Our brains contain a striking amount of ‘brain wires’, which allow electrical signals to send important information from one corner of the brain to another. Although these brain wires are made up of biological material, they also bear surprising resemblances to the electrical wires you can see when you do a DIY job in your home. For instance, one key feature that allows the brain wires to work is that they are tightly insulated. A little bit like metal wires are coated with plastic, brain wires are also wrapped in an insulation material, called ‘myelin’. Myelin is essentially a fatty layer of insulation, wrapped around many of the wires in your brain.
Myelin is incredibly important. When this insulation layer breaks down, the brain struggles to transmit signals at its usual speed, which is what happens in conditions like multiple sclerosis. However, the insulation of brain wiring has often been overlooked by scientists. It is particularly difficult to measure non-invasively in a live human. On top of that, this insulation has long been considered a static part of the brain which is not particularly relevant to understanding the brains of healthy adults. While myelin is clearly important in multiple sclerosis, until recently very few scientists had studied myelin beyond the realm of disease.
However, recent studies have now called some assumptions about myelin into question. In particular, in the past decade many labs around the world, including here at Oxford, have shown that myelin is more complex and dynamic than previously thought. Ground-breaking new methods have also been developed to effectively measure fat-rich insulation through magnetic resonance imaging (MRI), allowing us to ask new questions about this ever-elusive insulation layer that envelops our brain wiring.