Auditory stream segregation in children with Asperger syndrome

Brain Signatures of Early and Late Neural Measures of Auditory Habituation and Discrimination in Autism and Their Relationship to Autistic Traits and Sensory Overresponsivity

Sensory differences are included in the DSM-5 criteria of autism for the first time, yet it is unclear how they relate to neural indicators of perception. We studied early brain signatures of perception and examined their relationship to sensory behaviors and autistic traits. Thirteen autistic children and 13 Typically Developing (TD) children matched on age and nonverbal IQ participated in a passive oddball task, during which P1 habituation and P1 and MMN discrimination were evoked by pure tones. Autistic children had less neural habituation than the TD comparison group, and the MMN, but not P1, mapped on to sensory overresponsivity. Findings highlight the significance of temporal and contextual factors in neural information processing as it relates to autistic traits and sensory behaviors.

Development of auditory scene analysis: a mini-review

Most auditory environments contain multiple sound waves that are mixed before reaching the ears. In such situations, listeners must disentangle individual sounds from the mixture, performing the auditory scene analysis. Analyzing complex auditory scenes relies on listeners ability to segregate acoustic events into different streams, and to selectively attend to the stream of interest. Both segregation and selective attention are known to be challenging for adults with normal hearing, and seem to be even more difficult for children. Here, we review the recent literature on the development of auditory scene analysis, presenting behavioral and neurophysiological results. In short, cognitive and neural mechanisms supporting stream segregation are functional from birth but keep developing until adolescence. Similarly, from 6 months of age, infants can orient their attention toward a target in the presence of distractors. However, selective auditory attention in the presence of interfering streams only reaches maturity in late childhood at the earliest. Methodological limitations are discussed, and a new paradigm is proposed to clarify the relationship between auditory scene analysis and speech perception in noise throughout development.

Enhanced sensitivity to pitch perception and its possible relation to language acquisition in autism

Background and aims

Fascinations for or aversions to particular sounds are a familiar feature of autism, as is an ability to reproduce another person's utterances, precisely copying the other person's prosody as well as their words. Such observations seem to indicate not only that autistic people can pay close attention to what they hear, but also that they have the ability to perceive the finer details of auditory stimuli. This is consistent with the previously reported consensus that absolute pitch is more common in autistic individuals than in neurotypicals. We take this to suggest that autistic people have perception that allows them to pay attention to fine details. It is important to establish whether or not this is so as autism is often presented as a deficit rather than a difference. We therefore undertook a narrative literature review of studies of auditory perception, in autistic and nonautistic individuals, focussing on any differences in processing linguistic and nonlinguistic sounds.

Main contributions

We find persuasive evidence that nonlinguistic auditory perception in autistic children differs from that of nonautistic children. This is supported by the additional finding of a higher prevalence of absolute pitch and enhanced pitch discriminating abilities in autistic children compared to neurotypical children. Such abilities appear to stem from atypical perception, which is biased toward local-level information necessary for processing pitch and other prosodic features. Enhanced pitch discriminating abilities tend to be found in autistic individuals with a history of language delay, suggesting possible reciprocity. Research on various aspects of language development in autism also supports the hypothesis that atypical pitch perception may be accountable for observed differences in language development in autism.

Conclusions

The results of our review of previously published studies are consistent with the hypothesis that auditory perception, and particularly pitch perception, in autism are different from the norm but not always impaired. Detail-oriented pitch perception may be an advantage given the right environment. We speculate that unusually heightened sensitivity to pitch differences may be at the cost of the normal development of the perception of the sounds that contribute most to early language development.

Implications

The acquisition of speech and language may be a process that normally involves an enhanced perception of speech sounds at the expense of the processing of nonlinguistic sounds, but autistic children may not give speech sounds this same priority.

John T, Lau BK. Auditory Attention Deployment in Young Adults with Autism Spectrum Disorder

Difficulty listening in noisy environments is a common complaint of individuals with autism spectrum disorder (ASD). However, the mechanisms underlying such auditory processing challenges are unknown. This preliminary study investigated auditory attention deployment in adults with ASD. Participants were instructed to maintain or switch attention between two simultaneous speech streams in three conditions: location (co-located versus ± 30° separation), voice (same voice versus male-female contrast), and both cues together. Results showed that individuals with ASD can selectively direct attention using location or voice cues, but performance was best when both cues were present. In comparison to neurotypical adults, overall performance was less accurate across all conditions. These findings warrant further investigation into auditory attention deployment differences in individuals with ASD.

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.

