Title: Neural excitation and neural damage studied using Diffusion
MRI.
Abstract: If neuronal activity is an electro-chemical event, why
does it slow displacement in cellular water? How can flow of electrolytes
into neurons create beading? Why, surprisingly, do these phenomena occur
immediately following two opposite events - stress and electrical
activity? We study, using MRI, the biophysical phenomena observed in
neurons such as the observed changes in the displacement of water
molecules and neuronal beading. Our approach is that known soft matter
dynamics in an active hydrogel can link these phenomena to neuronal
beading. In the coming lecture I will describe our works that use
diffusion weighted MRI to study changes in neural physiology. We developed
unique theoretical and experimental methods to study the cytoplasmic
dynamics in neurons. We use a novel diffusion weighted NMR experiment to
quantify diffusion and micro-streaming in an isolated vital neural tissue.
We extended previously suggested diffusion NMR methods that use
double-pulsed gradients, and provided a framework to reconstruct size
distributions of porous poly-disperse materials (as cells of varying
sizes). Finally, we quanified for the first time, by NMR, basic physical
properties of fluid in a synthetic (biomimicry) hydrogel under salt
induced phase transition. This work quantified diffusion, correlation time
and fluid-hydrogel binding coefficient. Our goal is to unify electrical
activity in neurons with these soft-matter and mechanical dynamics to a
single model.