You’d think that a drug prescribed to 10 million Americans would be well understood. But until now, scientists haven’t firmly grasped why Ritalin helps the scatterbrained. In a University of Wisconsin-Madison study published recently in Biological Psychiatry, researchers found that the stimulant works by optimizing brain signals in the prefrontal cortex.

The researchers fed rats different doses of Ritalin and then studied their neural activity, which was measured by electrodes implanted in their brains.

They found that brain signals voyaging between the hippocampus (responsible for memory, among other things) and the prefrontal cortex (also responsible for memory) became more precise. Ritalin also made neurons play well with others – more neurons fired together, and less wandered off by themselves. When scientists upped the doses, however, the rats lost their focus – proving that, at least in the case of Ritalin, less is more.

[via Scientific American]