Figure 2.

Astrocytic structural plasticity contributes to the maintenance of activated synapses. Left panel: excitatory synapses are surrounded by astrocytic processes that show a high level of motility. Middle panel: this astrocytic motility is regulated by the released neurotransmitter, which activates glutamate metabotropic receptors on the astrocytic process leading to an increased calcium flux and motility of the astrocytic process. Right panel: when driven by learning related paradigms (LTP, upper synapse), this enhanced motility leads to an increased and more stable coverage of the synapse by the astrocytic process resulting in a long-lasting stabilization of the synapse. This mechanism might involve, among other possibilities, a contribution of adhesion molecules.