Effects of perinatal inflammation on brain development. Infants born at extremely low gestational age have a markedly increased risk of brain dysfunction, which is attributable to damage and developmental impairment in both white and grey matter. In such situations, microglia become activated. The resulting CNS inflammation impairs oligodendrocyte precursor maturation, which leads to a myelination defect. Furthermore, the cerebral cortex and deep grey matter will be affected by impairments in interneuron survival, axonal integrity, neurite branching, spine density, and synaptogenesis, leading to abnormal connectivity and brain microstructure.