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.