BOX 1.

Select unresolved questions

	Overall How do astrocytes integrate and respond to diverse molecular signals in their extracellular environment at the cellular and population level? How do they convert this task- and animal state-dependent information into functional outputs that modulate neural circuit structure or function on various temporal and spatial scales? Does this influence on neurons serve homeostatic functions, augment/complement neural circuit properties, or both? Do astrocytes perform similar computations in different brain and spinal cord regions? Do astrocytes temporally hold/store information and, if so, for what purpose?
	Indicators What new or improved indicators are needed to address the above questions (e.g., for neuropeptides, neuroactive substances, ions, transcriptional processes, synapse interactions)? How can current limitations to multiplex measurements be overcome (e.g., indicator signal-to-noise ratio, spectral variants, interference with endogenous signaling, buffering effects)?
	Actuators Given astrocytes’ complex spatiotemporal signals, how can physiologically meaningful regulation be achieved? Which approaches allow astrocyte “inhibition” at high spatial and temporal resolution? Which astrocyte signaling mechanisms other than calcium control neural circuit function and animal behavior on different timescales (e.g., K+, Na+, cAMP)?
	Genetic targeting approaches What genetic (or other) approaches allow targeting functionally homogeneous astrocyte populations for interrogating their function? What approaches allow circuit-specific astrocyte targeting?
	Behavioral assays How can quantitative behavioral assays be used to understand better astrocyte signal integration in vivo (e.g., noradrenergic, cholinergic, and dopaminergic signaling)? How can these assays be used to uncover astrocyte effects on neural circuit function in vivo (e.g., leveraging astrocytes’ refractory period-dependent excitation)?
	Computational approaches What molecular, structural, or gene expression changes should be measured to understand better astrocytes’ signal integration (with existing or novel indicators)? How do astrocytes control (directly or indirectly) neural circuit properties on various spatial and temporal scales (e.g., spike frequency, synchrony, oscillations, excitation-inhibition balance)? How is astrocytes’ structural and functional heterogeneity relevant to neural circuit operation? How can modeling help predict circuit functions of astrocytes unique to humans?
	Astrocyte heterogeneity How does astrocyte heterogeneity at the synaptic, cellular, circuit, and systems levels influence neural circuit function? What intrinsic and environmental factors determine this heterogeneity in health and disease?
	Astrocyte metabolism How do astrocyte-derived metabolites (e.g., lactate) regulate neural circuit function and animal behavior? How does altered metabolism in astrocyte-neuron assemblies influence neural circuit function and animal behavior?
	Contribution of other non-neuronal cells To what extent does astrocyte modulation of neural circuit function rely on other non-neuronal cells? How do these cells modulate astrocyte-neuron communication in health and disease? How do these cells influence neuronal circuit function directly?
	Disease How does disruption of astrocyte-neuron communication contribute to disease onset or progression? How does astrocyte heterogeneity or diversity relate to disease phenotype?