A study led by neuroscientists from UChicago shows that artificial touch is highly
dependent on several features of electrical stimuli, such as the strength and frequency
of signals, and describes the specific characteristics of these signals.
Courtesy of Johns Hopkins University Applied Physics Laboratory
(October 26, 2015) A new study led by University of Chicago neuroscientists brings them one step closer to building prosthetic limbs for humans that recreate a sense of touch through a direct interface with the brain.
The research, published Oct. 26 in the Proceedings of the National Academy of Sciences, shows that artificial touch is highly dependent on several features of electrical stimuli, such as the strength and frequency of signals. It describes the specific characteristics of these signals, including how much each feature needs to be adjusted to produce a different sensation.
“This is where the rubber meets the road in building touch-sensitive neuroprosthetics,” said Sliman Bensmaia, associate professor of organismal biology and anatomy and senior author of the study. “Now we understand the nuts and bolts of stimulation, and what tools are at our disposal to create artificial sensations by stimulating the brain.”
Bensmaia’s research is part of Revolutionizing Prosthetics, 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. The project has brought together an interdisciplinary team of experts from government agencies, private companies and academic institutions, including the Johns Hopkins University Applied Physics Laboratory and the University of Pittsburgh.
Bensmaia and his UChicago colleagues are working specifically on the sensory aspects of these limbs. For this study, monkeys, whose sensory systems closely resemble those of humans, had electrodes implanted into the area of the brain that processes touch information from the hand. The animals were trained to perform two perceptual tasks: one in which they detected the presence of an electrical stimulus, and a second in which they indicated which of two successive stimuli was more intense.
During these experiments, Bensmaia and his team manipulated various features of the electrical pulse train, such as its amplitude, frequency and duration, and noted how the interaction of each of these factors affected the animals’ ability to detect the signal.