|Title||Dynamic Modulation of Myelination in Response to Visual Stimuli Alters Optic Nerve Conduction Velocity.|
|Publication Type||Journal Article|
|Year of Publication||2016|
|Authors||Etxeberria A, Hokanson KC, Dao DQ, Mayoral SR, Mei F, Redmond SA, Ullian EM, Chan JR|
|Date Published||2016 06 29|
|Keywords||Action Potentials, Age Factors, Animals, Animals, Newborn, Antigens, Cholera Toxin, Geniculate Bodies, LIM-Homeodomain Proteins, Mice, Mice, Inbred C57BL, Mice, Transgenic, Myelin Sheath, Nerve Fibers, Myelinated, Neural Conduction, Optic Nerve, Organogenesis, Photic Stimulation, Proteoglycans, Retinal Ganglion Cells, Synaptic Transmission, Transcription Factors, Vesicular Glutamate Transport Protein 2, Vision, Monocular, Visual Pathways|
UNLABELLED: Myelin controls the time required for an action potential to travel from the neuronal soma to the axon terminal, defining the temporal manner in which information is processed within the CNS. The presence of myelin, the internodal length, and the thickness of the myelin sheath are powerful structural factors that control the velocity and fidelity of action potential transmission. Emerging evidence indicates that myelination is sensitive to environmental experience and neuronal activity. Activity-dependent modulation of myelination can dynamically alter action potential conduction properties but direct functional in vivo evidence and characterization of the underlying myelin changes is lacking. We demonstrate that in mice long-term monocular deprivation increases oligodendrogenesis in the retinogeniculate pathway but shortens myelin internode lengths without affecting other structural properties of myelinated fibers. We also demonstrate that genetically attenuating synaptic glutamate neurotransmission from retinal ganglion cells phenocopies the changes observed after monocular deprivation, suggesting that glutamate may constitute a signal for myelin length regulation. Importantly, we demonstrate that visual deprivation and shortened internodes are associated with a significant reduction in nerve conduction velocity in the optic nerve. Our results reveal the importance of sensory input in the building of myelinated fibers and suggest that this activity-dependent alteration of myelination is important for modifying the conductive properties of brain circuits in response to environmental experience.
SIGNIFICANCE STATEMENT: Oligodendrocyte precursor cells differentiate into mature oligodendrocytes and are capable of ensheathing axons with myelin without molecular cues from neurons. However, this default myelination process can be modulated by changes in neuronal activity. Here, we show, for the first time, that experience-dependent activity modifies the length of myelin internodes along axons altering action potential conduction velocity. Such a mechanism would allow for variations in conduction velocities that provide a degree of plasticity in accordance to environmental needs. It will be important in future work to investigate how these changes in myelination and conduction velocity contribute to signal integration in postsynaptic neurons and circuit function.
|Alternate Journal||J. Neurosci.|
|PubMed Central ID||PMC4926240|
|Grant List||K12 GM081266 / GM / NIGMS NIH HHS / United States |
R01 NS062796 / NS / NINDS NIH HHS / United States
R01 NS095889 / NS / NINDS NIH HHS / United States
T32 EY007120 / EY / NEI NIH HHS / United States