(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.