Friday, March 12, 2010

optogenetic engineering

Wired | Flashes of light may one day be used to control the human brain, and that day just got a lot closer.

Using lasers, researchers at the MIT Media Lab were able to activate a specific set of neurons in a monkey’s brain. Though the technique has been used to control and explore neural circuits in fish, flies and rodents, this is the first time the much-hyped technology has ever been used in primates.

“It paves the way for new therapies that could target a number of psychiatric disorders,” said MIT neuroscientist Ed Boyden, who led the research with postdoctoral fellow Xue Han. “This is very exciting from a translational standpoint.”

The beauty of this optogenetic technique is its specificity. By using a combination of lasers and genetic engineering, scientists can control, to the millisecond, the firing of a specific class of neurons, allowing them to pinpoint problematic cells and circuits while leaving innocent bystanders alone, thus minimizing potential side effects.

Viruses are engineered to infect neurons with a special type of channel, originally discovered in algae, which is sensitive to blue light. Once a blue laser shines on the infected neurons, the channels snap open, ions rush into the cell, and the neuron fires.

Crucial to the technique is that the virus is only injected into a very small part of the brain, and only a certain class of neurons, once infected, actually turn the channel on. The sharp laser beam further zeros in on a small portion of the brain. This precise aim is in contrast to current techniques, such as drugs and electrodes, both of which have a much broader reach.

The optogenetic method was pioneered in 2005 by Boyden and Karl Deisseroth at Stanford University and has since been used to understand how circuits of neurons control various behaviors, such as learning in mice and predator escape in fish. But until now, scientists had never demonstrated the technique in primates — a move essential for developing therapeutic uses for the technology in humans.