In labs testing how brain implants could help people with physical disabilities, tales of success can be bittersweet.
Experiments like those that let a paralyzed person swig coffee using a robotic arm, or that let blind people “see” spots of light, have proven the huge potential of computers that interface with the brain. But the implanted electrodes used in such trials eventually become useless, as scar tissue forms that degrades their electrical connection to brain cells (see “The Thought Experiment”).
Next month, tests will begin in monkeys of a new implant for piping data into the brain that is designed to avoid that problem. The project is intended to lead to devices that can restore vision to blind people long-term.
Researchers at Harvard Medical School will use a new kind of implant that will go beneath the skull but can rest on the surface of an animal’s brain, instead of penetrating inside the organ. An array of microscopic coils inside the hair-like device can generate powerful, highly targeted magnetic fields to induce electrical activity at particular locations in the brain tissue underneath. The implant will also be tested when placed inside brain tissue.
The device will be used to stimulate the visual cortex of the monkeys to try and re-create the activity normally triggered by signals from the eyes—creating the sensation of sight without the eyes’ input. Ultimately, the goal is to use the implant to convert signals from a camera into brain activity. Unlike conventional electrodes, the coils’ effectiveness shouldn’t degrade over time. Magnetic fields aren’t impeded by tissue forming around an implant as electric currents are.