Uncovering Mechanisms of Myelin Plasticity in the Live Brain

Unlike any other cell in the cerebral cortex, myelinating oligodendrocytes are continuously generated in the adult. Little is known about how new cells integrate into the preexisting neural architecture and whether the distribution of myelin processes along single axons is fixed throughout life. Dr. Hill and his research team have developed a novel combination of optical tools that allow high-resolution longitudinal in vivo imaging of these processes. Using these tools, Dr. Hill and his research team have discovered distinct patterns of protracted oligodendrocyte generation occurring in parallel with continuous changes in myelin internode deposition, length, and distribution along single axons. Formation of new myelin occurs on both previously myelinated and unmyelinated axons and the distribution of internodes and total myelin coverage of single axons progresses up to two years of age in the mouse cortex. This demonstrates that these processes continue to evolve into late adulthood in the mammalian brain revealing novel forms of lifelong myelin-dependent plasticity with broad implications for flexibility within adult cortical circuits.