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Reading Front to Back: MEG Evidence for Early Feedback Effects During Word Recognition

Lookup NU author(s): Sundeep Teki



Magnetoencephalography studies in humans have shown word-selective activity in the left inferior frontal gyrus (IFG) approximately 130 ms after word presentation ( Pammer et al. 2004; Cornelissen et al. 2009; Wheat et al. 2010). The role of this early frontal response is currently not known. We tested the hypothesis that the IFG provides top-down constraints on word recognition using dynamic causal modeling of magnetoencephalography data collected, while subjects viewed written words and false font stimuli. Subject-specific dipoles in left and right occipital, ventral occipitotemporal and frontal cortices were identified using Variational Bayesian Equivalent Current Dipole source reconstruction. A connectivity analysis tested how words and false font stimuli differentially modulated activity between these regions within the first 300 ms after stimulus presentation. We found that left inferior frontal activity showed stronger sensitivity to words than false font and a stronger feedback connection onto the left ventral occipitotemporal cortex (vOT) in the first 200 ms. Subsequently, the effect of words relative to false font was observed on feedforward connections from left occipital to ventral occipitotemporal and frontal regions. These findings demonstrate that left inferior frontal activity modulates vOT in the early stages of word processing and provides a mechanistic account of top-down effects during word recognition.

Publication metadata

Author(s): Woodhead ZVJ, Barnes GR, Penny W, Moran R, Teki S, Price CJ, Leff AP

Publication type: Article

Publication status: Published

Journal: Cerebral Cortex

Year: 2014

Volume: 24

Issue: 3

Pages: 817-825

Print publication date: 21/11/2012

Date deposited: 06/08/2015

ISSN (print): 1047-3211

ISSN (electronic): 1460-2199

Publisher: Oxford University Press


DOI: 10.1093/cercor/bhs365


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Funder referenceFunder name
Wellcome Trust
ES/J003174/1Economic and Social Research Council