In this talk we will present the first two neuro-mechanical models of the brain that establish critical interrelationships between the material structure and the electro-chemical activity of the brain. One model can predict the shrinkage of the brain tissue seen in patients with normal pressure hydrocephalus due to a change in ionic concentrations of the ventricular CSF and in the absence of an elevated intracranial pressure, and thus it opens the possibility of pharmaceutical treatment of hydrocephalus. Our second model uses neuroimaging measurements to predict stress-softening of the brain tissue when the neurons are activated. In addition we will show how one can use cine MRI to estimate the apparent stiffness of the brain in patients with chiari malformations before and after surgery. Before surgery, the brain tissue appears to be stiffer and inhomogeneous, while after the surgery, the brain becomes softer and more homogeneous. This finding could help measure the success of surgery of chiari malformations, in a non-invasive and safe way. Finally, we show a novel technique of differentiating between low and high grade gliomas based on their stiffness values obtained using information provided by image mass spectroscopy.