title: Diminished activation of motor working-memory networks in Parkinson's disease.
abstract: Parkinson's disease (PD) is characterized by typical extrapyramidal motor features and increasingly recognized non-motor symptoms such as working memory (WM) deficits. Using functional magnetic resonance imaging (fMRI), we investigated differences in neuronal activation during a motor WM task in 23 non-demented PD patients and 23 age- and gender-matched healthy controls. Participants had to memorize and retype variably long visuo-spatial stimulus sequences after short or long delays (immediate or delayed serial recall). PD patients showed deficient WM performance compared to controls, which was accompanied by reduced encoding-related activation in WM-related regions. Mirroring slower motor initiation and execution, reduced activation in motor structures such as the basal ganglia and superior parietal cortex was detected for both immediate and delayed recall. Increased activation in limbic, parietal and cerebellar regions was found during delayed recall only. Increased load-related activation for delayed recall was found in the posterior midline and the cerebellum. Overall, our results demonstrate that impairment of WM in PD is primarily associated with a widespread reduction of task-relevant activation, whereas additional parietal, limbic and cerebellar regions become more activated relative to matched controls. While the reduced WM-related activity mirrors the deficient WM performance, the additional recruitment may point to either dysfunctional compensatory strategies or detrimental crosstalk from "default-mode" regions, contributing to the observed impairment.
authors.affiliation: Department of Neurology, RWTH Aachen University, Aachen, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Rottschy
authors.forename: Alexandra
authors.initials: A
authors.lastname: Kleiman
authors.forename: Imis
authors.initials: I
authors.lastname: Dogan
authors.forename: Robert
authors.initials: R
authors.lastname: Langner
authors.forename: Shahram
authors.initials: S
authors.lastname: Mirzazade
authors.forename: Martin
authors.initials: M
authors.lastname: Kronenbuerger
authors.forename: Cornelius
authors.initials: C
authors.lastname: Werner
authors.forename: N Jon
authors.initials: NJ
authors.lastname: Shah
authors.forename: Jörg B
authors.initials: JB
authors.lastname: Schulz
authors.forename: Simon B
authors.initials: SB
authors.lastname: Eickhoff
authors.forename: Kathrin
authors.initials: K
authors.lastname: Reetz
mesh_terms: D000368:Aged; D001519:Behavior; D001921:Brain / Q000473:pathology / Q000503:physiopathology; D016022:Case-Control Studies; D003710:Demography; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D011939:Mental Recall; D009043:Motor Activity / Q000502:physiology*; D009434:Neural Pathways / Q000473:pathology / Q000503:physiopathology*; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000503:physiopathology*