The present proposal investigates the role of the cholinergic system (the neurotransmitter
acetylcholine) in improving vision and visual attention. Vision results from a complex
processing of particular stimuli of the visual field. Attention enhances and prolongs the
neural representations of visual input in the visual cortex. It has recently been shown that
attention in the visual cortex depends on cholinergic mechanisms. The action of acetylcholine
in the visual cortex consists in enhancement of the responsiveness to thalamocortical inputs,
depression of local neuronal connections or extrastriate feedback projections and induction
of gamma synchronisation. The investigators hypothesize that these effects are associated
with long-term changes in functional connectivity in the visual cortex, visual attention and
visual learning (improvement of the visual capacities).
In the present proposal, the investigators will test whether the administration of donepezil
(Aricept, 5mg), a drug that increases the level of acetylcholine in the brain, will enhances
the perceptual-cognitive abilities of young adult subjects. Perceptual-cognitive performance
will be assessed in a multiple object tracking (MOT) task in a 3D automatic virtual
environment. MOT is a task where observers are asked to maintain attentional focus on a
limited number of preselected subgroup of elements in a dynamic scene. Multifocal attentional
mechanisms are necessary to process the information. The task will be tested five time at one
week interval to test whether donepezil and training improved the task performance of the
subject, i.e. lead to perceptual learning. This study could help establish an intervention
procedure to improve visual performance of subjects that need it.