Atypical sound discrimination in children with ASD as indicated by cortical ERPs

Multiple talker processing in autistic adult listeners

Accommodating talker variability is a complex and multi-layered cognitive process. It involves shifting attention to the vocal characteristics of the talker as well as the linguistic content of their speech. Due to an interdependence between voice and phonological processing, multi-talker environments typically incur additional processing costs compared to single-talker environments. A failure or inability to efficiently distribute attention over multiple acoustic cues in the speech signal may have detrimental language learning consequences. Yet, no studies have examined effects of multi-talker processing in populations with atypical perceptual, social and language processing for communication, including autistic people. Employing a classic word-monitoring task, we investigated effects of talker variability in Australian English autistic (n = 24) and non-autistic (n = 28) adults. Listeners responded to target words (e.g., apple, duck, corn) in randomised sequences of words. Half of the sequences were spoken by a single talker and the other half by multiple talkers. Results revealed that autistic participants' sensitivity scores to accurately-spotted target words did not differ to those of non-autistic participants, regardless of whether they were spoken by a single or multiple talkers. As expected, the non-autistic group showed the well-established processing cost associated with talker variability (e.g., slower response times). Remarkably, autistic listeners' response times did not differ across single- or multi-talker conditions, indicating they did not show perceptual processing costs when accommodating talker variability. The present findings have implications for theories of autistic perception and speech and language processing.

Sounds Pleasantness Ratings in Autism: Interaction Between Social Information and Acoustical Noise Level

A lack of response to voices, and a great interest for music are part of the behavioral expressions, commonly (self-)reported in Autism Spectrum Disorder (ASD). These atypical interests for vocal and musical sounds could be attributable to different levels of acoustical noise, quantified in the harmonic-to-noise ratio (HNR). No previous study has investigated explicit auditory pleasantness in ASD comparing vocal and non-vocal sounds, in relation to acoustic noise level. The aim of this study is to objectively evaluate auditory pleasantness. 16 adults on the autism spectrum and 16 neuro-typical (NT) matched adults rated the likeability of vocal and non-vocal sounds, with varying harmonic-to-noise ratio levels. A group by category interaction in pleasantness judgements revealed that participants on the autism spectrum judged vocal sounds as less pleasant than non-vocal sounds; an effect not found for NT participants. A category by HNR level interaction revealed that participants of both groups rated sounds with a high HNR as more pleasant for non-vocal sounds. A significant group by HNR interaction revealed that people on the autism spectrum tended to judge as less pleasant sounds with high HNR and more pleasant those with low HNR than NT participants. Acoustical noise level of sounds alone does not appear to explain atypical interest for voices and greater interest in music in ASD.

Cortical dysmorphology and reduced cortico-collicular projections in an animal model of autism spectrum disorder

Autism spectrum disorder is a neurodevelopmental disability that includes sensory disturbances. Hearing is frequently affected and ranges from deafness to hypersensitivity. In utero exposure to the antiepileptic valproic acid is associated with increased risk of autism spectrum disorder in humans and timed valproic acid exposure is a biologically relevant and validated animal model of autism spectrum disorder. Valproic acid-exposed rats have fewer neurons in their auditory brainstem and thalamus, fewer calbindin-positive neurons, reduced ascending projections to the midbrain and thalamus, elevated thresholds, and delayed auditory brainstem responses. Additionally, in the auditory cortex, valproic acid exposure results in abnormal responses, decreased phase-locking, elevated thresholds, and abnormal tonotopic maps. We therefore hypothesized that in utero, valproic acid exposure would result in fewer neurons in auditory cortex, neuronal dysmorphology, fewer calbindin-positive neurons, and reduced connectivity. We approached this hypothesis using morphometric analyses, immunohistochemistry, and retrograde tract tracing. We found thinner cortical layers but no changes in the density of neurons, smaller pyramidal and non-pyramidal neurons in several regions, fewer neurons immunoreactive for calbindin-positive, and fewer cortical neurons projecting to the inferior colliculus. These results support the widespread impact of the auditory system in autism spectrum disorder and valproic acid-exposed animals and emphasize the utility of simple, noninvasive auditory screening for autism spectrum disorder.

