A new wrap for neuronal activity?

As we learn and experience the world around us, our brains are remodeling neuronal pathways. Is this remodeling only a property of neurons, or are other brain cell types also adapting and contributing to learning? A substantial proportion of cells in the mammalian brain are oligodendrocytes and their precursors (collectively called oligodendroglia). Oligodendrocytes generate multiple myelin sheaths, lipid-rich extensions of specialized plasma membrane that spirally coat condensed layers around neurons. This insulation facilitates rapid nerve conduction, increasing velocities of neuron signals 10-fold (1) by restricting current flow to the small gaps between sheaths—the nodes of Ranvier. More than half of the human brain is composed of myelinated nerves (“white matter”). With such extensive myelinated neural networks, it raises the questions: Do the myelin-producing oligodendrocytes in the brain also adapt as neural circuits are modified in response to activity, and does adaptation of oligodendrocytes then affect the underlying neural circuits? On page 487 of this issue, Gibson et al. (2) provide new evidence to address how neuron activity may promote oligodendroglia changes.