(October 27, 2010) Ed
Boyden is learning how to alter behavior by using light to turn neurons on and
off.
The equipment in Ed Boyden’s lab at MIT is nothing if not
eclectic. There are machines for analyzing and assembling genes; a 3-D printer;
a laser cutter capable of carving an object out of a block of metal; apparatus
for cultivating and studying bacteria, plants, and fungi; a machine for
preparing ultrathin slices of the brain; tools for analyzing electronic
circuits; a series of high-resolution imaging devices. But what Boyden is most
eager to show off is a small, ugly thing that looks like a hairy plastic tooth.
It’s actually the housing for about a dozen short optical fibers of different
lengths, each fixed at one end to a light-emitting diode. When the tooth is
implanted in, say, the brain of a mouse, each of those LEDs can deliver light
to a different location. Using the device, Boyden can begin to control aspects
of the mouse’s behavior.
Mouse brains, or any other brains, wouldn’t normally respond
to embedded lights. But Boyden, who has appointments at MIT as eclectic as his
lab equipment (assistant professor at the Media Lab, joint professor in the
Department of Biological Engineering and the Department of Brain and Cognitive
Sciences, and leader of the Synthetic Neurobiology Group), has modified certain
brain cells with genes that make light-sensitive proteins in plants, fungi, and
bacteria. Because the proteins cause the brains cells to fire when exposed to
light, they give Boyden a way to turn the genetically engineered neurons on and
off.
