Select your localized edition:

Close ×

More Ways to Connect

Discover one of our 28 local entrepreneurial communities »

Be the first to know as we launch in new countries and markets around the globe.

Interested in bringing MIT Technology Review to your local market?

MIT Technology ReviewMIT Technology Review - logo


Unsupported browser: Your browser does not meet modern web standards. See how it scores »

{ action.text }

Researchers at Medtronic are developing a prototype neural implant that uses light to alter the behavior of neurons in the brain. The device is based on the emerging science of optogenetic neuromodulation, in which specific brain cells are genetically engineered to respond to light. Medtronic, the world’s largest manufacturer of biomedical technologies, aims to use the device to better understand how electrical therapies, currently used to treat Parkinson’s and other disorders, assuage symptoms of these diseases. Medtronic scientists say they will use the findings to improve the electrical stimulators the company already sells, but others ultimately hope to use optical therapies directly as treatments.

Today’s neural implants work by delivering measured doses of electrical stimulation via a thin electrode surgically inserted through a small hole in a patient’s skull, with its tip implanted in a localized brain area. Since the U.S. Food and Drug Administration approved such “brain pacer” devices and the electrically based treatment they deliver –called Deep Brain Stimulation (DBS)–for a disorder called essential tremor in 1997, for Parkinson’s disease in 2002, and for dystonia in 2003, over 75,000 people have had them installed. The electrical pulses are thought to counter the abnormal neural activity that results from different diseases, though physicians know little about how DBS works.

Despite their success, such neural prostheses have serious drawbacks. Beyond the blunt fact of their physical locations, they stimulate neurons near the electrode indiscriminately. That overactivity can trigger dizziness, tingling, and other side effects. Furthermore, they produce electrical “noise” that makes tracking quieter neural signals difficult and the simultaneous use of scanning systems like MRI practically impossible, which in turn prevents researchers from gaining any evidence about how DBS actually works.

In the last few years, scientists have developed a way to stimulate neurons using light rather than electricity. Researchers first introduce a gene for a light-sensitive molecule, called channelrhodopsin 2 (ChR2), into a specific subset of neurons. Shining blue light on these neurons then causes them to fire. One advantage of this approach is its specificity–only the neurons with the gene are activated. It also provides a way to shut neurons off–introducing a different molecule, halorhodopsin (NpHR), silences the cells in response to yellow light. “That’s the other unique thing about this approach,” says Tim Denison, senior IC engineering manager in Medtronic’s neuromodulation division. “It allows us to silence neurons’ activity, which is extraordinarily difficult with electrostimulation.”

While academic scientists are developing new tools to deliver light to the brain, Medtronic is developing an optogenetically based implant for commercial use. The module, which is approximately the size and shape of a small USB flash drive, has wireless data links, a power management unit, a microcontroller, and an optical stimulator. It uses a fiber-optic wire to direct light from a blue or green LED at target neurons in the brain. The company plans to market the device to neuroscience researchers and use it for in-house research on the effects of DBS.

0 comments about this story. Start the discussion »

Credit: Karl Deisseroth, Stanford University

Tagged: Biomedicine, brain, optogenetics, fiber optics, deep brain stimulation, neuron, Medtronic, channelrhodospin

Reprints and Permissions | Send feedback to the editor

From the Archives


Introducing MIT Technology Review Insider.

Already a Magazine subscriber?

You're automatically an Insider. It's easy to activate or upgrade your account.

Activate Your Account

Become an Insider

It's the new way to subscribe. Get even more of the tech news, research, and discoveries you crave.

Sign Up

Learn More

Find out why MIT Technology Review Insider is for you and explore your options.

Show Me