A paradigm shift in brain research.

As late as the 1950s, it was assumed that communication between nerve cells in the brain occurred predominantly, if not entirely, by electrical impulses. A decade later, the theory of chemical transmission, which until then had been thought to occur only in the peripheral nervous system, had gained strong entrance for the central nervous system. This paradigm shift opened up an enormous new perspective in brain research, not least by facilitating the study of brain function by means of chemical tools, which in different ways could modify the chemical signaling between nerve cells. Moreover, such tools sometimes turned out to be useful as therapeutic agents. Thus for the first time, a variety of disorders in the central nervous system could be treated effectively.