Report
Teaser, summary, work performed and final results
Periodic Reporting for period 1 - BIOMARK (Biomarkers of disordered language in autism)
Teaser
Evidence shows us that autism refers to a heterogeneous group of neurodevelopmental disorders. This heterogeneity has greatly hindered our understanding of autism. This proposal attempted to disentangle this heterogeneity by focusing on one piece of the autism phenotype:...
Summary
Evidence shows us that autism refers to a heterogeneous group of neurodevelopmental disorders. This heterogeneity has greatly hindered our understanding of autism. This proposal attempted to disentangle this heterogeneity by focusing on one piece of the autism phenotype: disordered language. More specifically, we focused on impairments involving phonology, the sounds of language. Infants acquire phonological skills in the first year of life. A disruption in the development of these skills can compromise or even preclude language acquisition. Behavioral studies have provided evidence for an autism subgroup defined by phonological deficits. This subgroup is hypothesized to overlap with specific language impairment (SLI), a developmental language disorder clinically marked by phonological deficits. Given that the presence of speech before age five is the strongest predictor of a better outcome for a child with autism, understanding language deficits that can be present at a very early age is critical. This study utilized EEG to examine neural activity relevant to phonological processing in children with autism. Our primary goal is to identify biomarkers indexing impaired phonology that can inform earlier diagnoses and treatments for children with disordered language. In addition to this goal, undertaking this research at the BCBL and the University of Seville, provided access to both mono- and bilingual children.. Developing bilinguals are the rule in the world. Despite this, little is known about bilingualism in autism. Preliminary results show differences in delta and gamma bands between autistic children and controls, but no differences between bilinguals and monolinguals. In addition, when presented with electronic sinusoidal and complex sounds with human features, in a habituation paradigm, autistic children and controls responded to deviant stimuli. However, the amplitude of the P1 component, induced by human sounds, was higher in amplitude only in the controls. Autistic children did not habituate to human sounds.
Work performed
In the present study brain activity has been examined during the following scans:
1. Speech stimuli consisting of 1 minute segments of forward speech, spectrally rotated speech, and rest periods. A total of 6 trials of each stimulus type resulting in a scan of 18 minutes.
2. Frequency tagged stimuli. 6 minutes of frequency tagged stimuli (3,11 and 37 Hz).
3. Electronic sinusoidal and complex sounds with human features
Stimuli were presented via loudspeakers at 75 dB. Children were able to watch a silent video during the scan. Caregivers were present at all times and were seated with the children during scanning procedures. EEG and fNIRS sensors were incorporated into a single cap. For the EEG electrodes a gel was placed in each sensor. The gel made the child’s head and hair a bit messy, but after completion of the tasks, the cap was removed and the parent had the opportunity to wash their child’s head. The gel used for imaging procedures can in rare instances cause a slight irritation of the skin (itching and/or rash). If there was any indication of an irritation, the cap was immediately removed. Children were able to rest between the two scanning tasks. Including cap set up, scanning procedures lasted approximately one hour depending on the amount of breaks required by the participant. While completely noninvasive, the cap can be uncomfortable for some infants and children, for example some children do not even like having winter hats or caps on. If the participant showed discomfort, scanning procedures were immediately ceased.
Final results
This project is an attempt to disentangle this heterogeneity by narrowing our focus to the language component of the autism phenotype.
Impairments in language are a hallmark of autism. The most common first concern for a parent with a child that is later diagnosed with autism is delayed or absent language development. However, language ability varies from nonverbal to fluent language across individuals with autism. As a first step to parse apart this heterogeneity, we have tried to refine our focus to a specific aspect of language: phonology. Phonology refers to the sounds of a language. We have chosen to focus on phonology for two reasons:
1. Skills involving phonology are one of the earliest language abilities acquired by infants in the first year of life.
2. Behavioral evidence shows us that there is a subgroup estimated to range as high as 77% primarily defined by deficits involving phonology within the spectrum. This subgroup is hypothesized to overlap behaviorally and etiologically with children with specific language impairment (SLI).