Tripartite synapse
Tripartite synapse refers to the functional integration and physical proximity of the presynaptic membrane, postsynaptic membrane, and their intimate association with surrounding glia as well as the combined contributions of these three synaptic components to the production of activity at the chemical synapse. Tripartite synapses occur at a number of locations in the central nervous system with astrocytes and may also exist with Muller glia of retinal ganglion cells and Schwann cells at the neuromuscular junction. The term was first introduced in the late 1990s to account for a growing body of evidence that glia are not merely  passive neuronal support cells but, instead, play an active role in the integration of synaptic information through bidirectional communication with the neuronal components of the synapse as mediated by neurotransmitters and gliotransmitters. Evidence of the Tripartite Synapse. Evidence for the role of astrocytes in the integration and processing of synaptic integration presents itself in a number of ways: