Reviewed by Kate Anderton, B.Sc. (Editor)Feb 18 2020
The wiring network of the brain is made up of billions of nerve fibers called axons. The thickness of axons - together with other properties - significantly impacts the way in which they conduct neural signals, and therefore the overall processing speed of connected neurons and brain areas. In addition, many neurodegenerative conditions, such as Multiple Sclerosis and Alzheimer's disease, as well as conditions such as cancer, brain injury, and stroke, are known to exhibit axonal damage.
It is clear that axons are crucially important for the functioning of the brain, but they are also rather mysterious. They are so thin (mere micrometers in diameter) that probing them non-invasively inside a living brain has been, until now, impossible.
A new collaborative study by researchers working at the NYU Grossman School of Medicine in the USA, Champalimaud Centre for the Unknown in Portugal and the Cardiff University Brain Research Imaging Centre (CUBRIC) in the UK, established a way to measure these microscopic wires using MRI (Magnetic Resonance Imaging). Their results were published in the scientific journal eLife.
What was the breakthrough that led the team to overcome this long-standing challenge? Jelle Veraart, the first author of the study, explains that the key was to find a way to tease apart two types of signals: those originating from inside of the axons, and those arising from the surrounding tissue.