Johns Hopkins scientists say they have used 3D imaging, special microscopes and artificial intelligence (AI programs) to construct a new map of mouse brains showing a more precise location of more than 10 million cells called oligodendrocytes. These cells form myelin, a protective sleeve around nerve cell axons that speed transmission of electrical signals and support brain health. The map not only more clearly paints a whole-brain picture of how myelin content varies between brain circuits, but also provides insights into how the loss of such cells impacts human diseases such as multiple sclerosis, Alzheimer’s disease and other disorders that affect learning, memory, sensory ability and movement, say the researchers. Although mouse and human brains are not the same, they share many characteristics and most biological processes. Credit: Yu Kang T. Xu and Dwight Bergles, Johns Hopkins Medicine, originally published in Cell, Feb. 18, 2026.