"Multiple Sclerosis (MS) is an inflammatory CNS disease that affects more than 2.5 million individuals worldwide. Damage to axonal connections determines the functional deficits of MS patients. How axons are damaged in MS is only incompletely understood. Using in vivo multiphoton imaging we have discovered a novel axon loss process that underlies axonal damage in experimental and human neuroinflammatory lesions. We have termed this process Focal Axonal Degeneration (FAD). FAD is characterized by a sequence of morphologically defined stages that ultimately result in axonal fragmentation. Notably, intermediate stages of FAD can persist for several days in vivo and still recover spontaneously. In this proposal I want to explore the biological and medical significance of FAD by addressing its:1. Functional CharacteristicsI want to analyze two key aspects of axonal function, the ability to transport cargoes and the ability to propagate action potentials, in experimental neuroinflammatory lesions to better understand the in vivo relation between structural and functional deficits during axon damage.2. Molecular MechanismsI want to deploy new molecular imaging approaches to directly monitor the redox potential, calcium and ATP levels of axons and their mitochondria in experimental neuroinflammatory lesions. This will allow us to reveal the key effector mechanisms of FAD and the sequence in which they are activated in vivo.3.Therapeutic OpportunitiesI plan to make use of advances in automated imaging and microfluidics to develop new in vivo assays for high-throughput screening of therapeutic interventions. This will help us to identify novel strategies for limiting progression and improving recovery of axon damage.The proposed project should provide new insights into the functional and molecular underpinnings of axon damage in vivo, establish new tools and models to study it and guide the development of therapeutic strategies that can prevent or reverse it."