A functional neuroimaging investigation of the roles of structural complexity and task-demand during auditory sentence processing.
Using functional magnetic resonance imaging (fMRI), this study directly examined an issue that bridges the potential language processing and multi-modal views of the role of Broca's area: the effects of task-demands in language comprehension studies. We presented syntactically simple and complex sentences for auditory comprehension under three different (differentially complex) task-demand conditions: passive listening, probe verification, and theme judgment. Contrary to many language imaging findings, we found that both simple and complex syntactic structures activated left inferior frontal cortex (L-IFC). Critically, we found activation in these frontal regions increased together with increased task-demands. Specifically, tasks that required greater manipulation and comparison of linguistic material recruited L-IFC more strongly; independent of syntactic structure complexity. We argue that much of the presumed syntactic effects previously found in sentence imaging studies of L-IFC may, among other things, reflect the tasks employed in these studies and that L-IFC is a region underlying mnemonic and other integrative functions, on which much language processing may rely.
Love
Tracy
T
School of Speech, Language and Hearing Sciences, San Diego State University, CA 92182-1518, USA. Hove@mail.sdsu.edu
Haist
Frank
F
Nicol
Janet
J
Swinney
David
D
D000328:Adult; D001931:Brain Mapping; D032882:Comprehension / Q000502:physiology*; D005260:Female; D005625:Frontal Lobe / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007802:Language; D008279:Magnetic Resonance Imaging; D008297:Male; D008568:Memory / Q000502:physiology; D011578:Psycholinguistics; D011597:Psychomotor Performance / Q000502:physiology; D013067:Speech Perception / Q000502:physiology*