Unveiling the development of human voice perception: Neurobiological mechanisms and pathophysiology

The human voice is a critical stimulus for the auditory system that promotes social connection, informs the listener about identity and emotion, and acts as the carrier for spoken language. Research on voice processing in adults has informed our understanding of the unique status of the human voice in the mature auditory cortex and provided potential explanations for mechanisms that underly voice selectivity and identity processing. There is evidence that voice perception undergoes developmental change starting in infancy and extending through early adolescence. While even young infants recognize the voice of their mother, there is an apparent protracted course of development to reach adult-like selectivity for human voice over other sound categories and recognition of other talkers by voice. Gaps in the literature do not allow for an exact mapping of this trajectory or an adequate description of how voice processing and its neural underpinnings abilities evolve. This review provides a comprehensive account of developmental voice processing research published to date and discusses how this evidence fits with and contributes to current theoretical models proposed in the adult literature. We discuss how factors such as cognitive development, neural plasticity, perceptual narrowing, and language acquisition may contribute to the development of voice processing and its investigation in children. We also review evidence of voice processing abilities in premature birth, autism spectrum disorder, and phonagnosia to examine where and how deviations from the typical trajectory of development may manifest.

Autism Spectrum Disorder and auditory sensory alterations: a systematic review on the integrity of cognitive and neuronal functions related to auditory processing

Autism Spectrum Disorder (ASD) is a neurodevelopmental condition with a wide spectrum of symptoms, mainly characterized by social, communication, and cognitive impairments. Latest diagnostic criteria according to DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, 2013) now include sensory issues among the four restricted/repetitive behavior features defined as "hyper- or hypo-reactivity to sensory input or unusual interest in sensory aspects of environment". Here, we review auditory sensory alterations in patients with ASD. Considering the updated diagnostic criteria for ASD, we examined research evidence (2015-2022) of the integrity of the cognitive function in auditory-related tasks, the integrity of the peripheral auditory system, and the integrity of the central nervous system in patients diagnosed with ASD. Taking into account the different approaches and experimental study designs, we reappraise the knowledge on auditory sensory alterations and reflect on how these might be linked with behavior symptomatology in ASD.

Prediction of autism spectrum disorder diagnosis using nonlinear measures of language-related EEG at 6 and 12 months

BACKGROUND

Early identification of autism spectrum disorder (ASD) provides an opportunity for early intervention and improved developmental outcomes. The use of electroencephalography (EEG) in infancy has shown promise in predicting later ASD diagnoses and in identifying neural mechanisms underlying the disorder. Given the high co-morbidity with language impairment, we and others have speculated that infants who are later diagnosed with ASD have altered language learning, including phoneme discrimination. Phoneme learning occurs rapidly in infancy, so altered neural substrates during the first year of life may serve as early, accurate indicators of later autism diagnosis.

METHODS

Using EEG data collected at two different ages during a passive phoneme task in infants with high familial risk for ASD, we compared the predictive accuracy of a combination of feature selection and machine learning models at 6 months (during native phoneme learning) and 12 months (after native phoneme learning), and we identified a single model with strong predictive accuracy (100%) for both ages. Samples at both ages were matched in size and diagnoses (n = 14 with later ASD; n = 40 without ASD). Features included a combination of power and nonlinear measures across the 10‑20 montage electrodes and 6 frequency bands. Predictive features at each age were compared both by feature characteristics and EEG scalp location. Additional prediction analyses were performed on all EEGs collected at 12 months; this larger sample included 67 HR infants (27 HR-ASD, 40 HR-noASD).

RESULTS

Using a combination of Pearson correlation feature selection and support vector machine classifier, 100% predictive diagnostic accuracy was observed at both 6 and 12 months. Predictive features differed between the models trained on 6- versus 12-month data. At 6 months, predictive features were biased to measures from central electrodes, power measures, and frequencies in the alpha range. At 12 months, predictive features were more distributed between power and nonlinear measures, and biased toward frequencies in the beta range. However, diagnosis prediction accuracy substantially decreased in the larger, more behaviorally heterogeneous 12-month sample.

CONCLUSIONS

These results demonstrate that speech processing EEG measures can facilitate earlier identification of ASD but emphasize the need for age-specific predictive models with large sample sizes to develop clinically relevant classification algorithms.

