Rebuilding Brain Control

We have discussed using amputated nerves to work with a machine to give the user control over that machine. These nerves can even be trained to perform different tasks. But what if we were to reattach a donors limb instead of a machine? The complexity of reattaching a human body part makes the possibility of more more advance prostheses a much closer reality.

French researchers were successful in transplanting 2 hands onto each of 2 amputee patients last year. Their goal was to investigate whether the patients could relearn to use their hands in a natural way. This research had great implications. If a patient can relearn to use an implanted hand, they may be able to learn how to use a prosthetic that has as many electrical connections as a human hand. This prosthetic could then be as functionally complex and as realistic as a human hand. This research could even have implications as great as eventually being able to use a human brain to control a fully robotic machine, eliminating the need for advance artificial intelligence to make a fully bionic being possible. Perhaps Ishiguro (from previous post), could build an android with real human body parts that is control with an advanced future version of his existing software for remote control. Or perhaps he could control such an android with his own brain!

Transplanting full human body parts has only been possible in the past 10 years. The difference between limbs and organs is that limbs are much more complex in terms of their connection to the nervous system is much more complex and that they are made up of multiple tissue tissue types, as opposed to an organ such as the liver. Although nerves are the most important connections in such a transplant, reconnecting the other physical tissue types, such as bone and muscle, is also essential.

When the transplantation of the donor hands has been completed, the brain actually starts to regenerate those nerves by 1mm each day! This means that in as little as a few months, the patient is able to feel and move their new hand. The ability of the brain to regenerate the nerves after they have been connected also shows a great level of promise for the future of prostheses. This research leads to the possibility of connecting artificial nerves for a few months in the hopes of regenerating a person's natural nerves in order to be able to use them to control an artificial limb or other body part. They explain, "Our findings show that newly transplanted muscles can be recognized and integrated into the patient’s motor cortex."

One interesting this to note is that although both patients were right handed, they both agree that after the transplant they had significantly better control of their new left hand. Although the researchers dismisses this as insignificant, due to lack of data points (only two patients), it still remains an interesting phenomenon to me. According to Kass, "It could depend on just technical things. It could depend on how well the hand is connected or how much damage there was done to the nerves and muscles." Maybe the donors were actually left handed, and this has a greater effect that the fact that the patients were right handed?

I always like to read the comments at the end of such an article. I think that the average person's reaction to advances in these fields may be a good indicator of the general acceptance of these ideas, as well as the proximity of their realization. One person brings up the possibility of using a person's own stem cells (although they do not specify whether these would be adult stem cells or embryonic stem cells, and this technology is still in the distant future) to grow a donor hand that would have no chance or rejection and would eliminate the need for the patient to take immunosuppressant drugs for the rest of their lives, while preventing other complications. Another person writes: "Nah. Someone will just patent the process and then the BPAA (like MPAA, but stands for Body Parts Administration of America) will try to make it illegal to make backup copies of ourselves. Of course, we’ll just get black market versions via B-Bay (Body Bay) and BodTorrent. We’ll upload genetic blueprints that others can copy into their human DNA coding/decoding machine, downloading only compatible parts, of course. We will translate this blueprint into gene maps via the coding machine and use its store of our pre-created stem cells to “print” our organs and body parts."

A third person writes, "How much do you want to bet that by 2209 people will consider adding an extra limb or finger just like getting a tattoo. It will bring body modification to a whole new level." Although right now tissue rejection would not allow this to be possible, they did say 2209!



http://www.wired.com/wiredscience/2009/04/handtransplant/