The central nervous system contains both myelinated and unmyelinated axons. Myelination significantly increases the speed of action potential propagation and is associated with Hebbian learning. It essentially acts by isolating the axons it envelops, thus allowing beneficial conduction. Oligodendrocytes are glial cells responsible for the initial myelination and subsequent maintenance of CNS myelin. Electrically active neurons have been shown to promote myelination. Say no to plagiarism. Get a tailor-made essay on 'Why violent video games should not be banned'?Get the original essay It has been hypothesized that electrically active axons may act via oligodendrocytes to influence their myelination. However, despite intense studies, there are still many controversies on this subject. to what extent this occurs and whether axons are able to influence their own myelination. The author will discuss this area of ​​study by evaluating published research in three high-profile articles; using the evidence they provide to investigate this hypothesis. In the field, there are many hypotheses about how neuronal activity might influence oligodendrocytes to myelinate active axons, with many different experimental approaches to study this phenomenon. One of these hypotheses is that neuronal activity regulates the proliferation and differentiation of oligodendritic progenitor cells (OPCs), which in turn may influence axonal myelination. The three articles discussed in this essay all investigate this hypothesis to varying degrees and depths. Gibson et al, 2014 set out to examine myelination in the premotor cortex. To achieve this, the authors used a mouse model designed to express the excitatory opsin under the control of a Thy1 promoter. This allowed a subset of neurons to be stimulated at will by blue light. Mitew et al 2018 also used a mouse model, genetically adding a synthetic receptor and GFP marker to enable stimulation and visualization of axons. Hines et al, 2015 also investigate the aforementioned hypothesis, using zebrafish to enable the identification and analysis of uniquely defined axons. , which previously had limited studies on the mechanism of axonal selection. Neuronal activity leads to the proliferation and differentiation of oligodendrocytes. CNS oligodendrocytes synthesize and maintain myelin. Oligodendrocytes cultured in vitro will randomly myelinate axons with a diameter of 0.4 μm or greater, suggesting that other mechanisms may be involved in myelination in vivo, as not all large diameter axons are myelinated. Gibson and his colleagues found that in juvenile and adult mice, neuronal activity leads to the proliferation of cells in the premotor cortex. Furthermore, when stained by immunofluorescence for cell identity markers, 54% of these dividing cells expressed the Oligo2 oligodendritic promoter; suggesting that OPCs are directly influenced by neuronal activity. This is supported by Mitew et al 2015, with OPC proliferation in the corpus callosum observed following a small subset of axons. Using both a viral and pharmacogenetic approach to measure OPC proliferation in the corpus callosum, they found that OPC proliferation was observed with both methods. Additionally, the density of mature oligodendrocytes increased, suggesting that OPC differentiation was amplified. This was also observed.