Ben-Gurion University study finds brain myelin mainly saves energy, not time

Myelin, the fatty sheath wrapped around nerve fibres, is usually described as insulation that makes nerve signals travel faster. A study from Ben-Gurion University of the Negev, published in the Proceedings of the National Academy of Sciences on 22 July 2026 and reported by JNS a week later, suggests that in the brain's grey matter its main job is different: it saves energy.

The research was carried out by doctoral student Oron Kotler under the supervision of Professor Ilya Fleidervish of BGU's Department of Physiology and Cell Biology, with colleagues from Soroka University Medical Center, the Weizmann Institute of Science and New York Medical College. Using advanced imaging, electrical recordings and computer models, the team compared thin nerve fibres in the cerebral cortex that were wrapped in myelin with fibres that were not.

The two kinds of fibre carried impulses at almost the same speed, about a third of a metre per second. The big difference was the amount of sodium that flowed into the fibre with each signal: myelinated fibres let in about half as much. Because neurons must burn energy, in the form of the molecule ATP, to pump that sodium back out, myelin effectively cuts the energy cost of sending a signal in half. The researchers also found that myelin in the cortex is built differently from myelin in the body's peripheral nerves, with shorter insulated segments and more flexible junctions, an arrangement suited to saving energy rather than maximising speed.

The brain is one of the most energy-hungry organs in the body, and the authors say the results could change how scientists think about diseases in which myelin is damaged, such as multiple sclerosis, where the loss may strain neurons' energy budget as well as disrupt signalling.