Central Auditory and Vestibular Dysfunction Are Key Features of Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by repetitive behaviors, poor social skills, and difficulties with communication. Beyond these core signs and symptoms, the majority of subjects with ASD have some degree of auditory and vestibular dysfunction. Dysfunction in these sensory modalities is significant as normal cognitive development depends on an accurate representation of our environment. The hearing difficulties in ASD range from deafness to hypersensitivity and subjects with ASD have abnormal sound-evoked brainstem reflexes and brainstem auditory evoked potentials. Vestibular dysfunction in ASD includes postural instability, gait dysfunction, and impaired gaze. Untreated vestibular dysfunction in children can lead to delayed milestones such as sitting and walking and poor motor coordination later in life. Histopathological studies have revealed that subjects with ASD have significantly fewer neurons in the auditory hindbrain and surviving neurons are smaller and dysmorphic. These findings are consistent with auditory dysfunction. Further, the cerebellum was one of the first brain structures implicated in ASD and studies have revealed loss of Purkinje cells and the presence of ectopic neurons. Together, these studies suggest that normal auditory and vestibular function play major roles in the development of language and social abilities, and dysfunction in these systems may contribute to the core symptoms of ASD. Further, auditory and vestibular dysfunction in children may be overlooked or attributed to other neurodevelopmental disorders. Herein we review the literature on auditory and vestibular dysfunction in ASD. Based on these results we developed a brainstem model of central auditory and vestibular dysfunction in ASD and propose that simple, non-invasive but quantitative testing of hearing and vestibular function be added to newborn screening protocols.

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.

Enhanced Memory for Vocal Melodies in Autism Spectrum Disorder and Williams Syndrome

Adults and children with typical development (TD) remember vocal melodies (without lyrics) better than instrumental melodies, which is attributed to the biological and social significance of human vocalizations. Here we asked whether children with autism spectrum disorder (ASD), who have persistent difficulties with communication and social interaction, and adolescents and adults with Williams syndrome (WS), who are highly sociable, even indiscriminately friendly, exhibit a memory advantage for vocal melodies like that observed in individuals with TD. We tested 26 children with ASD, 26 adolescents and adults with WS of similar mental age, and 26 children with TD on their memory for vocal and instrumental (piano, marimba) melodies. After exposing them to 12 unfamiliar folk melodies with different timbres, we required them to indicate whether each of 24 melodies (half heard previously) was old (heard before) or new (not heard before) during an unexpected recognition test. Although the groups successfully distinguished the old from the new melodies, they differed in overall memory. Nevertheless, they exhibited a comparable advantage for vocal melodies. In short, individuals with ASD and WS show enhanced processing of socially significant auditory signals in the context of music. LAY SUMMARY: Typically developing children and adults remember vocal melodies better than instrumental melodies. In this study, we found that children with Autistic Spectrum Disorder, who have severe social processing deficits, and children and adults with Williams syndrome, who are highly sociable, exhibit comparable memory advantages for vocal melodies. The results have implications for musical interventions with these populations.

Autism Adversely Affects Auditory Joint Engagement During Parent-toddler Interactions

This study documents the early adverse effects of autism spectrum disorder (ASD) on auditory joint engagement-the sharing of sounds during interactions. A total of 141 toddlers (49 typically developing [TD], 46 with ASD, and 46 with non-ASD developmental disorders [DD]; average age 22.6 months) were observed during a semi-naturalistic play session with a parent. Reactions to four types of sounds-speech about the child, instrumental music, animal calls, and mechanical noises-were observed before and as parents tried to scaffold joint engagement with the sound. Toddlers with ASD usually appeared aware of a new sound, often alerting to and orienting toward it. But compared to TD toddlers and toddlers with DD, they alerted and oriented less often to speech, a difference not found with the other sounds. Furthermore, toddlers with ASD were far less likely to spontaneously try to share the sound with the parents and to engage with the parent and the sound when parents tried to share it with them. These findings reveal how ASD can have significant effects on shared experiences with nonvisible targets in the environment that attract toddlers' attention. Future studies should address the association between auditory joint engagement difficulties and variations in multimodal joint engagement, sensory profiles, and ASD severity and the reciprocal influence over time of auditory joint engagement experience and language development. LAY SUMMARY: Like most toddlers, toddlers with autism spectrum disorder often alert when they hear sounds like a cat's meow or a train's rumble. But they are less likely to alert when they hear their own name, and they are far less likely to share new sounds with their parents. These findings raise important questions about how toddlers with autism spectrum disorder experience their everyday auditory world, including how they share it with parents who can enrich this experience.

