Processing of the fine temporal structure of sound in children with autism spectrum disorders (ASD)
To convey time-varying information of sounds in speech and to encode phonemes, the auditory cortex has to operate with a fine temporal resolution. The capacity of the auditory cortex to resolve sound frequency is reflected in the auditory steady state response (ASSR) –– a sustained response to periodic sound. Animal studies link ASSR abnormalities with excitation/inhibition imbalance caused by NMDA receptor dysfunction (Sivarao et al., 2014; 2015). This mechanism might be responsible for the speech processing abnormalities observed in a subgroup of patients with autism spectrum disorders.
In this study we search for neurophysiological correlates of atypical speech processing in children with ASD using the ASSR paradigm. We assess presence and degree of phonetic abnormalities in our participants using the Russian Aphasiа Test (РАТ, Dragoi et al., 2015) developed in the laboratory of neuro-linguistics, Higher School of Economics, for assessment of speech processing abnormalities in children with aphasia. Importantly, this study is the first one that thoroughly investigates the low-level (phonetic) and high-level (lexical, semantic and pragmatic) speech functions in Russian-speaking children with ASD. We assess severity of language problems in children with ASD and relate them to the indices of neural activity that reflect balance between neural excitation and inhibition in the auditory cortex. This study should help us understand mechanisms of speech and language problems in ASD and to find optimal approaches to their correction and treatment.