The human brain contains more than a billion neurons which interconnect to form networks that process, store, and recall sensory information. These neuronal activities are supported by a group of accessory brain cells coll- tively known as neuroglia. Surprisingly, glial cells are ten times more - merous than neurons, and occupy more than half the brain volume (Hyd n, 1961). Although long considered a passive, albeit necessary, component of the nervous...