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Open Journal of Neuroscience

ISSN: 2075-9088
Volume 5, 2017


Open Journal of Neuroscience, 2013, 3-1 [Research Article]

Silent lipreading and covert speech production suppress processing of non-linguistic sounds in auditory cortex

Marja H. Balk1,2, Heini Kari1, Jaakko Kauramäki1, Jyrki Ahveninen3, Mikko Sams1, Taina Autti2, Iiro P. Jääskeläinen1,3,4

1 Brain and Mind Laboratory, Department of Biomedical Engineering and Computational Science (BECS), Aalto University School of Science, Espoo, Finland
2 Department of Radiology, HUS Medical Imaging Center, Helsinki University Central Hospital and University of Helsinki, Finland
3 Harvard Medical School – Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, USA
4 Advanced Magnetic Imaging Center, Aalto University School of Science, Espoo, Finland

Corresponding Author & Address:

Marja H. Balk
Department of Radiology, HUS Medical Imaging Center, Helsinki University Central Hospital, P.O.BOX 180, FIN-00029 HUS, Finland; Tel: +358 50427 2843; Fax +358 9 472 3182; Email: marja.balk@hus.fi

Iiro P. Jääskeläinen
Brain and Mind Laboratory, Department of Biomedical Engineering and Computational Science, Aalto University, P.O.Box 12200, FIN-00076 Aalto University, Finland; Tel: +358 50560 9503; Fax: +358 9 470 23182; Email: iiro.jaaskelainen@aalto.fi

Article History:
Published: 6th February, 2013   Accepted: 6th February, 2013
Received: 19th December, 2012      

© Balk and Jääskeläinen et al.; licensee Ross Science Publishers

ROSS Open Access articles will be distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided that the original work will always be cited properly.

Keywords: auditory cortex, lipreading, covert speech production, speech motor theory, functional magnetic resonance imaging, tonotopy

Abstract:

Previous studies have suggested that speech motor system mediates suppression by silent lipreading of electromagnetic auditory cortex responses to pure tones at about 100 ms from sound onset. We used sparse sampling functional magnetic resonance imaging (fMRI) at 3 Tesla to map auditory-cortex foci of suppressant effects during silent lipreading and covert self-production. Streams of video clips were presented simultaneously with 1/3 octave noise bursts centered at 250 Hz (low frequency, LF) or 2000 Hz (mid-frequency, MF), or during no auditory stimulation. In different conditions, the subjects were a) to press a button whenever they lipread the face articulate the same consecutive Finnish vowels /a/, /i/, /o/, and /y/, b) covertly selfproducing vowels while viewing still face image, or c) to press a button whenever a circle pictured on top of the lips expanded into oval shape of the same orientation twice in a row. The regions of interest (ROIs) within the superior temporal lobes of each hemisphere were defined by contrasting MF and LF stimulation against silence. Contrasting the non-linguistic (i.e., expanding circle) vs. linguistic (i.e., lipreading and covert self-production) conditions within these ROIs showed significant suppression of hemodynamic activity to MF sounds in the linguistic condition in left hemisphere first transverse sulcus (FTS) and right hemisphere superior temporal gyrus (STG) lateral to Heschl’s sulcus (HS). These findings suggest that the speech motor system mediates suppression of auditory-cortex processing of non-linguistic sounds during silent lipreading and covert self-production in left hemisphere FST and right hemisphere STG lateral to HS.



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