Myelin sheaths in the central nervous system can withstand damage and dynamically rebuild instead of being completely lost. The study used zebrafish and rodent models of demyelination, where myelin swelling was an early sign of damage before myelin loss. Longitudinal live imaging in zebrafish and in rodent organotypic cortical slice culture have shown that myelin swelling does not necessarily lead to loss and the damage can resolve over time. Increased neuronal activity during early demyelination exacerbates myelin damage, whereas decreased neuronal activity attenuates swelling in both zebrafish and mice. In the tissue of patients with multiple sclerosis, myelin swelling is dynamic and prominent around active lesions. These findings suggest that myelin swelling is a conserved feature of demyelination across species, including humans, and may lead to new therapeutic opportunities against myelin loss.[1][4]