Independent component analysis of the effect of L-dopa on fMRI of language processing.
L-dopa, which is a precursor for dopamine, acts to amplify strong signals, and dampen weak signals as suggested by previous studies. The effect of L-dopa has been demonstrated in language studies, suggesting restriction of the semantic network. In this study, we aimed to examine the effect of L-dopa on language processing with fMRI using Independent Component Analysis (ICA). Two types of language tasks (phonological and semantic categorization tasks) were tested under two drug conditions (placebo and L-dopa) in 16 healthy subjects. Probabilistic ICA (PICA), part of FSL, was implemented to generate Independent Components (IC) for each subject for the four conditions and the ICs were classified into task-relevant source groups by a correlation threshold criterion. Our key findings include: (i) The highly task-relevant brain regions including the Left Inferior Frontal Gyrus (LIFG), Left Fusiform Gyrus (LFUS), Left Parietal lobe (LPAR) and Superior Temporal Gyrus (STG) were activated with both L-dopa and placebo for both tasks, and (ii) as compared to placebo, L-dopa was associated with increased activity in posterior regions, including the superior temporal area (BA 22), and decreased activity in the thalamus (pulvinar) and inferior frontal gyrus (BA 11/47) for both tasks. These results raise the possibility that L-dopa may exert an indirect effect on posterior regions mediated by the thalamus (pulvinar).
Kim
Namhee
N
Department of Statistics, The Ohio State University, Columbus, Ohio, United States of America.
Goel
Prem K
PK
Tivarus
Madalina E
ME
Hillier
Ashleigh
A
Beversdorf
David Q
DQ
D000328:Adult; D004298:Dopamine / Q000378:metabolism; D005260:Female; D006801:Humans; D007807:Language Tests; D007980:Levodopa / Q000494:pharmacology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010919:Placebos; D012660:Semantics; D013788:Thalamus / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D055815:Young Adult
D010919:Placebos; D007980:Levodopa; D004298:Dopamine
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