In a fantastic leap in neuro-prosthetics, University of Pittsburgh scientists have created a mind-controlled robotic arm capable of ‘feeling’. Nathan Copeland, 28, was paralysed from the chest down in a motor accident in 2004. Twelve years after losing his sense of touch, he has become the first person to experience a sensory-enhanced prosthetic.
Sense of touch is mapped out in the somatosensory cortex (S1) region of the brain. Different areas of the body correspond to different regions of S1. Copeland’s hand-area was mapped by imaging his brain whilst asking him to imagine sensation in different areas of his hand. Microelectrodes were then positioned in the areas of the S1 region corresponding to the fingers and palm. Stimulation of the implants elicited tactile sensation in the fingers and an increase in stimulation, which corresponded to an increase in perceived pressure. Copeland was able to determine which prosthetic finger was being pressed while blindfolded with a high degree of accuracy, and was even able to tell when two fingers had been pressed simultaneously. Not only did he experience tactile sensation but the feeling was consistently graded as natural or almost natural.
While similar neuro-prosthetics have been used with success in non-human primates it has been impossible to determine how natural the sensations were. The restoration of sense of touch not only has huge emotional significance for the individual but is also important for developments in brain-computer interface prosthetics. We are looking at a new age of prosthetics that will lead to adjustable grip of objects and coordinated fine motor skills.
While we have a long way to go before neuro-prosthetics become the norm, this is a large and positive step for medical technology.