CAMBRIDGE, Mass.--Scientists at the MIT Media Lab have invented a way to reversibly silence brain cells using pulses of yellow light, offering the prospect of controlling the haywire neuron activity that occurs in diseases such as epilepsy and Parkinson's disease.
Such diseases often must be treated by removing neurons that fire incorrectly. The new MIT research could lead to the development of optical brain prosthetics to control neurons, eliminating the need for irreversible surgery.
"In the future, controlling the activity patterns of neurons may enable very specific treatments for neurological and psychiatric diseases, with few or no side effects," said Edward Boyden, assistant professor in the Program in Media Arts and Sciences and leader of the Media Lab's new Neuroengineering and Neuromedia Group.
Boyden and Media Lab research affiliate Xue Han published their results in the March 21 issue of the online journal Public Library of Science ONE (PLOS One).
The work takes advantage of a gene called halorhodopsin found in a bacterium that grows in extremely salty water, such as the Great Salt Lake in Utah. In the bacterium, Natronomas pharaonis, the gene codes for a protein that serves as a light-activated chloride pump, which helps the bacterium make energy.
When neurons are engineered to express the halorhodopsin gene, the researchers can inhibit their activity by shining yellow light on them. Light activates the chloride pumps, which drive chloride ions into the neurons, lowering their voltage and silencing their firing.
That inhibitory effect may be extremely useful in dealing with diseases caused by out-of-control neuron firing, said Boyden. "In such diseases, inhibition is more direct than excitation, because you can shut down neural circuits that are behaving erratically," he said.
Many epilepsy patients have implanted electrodes that periodically give their brains an electric jolt, act
Contact: Elizabeth Thomson
Massachusetts Institute of Technology