First-ever human head transplant is now possible, says neuroscientist | Hacker News Reader

First-ever human head transplant is now possible, says neuroscientist

qz.com

86 pointsLightning93 comments

This is pretty pie-in-the-sky stuff. Having studied spinal cord anatomy a bit, it seems to me that "full use" of the donor body is absolutely not an option. Cord cross sections are similar on a gross level but when you get down to specific pathways and such, there's huge variation. And you can't just rely on natural mending processes and neural plasticity to make up the difference.

I'm not saying we'll never have something like this, but the "cut the cord and put it on top of the other cord" method described here seems massively, massively naive, like pre-enlightenment level medicine.

Ability to control different parts of the body (assuming there is a connection) seems like it would be more a "software configuration" issue than a "hardware issue" (if such an analogy is at all appropriate).

Are you saying that even if the connection is there, the brain can never learn to utilize it if it doesn't jibe with the way the brain "is"?

The brain has zero software it's 100% hardware.

Basically each neuron in the spine is independent and really long so a local cut breaks connections several feet from the break because the cells die. You can't fix things because unlike fiber optics or cable each side does not line up even in the original person let alone someone else.

It does remap functions as needed however - avoiding damaged areas.

>>The brain has zero software it's 100% hardware.

I'm not sure if we can say this with any level of certainty. If anything, the nature vs. nurture dichotomy could translate directly to hardware vs. software. What nature gives you is hardware, and what you learn is software.

Nope, learning physically changes the brain. For example, learning to juggle will increase certain portions of their brain. [1]

It's like running Crysis, and having your video card's capability increase,

1. http://www.plosone.org/article/info:doi/10.1371/journal.pone...

Yes, and hard drives physically change when they're modified, too.

I think it's more like installing Crysis, and having more of your hard drive devoted to Crysis than before.

Memories are stored in the hippocampus, the changes took place in the occipito-temporal cortex.

I'm not a neuroscientist, but my understanding is that the changes were directly related to processing, not memory.

I'd imagine it's the difference between writing to executable code and writing to data files. It's still just the files inside the hard drives that's changed.

No one knows where memories are "stored," if stored is the proper term. But it is not exclusively in the hippocampus, that much is certain. The hippocampal region is definitely important in the function of memory but it is not where memories are located, and it is doubtful that they are located in any one structure in particular.

Definitely true, but not really responsive to my point.

On one hand, it's good to analogize and metaphorize brain functions with computers. But I think it's also not very wise to bet the whole farm on the whole thing being directly parallel.

>The brain has zero software it's 100% hardware.

Not really. Well, only true in the sense that a PC has zero software, it's 100% hardware, because, after all, a magnetic disk or a SSD is hardware too.

In the brain, the hardware is the software. (Kind of like an FPGA, if I'm not mistaken?) Neural plasticity, which is essentially the extent to which the software can be modified by reforging connections between neurons, has its limitations, both in magnitude and rate. If you cut off someone's hand and put a foot in its place, chances are you could get a little basic functions, but rewriting the area of the motor cortex corresponding to that hand takes a good long time and will likely never be complete.

It's not inconceivable that the brain could successfully send an action potential all the way from the cortex to the tip of the toe in a new body, but the 'rewiring' that would need to take place to make it happen in concert with the million other neurons (and many times that number in connections and networks) necessary for basic control or locomotion is simply not feasible on this scale.

Putting a new finger where an old finger was removed is hard enough, and the brain has enough trouble rewiring itself to make that halfway decent. Rewiring for a whole limb or body, to say nothing of all the viscera, I really just don't see happening without some kind of massive assistance on a nano level, stuff that's sci-fi for now.

Also keep in mind that your brain does not learn the same things at the same age. When your brain first forms and starts operating (< 18 days after conception) it will start learning very fast relations. It learns about the high frequency components of the human body, presumably things like how the electrical signals for a touch look like, or what the carrier signals are for your eye and the like. This also results in very, very fast sleep-wake cycles. When you "wake up from nothingness" so to speak, the cycle is less than a second. By 2-3 months it's about 5 minutes, and as any parent will know and complain about, at birth it's 2-3 hours. Obviously it eventually synchronizes to the sun, but that takes more than a year.

Then as you mature, the myelin sheath starts to grow, which "locks in" the high frequency stuff it's already learned. By the time you're born you've lost the ability to learn about events that takes less than 3-4 ms to complete. By the time you're twenty, it will be at about 50ms. This is why people who start learning a sport at 3-4 years at most effectively have an insurmountable advantage.

This has all sorts of effects that you will recognize in a growing human being. Short-term memory starts using progressively longer frequency signals to store itself. Reaction speed for anything new goes down (reflexes, and trained behaviors learned earlier stay in force though). Your ability to reason about things far away massively increases (a 4 year old kid cannot plan more than 20 minutes or so ahead without adult help, which mostly consists of reminding them what they were doing every 10 minutes or so).

Furthermore the way your brain compresses signals is by distributing itself. There are small parts of your brain everywhere in your body, and several big blobs in your head. Every muscle has a cluster of neurons on it, and things like the heart, bigger muscles (like stomach muscles, biceps, triceps, ...) have large clusters on them. Those are clusters that do the same learning process as the rest of your brain, they're not preprogrammed. So your brain does not directly control your body, it negotiates what should be done with those local clusters. Because of this your body is able to have very short feedback loops controlling your muscles despite the fact that the decision process itself takes tens of milliseconds (and happens 1-2 meters away from the actual muscle). Now these clusters start out as blank as the rest of your brain, but they grow together, and they learn to communicate together. Different people send signals differently (well, the basic structure of the signal is the same, the semantic meaning, such as which muscle it affects, what timeframe it's talking about, ... is not). This is why if you connect a robot arm to a human, they cannot use it for fine motor control, even after months of practice, it improves to a pretty pathetic level, and just doesn't improve further (certainly not enough to write at normal size with it). If you want to be pedantic, there is more than one level of indirection. The first is the "brain region" -> spinal cord interface, and then every 15 cm or so in your spinal cord is another layer of control, and every point where neurons split up is another control point.

