Figure 3.

(A) The moderate to late gestation in utero neural environment is characterized by a dominance of GABAergic activity, which plays a key role in promoting oligodendrocyte maturation and myelination. (B) The preterm ex utero environment is characterized by a loss of GABAergic activity following a reduction in placental neurosteroid supply. Subsequently, this loss disrupts the fetal “sleep” state, and may also coincide with additional adverse insults, including excessive glucocorticoid concentrations and periods of hypoxia. The resulting increase in glutamate action increases the amount of calcium ions flowing into the oligodendrocyte, thus preventing its normal development and production of myelin. Figure created with BioRender.com.