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Archive for November, 2013

Of robots and the connectome

Science fiction, by (almost) default, deals with the concept of “life as we do not know it”.  This is of course, the idea that life can include forms that may be fundamentally different from our own.  It is well-known that life is a notoriously difficult concept to define.  That said, a lot of progress is made each day on trying to determine all the possible paths that this phenomenon can take.

As science fiction fans, it is entirely possible that the first example of life as we do not know it that we ever heard about was robots.  The very word robot means “servant” and it seem that it was used for the first time in 1921 by the Czech writer, Karel Kapek in his play R.U.R, short forRossum’s Universal Robots”.

By far, the most interesting type of robots are the ones endowed with artificial intelligence.  We are all familiar with the most famous SciFi robots, from the robot in the iconic 1956 movie “Forbidden Planet” (nicknamed “Robbie”, although the phrase “Robbie the Robot”  was used before in science fiction stories) to Star Trek’s Data to the humanoid Cylons from the reimagined Battlestar Galactica.

The great Isaac Asimov was probably the first to come up with a plausible mechanism to build artificial human-like intelligence.  He imagined positronic brains, as opposed to electronic brains.  This concept was extensively borrowed in many later science fiction series and stories.  For example, did you see the movies “Bicentennial Man” starring Robin Williams and “I Robot” starring Will Smith?  These two stories are Asimov’s originals…

The topic of robots, especially intelligent ones is fascinating and merits a post of its own.  However, I would like instead to talk a little bit about what would it take to create a true example of artificial intelligence.

Intelligence in general is a broad term that can be defined in multiple ways, a little bit like consciousness.  However, the general accord is that whatever human consciousness or intelligence may be, they are a direct result of the architecture of the human brain.

A recent trend in neuroscience is to talk about mapping all the connections in the human brain, an effort called the human connectome project.  Basically, the idea is to map all the connections of the 100 billion neurons of the human brain (no, there are no 86 billion neurons in a human brain; don’t even get me started… What? You still want to know what I think about it?  Ok then, look here, here and here).

The connectome idea is very interesting and will be a wonderful tool to try to understand ourselves as well as for understanding a wide variety of neurological conditions (psychiatric conditions are by definition neurological as well, just so you know).  This will, without a doubt more than a blessing to those of us who care of a mentally ill loved one or those of us who are going through it ourselves.

As wonderful as this dream of a connectome is, even though imaging technology is advancing, we still do not have the optimal tools or the computer power to completely map these connections.  Moreover, not every important aspect of brain function is directly related to its physical circuitry.  To say that a physical map of a brain says all that there is to say about it is a little bit like saying that a map of a shopping mall tells you how all about how it works.  The real and complete picture of how a shopping mall works must include all the multiple activities within each store that are not accounted for in the “map”, as well as many related aspects like whether the manager of a particular store contacts the main offices to solve an issue, etc.

To make things even worse, there are many aspects of neuronal transmission that are controlled by processes that work beyond the direct neuron-neuron connections, of which I hope to talk about in a future post.  Also, there is the matter of the sheer physical complexity of a typical brain.  For example, 100 billion neurons, each one with an average of 30,000 contacts (synapses) with other neurons; you do the math (hint: it is a BIG number).  This fact, added to all the extraneuronal events that happen to make it work, makes even a simulation of an actual brain a tall order at our current level of technology (don’t get me wrong, it WILL happen, just not as fast as the hype states…).  In fact, about simulations and models, if you want to see some of my thoughts about it go here and here.

These are not the rumblings of a “bah, humbug!” guy.  There are other people taking a critical look at the connectome concept.

Let me finish this post with a couple of thoughts about the brain (which were generated by my very own brain… (:-D)…).

The human brain is oftentimes called the most complex structure in the known universe and rightfully so.

This being said, there are a couple of little details that one must not lose sight of.  (1) The brain is a biological construct, crafted by evolution and (2) the average speed of nerve transmission is in the order of 55 miles/second.  Fast enough, huh?

