Early ERF Responses to Final Words in a Sentence Context during Reading in Individuals with Autism Spectrum Disorders: An MEG Study

Abstract

This study used magnetoencephalography (MEG) to study the neural basis of abnormalities in sentence context effects in individuals with an autism spectrum disorder (ASD) and typically developing (TD) individuals. Early ERF responses (~150ms) to three different types of final words [dominant homonyms (DH), subordinate homonyms (SH), unambiguous words (UW)] were analyzed. In both participant groups, strong responses were observed at word response latency over left-occipito and mid-parietal regions. There were no significant differences between the participant groups in any of the final words at 150ms. The neural responses, however, were significantly modulated by the final word category within groups. In TD, the response to UW was significantly different than both DH and SH predominantly over the left hemisphere. There were no differences between DH and SH conditions in TD individuals. On the other hand, in ASD, there was a significant difference between each paired final word condition, where significant responses were observed mainly over the right hemisphere. These results are consistent with the argument that early semantic access takes place as early as 150ms after the onset of a word. Moreover, these findings suggest atypical semantic representations for more and less frequent meanings of the homonyms in individuals with ASD.