Human functional MRI

This chapter reviews the basic principles, main acquisition, and postprocessing techniques of functional magnetic resonance imaging (fMRI) applied to study multiple sclerosis (MS). First, we describe the blood-oxygenation level dependent (BOLD) effect and the principal analysis techniques used to process fMRI data, including those acquired during the performance of active tasks and those acquired at resting state. Subsequently, we summarize how the different fMRI techniques have contributed to investigate MS pathophysiology, by demonstrating that functional reorganization occurs as a consequence of structural damage accumulation in MS patients and can contribute, at least in the earliest phases of the disease, to limit the clinical consequences of widespread structural abnormalities. We discuss also how the failure or exhaustion of central nervous system adaptive properties might be among the factors responsible for the accumulation of irreversible clinical disability and cognitive impairment. The identification of MS-related adaptive and maladaptive reorganization is an attractive goal to understand the mechanisms of action of pharmacologic and rehabilitative treatments and to develop novel therapeutic strategies able to promote individual adaptive capacity.