Technologies for stimulating the brain and controlling the mind can have benefits, but they have a dark side that military and intelligence planners have been exploiting for decades.

It would also appear possible to create high fidelity speech in the human body, raising the possibility of covert suggestion and psychological direction… Thus, it may be possible to “talk” to selected adversaries in a fashion that would be most disturbing to them.1
— US Air Force, New World Vistas: Air and Space Power for the 21st Century1

The idea that the brain can be made to function at a more efficient and directed level has been the subject of research by scientists, mystics, health practitioners and others for as long as mankind has contemplated such matters. In the last decade, advances in the science of the brain have begun to yield significant results. The results of the research are startling, challenging…