Brainstem transcription of speech is disrupted in children with autism spectrum disorders

Authors

  • Nicole Russo,

    1. The Auditory Neuroscience Laboratory, Department of Communication Sciences, Northwestern University, USA
    2. Northwestern University Interdepartmental Neuroscience Program, USA
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  • Trent Nicol,

    1. The Auditory Neuroscience Laboratory, Department of Communication Sciences, Northwestern University, USA
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  • Barbara Trommer,

    1. Northwestern University Interdepartmental Neuroscience Program, USA
    2. Departments of Pediatrics and Neurology, Feinberg School of Medicine, Northwestern University and Evanston Northwestern Healthcare Center for Neurodevelopmental Disabilities, USA
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  • Steve Zecker,

    1. The Auditory Neuroscience Laboratory, Department of Communication Sciences, Northwestern University, USA
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  • Nina Kraus

    1. The Auditory Neuroscience Laboratory, Department of Communication Sciences, Northwestern University, USA
    2. Northwestern University Interdepartmental Neuroscience Program, USA
    3. Department of Neurobiology and Physiology and Department of Otolaryngology, Northwestern University, USA
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Address for correspondence: Nina Kraus, Department of Communication Sciences, Northwestern University, 2240 Campus Dr., Evanston, IL 60208, USA; e-mail: nkraus@northwestern.edu

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.

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