Structural and Functional Aberrations of the Auditory Brainstem in Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a neurodevelopmental condition associated with difficulties in the social, communicative, and behavioral domains. Most cases of ASD arise from an unknown etiologic process, but there are numerous risk factors, including comorbidities and maternal exposures. Although it is not part of the diagnostic criteria, hearing difficulties ranging from deafness to hyperacusis are present in the majority of persons with ASD. High-functioning children with ASD have been found to have significantly slower and asymmetric auditory brainstem reflexes. Additionally, histopathological studies of postmortem brainstems in decedents who had ASD have consistently revealed significantly fewer neurons in auditory nuclei compared with those in people who did not have ASD. The authors review the literature implicating auditory dysfunction in ASD along with results from human study participants and postmortem human brain tissue. Together, these results implicate significant structural and functional abnormalities in the auditory brainstem in ASD and support the utility of auditory testing to screen for ASD.

Atypical Sound Perception in ASD Explained by Inter-Trial (In)consistency in EEG

A relative indifference to the human voice is a characteristic of Autism Spectrum Disorder (ASD). Yet, studies of voice perception in ASD provided contradictory results: one study described an absence of preferential response to voices in ASD while another reported a larger activation to vocal sounds than environmental sounds, as seen in typically developed (TD) adults. In children with ASD, an absence of preferential response to vocal sounds was attributed to an atypical response to environmental sounds. To have a better understanding of these contradictions, we re-analyzed the data from sixteen children with ASD and sixteen age-matched TD children to evaluate both inter- and intra-subject variability. Intra-subject variability was estimated with a single-trial analysis of electroencephalographic data, through a measure of inter-trial consistency, which is the proportion of trials showing a positive activity in response to vocal and non-vocal sounds. Results demonstrate a larger inter-subject variability in response to non-vocal sounds, driven by a subset of children with ASD (7/16) who do not show the expected negative Tb peak in response to non-vocal sounds around 200 ms after the start of the stimulation due to a reduced inter-trial consistency. A logistic regression model with age and clinical parameters allowed demonstrating that not a single parameter discriminated the subgroups of ASD participants. Yet, the electrophysiologically-based groups differed on a linear combination of parameters. Children with ASD showing a reduced inter-trial consistency were younger and characterized by lower verbal developmental quotient and less attempt to communicate by voice. This data suggests that a lack of specialization for processing social signal may stem from an atypical processing of environmental sounds, linked to the development of general communication abilities. Discrepancy reported in the literature may arise from that heterogeneity and it may be inadequate to divide children with ASD based only on intellectual quotient or language abilities. This analysis could be a useful tool in providing complementary information for the functional diagnostic of ASD and evaluating verbal communication impairment.

Sensory processing in children with autism spectrum disorder and the mental health of primary caregivers

BACKGROUND

Sensory processing difficulties, which commonly occur in autism spectrum disorder (ASD), are expected to have negative effects on the primary caregiver's mental health. The aim of this study was to examine the association between sensory processing difficulties in children with ASD and the mental health of primary caregivers.

METHODS

A total of 707 primary caregivers (mothers in the present study) and their children with ASD (4-18 years of age) participated in this study. Sensory processing difficulties were indexed using the Short Sensory Profile (SSP). The mental health of primary caregivers was indexed using the General Health Questionnaire (GHQ12).

RESULTS

Higher scores on Auditory Filtering as measured with the SSP were associated with poorer mental health of primary caregivers, even after an adjustment for ASD symptom severity. Analyses of two age sub-groups, a young (4-10 years) and an old age group (11-18 years), revealed that higher scores on Tactile Sensitivity and Auditory Filtering were associated with poorer mental health of primary caregivers in younger children, whereas only higher scores on Auditory Filtering were associated with poorer mental health of primary caregivers in older children.

