HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Cornelissen, P. Articles by Salmelin, R. Search for Related Content PubMed PubMed Citation Articles by Cornelissen, P. Articles by Salmelin, R.

Cortical Effects of Shifting Letter Position in Letter Strings of Varying Length

Newcastle University

Antti Tarkiainen, Päivi Helenius and Riitta Salmelin

Helsinki University of Technology

Neuroimaging and lesion studies suggest that occipito-temporal brain areas play a necessary role in recognizing a wide variety of objects, be they faces, letters, numbers, or household items. However, many questions remain regarding the details of exactly what kinds of information are processed by the occipito-temporal cortex. Here, we address this question with respect to reading. Ten healthy adult subjects performed a single word reading task. We used whole-head magnetoencephalography to measure the spatio-temporal dynamics of brain responses, and investigated their sensitivity to: (1) lexicality (defined here as the difference between words and consonant strings), (2) word length, and (3) variation in letter position. Analysis revealed that midline occipital activity around 100 msec, consistent with low-level visual feature analysis, was insensitive to lexicality and variation in letter position, but was slightly affected by string length. Bilateral occipito-temporal activations around 150 msec were insensitive to lexicality and reacted to word length only in the timing (and not strength) of activation. However, vertical shifts in letter position revealed a hemispheric imbalance: The right hemisphere activation increased with the shifts, whereas the opposite pattern was evident in the left hemisphere. The results are discussed in the light of Caramazza and Hillis's (1990) model of early reading.

Key Words: MEG • letter string • reading • occipito-temporal • position

Abbreviations: ERP, event-related potential • fMRI, functional MRI • LH, left hemisphere • MEG, magnetoencephalography • RH, right hemisphere • SD, standard deviation • SEM, standard error of mean • SQUID, superconducting quantum interference device

This article has been cited by other articles:

				M. Mariol, C. Jacques, M.-A. Schelstraete, and B. Rossion The Speed of Orthographic Processing during Lexical Decision: Electrophysiological Evidence for Independent Coding of Letter Identity and Letter Position in Visual Word Recognition. J. Cogn. Neurosci., July 1, 2008; 20(7): 1283 - 1299. [Abstract] [Full Text] [PDF]

				W. Braet and G. Humphreys The "special effect" of case mixing on word identification: neuropsychological and transcranial magnetic stimulation studies dissociating case mixing from contrast reduction. J. Cogn. Neurosci., October 1, 2006; 18(10): 1666 - 1675. [Abstract] [Full Text] [PDF]

				T. Parviainen, P. Helenius, E. Poskiparta, P. Niemi, and R. Salmelin Cortical sequence of word perception in beginning readers. J. Neurosci., May 31, 2006; 26(22): 6052 - 6061. [Abstract] [Full Text] [PDF]

				L. Pylkkanen, R. Llinas, and G. L. Murphy The Representation of Polysemy: MEG Evidence J. Cogn. Neurosci., January 1, 2006; 18(1): 97 - 109. [Abstract] [Full Text] [PDF]