Biophysical observations suggest that neuronal activity, as well as other cellular mechanisms within neurons include a mechanical dimension.

We study the displacement of water molecules in neurons using theoretical analysis of the hydrodynamics that follow mechanical events in neurons, as well experiments performed using Diffusion Weighted Imaging of live brain tissues, and optical imaging of micro-injected quantum-dots.

Our theoretical analysis suggests that a significant component of micro-streaming occurs in neurons. We suggest that this micro-streaming has a physiological role in the transport of colloids and solutes inside neuronal projections (axons and dendrites).  Our experiments further reveal significant changes in water displacement during events of enhanced neuronal function, and upon dis-function of the cells. We further discuss the coherence of this result with other hypotheses in the field and speculate of the biophysical basis of the observed changes in water displacement.