Listening to speech recruits specific tongue motor synergies as revealed by transcranial magnetic stimulation and tissue-Doppler ultrasound imaging |
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Authors: | A. D'Ausilio L. Maffongelli E. Bartoli M. Campanella E. Ferrari J. Berry L. Fadiga |
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Affiliation: | 1.Robotics Brain and Cognitive Sciences Department, RBCS, Italian Institute of Technology, IIT, via Morego, 30, Genova 16163, Italy;2.Section of Human Physiology, Università di Ferrara, via Fossato di Mortara, 17/19, Ferrara 44100, Italy |
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Abstract: | The activation of listener''s motor system during speech processing was first demonstrated by the enhancement of electromyographic tongue potentials as evoked by single-pulse transcranial magnetic stimulation (TMS) over tongue motor cortex. This technique is, however, technically challenging and enables only a rather coarse measurement of this motor mirroring. Here, we applied TMS to listeners’ tongue motor area in association with ultrasound tissue Doppler imaging to describe fine-grained tongue kinematic synergies evoked by passive listening to speech. Subjects listened to syllables requiring different patterns of dorso-ventral and antero-posterior movements (/ki/, /ko/, /ti/, /to/). Results show that passive listening to speech sounds evokes a pattern of motor synergies mirroring those occurring during speech production. Moreover, mirror motor synergies were more evident in those subjects showing good performances in discriminating speech in noise demonstrating a role of the speech-related mirror system in feed-forward processing the speaker''s ongoing motor plan. |
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Keywords: | speech perception transcranial magnetic stimulation motor theory of speech perception mirror neurons motor synergies tongue |
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