Johns Hopkins Medicine Feb 22 2026 Johns Hopkins scientists say they have used 3D imaging, special microscopes and artificial intelligence (AI) programs to construct new maps of mouse brains showing a precise location of more than 10 million cells called oligodendrocytes. These cells form myelin, a protective sleeve around nerve cell axons, which speeds transmission of electrical signals and support brain health. Published online Feb. 18 in  Cell  and funded by the National Institutes of Health,