A Comparison Of Music And Prosodic Processing In Autism Spectrum Disorder
Autism Spectrum Disorders (ASDs) are frequently associated with communicative impairment, regardless of IQ or mental age. The most significant feature of this impairment tends to be in the dimension of both expressive and receptive prosody, possibly due to reduced neural connectivity between disparate brain areas responsible for language. Despite extensive overlap between the auditory and structural features linking prosody and music as well as extensive shared neural resources, music listening and performance are not impaired. In fact, there is some evidence that these abilities may even be heightened in some ASD individuals. Using behavioral and EEG/ERP methods, the present study sought to investigate this dissociation. A similar electrophysiological response has been observed for both prosody and music, the Closure Positive Shift (CPS), and Music CPS, respectively. This study used language and music stimuli in order to investigate the differences between language and music processing for individuals with ASDs and neuro-typicals. While a CPS was observed for language for the ASD group, it was substantially reduced in its distribution and amplitude. Further, the presence of an offset N1 response to the onset of pauses interfered with the clarity of the CPS response. In music, no music CPS was observed, however, a sustained centrally maximal positivity was observed for both the neuro-typical and ASD groups during the phrase boundary. Additionally, the ASD group showed a similar positivity in response to phrase boundaries in the condition in which the phrase-final note was prolonged. This positivity was similar to the language CPS in duration and amplitude, and suggests similar processing responses to phrase boundaries in language and music. The positivity in response to the second condition suggests that some individuals with ASDs may indeed have heightened processing ability for music. These results support the theories of functional under-connectivity in language and local bias toward sensory features of auditory information at the expense of global prosodic processing. Possible explanations, including the presence of repetition found in music, yet generally absent in language, are considered.