Klinische Neurophysiologie 2012; 43 - P074
DOI: 10.1055/s-0032-1301624

Cortical connectivity in Parkinson’s patients during initiation and selection of internally motivated actions

J Michely 1, MT Barbe 2, F Hoffstaedter 3, S Eickhoff 3, L Timmermann 4, GR Fink 4, C Grefkes 4
  • 1Max Planck Institute for Neurological Research, Köln
  • 2Klinik und Poliklinik für Neurologie, Uniklinik Köln, Köln
  • 3Institut für Neurowissenschaften und Medizin (INM-2), Forschungszentrum Jülich, Jülich
  • 4Klinik für Neurologie, Uniklinik Köln, Köln

Introduction: Patients suffering from Parkinson’s disease (PD) often show deficits in the self-initiation and selection of movements which can be partly compensated when using external cues. We investigated neural correlates of impairments in the initiation and selection of self-initiated versus externally cued movements in PD and how behavioral changes relate to medication and changes in fMRI activity and connectivity patterns.

Methods: 12 PD patients and 12 healthy controls performed a computerized motor task while being scanned with fMRI at 3 Tesla. Patients performed the task twice, under regular dopaminergic medication and after 12h off drug. In condition 1, subjects performed button presses with the left or right index finger at a self-chosen time point. In condition 2, subjects performed a reaction time (RT) task by pressing either the left or right button upon appearance of a visual cue. In condition 3, both time point and response lateralization were pre-determined by a visual cue. BOLD data was analysed with SPM8 and Dynamic Causal Modeling (DCM).

Results: Compared to healthy controls, patients showed a selective deficit in RTs when movement lateralization was not restricted by the cue irrespective of dopaminergic stimulation. In contrast, basic motor performance improved under dopaminergic drugs. The analyses of effective connectivity revealed that impaired motor performance in patients is associated with changes in interregional coupling between parietal, premotor and prefrontal areas. Dopaminergic stimulation did not induce a correction of abnormal cortical connectivity.

Discussion: Our findings implicate disturbances in premotor-prefrontal interactions in PD patients with advanced disease which do not respond to dopaminergic stimulation. Alternative stimulation strategies, e.g., by means of non-invasive brain stimulation, might be useful to correct pathological connectivity among cortical areas in PD patients.