People can control prosthetic limbs, computer programs and even remote-controlled helicopters with their mind, all by using brain-computer interfaces. What if we could harness this technology to control things happening inside our own body? A team of bioengineers in Switzerland has taken the first step toward this cyborglike setup by combining a brain-computer interface with a synthetic biological implant, allowing a genetic switch to be operated by brain activity. It is the world's first brain-gene interface.

The group started with a typical brain-computer interface, an electrode cap that can register subjects' brain activity and transmit signals to another electronic device. In this case, the device is an electromagnetic field generator; different types of brain activity cause the field to vary in strength. The next step, however, is totally new—the experimenters used the electromagnetic field to trigger protein production within human cells in an implant in mice.

The implant uses a cutting-edge technology known as optogenetics. The researchers inserted bacterial genes into human kidney cells, causing them to produce light-sensitive proteins. Then they bioengineered the cells so that stimulating them with light triggers a string of molecular reactions that ultimately produces a protein called secreted alkaline phosphatase (SEAP), which is easily detectable. They then placed the human cells plus an LED light into small plastic pouches and inserted them under the skin of several mice.

Human volunteers wearing electrode caps either played Minecraft or meditated, generating moderate or large electromagnetic fields, respectively, from a platform on which the mice stood. The field activates the implant's infrared LED, which triggers the production of SEAP. The protein then diffuses across membranes in the implant into the mice's bloodstream.

Playing Minecraft produced moderate levels of SEAP in the mice's bloodstream, and meditating produced high levels. A third type of mental control, known as biofeedback, involved the volunteers watching the light, which could be seen through the mice's skin, and learning to consciously turn the LED on or off—thereby turning SEAP production on or off.

“Combining a brain-computer interface with an optogenetic switch is a deceptively simple idea,” says senior author Martin Fussenegger of the Swiss Federal Institute of Technology in Zurich, “but controlling genes in this way is completely new.” By using an implant, the setup harnesses the power of optogenetics without requiring the user to have his or her own cells genetically altered. Fussenegger and his co-authors envision therapeutic implants one day producing chemicals to correct a wide variety of dysfunctions: neurotransmitters to regulate mood or anxiety, natural painkillers for chronic or acute pain, blood-clotting factors for hemophiliacs, and so on. Some patients would benefit greatly from having conscious control over intravenous dosage rather than relying on sensors—especially in cases such as pain, which is hard for anyone but the sufferer to measure, or locked-in patients or others who are conscious but cannot communicate.