CONICET | Buscador de Institutos y Recursos Humanos

Abstract: Two important questions in models of word processing are what information is accessed during word recognition, and which is the temporal dynamics of activation of this information. Concerning these issues, electroencephalographic (EEG) recordings are a valuable tool to study the fast dynamic changes that underlie cognitive processing, because of their high temporal resolution. During performance of language tasks several transient electrical components or event related potentials (ERPs) have been describe time-locked to stimulus onset. In addition, EEG recordings can be decomposed into oscillatory components, which allows to analyze the signal as a function of time and frequency. Increases (event related synchronization, ERS) and decreases (event related desynchronization, ERD) in frequency band power after stimulus presentation are considered a measure of the degree of synchronized neural firing over the analyzed regions. In the present work we aimed to study frequency band power changes associated with a prime-target mismatch at the syntactic level in a lexical decision task. 24 right-handed native speakers of Spanish, were visually presented with 100 relevant prime-target pairs and 100 prime-target fillers, in pseudo-random order. All prime and relevant target words were Spanish verbs in 3rd ppl form, while 100 target non-words were fillers. 50 relevant prime-target pairs shared all verbal syntactic information (Same condition), while 50 differed only in verbal mode between prime and target (Different condition). Prime and targets were matched in mean frequency of use and length, and shared no semantic or formal relation. Each trial consisted of a 3000 ms resting period followed by prime presentation (200 ms); inter-stimulus interval (250 ms) and target presentation (until response). EEG recordings were gathered during the task. A significant decrease was found in reaction time to targets of the Same compared to the Different group (paired t-test, p<0.02), showing activation of verbal mode during the task. Compared to baseline, in both conditions a significant ERS of theta and alpha rhythms was found from 50 to 350 ms after prime presentation, while a significant ERD of these same frequencies was found from 800 to 1500 ms after target presentation. In this period a significantly greater ERD was obtained in the Same compared to the Different condition. These differences are similar to those seen during visual n-back tasks in which a stronger alpha ERD is found after presentation of targets compared to non-targets. Present results could be related to differences in the matching process encountered when prime-targets share or not verbal mode information. C. Imperioso: None. V. Jaichenco: None. S. Lew: None. S. Zanutto: None. A.J. Wainselboim Keyword Verbal mode information Event related synchronization Alpha and theta frequencies Support: PICT 2007 1350 (ANPCYT) 2010 Neuroscience Meeting Planner. San Diego, CA: Society for Neuroscience, 2010. Online. 2010 Copyright by the Society for Neuroscience all rights reserved. Permission to republish any abstract or part of any abstract in any form must be obtained in writing by SfN office prior to publication. http://www.abstractsonline.com/Plan/ViewAbstract.aspx?sKey