Research aims at prosthetic arms with natural-like touch

University of Chicago scientists say touch-sensitive prosthetic limbs may one day convey real-time sensory information to amputees via a direct brain interface. Writing in the Proceedings of the National Academy of Sciences, the researchers say their efforts are a key step toward new technology that, if implemented successfully, would increase the dexterity and versatility of robotic prosthetic limbs. "To restore sensory motor function of an arm, you not only have to replace the motor signals that the brain sends to the arm to move it around, but you also have to replace the sensory signals that the arm sends back to the brain," said study senior author Sliman Bensmaia of the university's Department of Organismal Biology and Anatomy. The researchers are taking part in a multi-year Defense Advanced Research Projects Agency project that seeks to create a modular, artificial upper limb that will restore natural motor control and sensation in amputees. "We think the key is to invoke what we know about how the brain of the intact organism processes sensory information, and then try to reproduce these patterns of neural activity through stimulation of the brain," Bensmaia said. In a series of experiments with monkeys, whose sensory systems closely resemble those of humans, the researchers identified patterns of neural activity occurring during natural object manipulation and then successfully induced these patterns through artificial means. "The algorithms to decipher motor signals have come quite a long way, where you can now control arms with seven degrees of freedom," Bensmaia said. "It's very sophisticated. But I think there's a strong argument to be made that they will not be clinically viable until the sensory feedback is incorporated." "When it is, the functionality of these limbs will increase substantially."