CHAPTER 1 COGNITIVE IMPAIRMENT IN MULTIPLE SCLEROSIS:A MRI STUDYCognitive impairments is one of the most common symptom present in multiple sclerosis and could be a result of both white matter and gray matter damage. Conventional MRI (T1, T2 weighted, gadolinium enhanced) has been applied to identify the extent and the severity of pathological processes underlying cognitive dysfunction and have focused on the relationship between cognitive parameters and the extent of damage detected with conventional MRI to help further pinpoint the causal mechanisms.Due to the limited specificity of conventional imaging in determining the intricate details the application of established MRI technique such DIR (double inversion recovery) and T1-weighted phase-sensitive inversion recovery (PSIR) and advanced MRI has been introduced over the years and have helped in monitoring the disease in a more detailed manner. While conventional MRI techniques have proven to be useful in monitoring the activity and evolution of multiple sclerosis, the development and clinical application ofadvance MR techniques such as diffusion tensor imaging, magnetization transfer imaging, functional MRI has the potential to further increase the importance of MR in the evaluation of cognitive functions in MS by improving sensitivity and increasing the pathological specificity of the abnormalities detected (such as lesion loads, lesion volume and atrophy).These MR techniques and various neuropsychiatric assessment not only helps to understand the various aspects of cognitive impairment but also guides inthe treatment or rehabilitation of MS patients. This review summarizes the contributions provided by conventional, established and advanced MR techniques in the understanding of the factors associated with cognitive deficits in multiple sclerosis.CHAPTER 2 FUNCTIONAL MRI IN MULTIPLE SCLEROSISIn MS conventional, structural and modern functional MRI techniques have been extensively used for studies and to understand its mechanism responsible for the accumulation of irreversible disability. Multiple sclerosis (MS), is a disease in which physical and cognitive deficit not only reflect structural damage, but also functional damage between the brain networks. Cognitive dysfunction in MS occurs during several stages of disease duration. MS with severity of cognitive manifestation is not closely related to indicate structural brain damage. Brain network and neuroplasticity may contribute to maintain the normal performances despite of the brain lesion. Most of the fMRI studies reported, changes in functional reorganization of cerebral cortex is seen in MS and hence provides to understand how brain networks and reorganization changes in MS. Resting-statefunctional magnetic resonance imaging allows to investigate intrinsic, synchronized brain activity across the whole brain, and to measure the degree of functional correlation between different cortical regions. This functional reorganization of the brainmight be help full for the studies of the effect of rehabilitation and pharmacological therapy of the brain plasticity especially in different stages of the disease. In this study we try to focus on what kind of brain activity have been reported during the fMRI in MS of different phenotypes. This review describes the major findings obtained in MS patients at different clinical stages using resting state fMRI and discusses how the use of fMRI techniques may improve our ability to identify novel biomarkers useful in the context of the diagnostic work-up, establishing prognosis and monitoring treatment.