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Neurotechnology is an emerging field creating a variety of new devices with the potential restore lost functions as well as diagnose and treat nervous systems disorders. Currently available neurotechnologies based on stimulating the brain include cochlear implants to restore hearing and deep brain stimulators (DBS) for Parkinson’s disease. These implanted ‘brain interfaces’, already in use by tens of thousands of humans have dramatic effects on quality of life. Stimulation devices are also being developed for vision prostheses and for other applications.
Neural interface systems that sense neural signals are a newer neurotechology, now in early-stage human trials. These brain computer interfaces (BCI), aim to restore independence, communication and control for people with paralysis. BrainGate is a unique BCI in early stage human clinical trials being developed by our group at Brown University and Massachusetts General Hospital. BrainGate is being developed to allow paralyzed humans to use neural signals ordinarily used to control the arm to operate devices such as computer software or robotic assistants. Control signals are derived from the neural activity in arm area of motor cortex, through a 100 chronically implanted microelectrode array that enables recordings of action and field potentials, both of which can provided useful command signals. Preliminary experience from five tetraplegic participants, including one for more than 5 years, demonstrate that arm-related motor cortical signals remain in motor cortex long after injury or disease onset and can record for extended durations. Participants are able to perform point and click actions of a computer cursor or move a robotic arm to grasp objects. A major goal is to reanimate muscles by connecting motor output to implanted functional electrical stimulators, which has been demonstrated by a person with tetraplegia using a simulated FES system. Early stage wireless, implantable systems now in initial preclinical testing also suggest that high bandwidth implantable systems are feasible. Beyond BCI applications, the same technology may provide new approaches to monitor human brain activity patterns at a fine temporal and spatial scale. For example, such technology might allow early detection of an impeding seizure, or other changes in brain state. Finally, the ability to sense at the level of multiple single neurons and local field potentials opens up an entirely new perspective on the function of the human brain as well as the impact of disease and injury.
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