FIGURE 3.

Astrocytes regulate neural circuits directly and indirectly. Astrocytes can modulate neural circuit function directly through different mechanisms (see Figure 1). Microglia have also been shown to control neuronal synapse number and activity on various timescales. Similarly, oligodendrocytes can regulate neurons’ axonal properties (e.g., conduction velocity) in an activity- and behavior-dependent manner. Astrocytes bidirectionally communicate with and regulate both microglia and oligodendrocytes (e.g., through diffusible messengers and physical interactions), allowing them to influence neural circuits indirectly and in a spatially and temporally distinct manner than their direct routes