The second century C.E. Greek physician and philosopher Galen advised patients suffering from disorders of the spirit to bathe in and drink hot spring water. Modern day brain scientists have posited that GalenÂ’s prescription delivered more than a placebo effect. Lithium has for decades been recognized as an effective mood stabilizer in bipolar disease, and lithium salts may have been present in the springs Galen knew. Yet exactly how lithium soothes the mind has been less than clear. Now, a team led by Ben Cheyette, a neuroscientist at the University of California in San Francisco (UCSF), has linked its success...