Open AccessCortical dynamics of word recognition
Author(s) -
Mainy Nelly,
Jung Julien,
Baciu Monica,
Kahane Philippe,
Schoendorff Benjamin,
Minotti Lorella,
Hoffmann Dominique,
Bertrand Olivier,
Lachaux JeanPhilippe
Publication year - 2008
Publication title -
human brain mapping
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.005
H-Index - 191
eISSN - 1097-0193
pISSN - 1065-9471
DOI - 10.1002/hbm.20457
Subject(s) - temporal lobe , psychology , fusiform gyrus , temporal cortex , superior temporal gyrus , neuroscience , categorization , middle temporal gyrus , lexical decision task , inferior frontal gyrus , cognitive psychology , functional magnetic resonance imaging , epilepsy , cognition , computer science , artificial intelligence
While functional neuroimaging studies have helped elucidate major regions implicated in word recognition, much less is known about the dynamics of the associated activations or the actual neural processes of their functional network. We used intracerebral electroencephalography recordings in 10 patients with epilepsy to directly measure neural activity in the temporal and frontal lobes during written words' recognition, predominantly in the left hemisphere. The patients were presented visually with consonant strings, pseudo‐words, and words and performed a hierarchical paradigm contrasting semantic processes (living vs. nonliving word categorization task), phonological processes (rhyme decision task on pseudo‐words), and visual processes (visual analysis of consonant strings). Stimuli triggered a cascade of modulations in the gamma‐band (>40 Hz) with reproducible timing and task‐sensitivity throughout the functional reading network: the earliest gamma‐band activations were observed for all stimuli in the mesial basal temporal lobe at 150 ms, reaching the word form area in the mid fusiform gyrus at 200 ms, evidencing a superiority effect for word‐like stimuli. Peaks of gamma‐band activations were then observed for word‐like stimuli after 400 ms in the anterior and middle portion of the superior temporal gyrus (BA 38 and BA 22 respectively), in the pars triangularis of Broca's area for the semantic task (BAs 45 and 47), and in the pars opercularis for the phonological task (BA 44). Concurrently, we observed a two‐pronged effect in the prefrontal cortex (BAs 9 and 46), with nonspecific sustained dorsal activation related to sustained attention and, more ventrally, a strong reflex deactivation around 500 ms, possibly due to semantic working memory reset. Hum Brain Mapp, 2008. © 2007 Wiley‐Liss, Inc.