Periaxonal and nodal plasticities modulate action potential conduction in the adult mouse brain

Central nervous system myelination increases action potential conduction velocity. However, it is unclear how myelination is coordinated to ensure the temporally precise arrival of action potentials and facilitate information processing within cortical and associative circuits. Here, we show that myelin sheaths, supported by mature oligodendrocytes, remain plastic in the adult mouse brain and undergo subtle structural modifications to influence action potential conduction velocity. Repetitive transcranial magnetic stimulation and spatial learning, two stimuli that modify neuronal activity, alter the length of the nodes of Ranvier and the size of the periaxonal space within active brain regions. This change in the axon-glial configuration is independent of oligodendrogenesis and robustly alters action potential conduction velocity. Because aptitude in the spatial learning task was found to correlate with action potential conduction velocity in the fimbria-fornix pathway, modifying the axon-glial configuration may be a mechanism that facilitates learning in the adult mouse brain.

Automated summary

Research has shown that myelin sheaths in the adult mouse brain, supported by mature oligodendrocytes, remain plastic and undergo subtle structural modifications that influence action potential conduction velocity. Stimuli like repetitive transcranial magnetic stimulation and spatial learning can alter the axon-glial configuration in active brain regions, independently of oligodendrogenesis, robustly changing action potential conduction velocity. Modifying this structure may be a mechanism that facilitates learning in the adult mouse brain, as demonstrated by correlations between aptitude in a spatial learning task and conduction velocity in specific neural pathways.