Article

Present evidence suggests that medial temporal cortices subserve allocentric
representation and memory, whereas egocentric representation and memory also
depends on parietal association cortices and the striatum. Virtual reality
environments have a major advantage for the assessment of spatial navigation and
memory formation, as computer-simulated first-person environments can simulate
navigation in a large-scale space. Twenty-nine patients with amnestic MCI (aMCI)
were compared with 29 healthy matched controls on two virtual reality tasks
affording to learn a virtual park (allocentric memory) and a virtual maze
(egocentric memory). Participants further received a neuropsychological
investigation and MRI volumetry at the time of the assessment. Results indicate
that aMCI patients had significantly reduced size of the hippocampus bilaterally
and the right-sided precuneus and inferior parietal cortex. aMCI patients were
severely impaired learning the virtual park and the virtual maze. Smaller volumes
of the right-sided precuneus were related to worse performance on the virtual
maze. Participants with striatal lacunar lesions committed more errors than
participants without such lesions on the virtual maze but not on the virtual
park. aMCI patients later converting to dementia (n=15) had significantly smaller
hippocampal size when compared with non-converters (n=14). However, both groups
did not differ on virtual reality task performance. Our study clearly
demonstrates the feasibility of virtual reality technology to study spatial
memory deficits of persons with aMCI. Future studies should try to design spatial
virtual reality tasks being specific enough to predict conversion from MCI to
dementia and conversion from normal to MCI.
CI - Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Langue : ANGLAIS