Neural Responses to Novel and Existing Words in Children with Autism Spectrum and Developmental Language Disorder.

Victoria C P Knowland,Courtenay F Norbury,Lisa-Marie Henderson,M Gareth Gaskell,Sarah A Walker,Daniel H Baker,Elaine Van Rijn

doi:10.5334/joc.204

Abstract

The formation of new phonological representations is key in establishing items in the mental lexicon. Phonological forms become stable with repetition, time and sleep. Atypicality in the establishment of new word forms is characteristic of children with developmental language disorder (DLD) and autism spectrum disorder (ASD), yet neural changes in response to novel word forms over time have not yet been directly compared in these groups.This study measured habituation of event-related-potentials (ERPs) to novel and known words within and between two sessions spaced 24 hours apart in typically developing (TD) children, and their peers with DLD or ASD. We hypothesised that modulation of the auditory N400 amplitude would mark real-time changes in lexical processing with habituation evident within and across sessions in the TD group, while the DLD group would show attenuated habituation within sessions, and the ASD group attenuated habituation between sessions.Twenty-one typically developing children, 19 children with ASD, and 16 children with DLD listened passively to known and novel words on two consecutive days, while ERPs were recorded using dry electrodes. Counter to our hypotheses, no habituation effect emerged within sessions. However, responses did habituate between sessions, with this effect being reduced in the DLD group, indicating less pre-activation of lexical representations in response to words encountered the previous day. No differences in change over time were observed between the TD and ASD groups. These data are in keeping with theories stressing the importance of sleep-related consolidation in word learning.

Highlights

The process of word learning shows substantial variability across children, and is atypical in some groups with neurodevelopmental disorders, including developmental language disorder (DLD) and autism spectrum disorders (ASD). In this data report we present an experimental dataset designed to track change in the initial representation of novel phonological forms over 24 hours in children with DLD, ASD and their language-typical peers
Of a possible 600 trials in total for each remaining participant, 67.9% of trials were maintained for the typically developing (TD) group, 72.6% for the ASD group and only 50.1% for the DLD group
For the TD group, 2.10% of catch trials were lapses, for the ASD group 4.69%, and for the DLD group this rose to 13.57%, resulting in a significant group difference in lapses (χ2 = 78.026, df = 2, p < 0.001)

Summary

Introduction

While recognition is often possible after a single hearing, accurate retrieval benefits from repeated exposure (Roediger & Butler, 2011) and the integration of the new form with existing lexical knowledge. The process of word learning shows substantial variability across children, and is atypical in some groups with neurodevelopmental disorders, including developmental language disorder (DLD) and autism spectrum disorders (ASD). In this data report we present an experimental dataset designed to track change in the initial representation of novel phonological forms over 24 hours in children with DLD, ASD and their language-typical peers

Methods

Results

Conclusion