Very soon, an armless person can get a smart robotic hand which can feel the touch.
Not only this, the robot hand will convey real-time sensory information to the amputees via a direct interface with the brain, says a study by the University of Chicago which marks an important step toward a new technology that would increase the dexterity and clinical viability 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 the study's senior author, Sliman Bensmaia.
"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," said Bensmaia.
In a series of experiments with monkeys, whose sensory systems closely resemble those of humans, researchers identified patterns of neural activity that occur during natural object manipulation and then successfully induced these patterns through artificial means. The first set of experiments focused on contact location, or sensing where the skin has been touched. The animals were trained to identify several patterns of physical contact with their fingers.
Researchers then connected electrodes to areas of the brain corresponding to each finger and replaced physical touches with electrical stimuli delivered to the appropriate areas of the brain. The animals responded the same way to artificial stimulation as they did to physical contact.
The researchers then developed an algorithm to generate the appropriate amount of electrical current to elicit a sensation of pressure.
The animals' response was the same whether the stimuli were felt through their fingers or through artificial means.
Finally, Bensmaia and his colleagues studied the sensation of contact events. When the hand first touches or releases an object, it produces a burst of activity in the brain. Again, the researchers established that these bursts of brain activity can be mimicked through electrical stimulation.
The result of these experiments is a set of instructions that can be incorporated into a robotic prosthetic arm to provide sensory feedback to the brain through a neural interface. Bensmaia believes such feedback will bring these devices closer to being tested in human clinical trials.
The study was published in the journal Proceedings of the National Academy of Sciences.