Read my lips! Perception of speech in noise by preschool children with autism and the impact of watching the speaker's face

Background

Adults and adolescents with autism spectrum disorders show greater difficulties comprehending speech in the presence of noise. Moreover, while neurotypical adults use visual cues on the mouth to help them understand speech in background noise, differences in attention to human faces in autism may affect use of these visual cues. No work has yet examined these skills in toddlers with ASD, despite the fact that they are frequently faced with noisy, multitalker environments.

Methods

Children aged 2-5 years, both with and without autism spectrum disorder (ASD), saw pairs of images in a preferential looking study and were instructed to look at one of the two objects. Sentences were presented in the presence of quiet or another background talker (noise). On half of the trials, the face of the target person speaking was presented, while half had no face present. Growth-curve modeling was used to examine the time course of children’s looking to the appropriate vs. opposite image.

Results

Noise impaired performance for both children with ASD and their age- and language-matched peers. When there was no face present on the screen, the effect of noise was generally similar across groups with and without ASD. But when the face was present, the noise had a more detrimental effect on children with ASD than their language-matched peers, suggesting neurotypical children were better able to use visual cues on the speaker’s face to aid performance. Moreover, those children with ASD who attended more to the speaker’s face showed better listening performance in the presence of noise.

Conclusions

Young children both with and without ASD show poorer performance comprehending speech in the presence of another talker than in quiet. However, results suggest that neurotypical children may be better able to make use of face cues to partially counteract the effects of noise. Children with ASD varied in their use of face cues, but those children who spent more time attending to the face of the target speaker appeared less disadvantaged by the presence of background noise, indicating a potential path for future interventions.

Neural Evidence for Speech Processing Deficits During a Cocktail Party Scenario in Minimally and Low Verbal Adolescents and Young Adults with Autism

As demonstrated by the Cocktail Party Effect, a person's attention is grabbed when they hear their name in a multispeaker setting. However, individuals with autism (ASD) are commonly challenged in multispeaker settings and often do not respond to salient speech, including one's own name (OON). It is unknown whether neural responses during this Cocktail Party scenario differ in those with ASD and whether such differences are associated with expressive language or auditory filtering abilities. We measured neural responses to hearing OON in quiet and multispeaker settings using electroencephalography in 20 minimally or low verbal ASD (ASD-MLV), 27 verbally fluent ASD (ASD-V), and 27 neurotypical (TD) participants, ages 13-22. First, we determined whether TD's neural responses to OON relative to other names could be quantified with early frontal mismatch responses (MMRs) and late, slow shift parietal and frontal responses (LPPs/FNs). Second, we compared the strength of MMRs and LPPs/FNs across the three groups. Third, we tested whether participants with poorer auditory filtering abilities exhibited particularly weak neural responses to OON heard in a multispeaker setting. Our primary finding was that TDs and ASD-Vs, but not ASD-MLVs, had significant MMRs to OON in a multispeaker setting, and strength of LPPs positively correlated with auditory filtering abilities in those with ASD. These findings reveal electrophysiological correlates of auditory filtering disruption within a clinical population that has severe language and communication impairments and offer a novel neuroimaging approach to studying the Cocktail Party effect in neurotypical and clinical populations. Autism Res 2020, 13: 1828-1842. © 2020 International Society for Autism Research and Wiley Periodicals LLC. LAY SUMMARY: We found that minimally and low verbal adolescents and young adults with autism exhibit decreased neural responses to one's own name when heard in a multispeaker setting. In addition, decreased strength of neural responses in those with autism correlated with decreased auditory filtering abilities. We propose that these neural deficits may reflect the ineffective processing of salient speech in noisy settings and contribute to language and communication deficits observed in autism.

Atypical Perception of Sounds in Minimally and Low Verbal Children and Adolescents With Autism as Revealed by Behavioral and Neural Measures

The common display of atypical behavioral responses to sounds by individuals with autism (ASD) suggests that they process sounds differently. Within ASD, individuals who are minimally or low verbal (ASD-MLV) are suspected to have greater auditory processing impairments. However, it is unknown whether atypical auditory behaviors are related to receptive language and/or neural processing of sounds in ASD-MLV. In Experiment 1, we compared the percentage of time 47 ASD-MLV and 36 verbally fluent (ASD-V) participants, aged 5-21, displayed atypical auditory or visual sensory behaviors during the administration of the Autism Diagnostic Observation Schedule (ADOS). In Experiment 2, we tested whether atypical auditory behaviors were more frequent in ASD-MLV participants with receptive language deficits. In Experiment 3, we tested whether atypical auditory behaviors correlated with neural indices of sensitivity to perceptual sound differences as measured by the amplitude of neural responses to nonspeech intensity deviants. We found that ASD-MLV participants engaged in atypical auditory behaviors more often than ASD-V participants; in contrast, the incidence of atypical visual behaviors did not differ between the groups. Lower receptive language skills in the ASD-MLV group were predicted by greater incidence of atypical auditory behaviors. Exploratory analyses revealed a significant negative correlation between the amount of atypical auditory behaviors and the amplitude of neural response to deviants. Future work is needed to elucidate whether the relationship between atypical auditory behaviors and receptive language impairments in ASD-MLV individuals results from disruptions in the brain mechanisms involved in auditory processing. LAY SUMMARY: Minimally and low verbal children and adolescents with autism (ASD-MLV) displayed more atypical auditory behaviors (e.g., ear covering and humming) than verbally fluent participants with ASD. In ASD-MLV participants, time spent exhibiting such behaviors was associated with receptive vocabulary deficits and weaker neural responses to changes in sound loudness. Findings suggest that individuals with ASD with both severe expressive and receptive language impairments process sounds differently. Autism Res 2020, 13: 1718-1729. © 2020 International Society for Autism Research and Wiley Periodicals LLC.

