title: Independent component analysis of the effect of L-dopa on fMRI of language processing.
abstract: 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).
authors.affiliation: Department of Statistics, The Ohio State University, Columbus, Ohio, United States of America.
authors.forename: Namhee
authors.initials: N
authors.lastname: Kim
authors.forename: Prem K
authors.initials: PK
authors.lastname: Goel
authors.forename: Madalina E
authors.initials: ME
authors.lastname: Tivarus
authors.forename: Ashleigh
authors.initials: A
authors.lastname: Hillier
authors.forename: David Q
authors.initials: DQ
authors.lastname: Beversdorf
mesh_terms: 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
chemical_list: D010919:Placebos; D007980:Levodopa; D004298:Dopamine
references.citation: Cogn Affect Behav Neurosci. 2004 Mar;4(1):10-9
references.pmid: 15259886
references.citation: Neuropsychopharmacology. 2006 Feb;31(2):297-309
references.pmid: 16012531
references.citation: Neural Comput. 1995 Nov;7(6):1129-59
references.pmid: 7584893
references.citation: J Comp Neurol. 2007 Sep 20;504(3):265-74
references.pmid: 17640049
references.citation: Brain. 1998 Apr;121 ( Pt 4):561-79
references.pmid: 9577385
references.citation: Science. 1992 May 8;256(5058):846-9
references.pmid: 1589767
references.citation: Mov Disord. 2008 Aug 15;23(11):1580-7
references.pmid: 18618663
references.citation: Philos Trans R Soc Lond B Biol Sci. 2005 May 29;360(1457):1001-13
references.pmid: 16087444
references.citation: Trends Neurosci. 2004 Nov;27(11):683-90
references.pmid: 15474169
references.citation: Neuroimage. 2008 Feb 15;39(4):2002-9
references.pmid: 18061483
references.citation: Neural Netw. 2002 Jun-Jul;15(4-6):561-72
references.pmid: 12371512
references.citation: J Magn Reson Imaging. 2004 Mar;19(3):365-8
references.pmid: 14994306
references.citation: Curr Opin Neurobiol. 2002 Apr;12(2):223-9
references.pmid: 12015241
references.citation: Neurosci Biobehav Rev. 2006;30(1):1-23
references.pmid: 15935475
references.citation: Cogn Affect Behav Neurosci. 2004 Dec;4(4):483-500
references.pmid: 15849892
references.citation: J Comp Neurol. 1976 Oct 1;169(3):371-92
references.pmid: 823181
references.citation: Brain. 1992 Dec;115 ( Pt 6):1753-68
references.pmid: 1486459
references.citation: Neuron. 2002 Aug 15;35(4):803-12
references.pmid: 12194878
references.citation: Clin Neuropathol. 1997 Nov-Dec;16(6):328-31
references.pmid: 9401800
references.citation: Hum Brain Mapp. 1998;6(3):160-88
references.pmid: 9673671
references.citation: Psychopharmacology (Berl). 2004 Nov;176(3-4):331-42
references.pmid: 15114435
references.citation: Neuroimage. 1999 Jul;10(1):15-35
references.pmid: 10385578
references.citation: IEEE Trans Med Imaging. 2004 Feb;23(2):137-52
references.pmid: 14964560
references.citation: Proc Natl Acad Sci U S A. 1997 Dec 23;94(26):14792-7
references.pmid: 9405692
references.citation: Neuropsychologia. 1996 Nov;34(11):1107-13
references.pmid: 8904748
references.citation: J Comp Neurol. 1985 Nov 15;241(3):357-81
references.pmid: 4086661
references.citation: Neuropsychopharmacology. 1994 Dec;11(4):245-56
references.pmid: 7531978
references.citation: Neuroscience. 1991;40(3):657-71
references.pmid: 2062437
references.citation: J Neurosci. 1995 Sep;15(9):5870-8
references.pmid: 7666172
references.citation: J Cogn Neurosci. 2003 Jan 1;15(1):71-84
references.pmid: 12590844
references.citation: Neuroimage. 2005 Jan 1;24(1):235-43
references.pmid: 15588615
references.citation: J Neurosci. 1988 Nov;8(11):4049-68
references.pmid: 2846794
references.citation: Psychopharmacology (Berl). 2001 Dec;159(1):10-20
references.pmid: 11797064
references.citation: Neuroimage. 2002 Jul;16(3 Pt 1):551-63
references.pmid: 12169242
references.citation: Int J Psychophysiol. 2009 Jul;73(1):53-61
references.pmid: 19223007
references.citation: Brain. 2001 May;124(Pt 5):1020-32
references.pmid: 11335704
references.citation: Brain Lang. 2008 Jan;104(1):42-50
references.pmid: 17418888
references.citation: Neuropsychologia. 2003;41(3):293-303
references.pmid: 12457755
references.citation: Brain Res Brain Res Rev. 1995 Sep;21(2):117-27
references.pmid: 8866670
references.citation: Hum Brain Mapp. 2001 Nov;14(3):140-51
references.pmid: 11559959
references.citation: IEEE Trans Neural Netw. 1999;10(3):626-34
references.pmid: 18252563
references.citation: Exp Brain Res. 1977 Sep 28;29(3-4):299-322
references.pmid: 410652