Multiple Sclerosis (MS) is one the most important neurological diseases by virtue of its frequency, chronicity and tendency to attack young adults. Cognitive impairment may affect approximately all patients with MS, and has been reported to negatively impact employment, social functioning, quality of life, and the ability to perform instrumental activities of daily living, with a high social cost. Nowadays, the way the brain of people affected with MS perform a cognitive task is an enigma still unsolved. On the other hand, the integration of simultaneous event-related potentials (ERP) and functional magnetic resonance imaging (fMRI) is an emerging method in human brain mapping. Combining their complementary information both methods provide electrophysiological cerebral activity with high temporal resolution and hemodynamic response with high spatial resolution. Our purpose in this research will be to improve the assessment of cognitve dysfunction among MS patients with different stages of the disease using the simultaneous acquisition of ERP/fMRI to obtain physiological and pathological brain activity. In addiction, this temporal-spatial information will be correlated with diffusion tensor imaging (DTI) scores, a new imaging method that provide markers to assess the macroscopic and microscopic pathology. We have developed a detailed work plan including a first phase to verify the feasibility of co-recording of EEG and fMRI signals and a spatial-temporal description of the processing of stimuli. Thus, these achievements will allow us to obtain a powerful approach to assess performace of cognitive task in MS patients and further application in other neurolical disorders. Results of our ERP/fMRI study will provide unique insights on cognitive function in MS patients with different stages of the disease and the underlying neural basis, providing the first systematic investigation of simultaneous ERP/fMRI recording in these patients.