(UPDATE 03-05-2007 – Upon closer inspection, it is clear that while the surgery has enabled the woman to have sensation in the nerves of her missing hand when the surface of her chest is touched, the arm she is fitted with at the time of publication did not relay sensory signals from the arm back to her chest. As soon as she is fitted with an arm that has the appropriate sensors, however, she will not have to undergo further surgery to have this kind of direct feedback. Thanks to astute readers for pointing this out.)
The Guardian reports on an article published today in the Lancet about a successful surgical procedure giving an amputee a bionic arm that both responds to motor commands from her remaining motor nerves to control it and provides sensory feedback to sensory nerves when it is touched. If there was any doubt left, the worlds of neural prosthetics and brain-machine interfaces have officially collided.
The Lancet article is accompanied by two movies of the woman using the arm that you should really check out.
Given the recent progress in the decoding of motor signals from the brain and older progress on sensory feedback from neural prosthetics, this was to be expected. Nonetheless, watching this woman use her arm brings the message home in a visceral way. The spooky thesis of MIT CSAIL’s Rodney Brooks that “we will become a merger between flesh and machines” is one step closer today.
From the article:
Targeted reinnervation surgery was successful in this young woman. Four independent myoelectric sites were created that allowed improved control of a motorised artificial arm. Transfer sensation also developed; when the patient was touched on her reinnervated chest skin, she perceived the sensation to be in her missing hand.
An additional comment in the Lancet explains targeted reinnervation surgery:
Rather than record from these nerves directly, Todd Kuiken and colleagues report in today’s Lancet their development of targeted motor reinnervation (TMR), in which the disconnected ends of peripheral nerves are reimplanted into proximal musculature. Contraction of these proximal muscles shows the intended activation of the missing distal muscles. When combined with a myoelectric prosthesis, a command in the CNS to open the hand travels through its usual peripheral nerves, is amplified by the associated patch of reinnervated muscle, and is detected by myoelectric sensors, which trigger the prosthetic hand to open.
Todd A Kuiken, Laura A Miller, Robert D Lipschutz, Blair A Lock, Kathy Stubblefield, Paul D Marasco, Ping Zhou and Gregory A Dumanian, Targeted reinnervation for enhanced prosthetic arm function in a woman with a proximal amputation: a case study, The Lancet, Volume 369, Issue 9559, 3 February 2007-9 February 2007, Pages 371-380.