However, an electronic computer, which will inevitably be the “ancestor” of a robot brain has two very -and I mean VERY- important advantages; it is rationally designed and it works with a speed close to 186,000 miles/second.

Yes, light speed; the very speed limit of the universe itself.

I would not discount electronic brains just yet.

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Picture credits: Wikimedia Commons.

Wanna take a look at my blog, “Baldscientist”?  Click here.

If you want to know more

http://en.wikipedia.org/wiki/Positronic_brain

http://www.syfy.com/battlestar/

http://www.humanconnectomeproject.org/

http://www.nature.com/neuro/journal/v13/n12/full/nn1210-1441.html

Put Your Head on My Shoulder

Head transplants have been a staple for science fiction stories for a long time, from the monster in Mary Shelley’s Frankenstein to Pierce Brosnan and/or Sarah Jessica Parker having their head attached to a Chihuahua in Mars Attacks! to the movie Futurama: Bender’s Big Score, where Hermes is decapitated, then has Bender obtain an earlier version of his body and do a head transplant using Torgo’s Executive Powder. But how possible is a head transplant? And if it could be done, what are some of the implications?

In a paper published in the June issue of open source journal Surgical Neurology International, Dr. Sergio Canavero of the Turin Advanced Neuromodulation Group says he knows how to perform a complete human head transplant. According to Canavero, the transplant will work if surgeons can successfully link the spinal cord to the head by fusing severed axons, the nerve cells that transmit information to different neurons, muscles and glands. “The greatest technical hurdle to such endeavor is of course the reconnection of the donor’s and recipient’s spinal cords. It is my contention that the technology only now exists for such linkage.”

Surgeons would begin by cutting the cooled spinal cords with an “ultra-sharp blade” (the GEMINI procedure), then put the recipient’s head into a “hypothermia mode” for around 45 minutes between 12°C and 15°C (the HEAVEN process). Canavero belives that such a short time would create virtually no neurological damage. Cut axons would then be reconstituted using molecules such as poly-ethylene glycol (used in areas ranging from industrial manufacturing to pharmaceutical products) or chitosan.

Dr. Canavero has made headlines by using electrical stimulation to awaken a car accident victim who’d been in a persistent vegetative state for two years.

In June of this year, Dr. Jerry Silver of Case Western Reserve Medical School and a team of scientists at Case Western and the Cleveland Clinic successfully restored connectivity in rats whose spinal cords had been completely severed. In the study, the researchers used a chemical that promotes cell growth along with a scar-busting enzyme to create a more hospitable environment for the nerve graft at the injury site.

Although the rats didn’t regain the ability to walk, they recovered a remarkable measure of urinary control, a function that many spinal cord injury patients rank as one of the most important to regain following injury. Canavero argues that such recent advances in reconnective technology give scientists reason to believe the procedure he outlines will be successful in humans. Dr. Silver disagrees.

“It’s light years away from what they’re talking about,” he said. Silver’s research involved single rats, not connecting the spinal cords to heads of other rats. In these experiments, Silver explains, the animals are still able to breath, and their circulation is left intact. “It’s complete fantasy, that you could use [PEG technology] in such a traumatic injury in an adult mammal,” Silver says. “But to severe a head and even contemplate the possibility of gluing axons back properly across the lesion to their neighbors is pure and utter fantasy in my opinion.”

It may be fantasy, but Canavero is hardly the first to look at the possibility of human head transplants.

Vladimir Petrovich Demikhov was a Soviet scientist famous for his experiments in organ transplants during the 30s and 50s. In 1960, he published the first scientific monograph on transplantology, titled “Experimental transplantation of vital organs.” It was a seminal work, starting transplant science as we now know it. He was the first to perform a successful coronary bypass, the first to transplant an auxiliary heart into a warm-blooded animal, and the first to transplant a working heart and lungs into a living animal. But he also transplanted dog heads and upper bodies onto other dogs, effectively creating two-headed dogs.

