Prosthetic limbs of the future will not just replace an amputated hand or an amputated leg, but will help a person feel what he is holding or what he is stepping on. A group of scientists reported their achievements with a brain-computer interface that may pave the way for enhanced dexterity and functionality of artificial limbs.
The researchers led by Sliman Bensmaia, an assistant professor from the Organismal Biology and Anatomy of the University of Chicago, looked into the possibility of developing sensory inputs from an upper limb device fitted to rhesus macaques, monkeys with a sensory system that closely resembles the human’s. The results of the study appear on the Proceedings of the National Academy of Sciences.
The team focused on neural activities and neural patterns on the monkey’s brain as certain parts of its skin are stimulated. Later on, electrodes were placed on areas of the brain corresponding to areas that allow individual fingers of the subject to feel. Then, instead of touching areas of the skin, electrical stimuli were sent to the areas of the brain and as the group predicted, elicited the same results as physical touch.
The researchers also simulated pressure and the sensation of grabbing an object and the monkeys interpreted the artificial signals the same as natural ones.
"Our ability to manipulate objects relies fundamentally on sensory signals originating from the hand. To restore motor function with the upper-limb neuroprostheses require that somatosensory feedback be provided to the tetraplegic patient or amputee," explained Bensmaia.
"We have developed approaches to convey sensory information critical for object manipulation-- information about contact location, pressure, and timing-- through intracortical microstimulation of somatosensory cortex," he added.
Basically, the scientists now have a set of instructions that can be used to develop better prosthetics for amputees.
The group of scientists is working under the umbrella of the Defense Advanced Research Projects Agency (DARPA) that aims to make an upper limb prosthetic that will restore sensation and motor control for the patient.
"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. When it is, the functionality of these limbs will increase substantially," expressed Bensmaia through a press statement.