Differential activation of frontal lobe areas by lexical and semantic language tasks: a functional magnetic resonance imaging study.
To determine whether frontal lobe regions, including Broca's area, dorsolateral prefrontal cortex (DLPFC) and supplementary motor area (SMA), are differentially activated during lexical and semantic language tasks, we used functional magnetic resonance imaging in eight healthy right-handed subjects silently performing two semantic tasks (adjective and verb generation) and a lexical retrieval task (noun recall). Activation was observed in Broca's area, DLPFC and SMA for all tasks. Broca's area activation was approximately doubled during the semantic tasks compared with the lexical task (verbs vs nouns: 19.1+/-4.5 vs 8.9+/-1.6 voxels, p=0.02; adjectives vs nouns 24.4+/-7.5 vs 10.1+/-2.8 voxels, p=0.04); however, there were no significant differences in the DLFPC or SMA across tasks. We conclude that Broca's area is more active during tasks that have a semantic content, whereas areas involved in preparatory processing (SMA) and memory retrieval (DLPFC) are engaged equally during both types of task.
Blacker
David
D
Brain Research Laboratory, Centre for Neuromuscular and Neurological Disorders, University of Western Australia, Queen Elizabeth II Medical Centre, Nedlands, WA 6009, Australia.
Byrnes
Michelle L
ML
Mastaglia
Frank L
FL
Thickbroom
Gary W
GW
D000328:Adult; D001931:Brain Mapping; D005260:Female; D005625:Frontal Lobe / Q000098:blood supply* / Q000502:physiology*; D007839:Functional Laterality; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging; D008297:Male; D011939:Mental Recall / Q000502:physiology; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D012660:Semantics; D014825:Vocabulary
D010100:Oxygen