Figure 1.

Model structure. (A) Overview of an astrocyte structure. The endoplasmic reticulum (ER) covers the astrocyte core (soma and major processes). (B) In response to neuronal activity, Ca²⁺ enters the perisynaptic astrocyte processes via the Na⁺/Ca²⁺ exchanger and other Ca²⁺ channels. (C) Ca²⁺ influx from perisynaptic processes sums at the larger ER-holding processes, which can activate Ca²⁺-induced-Ca²⁺-release (CICR). Removal of Ca²⁺ occurs via ATPase and SERCA pumps. (D) The astrocyte soma and five of its major processes are approximated with single point models connected via diffusion across both the ER and the cytosol.