The Altered Roles of Glia in Neurodevelopmental Disorders

Abstract

For many decades in neuroscience, glial cells were thought almost exclusively to provide passive, primarily metabolic, support for the billions of neurons in our central nervous system (CNS). Today, however, the three types of CNS glial cells, astrocytes, oligodendrocytes, and microglia, are known to play a myriad of active roles that are necessary for normal neurodevelopment. Astrocytes have been found to regulate neurogenesis, support neuronal migration, promote axon elongation, guide the growth of processes, induce synapse formation, and modulate synaptic strength. Oligodendrocytes were thought to be important only for myelination of axons, but it has become clear that they are dynamic modulators of axonal conduction velocity and providers of metabolic support. Similarly, microglia were known almost exclusively as the immune cells of the CNS; however, recent research has exposed their importance in the regulation of cell number, cell differentiation, maturation of neural circuits, and synaptic remodeling. Recent findings suggest that aberrant glial cell function contributes to some of the unusual pathology seen in Noonan syndrome, schizophrenia, cerebral palsy, autism spectrum disorder, and other neurodevelopmental disorders. Moreover, new insights about the details of neuron-glia interactions allow for speculations about how altered glial cell function could actively contribute to abnormal neurodevelopment.