Astrocytic syncytium, non-synaptic communication

As non-synaptic message transmitters, astrocytes form a network in the neuropil called the astrocytic syncytium. Diffusion of molecules occurs in the syncytium via gap junctions between astrocytes.As non-synaptic message transmitters, astrocytes form a network in the neuropil called the astrocytic syncytium. Diffusion of molecules occurs in the syncytium via gap junctions between astrocytes.

Research has found that calcium waves propagate through the syncytium (Cornell-Bell et al., 1990), and that these waves can be induced by mechanical stimulation and by the neurotransmitter glutamate. The calcium waves could result in long-distance modulation of the composition and concentration of molecules in the extracellular space if the flux of calcium into astrocytes throughout the network leads to calcium-sensitive release and uptake of ions and neuromodulators. The astrocytic syncytium allows a non-synaptic means of communication within the brain. Astrocytes can sense and integrate information from a number of synapses simultaneously and can also receive information about the composition of the extracellular space and within the blood vessels. While astrocytes, unlike neurons, are incapable of being potentiated, they do have a capacity for long-range modulation and integration, and may therefore serve an integrative role in brain functioning (see Blomstrand et. al., 1997).