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Spatial and temporal analysis of fMRI data on word and sentence reading
Author(s) -
Haller Sven,
Klarhoefer Markus,
Schwarzbach Jens,
Radue Ernst W.,
Indefrey Peter
Publication year - 2007
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.1460-9568.2007.05816.x
Subject(s) - functional magnetic resonance imaging , sentence , inferior frontal gyrus , sentence processing , superior temporal gyrus , voxel , cognitive psychology , psychology , middle temporal gyrus , comprehension , computer science , artificial intelligence , neuroscience , programming language
Written language comprehension at the word and the sentence level was analysed by the combination of spatial and temporal analysis of functional magnetic resonance imaging (fMRI). Spatial analysis was performed via general linear modelling (GLM). Concerning the temporal analysis, local differences in neurovascular coupling may confound a direct comparison of blood oxygenation level‐dependent (BOLD) response estimates between regions. To avoid this problem, we parametrically varied linguistic task demands and compared only task‐induced within‐region BOLD response differences across areas. We reasoned that, in a hierarchical processing system, increasing task demands at lower processing levels induce delayed onset of higher‐level processes in corresponding areas. The flow of activation is thus reflected in the size of task‐induced delay increases. We estimated BOLD response delay and duration for each voxel and each participant by fitting a model function to the event‐related average BOLD response. The GLM showed increasing activations with increasing linguistic demands dominantly in the left inferior frontal gyrus (IFG) and the left superior temporal gyrus (STG). The combination of spatial and temporal analysis allowed a functional differentiation of IFG subregions involved in written language comprehension. Ventral IFG region (BA 47) and STG subserve earlier processing stages than two dorsal IFG regions (BA 44 and 45). This is in accordance with the assumed early lexical semantic and late syntactic processing of these regions and illustrates the complementary information provided by spatial and temporal fMRI data analysis of the same data set.