroencephalography (EEG) measured how the brain responds to rapidly repeating sounds and found that, while basic sound processing was intact, children with autism showed significantly reduced low-frequency responses that may reflect difficulty tracking speech rhythm. Interestingly, unaffected siblings showed an intermediate response, suggesting this may be a heritable marker of neural differences in autism.

Functional brain connectivity is altered in children and adults with autism spectrum disorder (ASD). Mapping pre-symptomatic functional disruptions in ASD could identify infants based on neural risk, providing a crucial opportunity to mediate outcomes before behavioral symptoms emerge. Here we quantify functional connectivity using scalable EEG measures of oscillatory phase coherence (6-12Hz). Infants at high and low familial risk for ASD (N=65) underwent an EEG recording at 3 months of age and were assessed for ASD symptoms at 18 months using the Autism Diagnostic Observation Schedule-Toddler Module. Multivariate pattern analysis was used to examine early functional patterns that are associated with later ASD symptoms. Support vector regression (SVR) algorithms accurately predicted observed ASD symptoms at 18 months from EEG data at 3 months (r=0.76, p=0.02). Specifically, lower frontal connectivity and higher right temporo-parietal connectivity predicted higher ASD symptoms. The SVR model did not predict non-verbal cognitive abilities at 18 months (r=0.15, p=0.36), suggesting specificity of these brain alterations to ASD. These data suggest that frontal and temporo-parietal dysconnectivity play important roles in the early pathophysiology of ASD. Early functional differences in ASD can be captured using EEG during infancy and may inform much-needed advancements in the early detection of ASD.

Clinical, neuroimaging and genomics evidence have increasingly underscored a degree of overlap between autism and attention-deficit/hyperactivity disorder (ADHD). This study explores the specific contribution of their core symptoms to shared biology in a sample of N=166 verbal children (6-12 years) with rigorously-established primary diagnoses of either autism or ADHD (without autism). We investigated the associations between inter-individual differences in clinician-based dimensional measures of autism and ADHD symptoms and whole-brain low motion intrinsic functional connectivity (iFC). Additionally, we explored their linked gene expression patterns in silico. Whole-brain multivariate distance matrix regression revealed a transdiagnostic association between autism severity and iFC of two nodes: the middle frontal gyrus of the frontoparietal network and posterior cingulate cortex of the default mode network. Across children, the greater the iFC between these nodes, the more severe the autism symptoms, even after controlling for ADHD symptoms. Results from segregation analyses were consistent with primary findings, underscoring the significance of internetwork iFC interactions for autism symptom severity across diagnoses. No statistically significant brain-behavior relationships were observed for ADHD symptoms. Genetic enrichment analyses of the iFC maps associated with autism symptoms implicated genes known to: (i) have greater rate of variance in autism and ADHD, and (ii) be involved in neuron projection, suggesting shared genetic mechanisms for this specific brain-clinical phenotype. Overall, these findings underscore the relevance of transdiagnostic dimensional approaches in linking clinically-defined phenomena to shared presentations at the macroscale circuit- and genomic-levels among children with diagnoses of autism and ADHD.

BackgroundWhile genetic risk factors for psychiatric and neurodevelopmental disorders have been identified, the neurobiological route from genetic risk to neuropsychiatric outcome remains unclear. 22q11.2 deletion syndrome (22q11.2DS) is a copy number variant (CNV) syndrome associated with high rates of neurodevelopmental and psychiatric disorders including autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD) and schizophrenia. Alterations in neural integration and cortical connectivity have been linked to the spectrum of neuropsychiatric disorders seen in 22q11.2DS and may be a mechanism by which the CNV acts to increase risk. Despite this, few studies have investigated electrophysiological activity and connectivity in this high-risk group. MethodsMagnetoencephalography (MEG) was used to investigate resting-state cortical oscillatory patterns in 34 children with 22q11.2DS and 25 controls aged 10-17 years old. Oscillatory activity and functional connectivity across six frequency bands were compared between groups. Regression analyses were used to explore the relationships between these measures, IQ and neurodevelopmental symptoms. ResultsChildren with 22q11.2DS had atypical oscillatory activity and functional connectivity across multiple frequency bands. In the 22q11.2DS group, low frequency (alpha band) activity was positively associated with cognitive ability, while connectivity was negatively associated with ASD and ADHD symptoms. Frontal high frequency (gamma band) activity and connectivity were positively associated with ASD and ADHD symptoms respectively, while posterior gamma activity was negatively associated with ASD symptoms. ConclusionsThese findings highlight that haploinsufficiency at the 22q11.2 locus alters both local and long-range cortical circuitry, which could be a mechanism underlying neurodevelopmental vulnerability in this high risk group.

