Similarities in the phenotype of the auditory neural substrate in children with Asperger syndrome and their parents

Mismatch Negativity in Children and Adolescents with Autism Spectrum Disorder

Introduction  Individuals with autism spectrum disorder (ASD) have abnormalities in auditory perception and sensitivity. The mismatch negativity (MMN) component of the evoked potential demonstrates a brain detection response to an auditory change due to memory, and enables the identification of changes in the auditory system. Objective  To analyze MMN responses in children and adolescents with ASD and compare them with those of a control group. Methods  Cross-sectional and comparative study. The sample was composed of 68 children and adolescents, divided into study group (SG), which contained those diagnosed with ASD, and the control group (CG), which contained those with typical development, normal hearing thresholds, and without hearing complaints. All participants were submitted to peripheral and central electrophysiological auditory evaluations. For the electrophysiological auditory evaluation and MMN recording, the electrodes were fixed in the following positions: Fz (active electrode), M1 and M2 (reference electrodes), and on the forehead (ground electrode). Auditory stimuli were presented in both ears simultaneously, with a frequency of 1,000 Hz for the frequent stimulus, and of 2,000 Hz for the rare stimulus, in an intensity of 80 dBNA. Results  Latency and amplitude values were increased in the SG, with a statistically significant difference in comparison with the CG. In the MMN analysis, there was no statistically significant difference in the comparison between right and left ears and between genders. Conclusion  Children and adolescents with ASD had higher latency and amplitude values in the MMN component than the individuals in the CG.

Non-linguistic comprehension, social inference and empathizing skills in autistic young adults, young adults with autistic traits and control young adults: Group differences and interrelatedness of skills

BACKGROUND

Despite increasing knowledge of social communication skills of autistic peole, the interrelatedness of different skills such as non-linguistic comprehension, social inference and empathizing skills is not much known about. A better understanding of the complex interplay between different domains of social communication helps us to develop assessment protocols for individuals with social communication difficulties.

AIMS

To compare the performances of autistic young adults, young adults with autistic traits identified in childhood and control young adults in social communication tasks measuring non-linguistic comprehension, social inference and empathizing skills. In addition, to examine associations between the different social communication measures.

METHODS & PROCEDURES

Autistic young adults (n = 34), young adults with autistic traits (n = 19) and control young adults (n = 36) completed the extra- and paralinguistic scales of the Assessment Battery for Communication (ABaCo), the Faux Pas Recognition Test, Social-Pragmatic Questions (SoPra) and the Empathy Quotient (EQ).

OUTCOMES & RESULTS

Group differences were found in the performance in the ABaCo, SoPra and EQ scores. Compared with the control young adults, autistic young adults scored lower. The performance of the young adults in the autistic traits group fell in between the other two groups. There were no group differences in the Faux Pas Recognition Test. The variability within the groups was large in all measurements. In the control group, there was a significant correlation between EQ and SoPra scores and between the Faux Pas and SoPra scores. In the autistic group, a significant correlation was found between Faux Pas and SoPra scores. Also, other patterns were observed but these were not statistically significant.

CONCLUSIONS & IMPLICATIONS

The young adults with autistic traits fell in between the control and autistic young adults, highlighting the presence of the continuum in the terms of features of social communication. The results support other current research that suggests that theory of mind and other social communication skills may not be universally or widely impaired in all autistic individuals without cognitive deficits. Although all tasks examined social communication skills, only a small number of significant correlations were found between test scores. This highlights that clinical conclusions about a person's social communication should be based on the outcomes of different types of methods measuring different aspects of social communication. It is clear that the interrelatedness of different social communication skills needs further research.

WHAT THIS PAPER ADDS

What is already known on this subject For successful communication, the ability to infer others' emotions, intentions and mental states is crucial. Autistic people have difficulty with many aspects of social communication. However, the associations between different aspects of social communication need to be better understood. What this paper adds to existing knowledge The unique contribution of this study is to compare the performance of autistic people not only with that of a control group but also with people with childhood autistic traits. This provides an understanding of the interrelatedness of different social communication skills in people with varying degrees of autistic traits. This study used four assessment methods focusing on three different social communication elements (non-linguistic comprehension, social inference and empathizing skills). These elements have complex relationships to one another, some being closely overlapping, some more distally related and some reflect more complex multifactorial elements. This study shows that although groups differ from each other in most of the assessments, the performance of different groups overlapped showing that many autistic young adults can perform well in non-linguistic and social inference tasks in structured assessment contexts. What are the potential or actual clinical implications of this work? Our findings suggest that in the assessment of social communication, self-reports and clinical assessments can be used effectively together. They can complement each other, pointing out the strengths and weaknesses of a person, leading to more personalized therapeutic interventions.