CONCLUSIONS

Our findings suggest that practitioners who support primary caregivers of children with ASD need to focus not only on the social and communication-related symptoms of the child but also on their specific sensory processing difficulties.

Influence of speech-language therapy on P300 outcome in patients with language disorders: a meta-analysis

Introduction

The patient's evolution in the audiology and speech-language clinic acts as a motivator of the therapeutic process, contributing to patient adherence to the treatment and allowing the therapist to review and/or maintain their clinical therapeutic conducts. Electrophysiological measures, such as the P300 evoked potential, help in the evaluation, understanding and monitoring of human communication disorders, thus facilitating the prognosis definition in each case.

Objective

To determine whether the audiology and speech-language therapy influences the variation of P300 latency and amplitude in patients with speech disorders undergoing speech therapy.

Methods

This is a systematic review with meta-analysis, in which the following databases were searched: Pubmed, ScienceDirect, SCOPUS, Web of Science, SciELO and LILACS, in addition to the gray literature bases: OpenGrey.eu and DissOnline. The inclusion criteria were randomized or non-randomized clinical trials, without language or date restriction, which evaluated children with language disorders undergoing speech therapy, monitored by P300, compared to children without intervention.

Results

The mean difference between the latencies in the group submitted to therapy and the control group was −20.12 ms with a 95% confidence interval of −43.98 to 3.74 ms (p = 0.08, I² = 25% and p value = 0.26). The mean difference between the amplitudes of the group submitted to therapy and the control group was 0.73 uV with a 95% confidence interval of −1.77 to 3.23 uV (p = 0.57, I² = 0% and p value = 0.47).

Conclusion

The present meta-analysis demonstrates that speech therapy does not influence the latency and amplitude results of the P300 evoked potential in children undergoing speech therapy intervention.

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.

A strategic plan to identify key neurophysiological mechanisms and brain circuits in autism

Autism and Autism Spectrum Disorder (ASD) cover a large variety of clinical profiles which share two main dimensions: social and communication impairment and repetitive behaviors or restricted interests, which are present during childhood. There is now no doubt that genetic factors are a major component in the etiology of autism but precise physiopathological pathways are still being investigated. Furthermore, developmental trajectories combined with compensatory mechanisms will lead to various clinical and neurophysiological profiles which together constitute this Autism Spectrum Disorder. To better understand the pathophysiology of autism, comprehension of key neurophysiological mechanisms and brain circuits underlying the different bioclinical profiles is thus crucial. To achieve this goal we propose a strategy which investigates different levels of information processing from sensory perception to complex cognitive processing, taking into account the complexity of the stimulus and whether it is social or non-social in nature. In order to identify different developmental trajectories and to take into account compensatory mechanisms, we further propose that such protocols should be carried out in individuals from childhood to adulthood representing a wide variety of clinical forms.

Atypical speech versus non-speech detection and discrimination in 4- to 6- yr old children with autism spectrum disorder: An ERP study

Previous event-related potential (ERP) research utilizing oddball stimulus paradigms suggests diminished processing of speech versus non-speech sounds in children with an Autism Spectrum Disorder (ASD). However, brain mechanisms underlying these speech processing abnormalities, and to what extent they are related to poor language abilities in this population remain unknown. In the current study, we utilized a novel paired repetition paradigm in order to investigate ERP responses associated with the detection and discrimination of speech and non-speech sounds in 4- to 6-year old children with ASD, compared with gender and verbal age matched controls. ERPs were recorded while children passively listened to pairs of stimuli that were either both speech sounds, both non-speech sounds, speech followed by non-speech, or non-speech followed by speech. Control participants exhibited N330 match/mismatch responses measured from temporal electrodes, reflecting speech versus non-speech detection, bilaterally, whereas children with ASD exhibited this effect only over temporal electrodes in the left hemisphere. Furthermore, while the control groups exhibited match/mismatch effects at approximately 600 ms (central N600, temporal P600) when a non-speech sound was followed by a speech sound, these effects were absent in the ASD group. These findings suggest that children with ASD fail to activate right hemisphere mechanisms, likely associated with social or emotional aspects of speech detection, when distinguishing non-speech from speech stimuli. Together, these results demonstrate the presence of atypical speech versus non-speech processing in children with ASD when compared with typically developing children matched on verbal age.