CAMBRIDGE, Mass., Nov. 19, 2012 — A new tool that delivers
precise points of light to living brain tissue in three
dimensions could one day help treat Parkinson’s disease and
epilepsy; it could even aid in the understanding of
consciousness and how memories form.  Biologists and engineers
at MIT developed the three-dimensional “light switch” using a
technique that manipulates neurons with light, known as
optogenetics. The method, only a few years old, sensitizes
select brain cells to a particular color of light. By
illuminating precise areas of the brain, scientists can
selectively activate or deactivate the individual neurons that
have been sensitized.  Optogenetics allows scientists to play a
more active role in probing the brain’s connections, to fire up
one type of cell or deactivate another and then observe the
effect on a behavior, such as quieting a seizure. “You can see
neural activity in the brain that is associated with specific
behaviors, but is it important?” said Ed Boyden, a synthetic
biologist