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.
Light therapy: A neuron (green) engineered to express a light-sensitive protein fires in response to specific wavelengths of light. A glass electrode (lower left corner) records the neuron’s electrical response. Researchers from Medtronic used this system to confirm that a new implantable stimulator can properly activate neurons with light.
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.