Autistic adults and adults with sub-clinical autistic traits differ from non-autistic adults in social-pragmatic inferencing and narrative discourse

Since prior research has mostly focused on children, less is known about how autistic adults and adults with sub-clinical autistic traits interpret pragmatically complex social situations and the kind of narrative discourse they produce. 32 autistic young adults, 18 young adults with sub-clinical autistic traits and 34 non-autistic young adults participated this study. They were shown videos of social interactions which required complex pragmatic processing and were asked to freely narrate what they thought was occurring in each video. Their narratives were coded for aspects of social-pragmatic and narrative discourse. The results indicate that the autistic and sub-clinical groups differed from the comparison group in what they inferred as relevant video content. The narratives of the autistic group also differed from the comparison group in meaning, focus and emphasis on details. In addition, the comparison group produced more holistic narratives whereas the autistic and sub-clinical groups produced more atomistic narratives. Correlational findings indicated that perceptual reasoning has stronger associations with pragmatic inferencing in the autistic and sub-clinical groups than in the comparison group. This study suggests that autistic adults and adults with sub-clinical autistic traits differ from non-autistic adults in what they perceive to be relevant in their social world.

Lay Abstract

Previous social-pragmatic and narrative research involving autistic individuals has mostly focused on children. Little is known about how autistic adults and adults who have autistic traits but do not have a diagnosis of an autism spectrum disorder (ASD) interpret complex social situations and tell narratives about these situations. We asked 32 autistic young adults, 18 adults with autistic traits but no ASD diagnosis, and 34 non-autistic young adults to watch socially complex situations and freely tell narratives about what they thought was occurring in each situation. These narratives were analysed for how the participants had interpreted the situations and for the type of narratives they produced. We found that the groups had both similarities and differences. Regarding the differences, we found that the autistic adults and adults with autistic traits interpreted the situations differently from the non-autistic adults. The autistic adults found different aspects of the situations relevant, had different foci and placed greater importance on details than the non-autistic adults. The autistic adults and adults with autistic traits also differed from the non-autistic adults by having more detail- and event-focused narratives whereas the non-autistic adults were more likely to base their narratives on their own broad interpretations of the situations. Perceptual processing styles appeared to play a bigger role in interpreting the situations for the autistic adults and adults with autistic traits than the non-autistic adults. Our findings suggest that autistic adults and adults with autistic traits focus on different aspects in their social world than non-autistic adults.

Electrophysiological Measures of Tactile and Auditory Processing in Children With Autism Spectrum Disorder

Behavioral differences in responding to tactile and auditory stimuli are widely reported in individuals with autism spectrum disorder (ASD). However, the neural mechanisms underlying distinct tactile and auditory reactivity patterns in ASD remain unclear with theories implicating differences in both perceptual and attentional processes. The current study sought to investigate (1) the neural indices of early perceptual and later attentional factors underlying tactile and auditory processing in children with and without ASD, and (2) the relationship between neural indices of tactile and auditory processing and ASD symptomatology. Participants included 14, 6–12-year-olds with ASD and 14 age- and non-verbal IQ matched typically developing (TD) children. Children participated in an event-related potential (ERP) oddball paradigm during which they watched a silent video while being presented with tactile and auditory stimuli (i.e., 80% standard speech sound/a/; 10% oddball speech sound/i/; 10% novel vibrotactile stimuli on the fingertip with standard speech sound/a/). Children’s early and later ERP responses to tactile (P1 and N2) and auditory stimuli (P1, P3a, and P3b) were examined. Non-parametric analyses showed that children with ASD displayed differences in early perceptual processing of auditory (i.e., lower amplitudes at central region of interest), but not tactile, stimuli. Analysis of later attentional components did not show differences in response to tactile and auditory stimuli in the ASD and TD groups. Together, these results suggest that differences in auditory responsivity patterns could be related to perceptual factors in children with ASD. However, despite differences in caregiver-reported sensory measures, children with ASD did not differ in their neural reactivity to infrequent touch-speech stimuli compared to TD children. Nevertheless, correlational analyses confirmed that inter-individual differences in neural responsivity to tactile and auditory stimuli were related to social skills in all children. Finally, we discuss how the paradigm and stimulus type used in the current study may have impacted our results. These findings have implications for everyday life, where individual differences in responding to tactile and auditory stimuli may impact social functioning.

Cortical Auditory Processing of Simple Stimuli Is Altered in Autism: A Meta-analysis of Auditory Evoked Responses

BACKGROUND

Auditory perceptual abnormalities are common in persons on the autism spectrum. The neurophysiologic underpinnings of these differences have frequently been studied using auditory event-related potentials (ERPs) and event-related magnetic fields (ERFs). However, no study to date has quantitatively synthesized this literature to determine whether early auditory ERP/ERF latencies or amplitudes in autistic persons differ from those of typically developing control subjects.

METHODS

We searched PubMed and ProQuest for studies comparing 1) latencies/amplitudes of P1/M50, N1b, N1c, M100, P2/M200, and/or N2 ERP/ERF components evoked by pure tones and 2) paired-click sensory gating (P1/N1b amplitude suppression) in autistic individuals and typically developing control subjects. Effects were synthesized using Bayesian 3-level meta-analysis.

