Activation of the left inferior frontal gyrus in the first 200 ms of reading:evidence from magnetoencephalography (MEG)

Abstract

Background - It is well established that the left inferior frontal gyrus plays a key role in the cerebral cortical network that supports reading and visual word recognition. Less clear is when in time this contribution begins. We used magnetoencephalography (MEG), which has both good spatial and excellent temporal resolution, to address this question. Methodology/Principal Findings - MEG data were recorded during a passive viewing paradigm, chosen to emphasize the stimulus-driven component of the cortical response, in which right-handed participants were presented words, consonant strings, and unfamiliar faces to central vision. Time-frequency analyses showed a left-lateralized inferior frontal gyrus (pars opercularis) response to words between 100–250 ms in the beta frequency band that was significantly stronger than the response to consonant strings or faces. The left inferior frontal gyrus response to words peaked at ~130 ms. This response was significantly later in time than the left middle occipital gyrus, which peaked at ~115 ms, but not significantly different from the peak response in the left mid fusiform gyrus, which peaked at ~140 ms, at a location coincident with the fMRI–defined visual word form area (VWFA). Significant responses were also detected to words in other parts of the reading network, including the anterior middle temporal gyrus, the left posterior middle temporal gyrus, the angular and supramarginal gyri, and the left superior temporal gyrus. Conclusions/Significance - These findings suggest very early interactions between the vision and language domains during visual word recognition, with speech motor areas being activated at the same time as the orthographic word-form is being resolved within the fusiform gyrus. This challenges the conventional view of a temporally serial processing sequence for visual word recognition in which letter forms are initially decoded, interact with their phonological and semantic representations, and only then gain access to a speech code.

Publication DOI: https://doi.org/10.1371/journal.pone.0005359
Divisions: College of Health & Life Sciences > School of Psychology
College of Health & Life Sciences > Clinical and Systems Neuroscience
College of Health & Life Sciences > Aston Institute of Health & Neurodevelopment (AIHN)
College of Health & Life Sciences
College of Health & Life Sciences > School of Optometry > Centre for Vision and Hearing Research
Additional Information: © 2009 Cornelissen et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Uncontrolled Keywords: brain mapping,female,frontal lobe,humans,language,magnetoencephalography,male,perception,reading,time factors,visual perception,General Agricultural and Biological Sciences,General Biochemistry,Genetics and Molecular Biology,General Medicine
Publication ISSN: 1932-6203
Last Modified: 03 Oct 2024 07:11
Date Deposited: 07 Aug 2012 13:51
Full Text Link: http://www.plos ... al.pone.0005359
Related URLs: http://www.scop ... tnerID=8YFLogxK (Scopus URL)
PURE Output Type: Article
Published Date: 2009-04-27
Authors: Cornelissen, Piers L.
Kringelbach, Morten L.
Ellis, Andrew W.
Whitney, Carol
Holliday, Ian E.
Hansen, Peter C.

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License: Creative Commons Attribution


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