Backward Masking Tasks to Decipher Impaired Input-Output Connections in MS @7T

To identify abnormalities in mesoscale input and output connectivity at structural and functional levels that differ between patients with and without cognitive impairment. To address this objective, the investigator will analyse and compare functional activations in the primary visual cortex and task-associated regions in our previous studies. Secondary objectives: To develop, improve and validate multimodal laminar imaging at ultra-high field strength (7T) in comparison to control subjects available in our database to identify and quantify focal impairment in MS. This is a cross-sectional study. 40 patients (20 patients with a cognitive deficit at least 2 SD below the norm and 20 patients without cognitive impairment) will be explored by multimodal ultra-high field (7T) MRI. The protocol included task, resting FMRI (functional connectivity), diffusion tensor (structural connectivity) and anatomical sequences (lesions and atrophy). In addition, the investigator will analyse standard clinical assessments including a neuropsychological examination. To understand the mechanisms underlying neurodegeneration and adaptation, it is important to contrast physiological and pathological alterations. In addition to comparing cognitively preserved and cognitively impaired patients, the investigator aim to compare our participants to a representative normative dataset available in our database of healthy individuals.