Autism has been hypothesised to involve atypicalities in the balance between neural excitation and inhibition (E/I). Aperiodic EEG activity, characterised by the 1/f exponent of the power spectrum, provides a proxy of cortical E/I dynamics, yet prior studies in autism report mixed findings. One potentially important modulator of EEG slope is task engagement. Here, we examined variations in aperiodic slopes in autistic (n = 35) and neurotypical (n = 39) adults during passive viewing and an active, goal-directed task. The data revealed that autistic participants exhibited steeper slopes (indicative of increased inhibition vs. excitation) during the active task relative to passive viewing, whereas neurotypical participants showed no significant task-related changes. These findings suggest that aperiodic activity reflects dynamic, task-dependent neural adaptation rather than baseline group differences. Task engagement may reveal compensatory inhibitory processes in autistic adults, underscoring the importance of considering task demands and individual variability when investigating E/I balance in autism.

BackgroundDespite high rates of autism spectrum disorder (ASD), understanding of pathophysiology is limited. The RAS-mitogen-activated protein kinase (RAS-MAPK) pathway plays a crucial role in ASD and is altered in children with Noonan syndrome (NS). Children with NS offer a unique model to disentangle genetic and neurological underpinnings of ASD. MethodsThis study aimed to examine functional brain network anatomy underlying ASD symptoms in children with NS (n=28, mean age=8.24), and tested generalizability of models developed in a non-syndromic cohort enriched for ASD (Autism Brain Imaging Data Exchange (ABIDE), n=352, mean age=11.0). Connectome-based predictive modeling (CPM) was applied to fMRI data to predict the severity of autism symptoms, indexed by the Social Responsive Scale (SRS), in children with NS. Next, we tested if a model developed to predict autism symptoms in an autism-enriched sample of children without genetic diagnosis (ABIDE) could predict autism symptoms in children with NS. ResultsPredicted SRS scores were significantly associated with observed SRS scores in NS (rs=0.43, p=.011). Application of the predictive model generated in the autism-enriched cohort (ABIDE) significantly predicted observed SRS scores in NS (rs=0.460, p=.018). Predictive brain networks in both NS and the non-syndromic cohorts included subcortical-cerebellar networks and visual processing networks. LimitationsThe size of our NS cohort is small, given the rarity of NS. However, the significant cross-dataset comparison yielded in this study suggests that use of large publicly available datasets can be useful in contextualizing smaller and harder to collect datasets in rare genetic syndromes. ConclusionsThe presence of shared brain networks suggests a converging pattern of functional connectivity underlying autism symptoms, irrespective of genetic diagnosis. Evidence of shared brain networks in children with idiopathic autism and NS highlights the role of RAS-MAPK in autism symptoms and points to the value of leveraging human genetic models to enhance our understanding of idiopathic ASD.

Homo sapiens and Neanderthals underwent hybridization during the Middle/Upper Paleolithic age, culminating in retention of small amounts of Neanderthal-derived DNA in the modern human genome. In the current study, we address the potential roles genic Neanderthal single nucleotide polymorphisms (SNP) may be playing in autism susceptibility using data from the Simons Foundation Powering Autism Research (SPARK) and Genotype-Tissue Expression (GTEx) databases. We have discovered that rare and uncommon variants are significantly enriched in both European- and African-American autistic probands and their unaffected siblings compared to race-matched controls. In addition, we have identified 51 SNPs (p51) significantly enriched in European-American cases of autism, 13 of which fall within autism-associated genes, as well as 1 SNP in African-American probands. In addition, SNPs within the p51 network display significant linkage disequilibrium with one another, indicating they may more often be co-inherited in autism. These results strongly suggest Neanderthal-derived DNA is playing a significant role in autism susceptibility across major populations in the United States.

