We examined central auditory processing in typically- and atypically-developing readers. Concurrent EEG and MEG brain measurements were obtained from a group of 16 children with dyslexia aged 8-12 years, and a group of 16 age-matched children with normal reading ability. Auditory responses were elicited using 500ms duration broadband noise. These responses were strongly lateralized in control children. Children with dyslexia showed significantly less lateralisation of auditory cortical functioning, and a different pattern of development of auditory lateralization with age. These results provide further evidence that the core neurophysiological deficit of dyslexia is a problem in the balance of auditory function between the two hemispheres.
Atypical auditory perception is a widely recognised but poorly understood feature of autism. In the current study, we used magnetoencephalography to measure the brain responses of 10 autistic children as they listened passively to dichotic pitch stimuli, in which an illusory tone is generated by sub-millisecond inter-aural timing differences in white noise. Relative to control stimuli that contain no inter-aural timing differences, dichotic pitch stimuli typically elicit an object related negativity (ORN) response, associated with the perceptual segregation of the tone and the carrier noise into distinct auditory objects. Autistic children failed to demonstrate an ORN, suggesting a failure of segregation; however, comparison with the ORNs of age-matched typically developing controls narrowly failed to attain significance. More striking, the autistic children demonstrated a significant differential response to the pitch stimulus, peaking at around 50 ms. This was not present in the control group, nor has it been found in other groups tested using similar stimuli. This response may be a neural signature of atypical processing of pitch in at least some autistic individuals.
for their excellent editorial comments, and Pat Laflin who is an expert in this field. Additional thanks goes to all the SEALS 2015 Conference participants who provided me with significant comments and advice during my presentation of this paper.
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