“…Myelin sheaths are well known to facilitate rapid action potential propagation along axons, through their lipid-rich, multilamellar composition ( Nave and Werner, 2014 ; Stadelmann et al, 2019 ), their physiology ( Suminaite et al, 2019 ), and their role in organising key ion channels along axonal subdomains, such as nodes of Ranvier ( Sherman and Brophy, 2005 ; Stassart et al, 2018 ). In addition, myelin sheaths are thought to represent a conduit for the metabolic support of axons by oligodendrocytes, which has also been proposed to regulate axonal function and integrity ( Nave, 2010 ; Nave and Ehrenreich, 2018 ) ( Figure 3 ). Furthermore, the fact that myelination can be modified by neuronal activity ( Figure 3 ), and that changes in myelination can affect conduction, has led to the hypothesis that activity regulated myelination may contribute to nervous system plasticity ( Fields, 2015 ; Chang et al, 2016 ; Almeida and Lyons, 2017 ; Monje, 2018 ; Suminaite et al, 2019 ).…”