Excitation-inhibition balance and auditory multistable perception are correlated with autistic traits and schizotypy in a non-clinical population

Individuals with autism spectrum disorder and individuals with schizophrenia have impaired social and communication skills. They also have altered auditory perception. This study investigated autistic traits and schizotypy in a non-clinical population as well as the excitation-inhibition (EI) balance in different brain regions and their auditory multistable perception. Thirty-four healthy participants were assessed by the Autism-Spectrum Quotient (AQ) and Schizotypal Personality Questionnaire (SPQ). The EI balance was evaluated by measuring the resting-state concentrations of glutamate-glutamine (Glx) and ϒ-aminobutyric acid (GABA) in vivo by using magnetic resonance spectroscopy. To observe the correlation between their traits and perception, we conducted an auditory streaming task and a verbal transformation task, in which participants reported spontaneous perceptual switching while listening to a sound sequence. Their AQ and SPQ scores were positively correlated with the Glx/GABA ratio in the auditory cortex but not in the frontal areas. These scores were negatively correlated with the number of perceptual switches in the verbal transformation task but not in the auditory streaming task. Our results suggest that the EI balance in the auditory cortex and the perceptual formation of speech are involved in autistic traits and schizotypy.

Auditory Deficits in Audiovisual Speech Perception in Adult Asperger's Syndrome: fMRI Study

Audiovisual (AV) integration deficits have been proposed to underlie difficulties in speech perception in Asperger’s syndrome (AS). It is not known, if the AV deficits are related to alterations in sensory processing at the level of unisensory processing or at levels of conjoint multisensory processing. Functional Magnetic-resonance images (MRI) was performed in 16 adult subjects with AS and 16 healthy controls (HC) matched for age, gender, and verbal IQ as they were exposed to disyllabic AV congruent and AV incongruent nouns. A simple semantic categorization task was used to ensure subjects’ attention to the stimuli. The left auditory cortex (BA41) showed stronger activation in HC than in subjects with AS with no interaction regarding AV congruency. This suggests that alterations in auditory processing in unimodal low-level areas underlie AV speech perception deficits in AS. Whether this is signaling a difficulty in the deployment of attention remains to be demonstrated.

Enhanced auditory disembedding in an interleaved melody recognition test is associated with absolute pitch ability

Absolute pitch (AP) and autism have recently been associated with each other. Neurocognitive theories of autism could perhaps explain this co-occurrence. This study investigates whether AP musicians show an advantage in an interleaved melody recognition task (IMRT), an auditory version of an embedded figures test often investigated in autism with respect to the these theories. A total of N = 59 professional musicians (AP = 27) participated in the study. In each trial a probe melody was followed by an interleaved sequence. Participants had to indicate as to whether the probe melody was present in the interleaved sequence. Sensitivity index d′ and response bias c were calculated according to signal detection theory. Additionally, a pitch adjustment test measuring fine-graded differences in absolute pitch proficiency, the Autism-Spectrum-Quotient and a visual embedded figures test were conducted. AP outperformed relative pitch (RP) possessors on the overall IMRT and the fully interleaved condition. AP proficiency, visual disembedding and musicality predicted 39.2% of variance in the IMRT. No correlations were found between IMRT and autistic traits. Results are in line with a detailed-oriented cognitive style and enhanced perceptional functioning of AP musicians similar to that observed in autism.

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.