RESULTS

In response to pure tones, autistic individuals exhibited prolonged P1/M50 latencies (g = 0.341 [95% credible interval = 0.166, 0.546]), prolonged M100 latencies (g = 0.319 [0.093, 0.550]), reduced N1c amplitudes (g = -0.812 [-1.278, -0.187]), and reduced N2 amplitudes (g = -0.374 [-0.633, -0.179]). There were no practically significant group differences in P2/M200 latencies, N2 latencies, P1/M50 amplitudes, N1b amplitudes, M100 amplitudes, or P2/M200 amplitudes. Paired-click sensory gating was also reduced in autistic individuals (g = -0.389 [-0.619, -0.112]), although this effect was primarily driven by smaller responses to the first click stimulus.

CONCLUSIONS

Relative to typically developing control subjects, autistic individuals demonstrate multiple alterations in early cortical auditory processing of simple stimuli. However, most group differences were modest in size and based on small numbers of heterogeneous studies with variable quality. Future work is necessary to understand whether these neurophysiologic measures can predict clinically meaningful outcomes or serve as stratification biomarkers for the autistic population.

Auditory Discrimination in Autism Spectrum Disorder

Autism spectrum disorder (ASD) is increasingly common with 1 in 59 children in the United States currently meeting the diagnostic criteria. Altered sensory processing is typical in ASD, with auditory sensitivities being especially common; in particular, people with ASD frequently show heightened sensitivity to environmental sounds and a poor ability to tolerate loud sounds. These sensitivities may contribute to impairments in language comprehension and to a worsened ability to distinguish relevant sounds from background noise. Event-related potential tests have found that individuals with ASD show altered cortical activity to both simple and speech-like sounds, which likely contribute to the observed processing impairments. Our goal in this review is to provide a description of ASD-related changes to the auditory system and how those changes contribute to the impairments seen in sound discrimination, sound-in-noise performance, and language processing. In particular, we emphasize how differences in the degree of cortical activation and in temporal processing may contribute to errors in sound discrimination.

Delayed cortical processing of auditory stimuli in children with autism spectrum disorder: A meta-analysis of electrophysiological studies

Several researchers have hypothesised that individuals with Autism Spectrum Disorder (ASD) show encoding delays in their obligatory event-related potentials (ERPs)/ event-related fields (ERFs) for low-level auditory information compared to neurotypical (NT) samples. However, empirical research has yielded varied findings, such as low-level auditory processing in ASD samples being unimpaired, superior, or impaired compared to NT samples. Diverse outcomes have also been reported for studies investigating ASD-NT differences in functional lateralisation of delays. The lack of consistency across studies has prevented a comprehensive understanding of the overall effects in the autistic population. Therefore, this meta-analysis compared long-latency ERPs and ERFs produced by autistic and NT individuals to non-linguistic auditory stimuli to test, firstly, the robustness of auditory processing differences and, secondly, whether these differences are observed in one or both hemispheres. Nine articles meeting the inclusion criteria were included in the meta-analysis. Meta-analytic results indicated that autistic individuals demonstrate bilaterally delayed P1/ M50 peaks and lateralised delays in the right but not left hemisphere N1/ M100 peak. These results further inform our understanding of auditory processing and lateralisation across the autism spectrum.

Social-Pragmatic Inferencing, Visual Social Attention and Physiological Reactivity to Complex Social Scenes in Autistic Young Adults

This study examined social-pragmatic inferencing, visual social attention and physiological reactivity to complex social scenes. Participants were autistic young adults (n = 14) and a control group of young adults (n = 14) without intellectual disability. Results indicate between-group differences in social-pragmatic inferencing, moment-level social attention and heart rate variability (HRV) reactivity. A key finding suggests associations between increased moment-level social attention to facial emotion expressions, better social-pragmatic inferencing and greater HRV suppression in autistic young adults. Supporting previous research, better social-pragmatic inferencing was found associated with less autistic traits.

Dynamic lag analysis reveals atypical brain information flow in autism spectrum disorder

This study investigated whole‐brain dynamic lag pattern variations between neurotypical (NT) individuals and individuals with autism spectrum disorder (ASD) by applying a novel technique called dynamic lag analysis (DLA). The use of 3D magnetic resonance encephalography data with repetition time = 100 msec enables highly accurate analysis of the spread of activity between brain networks. Sixteen resting‐state networks (RSNs) with the highest spatial correlation between NT individuals (n = 20) and individuals with ASD (n = 20) were analyzed. The dynamic lag pattern variation between each RSN pair was investigated using DLA, which measures time lag variation between each RSN pair combination and statistically defines how these lag patterns are altered between ASD and NT groups. DLA analyses indicated that 10.8% of the 120 RSN pairs had statistically significant (P‐value <0.003) dynamic lag pattern differences that survived correction with surrogate data thresholding. Alterations in lag patterns were concentrated in salience, executive, visual, and default‐mode networks, supporting earlier findings of impaired brain connectivity in these regions in ASD. 92.3% and 84.6% of the significant RSN pairs revealed shorter mean and median temporal lags in ASD versus NT, respectively. Taken together, these results suggest that altered lag patterns indicating atypical spread of activity between large‐scale functional brain networks may contribute to the ASD phenotype. Autism Res 2020, 13: 244–258. © 2019 The Authors. Autism Research published by International Society for Autism Research published by Wiley Periodicals, Inc.

