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Disturbed striatoprefrontal mediated visual behaviour in moderate to severe parkinsonian patients
1Department of Neurology, University of Ghent, Belgium.
Objectives:
To study visuospatial and visual memory functions in moderate to severe parkinsonian patients.
Methods:
Visual antisaccades (AS) and remembered saccades (RS) were examined in 30 patients with moderate to severe Parkinson's disease and in 44 age matched controls. AS are saccades in the direction opposite to the target. RS are saccades towards the remembered position of a target that is no longer visible.
Results:
Patients with Parkinson's disease had serious difficulties in suppressing a reflex saccade ("visual grasping") or they made no saccade at all ("visual akinesia"). The remembered saccade was often wrongly directed.
Conclusions:
These types of errors point to a dysfunction in the striatoprefrontal loop. The discrepancy of the results with those in the literature, which are mostly normal, could be explained by the more advanced stage of our patients. This might correspond to the development of unresponsiveness to levodopa or of non-dopaminergic lesions.