The impact of atypical sensory processing on social impairments in autism spectrum disorder

Altered sensory processing has been an important feature of the clinical descriptions of autism spectrum disorder (ASD). There is evidence that sensory dysregulation arises early in the progression of ASD and impacts social functioning. This paper reviews behavioral and neurobiological evidence that describes how sensory deficits across multiple modalities (vision, hearing, touch, olfaction, gustation, and multisensory integration) could impact social functions in ASD. Theoretical models of ASD and their implications for the relationship between sensory and social functioning are discussed. Furthermore, neural differences in anatomy, function, and connectivity of different regions underlying sensory and social processing are also discussed. We conclude that there are multiple mechanisms through which early sensory dysregulation in ASD could cascade into social deficits across development. Future research is needed to clarify these mechanisms, and specific focus should be given to distinguish between deficits in primary sensory processing and altered top-down attentional and cognitive processes.

Atypical preference for infant-directed speech as an early marker of autism spectrum disorders? A literature review and directions for further research

Autism spectrum disorders (ASD) refer to a complex group of neurodevelopmental disorders causing difficulties with communication and interpersonal relationships, as well as restricted and repetitive behaviours and interests. As early identification, diagnosis, and intervention provide better long-term outcomes, early markers of ASD have gained increased research attention. This review examines evidence that auditory processing enhanced by social interest, in particular auditory preference of speech directed towards infants and young children (i.e. infant-directed speech - IDS), may be an early marker of risk for ASD. Although this review provides evidence for IDS preference as, indeed, a potential early marker of ASD, the explanation for differences in IDS processing among children with ASD versus other children remains unclear, as are the implications of these impairments for later social-communicative development. Therefore, it is crucial to explore atypicalities in IDS processing early on development and to understand whether preferential listening to specific types of speech sounds in the first years of life may help to predict the impairments in social and language development.

The singular nature of auditory and visual scene analysis in autism

Individuals with autism spectrum disorder often have difficulty acquiring relevant auditory and visual information in daily environments, despite not being diagnosed as hearing impaired or having low vision. Resent psychophysical and neurophysiological studies have shown that autistic individuals have highly specific individual differences at various levels of information processing, including feature extraction, automatic grouping and top-down modulation in auditory and visual scene analysis. Comparison of the characteristics of scene analysis between auditory and visual modalities reveals some essential commonalities, which could provide clues about the underlying neural mechanisms. Further progress in this line of research may suggest effective methods for diagnosing and supporting autistic individuals.This article is part of the themed issue 'Auditory and visual scene analysis'.

Auditory Stream Segregation in Autism Spectrum Disorder: Benefits and Downsides of Superior Perceptual Processes

Auditory stream segregation allows us to organize our sound environment, by focusing on specific information and ignoring what is unimportant. One previous study reported difficulty in stream segregation ability in children with Asperger syndrome. In order to investigate this question further, we used an interleaved melody recognition task with children in the autism spectrum disorder (ASD). In this task, a probe melody is followed by a mixed sequence, made up of a target melody interleaved with a distractor melody. These two melodies have either the same [0 semitone (ST)] or a different mean frequency (6, 12 or 24 ST separation conditions). Children have to identify if the probe melody is present in the mixed sequence. Children with ASD performed better than typical children when melodies were completely embedded. Conversely, they were impaired in the ST separation conditions. Our results confirm the difficulty of children with ASD in using a frequency cue to organize auditory perceptual information. However, superior performance in the completely embedded condition may result from superior perceptual processes in autism. We propose that this atypical pattern of results might reflect the expression of a single cognitive feature in autism.

Auditory processing in noise is associated with complex patterns of disrupted functional connectivity in autism spectrum disorder

Autism spectrum disorder (ASD) is associated with difficulty in processing speech in a noisy background, but the neural mechanisms that underlie this deficit have not been mapped. To address this question, we used magnetoencephalography to compare the cortical responses between ASD and typically developing (TD) individuals to a passive mismatch paradigm. We repeated the paradigm twice, once in a quiet background, and once in the presence of background noise. We focused on both the evoked mismatch field (MMF) response in temporal and frontal cortical locations, and functional connectivity with spectral specificity between those locations. In the quiet condition, we found common neural sources of the MMF response in both groups, in the right temporal gyrus and inferior frontal gyrus (IFG). In the noise condition, the MMF response in the right IFG was preserved in the TD group, but reduced relative to the quiet condition in ASD group. The MMF response in the right IFG also correlated with severity of ASD. Moreover, in noise, we found significantly reduced normalized coherence (deviant normalized by standard) in ASD relative to TD, in the beta band (14-25 Hz), between left temporal and left inferior frontal sub-regions. However, unnormalized coherence (coherence during deviant or standard) was significantly increased in ASD relative to TD, in multiple frequency bands. Our findings suggest increased recruitment of neural resources in ASD irrespective of the task difficulty, alongside a reduction in top-down modulations, usually mediated by the beta band, needed to mitigate the impact of noise on auditory processing. Autism Res 2016,. © 2016 International Society for Autism Research, Wiley Periodicals, Inc. Autism Res 2017, 10: 631-647. © 2016 International Society for Autism Research, Wiley Periodicals, Inc.