Lay Summary

Autism spectrum disorder (ASD) is characterized by atypical neurodevelopment. Using an ultra‐fast neuroimaging procedure, we investigated communication across brain regions in adults with ASD compared with neurotypical (NT) individuals. We found that ASD individuals had altered information flow patterns across brain regions. Atypical patterns were concentrated in salience, executive, visual, and default‐mode network areas of the brain that have previously been implicated in the pathophysiology of the disorder.

Emotional prosodic change detection in autism Spectrum disorder: an electrophysiological investigation in children and adults

Background

Autism spectrum disorder (ASD) is characterized by atypical behaviors in social environments and in reaction to changing events. While this dyad of symptoms is at the core of the pathology along with atypical sensory behaviors, most studies have investigated only one dimension. A focus on the sameness dimension has shown that intolerance to change is related to an atypical pre-attentional detection of irregularity. In the present study, we addressed the same process in response to emotional change in order to evaluate the interplay between alterations of change detection and socio-emotional processing in children and adults with autism.

Methods

Brain responses to neutral and emotional prosodic deviancies (mismatch negativity (MMN) and P3a, reflecting change detection and orientation of attention toward change, respectively) were recorded in children and adults with autism and in controls. Comparison of neutral and emotional conditions allowed distinguishing between general deviancy and emotional deviancy effects. Moreover, brain responses to the same neutral and emotional stimuli were recorded when they were not deviants to evaluate the sensory processing of these vocal stimuli.

Results

In controls, change detection was modulated by prosody: in children, this was characterized by a lateralization of emotional MMN to the right hemisphere, and in adults, by an earlier MMN for emotional deviancy than for neutral deviancy. In ASD, an overall atypical change detection was observed with an earlier MMN and a larger P3a compared to controls suggesting an unusual pre-attentional orientation toward any changes in the auditory environment. Moreover, in children with autism, deviancy detection depicted reduced MMN amplitude. In addition in children with autism, contrary to adults with autism, no modulation of the MMN by prosody was present and sensory processing of both neutral and emotional vocal stimuli appeared atypical.

Conclusions

Overall, change detection remains altered in people with autism. However, differences between children and adults with ASD evidence a trend toward normalization of vocal processing and of the automatic detection of emotion deviancy with age.

Meta-analysis and systematic review of the literature characterizing auditory mismatch negativity in individuals with autism

A number of past studies have used mismatch negativity (MMN) to identify auditory processing deficits in individuals with autism spectrum disorder (ASD). Our meta-analysis compared MMN responses for individuals with ASD and typically developing controls (TD). We analyzed 67 experiments across 22 publications that employed passive, auditory-based MMN paradigms with ASD and TD participants. Most studies lacked design characteristics that would lead to an accurate description of the MMN. Variability between experiments measuring MMN amplitude was smaller when limited to studies that counterbalanced stimuli. Reduced MMN amplitude was found among young children with ASD compared to controls and in experiments that used nonspeech sounds. Still, few studies included adolescents or those with below-average verbal IQ. Most studies suffered from small sample sizes, and aggregating these data did not reveal significant group differences. This analysis points to a need for research focused specifically on understudied ASD samples using carefully designed MMN experiments. Study of individual differences in MMN may provide further insights into distinct subgroups within the heterogeneous ASD population.

How Young Adults with Autism Spectrum Disorder Watch and Interpret Pragmatically Complex Scenes

The aim of the current study was to investigate subtle characteristics of social perception and interpretation in high-functioning individuals with autism spectrum disorders (ASDs), and to study the relation between watching and interpreting. As a novelty, we used an approach that combined moment-by-moment eye tracking and verbal assessment. Sixteen young adults with ASD and 16 neurotypical control participants watched a video depicting a complex communication situation while their eye movements were tracked. The participants also completed a verbal task with questions related to the pragmatic content of the video. We compared verbal task scores and eye movements between groups, and assessed correlations between task performance and eye movements. Individuals with ASD had more difficulty than the controls in interpreting the video, and during two short moments there were significant group differences in eye movements. Additionally, we found significant correlations between verbal task scores and moment-level eye movement in the ASD group, but not among the controls. We concluded that participants with ASD had slight difficulties in understanding the pragmatic content of the video stimulus and attending to social cues, and that the connection between pragmatic understanding and eye movements was more pronounced for participants with ASD than for neurotypical participants.

Behavioral, Cognitive and Neural Markers of Asperger Syndrome

Asperger syndrome (AS) is a subtype of Autism Spectrum Disorder (ASD) characterized by major problems in social and nonverbal communication, together with limited and repetitive forms of behavior and interests. The linguistic and cognitive development in AS is preserved which help us to differentiate it from other subtypes of ASD. However, significant effects of AS on cognitive abilities and brain functions still need to be researched. Although a clear cut pathology for Asperger has not been identified yet, recent studies have largely focused on brain imaging techniques to investigate AS. In this regard, we carried out a systematic review on behavioral, cognitive, and neural markers (specifically using MRI and fMRI) studies on AS. In this paper, behavior, motor skills and language capabilities of individuals with Asperger are compared to those in healthy controls. In addition, common findings across MRI and fMRI based studies associated with behavior and cognitive disabilities are highlighted.

