With all the advancements in prosthetic limbs' everyday workability, all that is left perhaps is to restore a person's sense of touch, which may not too far off, accoridng to a press release.

Researchers at the University of Chicago are making those technological advances that could one day lead to prosthetic limbs that could allow the person to once again feel.

The study, published in the journal Proceedings of the National Academy of Science, details a big step forward in creating more dexterity and viability of advanced robotic prosthetic limbs. The ultimate goal for such limbs is, of course, real-time sensory information that can interact with the brain for amputees.

"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 senior author, Sliman Bensmaia, Ph.D., assistant professor in the Department of Organismal Biology and Anatomy at the University of Chicago. "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."

Part of a long-term Defense Advanced Research Projects Agency (DARPA) project known as Revolutionizing Prosthetics, Bensmaia's research aims to restore as much of what an amputee loses in a real limb as possible. The project has benefited from the support of the Johns Hopkins University Applied Physics Laboratory and the input of experts from several of the countries' institutions.

To achieve their goal, the researchers conducted experiments with monkeys because their nervous system resembles that of a human's. They charted neural activity patterns and replicated them artificially.

The first experiments addressed contact location and the areas of skin that have been touched. After being trained to identify several patterns of physical contact, the researchers connected electrodes to the area of animals' brain corresponding to each finger. The test subjects responded the same way to artificial stimulation as to the physical contact.

Using a similar method the scientists then artificially simulated pressure and, once again, the subjects responded the same way as to physical pressure. Lastly, the scientists attempted to simulate the wide range of brain activity that occurs when someone first touches and releases an object.

"The algorithms to decipher motor signals have come quite a long way, where you can now control arms with seven degrees of freedom. 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," Bensmaia said. "When it is, the functionality of these limbs will increase substantially."