The relationship between auditory processing and restricted, repetitive behaviors in adults with autism spectrum disorders

Current views suggest that autism spectrum disorders (ASDs) are characterised by enhanced low-level auditory discrimination abilities. Little is known, however, about whether enhanced abilities are universal in ASD and how they relate to symptomatology. We tested auditory discrimination for intensity, frequency and duration in 21 adults with ASD and 21 IQ and age-matched controls. Contrary to predictions, there were significant deficits in ASD on all acoustic parameters. The findings suggest that low-level auditory discrimination ability varies widely within ASD and this variability relates to IQ level, and influences the severity of restricted and repetitive behaviours (RRBs). We suggest that it is essential to further our understanding of the potential contributing role of sensory perception ability on the emergence of RRBs.

Enhanced segregation of concurrent sounds with similar spectral uncertainties in individuals with autism spectrum disorder

When acoustic signals from different sound sources are mixed upon arrival at the ears, the auditory system organizes these acoustic elements by their features. This study shows that individuals with autism spectrum disorder (ASD) performed better in terms of hearing a target sequence among distractors that had similar spectral uncertainties. Their superior performance in this task indicates an enhanced discrimination between auditory streams with the same spectral uncertainties but different spectro-temporal details. The enhanced discrimination of acoustic components may be related to the absence of the automatic grouping of acoustic components with the same features, which results in difficulties in speech perception in a noisy environment. On the other hand, the ASD group and the control group had similar performance in hearing a target sequence among distractors that had different spatial cues defined by interaural intensity differences.

Parent-mediated intervention versus no intervention for infants at high risk of autism: a parallel, single-blind, randomised trial

BACKGROUND

Risk markers for later autism identified in the first year of life present plausible intervention targets during early development. We aimed to assess the effect of a parent-mediated intervention for infants at high risk of autism on these markers.

METHODS

We did a two-site, two-arm assessor-blinded randomised controlled trial of families with an infant at familial high risk of autism aged 7-10 months, testing the adapted Video Interaction to Promote Positive Parenting (iBASIS-VIPP) versus no intervention. Families were randomly assigned to intervention or no intervention groups using a permuted block approach stratified by centre. Assessors, but not families or therapists, were masked to group assignment. The primary outcome was infant attentiveness to parent. Regression analysis was done on an intention-to-treat basis. This trial is registered with ISCRTN Registry, number ISRCTN87373263.

FINDINGS

We randomly assigned 54 families between April 11, 2011, and Dec 4, 2012 (28 to intervention, 26 to no intervention). Although CIs sometimes include the null, point estimates suggest that the intervention increased the primary outcome of infant attentiveness to parent (effect size 0.29, 95% CI -0.26 to 0.86, thus including possibilities ranging from a small negative treatment effect to a strongly positive treatment effect). For secondary outcomes, the intervention reduced autism-risk behaviours (0.50, CI -0.15 to 1.08), increased parental non-directiveness (0.81, 0.28 to 1.52), improved attention disengagement (0.48, -0.01 to 1.02), and improved parent-rated infant adaptive function (χ(2)[2] 15.39, p=0.0005). There was a possibility of nil or negative effect in language and responsivity to vowel change (P1: ES-0.62, CI -2.42 to 0.31; P2: -0.29, -1.55 to 0.71).

INTERPRETATION

With the exception of the response to vowel change, our study showed positive estimates across a wide range of behavioural and brain function risk-markers and developmental outcomes that are consistent with a moderate intervention effect to reduce the risk for later autism. However, the estimates have wide CIs that include possible nil or small negative effects. The results are encouraging for development and prevention science, but need larger-scale replication to improve precision.

FUNDING

Autistica, Waterloo Foundation, Autism Speaks, and the UK Medical Research Council.

Attention, memory, and auditory processing in 10- to 15-year-old children with listening difficulties

PURPOSE

The aim of this study was to examine attention, memory, and auditory processing in children with reported listening difficulty in noise (LDN) despite having clinically normal hearing.

METHOD

Twenty-one children with LDN and 15 children with no listening concerns (controls) participated. The clinically normed auditory processing tests included the Frequency/Pitch Pattern Test (FPT; Musiek, 2002), the Dichotic Digits Test (Musiek, 1983), the Listening in Spatialized Noise-Sentences (LiSN-S) test (Dillon, Cameron, Glyde, Wilson, & Tomlin, 2012), gap detection in noise (Baker, Jayewardene, Sayle, & Saeed, 2008), and masking level difference (MLD; Wilson, Moncrieff, Townsend, & Pillion, 2003). Also included were research-based psychoacoustic tasks, such as auditory stream segregation, localization, sinusoidal amplitude modulation (SAM), and fine structure perception. All were also evaluated on attention and memory test batteries.

