Modeling of Astrocyte Networks: Toward Realistic Topology and Dynamics.

Neuronal firing and neuron-to-neuron synaptic wiring are currently widely described as orchestrated by astrocytes-elaborately ramified glial cells tiling the cortical and hippocampal space into non-overlapping domains, each covering hundreds of individual dendrites and hundreds thousands synapses. A key component to astrocytic signaling is the dynamics of cytosolic Ca which displays multiscale spatiotemporal patterns from short confined elemental Ca events (puffs) to Ca waves expanding through many cells. Here, we synthesize the current understanding of astrocyte morphology, coupling local synaptic activity to astrocytic Ca in perisynaptic astrocytic processes and morphology-defined mechanisms of Ca regulation in a distributed model.

Sodium-Calcium Exchanger Can Account for Regenerative Ca Entry in Thin Astrocyte Processes.

Calcium transients in thin astrocytic processes can be important in synaptic plasticity, but their mechanism is not completely understood. Clearance of synaptic glutamate leads to increase in astrocytic sodium. This can electrochemically favor the reverse mode of the Na/Ca-exchanger (NCX) and allow calcium into the cell, accounting for activity-dependent calcium transients in perisynaptic astrocytic processes.