Attention and Working Memory in Adolescents with Autism Spectrum Disorder: A Functional MRI Study

The present study examined attention and memory load-dependent differences in the brain activation and deactivation patterns between adolescents with autism spectrum disorders (ASDs) and typically developing (TD) controls using functional magnetic resonance imaging. Attentional (0-back) and working memory (WM; 2-back) processing and load differences (0 vs. 2-back) were analysed. WM-related areas activated and default mode network deactivated normally in ASDs as a function of task load. ASDs performed the attentional 0-back task similarly to TD controls but showed increased deactivation in cerebellum and right temporal cortical areas and weaker activation in other cerebellar areas. Increasing task load resulted in multiple responses in ASDs compared to TD and in inadequate modulation of brain activity in right insula, primary somatosensory, motor and auditory cortices. The changes during attentional task may reflect compensatory mechanisms enabling normal behavioral performance. The inadequate memory load-dependent modulation of activity suggests diminished compensatory potential in ASD.

Psychophysiological Correlates of Developmental Changes in Healthy and Autistic Boys

This study investigated neurodevelopmental changes in sound processing by recording mismatch negativity (MMN) in response to various degrees of sound complexity in 18 mildly to moderately autistic versus 15 healthy boys aged between 6 and 15 years. Autistic boys presented with lower IQ and poor performance on a range of executive and social function measures when compared to their healthy counterparts. We found that MMN in response to duration deviants was less lateralized in the clinical group whereas larger amplitudes correlated with advanced age, thus capturing neurodevelopmental changes. Larger MMN in response to speech-like sound deviants was associated with better verbal fluency and executive function performance, respectively, but did not reliably discriminate the two groups.

Is it time to move mismatch negativity into the clinic?

Since its inception in the 1970s, the mismatch negativity (MMN) event-related potential has improved our understanding of pre-attentive detection of rule violations, which is a fundamental cognitive process considered by some a form of "primitive intelligence". The body of research to date ranges from animal studies (i.e. when investigating the neural mechanisms and pharmacological properties of MMN generation) to researching the psychophysiological nature of human consciousness. MMN therefore offers the possibility to detect abnormal functioning in the neural system involved in MMN generation, such as it occurs in some neurodevelopmental disorders or patients in vegetative state. While the clinical research data holds considerable promise for translation into clinical practice, standardization and normative data of an optimized (i.e. disorder-specific) MMN recording algorithm is needed in order for MMN to become a valuable clinical investigation tool.

Event-related potentials to repeated speech in 9-month-old infants at risk for autism spectrum disorder

Background

Atypical neural responses to repeated auditory and linguistic stimuli have been reported both in individuals with autism spectrum disorder (ASD) and their first-degree relatives. Recent work suggests that the younger siblings of children with ASD have atypical event-related potentials (ERPs) to repeated tones at 9 months of age; however, the functional significance is unclear, and it is unknown whether this atypicality is also present in response to linguistic stimuli.

Methods

We analyzed ERPs to repetitive and deviant consonant-vowel stimuli at 9 months in 35 unaffected high-risk-for-autism (HRA) infant siblings of children with ASD and 45 low-risk control (LRC) infants. We examined a positive component, the P150, over frontal and central electrode sites and investigated the relationships between this component and later behavior.

Results

Over frontal electrodes, HRA infants had larger-amplitude ERPs to repetitions of the standard than LRC infants, whereas ERPs to the deviant did not differ between HRA and LRC infants. Furthermore, for HRA infants, the amplitude of ERPs to the standards was positively correlated with later language ability.

Conclusions

Our work suggests that atypical ERPs to repeated speech during infancy are a possible endophenotype of ASD but that this atypicality is associated with beneficial, rather than disordered, language development. Potential mechanisms driving these relationships and implications for development are discussed.

Resting state fMRI reveals a default mode dissociation between retrosplenial and medial prefrontal subnetworks in ASD despite motion scrubbing

In resting state functional magnetic resonance imaging (fMRI) studies of autism spectrum disorders (ASDs) decreased frontal-posterior functional connectivity is a persistent finding. However, the picture of the default mode network (DMN) hypoconnectivity remains incomplete. In addition, the functional connectivity analyses have been shown to be susceptible even to subtle motion. DMN hypoconnectivity in ASD has been specifically called for re-evaluation with stringent motion correction, which we aimed to conduct by so-called scrubbing. A rich set of default mode subnetworks can be obtained with high dimensional group independent component analysis (ICA) which can potentially provide more detailed view of the connectivity alterations. We compared the DMN connectivity in high-functioning adolescents with ASDs to typically developing controls using ICA dual-regression with decompositions from typical to high dimensionality. Dual-regression analysis within DMN subnetworks did not reveal alterations but connectivity between anterior and posterior DMN subnetworks was decreased in ASD. The results were very similar with and without motion scrubbing thus indicating the efficacy of the conventional motion correction methods combined with ICA dual-regression. Specific dissociation between DMN subnetworks was revealed on high ICA dimensionality, where networks centered at the medial prefrontal cortex and retrosplenial cortex showed weakened coupling in adolescents with ASDs compared to typically developing control participants. Generally the results speak for disruption in the anterior-posterior DMN interplay on the network level whereas local functional connectivity in DMN seems relatively unaltered.