RESULTS

The LDN group was significantly slower switching their auditory attention and had poorer inhibitory control. Additionally, the group mean results showed significantly poorer performance on FPT, MLD, 4-Hz SAM, and memory tests. Close inspection of the individual data revealed that only 5 participants (out of 21) in the LDN group showed significantly poor performance on FPT compared with clinical norms. Further testing revealed the frequency discrimination of these 5 children to be significantly impaired.

CONCLUSION

Thus, the LDN group showed deficits in attention switching and inhibitory control, whereas only a subset of these participants demonstrated an additional frequency resolution deficit.

Brief report: atypical neuromagnetic responses to illusory auditory pitch in children with autism spectrum disorders

Atypical auditory perception is a widely recognised but poorly understood feature of autism. In the current study, we used magnetoencephalography to measure the brain responses of 10 autistic children as they listened passively to dichotic pitch stimuli, in which an illusory tone is generated by sub-millisecond inter-aural timing differences in white noise. Relative to control stimuli that contain no inter-aural timing differences, dichotic pitch stimuli typically elicit an object related negativity (ORN) response, associated with the perceptual segregation of the tone and the carrier noise into distinct auditory objects. Autistic children failed to demonstrate an ORN, suggesting a failure of segregation; however, comparison with the ORNs of age-matched typically developing controls narrowly failed to attain significance. More striking, the autistic children demonstrated a significant differential response to the pitch stimulus, peaking at around 50 ms. This was not present in the control group, nor has it been found in other groups tested using similar stimuli. This response may be a neural signature of atypical processing of pitch in at least some autistic individuals.

Prepulse inhibition of the acoustic startle reflex in high functioning autism

Background

High functioning autism is an autism spectrum disorder that is characterized by deficits in social interaction and communication as well as repetitive and restrictive behavior while intelligence and general cognitive functioning are preserved. According to the weak central coherence account, individuals with autism tend to process information detail-focused at the expense of global form. This processing bias might be reflected by deficits in sensorimotor gating, a mechanism that prevents overstimulation during the transformation of sensory input into motor action. Prepulse inhibition is an operational measure of sensorimotor gating, which indicates an extensive attenuation of the startle reflex that occurs when a startling pulse is preceded by a weaker stimulus, the prepulse.

Methods

In the present study, prepulse inhibition of acoustic startle was compared between 17 adults with high functioning autism and 17 sex-, age-, and intelligence-matched controls by means of electromyography.

Results

Results indicate that participants with high functioning autism exhibited significantly higher startle amplitudes than the control group. However, groups did not differ with regard to PPI or habituation of startle.

Discussion

These findings challenge the results of two previous studies that reported prepulse inhibition deficits in high-functioning autism and suggest that sensorimotor gating is only impaired in certain subgroups with autism spectrum disorder.

Reduced object related negativity response indicates impaired auditory scene analysis in adults with autistic spectrum disorder

Auditory Scene Analysis provides a useful framework for understanding atypical auditory perception in autism. Specifically, a failure to segregate the incoming acoustic energy into distinct auditory objects might explain the aversive reaction autistic individuals have to certain auditory stimuli or environments. Previous research with non-autistic participants has demonstrated the presence of an Object Related Negativity (ORN) in the auditory event related potential that indexes pre-attentive processes associated with auditory scene analysis. Also evident is a later P400 component that is attention dependent and thought to be related to decision-making about auditory objects. We sought to determine whether there are differences between individuals with and without autism in the levels of processing indexed by these components. Electroencephalography (EEG) was used to measure brain responses from a group of 16 autistic adults, and 16 age- and verbal-IQ-matched typically-developing adults. Auditory responses were elicited using lateralized dichotic pitch stimuli in which inter-aural timing differences create the illusory perception of a pitch that is spatially separated from a carrier noise stimulus. As in previous studies, control participants produced an ORN in response to the pitch stimuli. However, this component was significantly reduced in the participants with autism. In contrast, processing differences were not observed between the groups at the attention-dependent level (P400). These findings suggest that autistic individuals have difficulty segregating auditory stimuli into distinct auditory objects, and that this difficulty arises at an early pre-attentive level of processing.

