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Magnetic stimulation of the left visual cortex impairs expert word recognition

Skarratt, Paul A.; Lavidor, Michal


Michal Lavidor


One of the hallmarks of expert reading is the ability to identify arrays of several letters quickly and in parallel. Such length-independent reading has only been found for word stimuli appearing in the right visual hemifield (RVF). With left hemifield presentation (LVF), response times increase as a function of word length. Here we investigated the comparative efficiency with which the two hemispheres are able to recognize visually presented words, as measured by word length effects. Repetitive transcranial magnetic stimulation (rTMS) of the left occipital cortex disrupted expert processing of the RVF such that a length effect was created (Experiment 1). Right occipital rTMS, on the other hand, had no such effect on RVF words and nor did it modulate the length effect already present in the LVF. Experiment 2 explored the time course of these TMS-induced effects by applying single pulses of TMS at various stimulus-onset asynchronies for the same task. We replicated the TMS-induced length effect for RVF words, but only when a single pulse was applied to the left visual cortex 80 msec after target presentation. This is the first demonstration of TMS-induced impairment producing a word length effect, and as such confirms the specialization of the left hemisphere in word recognition. It is likely that anatomical differences in the pathway linking retinal input to higher level cortical processing drive this effect.


Skarratt, P. A., & Lavidor, M. (2006). Magnetic stimulation of the left visual cortex impairs expert word recognition. Journal of cognitive neuroscience, 18(10), 1749-1758.

Journal Article Type Article
Acceptance Date Oct 31, 2006
Publication Date Oct 1, 2006
Print ISSN 0898-929X
Electronic ISSN 1530-8898
Publisher Massachusetts Institute of Technology Press
Peer Reviewed Peer Reviewed
Volume 18
Issue 10
Pages 1749-1758
Keywords Cognitive Neuroscience
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