FIGURE 1.

Astrocytes regulate and are controlled by neural circuits and animal behavior. Animal behavior activates a subset of local excitatory, inhibitory, and projection neurons, leading to the release of diverse molecular signals. Astrocytes are thought to spatially and temporally integrate these time-varying signals in their environment, with calcium and/or PKA playing central roles in this process. Signal integration also involves intermediate signals, such as reactive oxygen species (ROS), IP₃, cAMP, and IRBIT. Astrocyte excitation, in turn, is thought to modulate neural circuit function (e.g., network state, excitation-inhibition balance, synaptic strength, or number) through different mechanisms (e.g., extracellular ion regulation, neuroactive factor release, perisynaptic process structure) and on various timescales (second to minutes) (see also Figures 2–3). Abbreviations: Ado, adenosine; cAMP, cyclic adenosine monophosphate; Glu, glutamate; IP₃, inositol-trisphosphate; IRBIT, IP₃ receptor-binding protein released with IP₃; PKA, protein kinase A