The neural basis of aberrant speech and audition in autism spectrum disorders

Autism spectrum disorders (ASD) are characterized by deficits in communication and social behavior and by narrow interests. Individuals belonging to this spectrum have abnormalities in various aspects of language, ranging from semantic-pragmatic deficits to the absence of speech. They also have aberrant perception, especially in the auditory domain, with both hypo- and hypersensitive features. Neurophysiological approaches with high temporal resolution have given novel insight into the processes underlying perception and language in ASD. Neurophysiological recordings, which are feasible for investigating infants and individuals with no speech, have shown that the representation of and attention to language has an abnormal developmental path in ASD. Even the basic mechanisms for fluent speech perception are degraded at a low level of neural speech analysis. Furthermore, neural correlates of perception and some traits typical of subgroups of individuals on this spectrum have helped in understanding the diversity on this spectrum.

Valence scaling of dynamic facial expressions is altered in high-functioning subjects with autism spectrum disorders: an fMRI study

FMRI was performed with the dynamic facial expressions fear and happiness. This was done to detect differences in valence processing between 25 subjects with autism spectrum disorders (ASDs) and 27 typically developing controls. Valence scaling was abnormal in ASDs. Positive valence induces lower deactivation and abnormally strong activity in ASD in multiple regions. Negative valence increased deactivation in visual areas in subjects with ASDs. The most marked differences between valences focus on fronto-insular and temporal regions. This supports the idea that subjects with ASDs may have difficulty in passive processing of the salience and mirroring of expressions. When the valence scaling of brain activity fails, in contrast to controls, these areas activate and/or deactivate inappropriately during facial stimuli presented dynamically.

HRV and EEG based indicators of stress in children with Asperger syndrome in audio-visual stimulus test

Asperger syndrome (AS) is a neurobiological condition which is characterized by poor skills in social communication, and restricted and repetitive patterns of behavior and interests. We studied whether stress-related indices of heart rate variability (HRV) and electroencephalography (EEG) are different in children with AS than normal controls. We analyzed retrospectively the data of the test where audiovisual stimuli were used. We hypothesized that this test is a stressful situation for individuals with AS and they would have a greater reaction than control subjects. EEG and one-channel electrocardiography (ECG) were collected for children with diagnosis of AS (N = 20) and their age-matched controls (N = 21). HRV indices, frontal EEG asymmetry index and brain load index were calculated. HRV based indices revealed increased sympathetic activity during the test in children with AS. EEG based indices increased more in children with AS during the test compared to baseline. Thus, the children with AS seems to have a greater reaction to stressful situation.

The mismatch negativity (MMN)--a unique window to disturbed central auditory processing in ageing and different clinical conditions

In this article, we review clinical research using the mismatch negativity (MMN), a change-detection response of the brain elicited even in the absence of attention or behavioural task. In these studies, the MMN was usually elicited by employing occasional frequency, duration or speech-sound changes in repetitive background stimulation while the patient was reading or watching videos. It was found that in a large number of different neuropsychiatric, neurological and neurodevelopmental disorders, as well as in normal ageing, the MMN amplitude was attenuated and peak latency prolonged. Besides indexing decreased discrimination accuracy, these effects may also reflect, depending on the specific stimulus paradigm used, decreased sensory-memory duration, abnormal perception or attention control or, most importantly, cognitive decline. In fact, MMN deficiency appears to index cognitive decline irrespective of the specific symptomatologies and aetiologies of the different disorders involved.

Auditory processing in autism spectrum disorder: a review

For individuals with autism spectrum disorder or 'ASD' the ability to accurately process and interpret auditory information is often difficult. Here we review behavioural, neurophysiological and imaging literature pertaining to this field with the aim of providing a comprehensive account of auditory processing in ASD, and thus an effective tool to aid further research. Literature was sourced from peer-reviewed journals published over the last two decades which best represent research conducted in these areas. Findings show substantial evidence for atypical processing of auditory information in ASD at behavioural and neural levels. Abnormalities are diverse, ranging from atypical perception of various low-level perceptual features (i.e. pitch, loudness) to processing of more complex auditory information such as prosody. Trends across studies suggest auditory processing impairments in ASD are most likely to present during processing of complex auditory information and are more severe for speech than for non-speech stimuli. The interpretation of these findings with respect to various cognitive accounts of ASD is discussed and suggestions offered for further research.

White matter in autism spectrum disorders - evidence of impaired fiber formation

BACKGROUND

Diffusion tensor imaging (DTI) enables measurements and visualization of the microstructure of neural fiber tracts. The existing literature on autism spectrum disorders (ASDs) and DTI is heterogenous both regarding methodology and results.

PURPOSE

To compare brain white matter of high-functioning individuals with ASDs and controls.

