Affiliations: [a] Department of Neuroscience, Erasmus MC, Rotterdam, The Netherlands | [b] Department of Internal Medicine, Section of Geriatric Medicine, Erasmus MC, Rotterdam, The Netherlands
Correspondence:
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Correspondence to: Johannes van der Steen, Department of Neuroscience, Erasmus MC, PO Box 2040, 3000 CA, Rotterdam, The Netherlands. Tel.: +31 10 704 3572; Fax: +31 10 704 4734; E-mail: j.vandersteen@erasmusmc.nl.
Note: [1] These authors contributed equally to this study.
Abstract: Although memory complaints are one of the first clinical symptoms in patients with Alzheimer's disease (AD), damage to the parietal lobe, a key structure in the visuomotor coordination network, was recently identified in early-stage AD. The aim of this study was to quantify visuomotor coordination in patients with probable AD and to compare their visuomotor performance with controls using five eye-hand coordination tasks of variable complexity. Eye and hand movements were measured in 16 AD patients and 18 controls. The measurement setup consisted of a touch screen, an eye-tracking device, and a motion capturing system. We investigated eye-hand coordination by quantifying absolute and relative latencies of eye and hand movements and by analyzing eye and hand kinematics. We found that AD patients need significantly more time to initiate and execute goal-directed hand movements. AD patients are also unable to suppress reflexive eye and, to a lesser extent, hand movements. Furthermore, AD patients use a stepwise approach of eye and hand movements to touch a sequence of stimuli, whereas controls more often show an anticipatory approach. The impairments in reflex suppression of eye and hand movements, and changes in relative timing of eye-hand coordination, in AD patients support the notion that cortical networks involving the posterior parietal cortex are affected at an early disease-stage. It also suggests that the problems of AD patients to perform daily activities that require eye-hand coordination are not only caused by cognitive decline, but also by degeneration of neural networks involved in visuomotor coordination.
Keywords: Alzheimer's disease, dementia, eye-hand coordination, motor activity, visuomotor integration
