Mind control with sound and light

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From a slew of new brainwave toys and bionic monkeys to advanced brain scans and wireless neuro-implants that will soon enable paralyzed people to remotely operate computers with their minds, the gap in the human-machine interface is closing. But while mind-reading gets all the glory, other researchers are developing new amazing non-drug methods to control the brain as well. We've posted many times about zapping regions of the brain with magnetic pulses, called transcranial magnetic stimulation, to treat depression, boost creativity, or even improve reaction time. And brain "pacemakers" are increasingly common treatments for epilepsy, Parkinson's, and even depression. What's next? Mind control through sound and light.

Brain Playground Day

Arizona State University researchers are using ultrasound pulses to stimulate activity deep inside the brain from the outside. The sound waves cause brain cells to spew certain chemical neurotransmitters, ultimately resulting in physical movements or other effects. The technique may also be used to lower the brain's metabolic rate after an injury to reduce secondary damage. "We're trying to develop the technology to the point where we can do away with the electrodes that are used in vagus nerve stimulation and deep brain stimulation," ASU professor William J. Tyler told IEEE Spectrum:

The low frequencies used can travel some distance through the air. So could you be zapped with a mood-altering blast from across a room? Probably not, Tyler says. In theory, the ultrasound technique could work from up to about a meter away, he says. "The farthest we've tried so far has been roughly 50 millimeters."
Meanwhile, other researchers are exploring how light, rather than sound, can be used to reprogram the brain. The field is called optogenetics and lies at the intersection of optics and biotechnology, specifically genetic engineering. By introducing genes that encode for channels and enzymes that are light-sensitive, scientists can "probe" the brain with light to learn about neuronal function. A fiber optic cable is literally plugged into the skull to excite the appropriate brain bits, essentially introducing an on/off switch in the head. (See the image at top from Stanford University's Optogenetics Resource Center, led by optogenetics pioneer Karl Deisseroth.)

"We are inventing new tools for analyzing and engineering brain circuits," says Ed Boyden, director of MIT's Synthetic Neurobiology Group and a leader in the field. We are devising technologies for controlling specific neural circuit elements, to understand their causal contribution to normal and pathological neural computations."

In the new issue of Wired, Institute for the Future affiliate Michael Chorost, author of the fantastic book Rebuilt, visits with Deisseroth and Boyden, and explains how optogenetics was used to make mice with paralyzing Parkinson's walk again. Fortunately, it doesn't sound like folks undergoing optogenetic treatments in the future will have fiber optic cables snaking out of their skulls. From Wired:

One of Deisseroth's colleagues designed a paddle about one-third the length of a popsicle stick. It has four LEDs: two blue ones to make neurons fire and two yellow ones to stop them. Attached to the paddle is a little box that provides power and instructions. The paddle is implanted on the surface of the brain, on top of the motor control area. The lights are bright enough to illuminate a fairly large volume of tissue, so the placement doesn't have to be exact. The light-sensitizing genes are injected into the affected tissue beforehand. It's a far easier surgery than deep brain electrical stimulation, and, if it works, a far more precise treatment. Researchers at Stanford are currently testing the device on primates. If all goes well, they will seek FDA approval for experiments in humans.