Paralyzed man feels physical sensation through a prosthetic hand

A 28-yr old paralyzed man in the US has been able to feel physical sensation through a robotic hand. This is the first case of its kind where a prosthetic hand directly connected to his brain has generated physical sensations, the US defence researchers have claimed.

The man has been paralyzed for more than a decade now due to a spinal cord injury. However, today he could even identify which mechanical finger was being gently touched, researchers said.

The clinical work involved the placement of electrode arrays onto the paralyzed volunteer's sensory cortex - the brain region responsible for identifying tactile sensations such as pressure, as further reported by PTI.

In the very first set of tests, in which researchers gently touched each of the prosthetic hand's fingers while the volunteer was blindfolded, he was able to report with nearly 100 per cent accuracy which mechanical finger was being touched.

The feeling, he reported, was as if his own hand were being touched.

"At one point, instead of pressing one finger, the team decided to press two without telling him," said Sanchez.

"He responded in jest asking whether somebody was trying to play a trick on him. That is when we knew that the feelings he was perceiving through the robotic hand were near-natural," he said.

The advance, made possible by sophisticated neural technologies developed under US Defence Advanced Research Projects Agency (DARPA)'s Revolutionising Prosthetics points to a future in which people living with paralysed or missing limbs will not only be able to manipulate objects by sending signals from their brain to robotic devices, but also be able to sense precisely what those devices are touching.

"We've completed the circuit" said DARPA programme manager Justin Sanchez.

"By wiring a sense of touch from a mechanical hand directly into the brain, this work shows the potential for seamless bio-technological restoration of near-natural function," said Sanchez.

The clinical work involved the placement of electrode arrays onto the paralysed volunteer's sensory cortex - the brain region responsible for identifying tactile sensations such as pressure.

In addition, the team placed arrays on the volunteer's motor cortex, the part of the brain that directs body movements.

Wires were run from the arrays on the motor cortex to a mechanical hand developed by the Applied Physics Laboratory (APL) at Johns Hopkins University.

That gave the volunteer - whose identity is being withheld to protect his privacy - the capacity to control the hand's movements with his thoughts.

Then, breaking new neurotechnological ground, the researchers went on to provide the volunteer a sense of touch.

The APL hand contains sophisticated torque sensors that can detect when pressure is being applied to any of its fingers, and can convert those physical "sensations" into electrical signals.