‘Spoken Vs Sung'- Investigating Auditory Brain Networks in Children with Autism

Background: A wide range of enhancements and impairments in auditory function have been reported in individuals with Autism Spectrum Disorders. These include impaired perception of speech and linguistic stimuli as well as enhanced responses to musical sounds. Recently, it has also been suggested that music-based interventions engage a large multimodal brain network and may hence be useful in entraining functions which might impaired in autism. However, not many studies have investigated the neural correlates of music processing in autism and how it might affect language and speech functions. 

Objectives:  The primary objective of our study is to identify the structural and functional networks involved in processing spoken speech, sung speech and music in children with autism as compared to typically developing children with a view to designing interventions targeted at entraining these communication networks via early music-based training.

Methods: We conducted a passive-listening task with three kinds of stimuli –spoken words, sung words and piano tones in a sparse-sampling, event-related fMRI paradigm. All words were bisyllabic nouns or verbs commonly used by children, such as ‘balloon’ and ‘sleeping’. The melodies for the sung words were combinations of two major notes, which were also used for creating the piano tones. Both the spoken and sung stimuli were delivered by a professionally trained musician. The task was performed by 13 participants, 6 children with autism (ASD) diagnosed using DSM IV criteria (mean age 13.6 years) and 7 typically developing (TYP) controls (mean age 11 years). 90 volumes in 3 runs were acquired with TR=10s in a 3T scanner. In addition, a high resolution anatomical T1 image was also acquired. Data analysis was performed using SPM5.

Results: Preliminary data showed that perception of spoken words as well as sung words elicited a bilateral superior temporal network in both the TYP group as well as the ASD group. We also found that sung words elicited greater activity when compared to spoken words. However, the pattern of activity differed between the TYP and ASD groups in that the Sung>Spoken contrast recruited bilateral auditory networks in the TYP group whereas it was more right-lateralized for the ASD group. The Spoken>Sung contrast on the other hand showed greater left temporal activity for the TYP group and left frontal activity for the ASD group. Tones elicited right>left activity for both groups.

Conclusions:  Our preliminary findings show that typically developing children recruit bilateral auditory brain networks for processing both spoken and sung word stimuli. However, children with autism show a rightward asymmetry in processing sung words. Given that sung stimuli are more salient than spoken words and show a greater recruitment of the right hemisphere, this finding may be explored further using connectivity studies to determine the notion of musical entrainment of speech and language.