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 To make an out-of-date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.
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