Abstract
Language impairment is a hallmark of autism spectrum disorders (ASD).
The origin of the deficit is poorly understood although deficiencies
in auditory processing have been detected in both perception and
cortical encoding of speech sounds. Little is known about the processing
and transcription of speech sounds at earlier (brainstem) levels
or about how background noise may impact this transcription process.
Unlike cortical encoding of sounds, brainstem representation preserves
stimulus features with a degree of fidelity that enables a direct
link between acoustic components of the speech syllable (e.g. onsets)
to specific aspects of neural encoding (e.g. waves V and A). We measured
brainstem responses to the syllable /da/, in quiet and background
noise, in children with and without ASD. Children with ASD exhibited
deficits in both the neural synchrony (timing) and phase locking
(frequency encoding) of speech sounds, despite normal click-evoked
brainstem responses. They also exhibited reduced magnitude and fidelity
of speech-evoked responses and inordinate degradation of responses
by background noise in comparison to typically developing controls.
Neural synchrony in noise was significantly related to measures of
core and receptive language ability. These data support the idea
that abnormalities in the brainstem processing of speech contribute
to the language impairment in ASD. Because it is both passively elicited
and malleable, the speech-evoked brainstem response may serve as
a clinical tool to assess auditory processing as well as the effects
of auditory training in the ASD population.
- acoustic
- development
- disorder,autistic
- disorder:
- disorders,language
- disorders:
- perception,speech
- perception:
- physiology
- physiology,child,female,humans,language
- physiology,speech:
- psychology,adolescent,autistic
- psychology,brain
- psychology,male,phonetics,speech,speech
- stem,brain
- stem:
- stimulation,acoustic
- stimulation:
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