Pharmacologically modulated fMRI--cortical responsiveness to levodopa in drug-naive hemiparkinsonian patients.

Full Abstract

According to the basal ganglia-thalamocortical circuit model, dopamine depletion in the nigrostriatal system leads to hypoactivation in the supplementary motor area (SMA) and the primary motor cortex (M1) in Parkinson's disease. This functional cortical deafferentation and its reversibility by levodopa (L-dopa) treatment has been established in previous studies for SMA but remains controversial for M1. We used functional MRI (fMRI) and a simple finger opposition task to correlate blood oxygenation level-dependent (BOLD) signal changes with motor performance, assessed separately for each hand between fMRI scanning sessions. Eight drug-naive patients with an akinetic idiopathic hemiparkinsonian syndrome (Hoehn and Yahr stage 1-1.5) and 10 healthy controls were studied. Patients performed a simple, auditory-paced random finger- opposition task every 3 s before and repeatedly every 20 min after intake of 300 mg of fast-release L-dopa. M1 contralateral to the affected hand and SMA, predominantly of the contralateral side, showed a BOLD signal increase after L-dopa intake. Furthermore, comparing BOLD responses of M1 and SMA between the patients and controls revealed that these areas were hypoactive before L-dopa treatment. Signal changes in M1 and SMA were highly correlated with motor performance, which increased after L-dopa intake. This result is not confounded by a performance effect because the motor task employed during scanning was identical throughout all sessions. In contrast to previous imaging studies in which cortical reorganization in Parkinson's disease was thought to have caused M1 hyperactivation, our data are in accordance with the hypothesis that, in de novo idiopathic hemiparkinsonian syndrome, motor cortex hypoactivation in contralateral M1 and bilateral SMA is caused by a decreased input from the subcortical motor loop, which is reversible by L-dopa.

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Author information

Author/s: Buhmann, C (C); Glauche, V (V); Stürenburg, H J (HJ); Oechsner, M (M); Weiller, C (C); Büchel, C (C);

Affiliation: Department of Neurology, University Hospital of Hamburg, Germany. buhmann(-atsign-)uke-uni-hamburg.de

Journal and publication information

Publication Type: Journal Article

Journal: Brain : a journal of neurology (Brain), published in England. (Language: eng)

Reference: 2003-Feb; vol 126 (issue Pt 2) : pp 451-61

Dates: Created 2003/01/22; Completed 2003/03/06; Revised 2004/11/17;

PMID: 12538411, status: MEDLINE (last retrieval date: 12/26/2008)

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Adult
Aged
Antiparkinson Agents - blood; pharmacology
Case-Control Studies
Female
Fingers - physiopathology
Humans
Image Processing, Computer-Assisted - methods

Image Processing, Computer-Assisted - methods
Levodopa - blood; pharmacology
Magnetic Resonance Imaging
Male
Middle Aged
Motor Cortex - drug effects; physiopathology
Motor Skills - drug effects
Parkinson Disease - blood; drug therapy; physiopathology

Associated Chemicals: Antiparkinson Agents (0) ; Levodopa (0)

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