Attention effects on auditory scene analysis: insights from event-related brain potentials

Sounds emitted by different sources arrive at our ears as a mixture that must be disentangled before meaningful information can be retrieved. It is still a matter of debate whether this decomposition happens automatically or requires the listener's attention. These opposite positions partly stem from different methodological approaches to the problem. We propose an integrative approach that combines the logic of previous measurements targeting either auditory stream segregation (interpreting a mixture as coming from two separate sources) or integration (interpreting a mixture as originating from only one source). By means of combined behavioral and event-related potential (ERP) measures, our paradigm has the potential to measure stream segregation and integration at the same time, providing the opportunity to obtain positive evidence of either one. This reduces the reliance on zero findings (i.e., the occurrence of stream integration in a given condition can be demonstrated directly, rather than indirectly based on the absence of empirical evidence for stream segregation, and vice versa). With this two-way approach, we systematically manipulate attention devoted to the auditory stimuli (by varying their task relevance) and to their underlying structure (by delivering perceptual tasks that require segregated or integrated percepts). ERP results based on the mismatch negativity (MMN) show no evidence for a modulation of stream integration by attention, while stream segregation results were less clear due to overlapping attention-related components in the MMN latency range. We suggest future studies combining the proposed two-way approach with some improvements in the ERP measurement of sequential stream segregation.

The brain's response to the human voice depends on the incidence of autistic traits in the general population

Optimal brain sensitivity to the fundamental frequency (F0) contour changes in the human voice is important for understanding a speaker's intonation, and consequently, the speaker's attitude. However, whether sensitivity in the brain's response to a human voice F0 contour change varies with an interaction between an individual's traits (i.e., autistic traits) and a human voice element (i.e., presence or absence of communicative action such as calling) has not been investigated. In the present study, we investigated the neural processes involved in the perception of F0 contour changes in the Japanese monosyllables "ne" and "nu." "Ne" is an interjection that means "hi" or "hey" in English; pronunciation of "ne" with a high falling F0 contour is used when the speaker wants to attract a listener's attention (i.e., social intonation). Meanwhile, the Japanese concrete noun "nu" has no communicative meaning. We applied an adaptive spatial filtering method to the neuromagnetic time course recorded by whole-head magnetoencephalography (MEG) and estimated the spatiotemporal frequency dynamics of event-related cerebral oscillatory changes in beta band during the oddball paradigm. During the perception of the F0 contour change when "ne" was presented, there was event-related de-synchronization (ERD) in the right temporal lobe. In contrast, during the perception of the F0 contour change when "nu" was presented, ERD occurred in the left temporal lobe and in the bilateral occipital lobes. ERD that occurred during the social stimulus "ne" in the right hemisphere was significantly correlated with a greater number of autistic traits measured according to the Autism Spectrum Quotient (AQ), suggesting that the differences in human voice processing are associated with higher autistic traits, even in non-clinical subjects.

The five myths of MMN: redefining how to use MMN in basic and clinical research

The goal of this review article is to redefine what the mismatch negativity (MMN) component of event-related potentials reflects in auditory scene analysis, and to provide an overview of how the MMN serves as a valuable tool in Cognitive Neuroscience research. In doing so, some of the old beliefs (five common 'myths') about MMN will be dispelled, such as the notion that MMN is a simple feature discriminator and that attention itself modulates MMN elicitation. A revised description of what MMN truly reflects will be provided, which includes a principal focus onto the highly context-dependent nature of MMN elicitation and new terminology to discuss MMN and attention. This revised framework will help clarify what has been a long line of seemingly contradictory results from studies in which behavioral ability to hear differences between sounds and passive elicitation of MMN have been inconsistent. Understanding what MMN is will also benefit clinical research efforts by providing a new picture of how to design appropriate paradigms suited to various clinical populations.

Age and sensory processing abnormalities predict declines in encoding and recall of temporally manipulated speech in high-functioning adults with ASD

While temporal and perceptual processing abnormalities, identified in a number of electrophysiological and brain imaging studies of individuals with (ASD), are likely to impact on speech perception, surprisingly little is known about the behavioral outcomes of such abnormalities. It has been hypothesized that rapid temporal processing deficits may be linked to impaired language development through interference with acoustic information during speech perception. The present study aimed to investigate the impact of temporal changes on encoding and recall of speech, and the associated cognitive, clinical, and behavioral correlates in adults with ASD. Research carried out with typically developing (TD) adults has shown that word recall diminishes as the speed of speech increases, and it was predicted that the magnitude of this effect would be far greater in those with ASD because of a preexisting rapid temporal processing deficit. Nineteen high-functioning adults with ASD, and age- and intelligence-matched TD controls performed verbatim recall of temporally manipulated sentences. Reduced levels of word recall in response to increases in presentation speed were observed, and this effect was greater in the older participants in the ASD group than in the control group. This is the first study to show that both sensory abnormalities and aging impact on speech encoding in ASD. Auditory processing deficits in ASD may be indicative of an association with the sensory abnormalities and social and communication impairments characterizing the disorder.