MATERIAL AND METHODS

Tract-based spatial statistics (TBSS), a voxel-based approach to DTI, was used to compare 27 subjects with ASDs (mean age 14.7 years, range 11.4-17.6 years, 20 boys, 7 girls) and 26 control subjects (mean age 14.5 years, range 11.7-17.3 years, 17 boys, 9 girls). Mean fractional anisotropy (FA) image (skeleton) was created and each subject's aligned FA data were then projected onto this skeleton. Voxelwise cross-subject statistics on the skeletonized FA data, mean diffusivity (MD), and measures of diffusion direction were calculated. Importantly, the data were corrected across the whole image instead of using ROI-based methods.

RESULTS

The ASD group showed significantly greater FA (P < 0.05, corrected) in the area containing clusters of optic radiation and the right inferior fronto-occipital fasciculus (iFOF). In the same area, λ(3) (representing transverse diffusion) was significantly reduced in the ASD group. No age-related changes were found.

CONCLUSION

The results suggest that the reduced transverse diffusion within the iFOF is related to abnormal information flow between the insular salience processing areas and occipital visual areas.

Developmental and individual differences on the P1 and N170 ERP components in children with and without autism

The P1 and N170 components, two event-related potentials sensitive to face processing, were examined in response to faces and vehicles for children with autism and typical development. P1 amplitude decreased, P1 latency decreased, and N170 amplitude became more negative with age. Children with typical development had larger P1 amplitudes for inverted faces than upright faces, but children with autism did not show this pattern. Children with autism had longer N170 latencies than children with typical development. Smaller P1 amplitudes and more negative N170 amplitudes for upright faces were associated with better social skills for children with typical development.

Comorbid psychiatric disorders associated with Asperger syndrome/high-functioning autism: a community- and clinic-based study

The present study identifies the prevalence and types of comorbid psychiatric disorders associated with Asperger syndrome (AS)/high-functioning autism (HFA) in a combined community- and clinic-based sample of fifty 9- to 16-year-old subjects using the Schedule for Affective Disorders and Schizophrenia for School-Age Children, Present and Lifetime Version. The level of functioning was estimated using the Children's Global Assessment Scale. The results support common (prevalence 74%) and often multiple comorbid psychiatric disorders in AS/HFA; behavioral disorders were shown in 44%, anxiety disorders in 42% and tic disorders in 26%. Oppositional defiant disorder, major depressive disorder and anxiety disorders as comorbid conditions indicated significantly lower levels of functioning. To target interventions, routine evaluation of psychiatric comorbidity in subjects with AS/HFA is emphasized.

Alterations in regional homogeneity of resting-state brain activity in autism spectrum disorders

Measures assessing resting-state brain activity with blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) can reveal cognitive disorders at an early stage. Analysis of regional homogeneity (ReHo) measures the local synchronization of spontaneous fMRI signals and has been successfully utilized in detecting alterations in subjects with attention-deficit hyperactivity disorder (ADHD), depression, schizophrenia, Parkinson's disease and Alzheimer's dementia. Resting-state brain activity was investigated in 28 adolescents with autism spectrum disorders (ASD) and 27 typically developing controls being imaged with BOLD fMRI and analyzed with the ReHo method. The hypothesis was that ReHo of resting-state brain activity would be different between ASD subjects and controls in brain areas previously shown to display functional alterations in stimulus or task based fMRI studies. Compared with the controls, the subjects with ASD had significantly decreased ReHo in right superior temporal sulcus region, right inferior and middle frontal gyri, bilateral cerebellar crus I, right insula and right postcentral gyrus. Significantly increased ReHo was discovered in right thalamus, left inferior frontal and anterior subcallosal gyrus and bilateral cerebellar lobule VIII. We conclude that subjects with ASD have right dominant ReHo alterations of resting-state brain activity, i.e., areas known to exhibit abnormal stimulus or task related functionality. Our results demonstrate that there is potential in utilizing the ReHo method in fMRI analyses of ASD.

An epidemiological and diagnostic study of Asperger syndrome according to four sets of diagnostic criteria

OBJECTIVE

This study evaluated the diagnostic process and prevalence rates of Asperger syndrome (AS) according to the DSM-IV, ICD-10, and criteria developed by Gillberg and Gillberg and by Szatmari and colleagues and clarified confusion about AS.

METHOD

An epidemiological study of 5,484 eight-year-old children in Finland, 4,422 (80.6%) of whom rated on the high-functioning Autism Spectrum Screening Questionnaire by parents and/or teacher, 125 of them screened and 110 examined by using structured interview, semistructured observation, IQ measurement, school day observation, and patient records. Diagnoses were performed by following the DSM-IV, ICD-10, and criteria developed by Gillberg and Gillberg and by Szatmari and colleagues in detail.

RESULTS

The prevalence rates per 1,000 were 2.5 according to the DSM-IV, 2.9 to ICD-10, 2.7 to Gillberg and Gillberg's criteria, and 1.6 to the criteria of Szatmari et al.

CONCLUSIONS

The results emphasize the need to reconsider the diagnostic criteria of AS. The importance of multi-informant sources came up, and the need of several informants was highlighted, especially when diagnosing the broader pervasive developmental disorders.

