Brain Transplant

[CraigD]

Originally Posted by Deepak Modak

Dr. Robert J. White, now retired, from Cleveland, Ohio has already performed countless successful head transfer experiments on monkeys …

Wow. I consider my self pretty rational and emotionally well-controlled, but found this a bit disturbing.

At first reading, I suspected Deepak, Buckyball, and others were victims or perpetrators of a hoax. Argument’s such as

Originally Posted by UncleAl

A human body is severely tapped keeping one brain alive. Brains have huge exclusively aerobic metabolism and enormous heat production. Getting raw materials in and wastes out is a near thing.

seemed credible to me.

However, it appears White really did transplant the head of a rhesus monkey onto the body of another rhesus (see http://en.wikipedia.org/wiki/Head_tr...tual_instances, attached image.) in 1971, with considerable success – afterwards the monkey was conscious, able to perceive the world, and control the muscles of its head. The monkey survived for “hours”. I’ve found no evidence to suggest that any effort was made to attach the spinal chord nerves, so the monkey could not control the new body, or the body live long without artificial life support. Detailed descriptions of this surgery appear to be difficult to find electronically.

The claim that White performed “countless” such operations appears unfounded – one side describes him as performing “more than 30” such operations, but it is a site supporting bans on medical experimentation on animals that makes several clearly false claims, so I don’t consider it credible.

There’s also good evidence that it’s possible to reduce brain metabolism to levels that would permit a similar operation to be done with a human patient – presumably including an effort to connect enough spinal nerves so that the transplanted head could control the new body, and the heart and lungs operate without artificial assistance.

The people who would most benefit from the development of such a surgery appear to be the quadriplegic victims of severe neck injuries. Such people usually have much shortened lifespans (they rarely live to be 50) due to non-brain organ failure resulting from their injuries. Even if such a surgery could not provide full or even partial use of the donor body limbs, it would permit these people to have more normal lifespans. There is, unfortunately, no shortage of healthy bodies with irreparably injured heads, and the brain (though not necessarily the rest of the tissues of the head) appears to be “immunologically sound” – that is, not prone to attack by the donor body’s immune system.

[Deepak Modak]

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[CraigD]

Originally Posted by CraigD

The people who would most benefit from the development of such a surgery appear to be the quadriplegic victims of severe neck injuries.

Originally Posted by Deepak Modak

Brain transplants can probably also be used for patients with cancer, …

For certain forms of cancer – ones with low probability of metastasizing into brain and spinal tissue - head (or “whole body”) transplants do appear to offer a potentially valuable treatment. If such an operation becomes possible, however, I expect it will be a surgery of last resort, used only after all other cancer treatment options are exhausted.

… people without limbs etc.

I doubt whole body transplants will become a viable limb replacement option. Attaching the patient’s head to the donor body – particularly the spinal cord – appears more difficult than would be attaching a new donor limb, and poses much lower risk of injury to the patient’s brain, or risk of loss of function of their remaining limbs. There’s no reason to expect that head or whole limb transplant recipients would experience greater function than patients who have had severed limbs and appendages reattached. In all cases to date, these patients have experienced significant (sometimes as great at 100%) loss of sensation and mobility of the reattached part. Until reattachment surgery outcomes has reached a state of the art that most patients regain nearly 100% function, I doubt that patients will be willing to give up the perfect function of their remaining limbs in order to replace one or a few lost ones via a whole body transplant.

Note that reattachment surgery has not yet advanced to the point where it can reattach an entire limb. The majority of reattachment surgeries involve severed fingers. There have been a small number of successful hand transplants – see http://www.handtransplant.org

Unless the donor is the patient’s identical twin, both head transplants and whole limb transplants would require the patient to receive immunosuppressant therapy for the rest of their life. Although the brain and spinal cord appear to be “immunological sound”, and are not attacked by the donor body’s immune system, other tissues in the head are not, and would remain at risk or rejection. This is a very daunting prospect, as it equates to the risk of the patients head literally “rotting alive”.

“Quality of life” is always an important consideration when deciding to undertake any major surgery. As a case in point, Clint Hallam, the first hand transplant recipient, was so unhappy with his outcome that he refused to continue taking his immunosuppressant drugs, requiring his hand to be amputated and replace with a prosthesis. Hallam reports that he is much happier with a prosthesis.

Head transplants would introduce many new complications not experience in current organ and limb replacement surgeries. For example, the brain is the source of many important hormones (proteins) that vary importantly in fine structure between individuals. A whole body transplant recipient would likely require life-long hormone replacement therapy of a kind currently unknown to avoid serious endocrine disease.

Originally Posted by Deepak Modak

Actually, the people who would benefit from brain transplantation the most, would be everyone - we would all have a chance to live for ever (until at least the brain itself deteriorates) or for much longer.

Unfortunately, the brain senesces (deteriorates) at about the same rate as other body tissues. Brain tissue is subject to the same major causes of senescence as other tissues (eg: the breakdown of mitochondria due to their activity in metabolism, loss of DNA telomeres). In many functional areas, brains appear so senesce faster than other organs.

The belief that aging and death is accurately described as “a young brain trapped in an aging body” is, I believe, incorrect.

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[billg]

There is no way the technology currently exists to peform successful brain OR head/body transplantations (whatever you want to call it). Currently we cannot even heal damaged spinal cords. Even if nervous tissue can be made to grow, we are only able to control our body by a particular setup of neural links between the brain and spinal cord. Getting the nervous tissue to grow is actually the easy part - getting it to grow in the right way in the right places is currently impossible. You can't just put the brain or head in place and hook it up to the blood and expect it to work. Even assuming you can attach the spinal cord and cranial nerves, it may well be that one brain outputs and inputs CANNOT match a bodies outputs and inputs. You could end up being hooked up in ways that will never actually allow you to perform any useful action.

Also as far as transferring memories from one brain to another, it's again much more complex than what's being proposed in this thread. Aswell as a lifetime of semantic memory (i.e. "facts you know" like 1+1=2, blue is spelled B L U E) and episodic memory (as in "when I was 15 I dated Melinda Bruns for a year"), there is a massive part of the brain devoted to organising sensory information into meaningful things and turning abstract "move arm there" signals into the complex muscle movements that actually allow us to move. There's also huge amounts of information you're not ordinarily even aware you know because it's below the threshold of consciousness, like what certain facial movements or inflections of voice mean. You can't just right the information down and then read it into your new brain.

And finally, whoever this scientist is who did the Rhesus monkey experiment should be imprisoned. A pointless experiment with no medical applications. I think it's profoundly unethical. According to wikipedia he did it once in the 70's, which I can almost understand, but repeated it in 2001. What ethics board allowed that experiment to go ahead? It's insane.