Project Aim(s): This proposal aims to combine our novel EEG based technology with detailed neuropsychological assessment to provide a quantitative measure of cognitive change in MS that could be used in a clinical trial setting.  The study will also  provide an opportunity to assess for the first time the impact of Cladribine on cognitive performance using conventional screening tools, detailed neuropsychological batteries, and experimental neurophysiology based paradigms that could be harnessed for future nested case control studies.