( o shut down overactive neurons. This ne...)MIT: Pulsing light silences overactive neurons

The group also plans to use the new method to study neural circuits. Last year, Boyden devised a technique to stimulate neurons by shining blue light on them, so with blue and yellow light the researchers can now exert exquisite control over the stimulation and inhibition of individual neurons.

Learning more about the neural circuits involved in epilepsy could help scientists develop devices that can predict when a seizure is about to occur, allowing treatment (either shock or light) to be administered only when necessary, Boyden said.

The technique also offers a way to study other brain diseases, as well as normal brain circuitry, offering insight into which brain regions and neurons contribute to specific behaviors or pathological states, Boyden said.

The halorhodopsin gene was originally discovered in the 1980s, but Boyden didn't think its full potential had been explored. The protein expressed by the gene turned out to have exactly the right characteristics to make it useful in neuron inhibition.

"Often if you are patient and think carefully about what you want to do, you can find a molecule that is very close to what you want, and with a little bit of luck it will turn out to work," Boyden said.

The halorhodopsin work is one of the first projects from the Media Lab Neuroengineering and Neuromedia Group, which was formed about six months ago to enhance the Media Lab's study of the brain-body relationship.

"The Media Lab has always been interested in studying the interface between people and the world," Boyden said, "but now people are getting interested in the interface between bodies and brains in the world."