抄録
The concept for glial cells as non-excitable- supporting elements has been accepted until almost the end of 20th century without doubt. However, total number of glial cells in human brain was found to be far larger than that of neuronal cells, and the ratio of glial cells to neurons in the brain was found to be higher in the highly developed animals than that in primitive animals. Those evidences suggested that the cells may be required for establishing higher order brain function. The dynamic feature of the cells has been revealed by the Ca2+ imaging techniques. Since then astrocytes have been recognized as dynamic cells and are regarded as intimate collaborators with neuronal cells. The concept of"tri-partite synapse" has been put forward to explain the possible participation of astrocytes into the synaptic transmission and information processing in the brain. However, the interaction among neuronal cells and astrocytes may not be such small scale. The transmission of the Ca2+ waves from an astrocyte to the other has been found to be performed through gap-junctions and also specific transmitters and receptors system. Thus astrocytes themselves form a wide network among them, which may be woven into the neuronal networks and construct large and highly organized information processing system. Neuronal networks as main system in the brain information processing may be controlled slowly and widely by astrocytes networks. This "glia-neuron functional coupling" will establish a higher order brain function and its deficit will cause brain dysfunctions. [J Physiol Sci. 2006;56 Suppl:S44]