Auditory processing in high-functioning adolescents with Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) is a pervasive developmental disorder including abnormalities in perceptual processing. We measure perception in a battery of tests across speech (filtering, phoneme categorization, multisensory integration) and music (pitch memory, meter categorization, harmonic priming). We found that compared to controls, the ASD group showed poorer filtering, less audio-visual integration, less specialization for native phonemic and metrical categories, and a higher instance of absolute pitch. No group differences were found in harmonic priming. Our results are discussed in a developmental framework where culture-specific knowledge acquired early compared to late in development is most impaired, perhaps because of early-accelerated brain growth in ASD. These results suggest that early auditory remediation is needed for good communication and social functioning.

Research review: structural language in autistic spectrum disorder - characteristics and causes

BACKGROUND

Structural language anomalies or impairments in autistic spectrum disorder (ASD) are theoretically and practically important, although underrecognised as such. This review aims to highlight the ubiquitousness of structural language anomalies and impairments in ASD, and to stimulate investigation of their immediate causes and implications for intervention.

METHOD

Studies of structural language in ASD are reviewed (based on a search of the literature and selected as meeting defined inclusion criteria), and explanatory hypotheses are discussed.

RESULTS

Some individuals with ASD never acquire language. Amongst those who do, language abilities range from clinically normal (ALN) to various degrees of impairment (ALI). Developmental trajectories and individual profiles are diverse, and minority subgroups have been identified. Specifically: language is commonly but not always delayed and delayed early language is always characterised by impaired comprehension and odd utterances, and sometimes by deviant articulation and grammar. Nevertheless, by school age an 'ASD-typical' language profile emerges from group studies, with articulation and syntax least affected, and comprehension, semantics and certain facets of morphology most affected. Thus, even individuals with ALN have poor comprehension relative to expressive language; also semantic-processing anomalies and idiosyncratic word usage. It is argued that impaired socio-emotional-communicative relating, atypical sensory-perceptual processing, and uneven memory/learning abilities may underlie shared language anomalies across the spectrum; and that varying combinations of low nonverbal intelligence, semantic memory impairment and comorbidities including specific language impairment (SLI), hearing impairment, and certain medical syndromes underlie ALI and variation in individual profiles.

CONCLUSIONS

Structural language is universally affected in ASD, due to a complex of shared and unshared causal factors. There is an urgent need for more research especially into the characteristics and causes of clinically significant language impairments.

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.

Pattern of BOLD signal in auditory cortex relates acoustic response to perceptual streaming

BACKGROUND

Segregating auditory scenes into distinct objects or streams is one of our brain's greatest perceptual challenges. Streaming has classically been studied with bistable sound stimuli, perceived alternately as a single group or two separate groups. Throughout the last decade different methodologies have yielded inconsistent evidence about the role of auditory cortex in the maintenance of streams. In particular, studies using functional magnetic resonance imaging (fMRI) have been unable to show persistent activity within auditory cortex (AC) that distinguishes between perceptual states.

RESULTS

We use bistable stimuli, an explicit perceptual categorization task, and a focused region of interest (ROI) analysis to demonstrate an effect of perceptual state within AC. We find that AC has more activity when listeners perceive the split percept rather than the grouped percept. In addition, within this ROI the pattern of acoustic response across voxels is significantly correlated with the pattern of perceptual modulation. In a whole-brain exploratory test, we corroborate previous work showing an effect of perceptual state in the intraparietal sulcus.

CONCLUSIONS

Our results show that the maintenance of auditory streams is reflected in AC activity, directly relating sound responses to perception, and that perceptual state is further represented in multiple, higher level cortical regions.

Abnormal auditory forward masking pattern in the brainstem response of individuals with Asperger syndrome

Abnormal auditory information processing has been reported in individuals with autism spectrum disorders (ASD). In the present study auditory processing was investigated by recording auditory brainstem responses (ABRs) elicited by forward masking in adults diagnosed with Asperger syndrome (AS). Sixteen AS subjects were included in the forward masking experiment and compared to three control groups consisting of healthy individuals (n = 16), schizophrenic patients (n = 16) and attention deficit hyperactivity disorder patients (n = 16), respectively, of matching age and gender. The results showed that the AS subjects exhibited abnormally low activity in the early part of their ABRs that distinctly separated them from the three control groups. Specifically, wave III amplitudes were significantly lower in the AS group than for all the control groups in the forward masking condition (P < 0.005), which was not the case in the baseline condition. Thus, electrophysiological measurements of ABRs to complex sound stimuli (eg, forward masking) may lead to a better understanding of the underlying neurophysiology of AS. Future studies may further point to specific ABR characteristics in AS individuals that separate them from individuals diagnosed with other neurodevelopmental diseases.