Three's company

For many years, textbooks portrayed nerve communication as a straightforward process in which a signal simply hopped from one cell to the next. This traditional view also cast cells known as glia as passive bystanders to the signaling action between neurons. But scientists increasingly regard glia as influential third players in the space where signals pass between neurons, a space they have termed the 'tripartite synapse'. On the basis of this concept, some have begun to study the involvement of glia in nervous system disorders and to develop therapeutic compounds that target these cells. David Gruber reports.