3. Microstructural determinants of functional modulations leading to behavioral changes in healthy and diseased CNS

Modulations in brain function (e.g., enhancements arising from plasticity or aberrations arising from neurodegeneration) are intimately correlated with underlying micro-architectural modifications in the neural tissues. We are interested in studying the links between the two, in vivo, in a longitudinal fashion in animal models of plasticity on the one hand and neurodegeneration on the other hand. We investigate functional modulations (such as neural network reorganizations) using optogenetics as the specific source of stimulation, and BOLD- and nonBOLD-fMRI as the functional readouts. We augment this functional information with advanced in vivo MRI methodologies that are selectively designed to probe even subtle changes in microstructures arising from plasticity or, conversely, neurodegenerative processes. We target microstructural changes in white matter, where we study variations in axonal size distributions (that govern the conduction velocity) as well as in gray matter, where we study changes in randomly oriented tissue components. We further aim to investigate the diagnostic potential arising from the identification of structural changes preceding functional/behavioral modifications.