Superior Colliculus Activity in Parkinson Disease: a Potential Marker?

The investigators will use a non invasive fMRI technique centred on the superior colliculus during the presentation of flickered check-boards with varying contrast (1, 3, 5 and 9 %).

The aim of this experiment is the evaluate the functional state of a visual structure. Therefore, with this ophthalmologic test, the investigators will control if the participant does not present major visual deficits. This examination will evaluate the visual acuity and the visual field. A funduscopic examination will also be performed to check the retina.

This test will allow to control the sensitivity of the participant to our contrast. The participant will be asked to look at screen on which three static check-boards will be presented. The participant will have to choose the two check-boards with the closest contrast.