Patients think, and a limb moves. Advanced prosthetics have begun tapping into brain signals to provide amputees with new levels of control. But getting robotic limbs or hand to sense what it’s touching is a harder task.
The U.S. Defense Department’s research division last week claimed a breakthrough in this area, issuing a press release touting a 28-year-old paralyzed person’s ability to “feel” physical sensations through a prosthetic hand. Researchers have directly connected the artificial appendage to his brain, giving him the ability to even identify which mechanical finger is being gently touched, according to the Defense Advanced Research Projects Agency (DARPA). The extent of this feat will depend upon the details that DARPA still hasn’t disclosed. Nerves and the electrical wires needed to regulate the electronics in a prosthesis use very different kinds of signals. The latter depend on the flow of electronics across conductive materials, semiconductors and other components. The nervous system, meanwhile, is based on the release of signaling chemicals in the gaps between nerve cells. Nor would the human body take kindly to the wires and other devices needed to enable two-way communications between a prosthetic hand and the brain. A team of University of Pennsylvania neurosurgeons laid out these challenges in the January 2013 Scientific American article, “Bionic Connections.”
What’s needed is an adapter plug—a “living bridge”—that can translate signals between nerves and artificial limbs, according to the Penn neurosurgeons/researchers D. Kacy Cullen and Douglas Smith. The above graphic illustrates how such an adapter might work. This approach—being investigated by a number of different researchers—would enable the brain to interpret the incoming signals as coming from a forearm, a hand and fingers. As mentioned above, the DARPA-funded research tied directly into the brain, a much more delicate and dangerous approach……
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