Die zerebralen Korrelate des Arbeitsgedächtnisses bei Patienten mit idiopathischem Parkinson-Syndrom und ihre Modulation durch L-Dopa
Auch gedruckt in der BibliothekZ: J-H 11.565 ; W: W-H 9.770
Ressourcen- / MedientypDissertation, Text
Datum der Freischaltung2007-07-23
Objective: We compared brain activity during performance of domain specific working memory (WM) tasks in non-demented patients with early Parkinson´s Disease (PD) to healthy controls and to test whether levodopa modifies possible dysfunctions of the activated brain circuitry in PD. Methods: Nine patients with PD (Hoehn-Yahr stages I-II) underwent fMRI investigation twice with a modified Sternberg-item recognition paradigm. In the first session dopaminergic medication had been withdrawn for at least 12 hours (off-state). The second session was performed one hour after administration of 200 mg levolopa (on-state). 11 healthy volunteers were studied with the same protocol once. Results: Behavioural data showed no significant difference of accuracy in performance of the WM tasks between PD and healthy controls in none of the investigated tasks. FMRI revealed in patients with PD during performance of the verbal WM task reduced activity within the left middle frontal gyrus (area corresponding to the dorsolateral prefrontal cortex), right cerebellum and left posterior part of the inferior temporal gyrus. These reduced activities were partly reversibel after levodopa administration. The visuospatial WM task revealed reduced activity within the right dorsolateral prefrontal cortex (middle and inferior frontal gyrus), which were not levodopa responsive and appeared again during the on-state within the inferior frontal gyrus and right inferior temporal gyrus. Conclusions: Our findings indicate dysfunctional activity in PD during verbal and visuo-spatial WM tasks despite correct behavioural performance. These results are consistent with previous reports of dysfunctional striatofrontal network activity during WM task performance in PD. Further studies should intend to characterize more precisely subgroups of patients with dysfunctional network activity during WM performance and study the predictive value of these dysfunctions to the risk of developing dementia.
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