Project “Speech reception in young autistic children is selectively indexed by a coupling abnormality of neural oscillations”

Winning project of the 2023 scientific research prize from “5 senses for kids Foundation” in partnership with the Société des Neurosciences.

The research “Speech reception in young autistic children is selectively indexed by neural oscillation. It is coupled abnormality” and conducted by Dr. Xiaoyue WANG, post-doctoral researcher in neuroscientist. Non-profit public research.

“Neural coding and speech function engineering” team, Hearing Institute, Institut Pasteur, Paris-Cité University: 63 Rue de Charenton, 75012 Paris

Scientific context of the project

1. Autism Spectrum Disorder (ASD)

Autism Spectrum Disorder (ASD) mainly refers to disorders of social interactions. Many people with ASD have severe language disabilities. Sometimes even high-functioning individuals with excellent language skills have difficulty understanding speech in noisy environments and/or when exposed to multiple speakers.

2. People with Autism Spectrum Disorder (ASD)

People with Autism Spectrum Disorder (ASD) sometimes report that during childhood, their speech was difficult or partially intelligible. It sounded like a sequence of vowels, especially when many consonants were present. Furthermore, even with an excellent level of language, they often present atypical speech, suggesting other abnormalities in speech reception.

3. Various neuronal oscillations

Researchers have identified various neural oscillations that play a critical role in speech processing at different levels. These oscillations, range from phonemes (individual sounds) to sentences. Each one makes a unique contribution to how we understand and encode spoken language.

4. The ability to discern speech rhythms

The ability to discern speech rhythms is present from an early age in typically developing children. Newborns can detect changes in speech sounds and infants are able to follow syllabic rhythms and sentences in their native language, indicating the fundamental role of these skills in early phonological learning.

5. Disruption of the development of neuronal mechanisms

Disruption in the development of neural mechanisms for speech rhythm processing could be a contributing factor to speech decoding difficulties in children with ASD. This impairment may also affect the development of social skills, highlighting the importance of these neural processes in overall cognitive and social development.

Project issues

Our approach

1. Various abnormalities of neuronal oscillations in response to speech in individuals with ASD.
2. Young adults with ASD show joint abnormalities of theta (syllabic level) and low gamma (phonemic level) neural activity, originating primarily from the auditory cortex. This abnormal interaction between theta and gamma activities suggests a misalignment of phonemic coding with syllable tracking, potentially disrupting real-time speech reception.
3. Although these swing abnormalities correlate with verbal scores in individuals with ASD, it remains unclear whether they are specifically related to speech reception deficits and whether they are present in very young children during critical stages of speech development.

The project’s objectives

Our study

Our study using high-density electroencephalography (EEG) compared oscillatory neural processing of naturalistic speech in young children (aged 1.31–5.56 years) with and without ASD. The research aimed to determine whether oscillation abnormalities, particularly in the delta-theta, low beta and low gamma bands, are present at this early age and how they relate to language reception.

Precise characterization of these oscillation abnormalities is crucial to understanding speech reception difficulties in ASD. This may lead to the development of targeted interventions, such as normalizing (increasing or downregulating) oscillatory activity, to help individuals with ASD.

This study took place between 2018 and 2021.

Project results and impacts

Results

The results of this study provide a better understanding of the brain mechanisms underlying speech perception in young autistic children of diagnosed age (around three years), and their role in language acquisition. Our research uncovered atypical and distinct brain processes in autistic children. These processes highlight abnormal ways autistic children process the fundamental building blocks of speech. This finding suggests that speech perception in young autistic children is significantly impaired compared to neurotypical children. These abnormalities in speech perception have all the more clinical relevance as they are observable during a critical period of language development in children.

The most notable result of this study was the disruption of the coupling between theta and gamma oscillations in autistic children. This brain mechanism underlies hierarchical speech processing (the segmentation into speech units such as phonemes and syllables). If this mechanism is impaired, the children’s brain perceives and processes speech differently in autistic children compared to neurotypical children. This work also made it possible to observe an atypical brain process in autistic children. An unprecedented coupling between beta and gamma oscillations. This brain process appears to have a clear disruptive effect on language learning as it correlates negatively with language levels within our group of children.

Impacts

These findings are of great clinical importance because they show differences in sensory perception. During a critical period of children’s language development, the brain exhibits high plasticity and responsiveness, and impaired language acquisition is associated with differences in sensory processing. Abnormal speech perception at this age could create gaps in early cognitive development, and ultimately lead to lasting consequences on cognitive abilities.

This study paves the way for developing therapeutic interventions to address verbal communication deficits in autistic children. It achieves this by pinpointing the specific brain processes that need correction. Given the results of this study, it would appear that specific strategies targeting improved theta-gamma. Coupling and correcting atypical beta-gamma coupling could help restore more typical speech perception in these children. These interventions, if carried out during the critical period of speech acquisition, could prevent gaps from widening in the language development of autistic children compared to neurotypical children, and thus significantly improve their quality of life.