Studying neurons and glia non-invasively via anomalous subdiffusion of intracellular metabolites

Cells in the central nervous system, neurons and glia, display a wide range of structural features. Molecular diffusion properties in the intracellular space of these cells reflect this structural diversity, deviating from standard Gaussian dynamics and resulting in anomalous subdiffusion. By tracking the displacement of intracellular metabolites, diffusion-weighted magnetic resonance spectroscopy allows for in vivo compartment-specific and cell-preferential morphological analysis of neurons and glia in the human brain. Suggestive of different intracellular environments between tissue type, the neuronal and glial intracellular space in gray matter is significantly more subdiffusive than in white matter. An important difference is found between the subdiffusion of choline, a predominantly glial metabolite, in gray and white matter, potentially reflecting differences in structural complexity between fibrous and protoplasmic astrocytes. The exclusively intracellular metabolite subdiffusive dynamics, taken together with water intra- and extracellular displacement, provide new insight of differing extracellular gray and white matter properties and exchange between tissue compartments.