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Sensorimotor integration for speech motor learning involves the inferior parietal cortex

Authors

  • Mamie Shum,

    1. Neuroscience Major Program, McGill University, Montreal, Quebec, Canada
    2. Centre for Research on Brain, Language & Music, 3640 de la Montagne, Montreal, Quebec H3G 2A8, Canada
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  • Douglas M. Shiller,

    1. Centre for Research on Brain, Language & Music, 3640 de la Montagne, Montreal, Quebec H3G 2A8, Canada
    2. CHU Sainte-Justine Research Centre, Montreal, Quebec, Canada
    3. École d’orthophonie et d’audiologie, Université de Montréal, Quebec, Canada
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  • Shari R. Baum,

    1. Centre for Research on Brain, Language & Music, 3640 de la Montagne, Montreal, Quebec H3G 2A8, Canada
    2. School of Communication Sciences and Disorders, McGill University, Montreal, Quebec, Canada
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  • Vincent L. Gracco

    1. Centre for Research on Brain, Language & Music, 3640 de la Montagne, Montreal, Quebec H3G 2A8, Canada
    2. School of Communication Sciences and Disorders, McGill University, Montreal, Quebec, Canada
    3. Haskins Laboratories, New Haven, CT, USA
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Dr V. L. Gracco, as above.
E-mail: vincent.gracco@mcgill.ca

Abstract

Sensorimotor integration is important for motor learning. The inferior parietal lobe, through its connections with the frontal lobe and cerebellum, has been associated with multisensory integration and sensorimotor adaptation for motor behaviors other than speech. In the present study, the contribution of the inferior parietal cortex to speech motor learning was evaluated using repetitive transcranial magnetic stimulation (rTMS) prior to a speech motor adaptation task. Subjects’ auditory feedback was altered in a manner consistent with the auditory consequences of an unintended change in tongue position during speech production, and adaptation performance was used to evaluate sensorimotor plasticity and short-term learning. Prior to the feedback alteration, rTMS or sham stimulation was applied over the left supramarginal gyrus (SMG). Subjects who underwent the sham stimulation exhibited a robust adaptive response to the feedback alteration whereas subjects who underwent rTMS exhibited a diminished adaptive response. The results suggest that the inferior parietal region, in and around SMG, plays a role in sensorimotor adaptation for speech. The interconnections of the inferior parietal cortex with inferior frontal cortex, cerebellum and primary sensory areas suggest that this region may be an important component in learning and adapting sensorimotor patterns for speech.

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