Functional Roles of Astrocyte Calcium Elevations: From Synapses to Behavior

Abstract

Astrocytes are fundamental players in the regulation of synaptic transmission and plasticity. They display unique morphological and phenotypical features that allow to monitor and to dynamically respond to changes. One of the hallmarks of the astrocytic response is the generation of calcium elevations, which further affect downstream cellular processes. Technical advances in the field have allowed to spatially and to temporally quantify and qualify these elevations. However, the impact on brain function remains poorly understood. In this review, we discuss evidences of the functional impact of heterogeneous astrocytic calcium events in several brain regions, and their consequences in synapses, circuits, and behavior.

Keywords: astrocyte; behavior; calcium; neural circuit; synapse.

FIGURE 1

Excitatory and/or inhibitory signals trigger Ca²⁺ elevations in astrocytes and lead to gliotransmitter release. Scheme depicting input signals that trigger astrocyte Ca²⁺ elevations and respective transmitter release. Both excitatory (+) and inhibitory (–) signals cause global or focal Ca²⁺ elevations in astrocytes (Left), and precede gliotransmitter release that might exert excitation or inhibition of neighboring synapses (Right). For each reference, the region studied is indicated in black (Amy, Amygdala; BrSt, brainstem; CA1, CA1 subfield of the hippocampus; Ctx, cortex; DG, dentate gyrus; hHip, human hippocampus; Str, Striatum). ^∗Indicates the studies that described functional consequences to focal Ca²⁺, rather than global Ca²⁺ responses.