Quadriplegics may be celebrating their own independence day in the not-too-distant future. The U.S. Food and Drug Administration recently cleared a pilot study of the BrainGate Neural Interface System. Developed by Cyberkinetics Inc., this technology has been designed to enable quadriplegics to control a computer cursor using just their thoughts.
The system is a proprietary, investigational brain-computer interface device that consists of an internal neural signal sensor and external processors. These processors convert neural signals into an output signal under the patient's control. The sensor consists of a chip that measures 4 by 4 mm, about the size of a baby aspirin, with 100 electrode sensors that detect brain-cell electrical activity. Each electrode sensor is thinner than a human hair.
The chip is implanted on the primary motor cortex, the area of the brain responsible for movement, extending 1 mm into the brain. A small wire connects the sensor to a pedestal mounted on the skull, extending through the scalp by just a few threads (see the figure). A cable connects the pedestal to a cart with several computers and a monitor, recording how well patients can control their neural output.
The pilot study will enroll a maximum of five quadriplegics. A sensor will be implanted on each patient's primary motor cortex. First, the study will characterize the device's safety profile. Second, researchers will evaluate the patients' neural output control. The study will last approximately 13 months for each patient. During that time, they will attempt to control the cursor's movement by imagining that they are using their arm to move the cursor toward a specific target. Researchers hope that the sensors will read that brain activity and translate those signals into cursor movement.
Initial study results should be ready by the year's end. Eventually, the research could lead to devices that let quadriplegics enjoy everyday activities like typing, maneuvering wheelchairs, and operating a host of other computerized systems. For details, go to www.cyberkineticsinc.com.