Autism with co-occurring exceptional cognitive ability is often accompanied by severe internalizing symptoms and feelings of inadequacy. Whether cognitive ability also translates into greater risk for suicidal ideation is unclear. To investigate this urgent question, we examined two samples of high-ability individuals with autism for factors that were predictive of suicidal ideation. In the first sample (N=1,074 individuals seen at a clinic specializing in gifted/talented youth), we observed a striking excess of parent-reported suicidal ideation in autistic individuals with IQ[&ge;]120 (OR=5.9, p = 0.0007). In separate sample of N=1,983 SPARK participants, we confirmed higher rates of suicidal thoughts compared to non-autistic children from the ABCD cohort (OR=6.8, p < 2.2 x 10-16), and further that autistic children with suicidal thoughts had significantly higher cognitive ability (p < 2.2 x 10-16) than those without. Elevated polygenic scores (PGS) for cognitive performance were associated with increased suicidal thoughts (Z = 2.16, p = 0.03), with PGS for educational attainment trending in the same direction (Z = 1.4, p = 0.17). Notably, similar results were found in parents of these autistic youth, where higher PGS for educational attainment was associated with increasing thoughts of suicide (Z=2.28, p=0.02). Taken together, these results suggest that on a phenotypic and genetic level, increasing cognitive ability is an unexpected risk factor for suicidal ideation in individuals diagnosed with, or at risk for autism.

BackgroundDifficulties with speech-in-noise perception in autism spectrum disorders (ASD) may be associated with impaired analysis of speech sounds, such as vowels, which represent the fundamental phoneme constituents of human speech. Vowels elicit early (< 100 ms) sustained processing negativity (SPN) in the auditory cortex that reflects the detection of an acoustic pattern based on the presence of formant structure and/or periodic envelope information (f0) and its transformation into an auditory "object". MethodsWe used magnetoencephalography (MEG) and individual brain models to investigate whether SPN is altered in children with ASD and whether this deficit is associated with impairment in their ability to perceive speech in the background of noise. MEG was recorded while boys with ASD and typically developing boys passively listened to sounds that differed in the presence/absence of f0 periodicity and formant structure. Word-in-noise perception was assessed in the separate psychoacoustic experiment using stationary and amplitude modulated noise with varying signal-to-noise ratio. ResultsSPN was present in both groups with similarly early onset. In children with ASD, SPN associated with processing formant structure was reduced predominantly in the cortical areas lateral to and medial to the primary auditory cortex, starting at [~] 150 - 200 ms after the stimulus onset. In the left hemisphere, this deficit correlated with impaired ability of children with ASD to recognize words in amplitude-modulated noise, but not in stationary noise ConclusionsThese results suggest that perceptual grouping of vowel formants into phonemes is impaired in children with ASD and that, in the left hemisphere, this deficit contributes to their difficulties with speech perception in fluctuating background noise.

BackgroundEarly preferential attention to biological motion is a fundamental mechanism priming the development of sophisticated skills to detect and react to social stimuli. Children diagnosed with autism spectrum disorders (ASD) demonstrate reduced visual orientation towards biological motion, however, the underlying neurobiological mechanisms are unknown. MethodsWe measured the neural oscillations in children with ASD (n=34, mean age 3.43 years) and age and gender matched typically developing children (TD, n=27) while watching videos of social biological (BM) and geometrical motion (GM). Their visual interest in BM stimuli was measured with eye-tracking techniques. Neural oscillations were measured as amplitude modulation of the frequency bands with the electroencephalogram and calculated as the power ratio between BM and GM conditions using scalp and brain source reconstruction analyses. ResultsWe observed a reduced visual exploration of the BM stimuli along with (1) unchanged sensorimotor mu rhythm and (2) altered cortical alpha and beta power ratio in widespread right prefrontal areas associated with default mode and fronto-parietal networks in young children with ASD as compared to their TD peers. Furthermore, we measured significant correlations between prefrontal and posterior cingulate regions of the default mode network with the developmental quotient in both the ASD and TD groups. ConclusionWe observed abnormal alpha and beta modulation of the fronto-parietal and default mode networks along with altered visual exploration of the social biological motion. These deficits represent core impairments of the disorder and may be informative in developing future behavioural and neuroregulation interventions, such as neurofeedback.