Your head is a very personal thing. It is what people use to identify you. It is the exclusive home of four of our five commonly recognized senses. It is the case that contains our brains, the source of everything we know, think and feel. Even our language recognizes the importance of the head in personality and intelligence. Someone acting crazy is said to have “lost their head” and a company’s primary office is their “head”quarters. There is one surgeon currently working in China, however, who might force us to raise some questions about where our heads fit into our identities.
Earlier this year, Dr. Sergio Canavero duplicated an experiment first attempted in the 1970’s. He cut the heads off of two rhesus monkeys, tossed one in the medical waste bin and sewed the other onto a body to which it didn’t belong. By lowering the temperature of the head to 15°C (59°F) and carefully maintaining the blood supply, Dr. Canavero demonstrated that the monkey could survive the operation without sustaining brain damage. His goal is to carry out the procedure on a Russian (human) volunteer, who suffers from a fatal, muscle-wasting condition called Werdnig-Hoffman disease.
The story isn’t all head-swapping good times, however. The monkey that survived the procedure may have found itself envying the one whose head ended up in the waste bin because, while it may be technically possible to maintain blood flow and avoid brain damage, there is one significant obstacle to performing totally successful head transplants: reconnecting the spinal cord. In the end, the monkey was euthanized a few days after the operation due to ethical concerns. Those concerns included the subject not being able to walk, breath, make noises, or control its bladder. The actions the transplanted head was capable of were limited to moving its eyes and facial muscles and attempting to bite whoever came near it… not that you could blame him.
What it comes down to is that your spinal cord is a remarkably complicated thing. The twisting rope of nerves, that winds its way down your backbone and into every part of your body, is what allows the lump of grey matter up in your skull to interact with the world. To make an out-of-date gaming reference, it is the equivalent of the cable connecting your Nintendo 64 controller to the game console. Sever it, and Mario becomes pretty immobile pretty fast. And the real kicker is that over the thousands of years we’ve been making progress in medicine, we still haven’t figured out a way to fix a disconnected spinal cord.
The problem is that, unlike most parts of your body, your spinal cord doesn’t regenerate on its own. We know that after an injury, nerves begin to reach out to reconnect with other parts of the body but chemicals released at the point of injury and scar tissue prevent the recovery from having any real effect.
Things aren’t all doom and gloom, however. Some research in the past decade has begun to inch closer to a treatment for spinal cord damage, making head transplants a slightly less crazy notion. In 2013, researchers at the Case Western Reserve University and the Cleveland Clinic showed that when they severed the spinal cords of 15 rats, they were able to regain some basic functions, like bladder control, by bathing the nerves in a mix of two chemicals, Chondroitinase and Fibroblast Growth Factor (FGF), and reinforcing the connection with some metal wiring.
Even more impressive, in 2014, surgeons in Poland, lead by Prof Geoff Raisman, chair of neural regeneration at University College London's Institute of Neurology, treated a paralyzed man’s spinal cord using cells from his own body and observed that, with physical therapy, he was eventually able to regain the ability to walk with the help of a metal frame. The treatment took cells from one of the man’s olfactory bulbs – normally used to smell stuff – and transplanted them into his spinal cord above and below the site of the injury. The gap between the two sections of the cord was reconnected using nerve tissue from the man’s ankle. Researchers believe that because the olfactory bulbs are one of very few areas where neurons regrow throughout a person’s lifetime, they may be the key to treating paralysis without fear of the body rejecting the new tissue.