In 1954 he created the first transplant in a lab on the outskirts of Moscow by grafting the head and forelegs of a smaller dog, Shavka onto a bigger dog, Brodyaga. Both initially survived the procedure and could see and move around independently, but died four days later. None lived for more than 29 days, and they inevitably died because of the tissue rejection. You can see photos from a LIFE magazine article in July, 1959 that documented the surgery. You can also watch video of one of the operations.

Then in 1970 a group of scientists from Case Western Reserve University School of Medicine led by Robert J. White, a neurosurgeon and a professor of neurological surgery inspired by the work of Vladimir Demikhov, transplanted the head of one rhesus monkey onto another’s body. The operation was so successful that once awake, the first transplant subject even tried to bite a doctor. Canavero cites White’s experiment as the first successful primate head transplant, writing that, “The monkey lived 8 days and was, by all accounts, normal, having suffered no complications.” White himself referred to it as a “whole body transplant.” (You can see a two-part interview with Dr. White with some snippets of footage of the operation here and here, and more footage of the surgery here.)

Despite Canavero’s description, Dr. Silver. who was a part of Dr. White’s transplant group, remembers it differently.

“I remember that the head would wake up, the facial expressions looked like terrible pain and confusion and anxiety in the animal. The head will stay alive, but not very long,” the Case Western Reserve University neurologist told CBSNews.com. When doctors attempted to feed the re-connected head, the food fell to the floor. “It was just awful. I don’t think it should ever be done again.”

Even if such a transplant could be done, it would be fraught with ethical issues. Canavero estimates the procedure would cost about $13 million, likely placing such an operation out of the reach of all but the wealthy. He adds that a risk could develop whereby people with adequate funds try to secure the bodies of healthy young individuals on the black market and have them transplanted by dishonest surgeons.

Then there’s the philosophical questions. Dr. Christopher Scott, a bioethicist and regenerative medicine expert at Stanford notes “What is the donor and what’s the recipient? We all have an idea of personhood, right? Of what a person is. You know, a baby or a human becomes a person. And this procedure turns it on its head. Is this a person that the body belongs to, or the person the head belongs to? It’s a chimera, a hybrid person. …Those are some of the deeper questions that we should have a real discussion about.” And what if the body recipient has children? Should we attach a living man’s head to a woman’s body, or vice-versa?

I suspect head transplants will be the fodder of science fiction stories for some time to come.

References

Berko, Lex. Meet the Late Dr. Robert White, Who Transplanted the First Monkey Head. http://motherboard.vice.com/blog/dr-robert-white-transplanted-first-monkey-head. Retrieved 11/15/2013.

Canavero S. HEAVEN: The head anastomosis venture Project outline for the first human head transplantation with spinal linkage (GEMINI). Surg Neurol Int 2013;4, Suppl S1:335-42.

Canavero S., Massa-Micon B., Cauda F., Montanaro, E. Bifocal extradural cortical stimulation-induced recovery of consciousness in the permanent post-traumatic vegetative state. Journal of Neurology, May 2009, Volume 256, Issue 5, pp 834-836.

Elliot, Danielle. Human head transplant is “bad science,” says neuroscientist, CBS News, July 2, 2013 http://www.cbsnews.com/8301-205_162-57591862/

Konstantinov IE. At the cutting edge of the impossible: a tribute to Vladimir P. Demikhov. Tex Heart Inst J 2009;36(5): 453–8.

Langer R.M., Vladimir P. Demikhov, a pioneer of organ transplantation. Transplant Proc. 2011 May;43(4):1221-2. doi: 10.1016.

Lee et al., Nerve Regeneration Restores Supraspinal Control of Bladder Function after Complete Spinal Cord Injury. The Journal of Neuroscience, 26 June 2013, 33(26):10591-10606.

Mangels, John. Cleveland researchers restore bladder control in rats with spinal cord injuries. The Plain Dealer, June 25, 2013. http://www.cleveland.com/science/index.ssf/2013/06/cleveland_researchers_restore.html

Northoff G. Do brain tissue transplants alter personal identity? Inadequacies of some “standard” arguments. J Med Ethics. 1996 Jun;22(3):174–180.