Atypical pattern of discriminating sound features in adults with Asperger syndrome as reflected by the mismatch negativity

Asperger syndrome, which belongs to the autistic spectrum of disorders, is characterized by deficits of social interaction and abnormal perception, like hypo- or hypersensitivity in reacting to sounds and discriminating certain sound features. We determined auditory feature discrimination in adults with Asperger syndrome with the mismatch negativity (MMN), a neural response which is an index of cortical change detection. We recorded MMN for five different sound features (duration, frequency, intensity, location, and gap). Our results suggest hypersensitive auditory change detection in Asperger syndrome, as reflected in the enhanced MMN for deviant sounds with a gap or shorter duration, and speeded MMN elicitation for frequency changes.

The Mismatch Negativity

In the present article, I will selectively review some of the recent research on the brain substrates of central-auditory processing using the mismatch negativity (MMN) and its magnetoencephalographic equivalent MMNm, trying to identify some of the most promising trends in this research work. Although the early MMN research dealt almost exclusively with basic cognitive-neuroscience issues, more recently, the usefulness of the MMN phenomenon with regard to a large number of clinical and other applied issues has also been realized. Nine research lines or issues with particular promise will be identified, many of which are of a clinical/applied nature. Cognitive brain research using the MMN, an automatic electric response to any discriminable change in auditory stimulation, has continued for three decades and seems continuously to gain in number, inspired by novel findings, there now being approximately 1,000 articles in English-language international journals using, or referring to, the MMN. There are several highly promising research lines or issues: (1) the MMN as an index of early cognitive development, (2) the MMN as an index of the functional condition of the NMDA-receptor system, (3) the MMN as an index of the different brain pathologies underlying schizophrenia, (4) the role of the MMN in genetic research of psychopathology, (5) the extremely wide range of MMN deficiency across different clinical conditions and diseases, (6) the MMN in prediction of coma outcome, (7) the MMN as an index of primitive sensory intelligence in audition, and (8) the MMN as an index of brain mechanisms of speech perception and understanding. These findings, in particular (8), extend the interpretation of the MMN, currently mainly confined to sensory representations, to involve auditory memory in general.

Processing of affective speech prosody is impaired in Asperger syndrome

Many people with the diagnosis of Asperger syndrome (AS) show poorly developed skills in understanding emotional messages. The present study addressed discrimination of speech prosody in children with AS at neurophysiological level. Detection of affective prosody was investigated in one-word utterances as indexed by the N1 and the mismatch negativity (MMN) of auditory event-related potentials (ERPs). Data from fourteen boys with AS were compared with those for thirteen typically developed boys. These results suggest atypical neural responses to affective prosody in children with AS and their fathers, especially over the RH, and that this impairment can already be seen at low-level information processes. Our results provide evidence for familial patterns of abnormal auditory brain reactions to prosodic features of speech.

The effect of visuospatial attentional load on the processing of irrelevant acoustic distractors

This work investigated the role of cognitive control functions in selective attention when task-relevant and -irrelevant stimuli come from different sensory modalities. We parametrically manipulated the load of an attentive tracking task and investigated its effect on irrelevant acoustic change-related processing. While subjects were performing the visual attentive tracking task, event-related potentials (ERPs) were recorded for frequent standard tones and rare deviant tones presented as auditory distractors. The deviant tones elicited two change-related ERP components: the mismatch negativity (MMN) and the P3a. The amplitude of the MMN, which indexes the early detection of irregular changes, increased with increasing attentional load, whereas the subsequent P3a component, which indicates the involuntary orienting of attention to deviants, was significant only in the lowest load condition. These findings suggest that active exclusion of the early detection process of irrelevant acoustic changes depends on available resources of cognitive control, whereas the late involuntary orienting of attention to deviants can be passively suppressed by high demand on central attentional resources. The present study thus reveals opposing visual attentional load effects at different temporal and functional stages in the rejection of deviant auditory distractors and provides a new perspective on the resolution of the long-standing early versus late attention selection debate.

Auditory perception and attention as reflected by the brain event-related potentials in children with Asperger syndrome

OBJECTIVE

Language development is delayed and deviant in individuals with autism, but proceeds quite normally in those with Asperger syndrome (AS). We investigated auditory-discrimination and orienting in children with AS using an event-related potential (ERP) paradigm that was previously applied to children with autism.

METHODS

ERPs were measured to pitch, duration, and phonetic changes in vowels and to corresponding changes in non-speech sounds. Active sound discrimination was evaluated with a sound-identification task.

RESULTS

The mismatch negativity (MMN), indexing sound-discrimination accuracy, showed right-hemisphere dominance in the AS group, but not in the controls. Furthermore, the children with AS had diminished MMN-amplitudes and decreased hit rates for duration changes. In contrast, their MMN to speech pitch changes was parietally enhanced. The P3a, reflecting involuntary orienting to changes, was diminished in the children with AS for speech pitch and phoneme changes, but not for the corresponding non-speech changes.

CONCLUSIONS

The children with AS differ from controls with respect to their sound-discrimination and orienting abilities.

SIGNIFICANCE

The results of the children with AS are relatively similar to those earlier obtained from children with autism using the same paradigm, although these clinical groups differ markedly in their language development.