Here's a rather basic introduction : http://en.wikipedia.org/wiki/Motor_control#Sensorimotor_feed...

All this means that your brain's lower level body control is effectively a ROM by the time you've grown up, and it is very dependant on tiny variations in the length of neurons to various parts of your body. Every single human body has a custom protocol for controlling the muscles that's different from everyone else's (so it's not possible, like in the movies, to mount something on the spinal column and take over motor control). Connecting up a brain to a new body, assuming you can keep it stable until the person wakes up, will immediately lead to a seizure (because the brain will be sending wrong signals to the heart), extremely rapid breathing, violent convulsions, ... until the patient is dead.

I don't think much of what you said is fact. Most of it reads as nonsense to me, or at best a misinterpretation of the facts.

I wonder if the nerve subsystem is generic at all. My bet is that genetic differences, life experiences and brain storage~ will be far too coupled for connecting two different bodies and expecting it too work. But I just remembered that there has been successful hand transplants so I'll just take the door.

My sister has a brain tumor. They attempted to surgically remove the tumor, it rests at the base cerebellum, where it meets the spinal cord.

In order to do this surgery, they had to cut a piece of her spine and in the process cut some nerve pathways. Post surgery, she still has trouble walking and other general motor skills. The brain is the software and hardware, any changes to it will alter its software.

And you can't just rely on natural mending processes and neural plasticity to make up the difference.

I wonder about that. I can see healing and plasticity going a very long way over time, but intuition is telling me there's not enough plasticity in the wiring of critical autonomic functions.

It goes pretty far, and it is amazing, but the limitations are real and are encountered even on seemingly "simple" transplants like a finger. Critical autonomic functions, actually, may work fine, because they are more self-contained - the heart regulates itself, the gut in many ways as well, and many actions like breathing and basic drives are, to my knowledge, rather "standardized" between humans in the lower part of the brain. That's why we all have similar reactions to touching something hot or sharp, being hungry, out of breath, etc.

Did you get down voted for voicing an opinion about a non-political, scientific topic? Only among nerds...

smosher got downvoted because intuition is not helpful here. We can sit around and talk about what we feel might be an answer, but if we don't have any information, it's just random noise.

I have a good bit of information about neurology, and that's exactly what my intuition draws from. I am extremely thankful I don't have the attitude you're endorsing.

This guy is a neuroscientist so presumably he has given this question some thought and I would imagine he too has 'studied spinal cord anatomy a bit.'

There are plenty of crazy doctors out there who make nutzo claims not backed up by evidence in their field. One neuroscientist chosen at random is probably reasonable and competent, but a neuroscientist chosen conditional on publishing an astounding claim that isn't shared by any of his colleagues is almost certain to be cray.

Good point. I imagine the spinal cross connecting step would have to be preceded by some careful electrical probing and labeling of which spinal pathways are connected to which nerve endings.

Yes, but unfortunately our microelectrodes are nowhere near good enough for this kind of thing. The bleeding edge is the arrays being implanted in retinas and visual cortex for prosthetic vision, and they're like a couple orders of magnitude too bulky and imprecise to be effective.

As a person who had retinal detachment and ended up being blind in one eye, this is what I'm hoping for within about ten years. A way to get to my depth perception back would be great.

Crazy. I don't think we as a society have even gotten used to the implications of face transplants.

My prediction: we'll be arguing for a long time whether this is a head transplant or a body transplant...at least in Philosophy 101 courses.

No, it's a head transplant. The head is part of the body. There is nothing metaphysical about a head. That's not where the philosophical language problems come into play. The problems start when you talk about WHO the combinated person is.

Right...but the head is sometimes considered to be the center of someone's identity...case in point, brain death is often considered to be the standard of actual death.

So if I find my head atop a different body...why shouldn't I label it as a body transplant? For those currently in cryogenic cranial freeze and who successfully are revived, would we not think of them as having new bodies, rather than the bodies having new heads?

Because "head transplant" is more fun to say. It's a self-deprecating joke to say "I need a head transplant". https://twitter.com/search/realtime?q=%22I%20need%20a%20head...

It probably is incorrect, though, as a head transplant would mean that the head would be assuming the identity of the person carrying the body. While amusing it seems a lot to ask of the person with the head.

Edit: even more people say "I need a brain transplant" https://twitter.com/search/realtime?q=%22I%20need%20a%20brai...

If you were diagnosed with brain cancer, would you be pleased if you were offered a head transplant as a cure?

No, you would not.

Now if you had terminal cancer spread all over your body, would you accept a body transplant as a treatment option?

It's a body transplant.

So you install a motherboard into a processor?

If you feel your identity is as trivial and interchangeable as a computer's CPU, be my guest. I don't think you'll get the result you're looking for.

You were arguing semantics, so was I.

We do now know nearly enough about the brain to understand what "identity" is for us to speculate on whether a brain transplant would mean losing part of it, let alone actually perform a successful brain transplant in a human.

http://lesswrong.com/lw/kj/no_one_knows_what_science_doesnt_...

I'm rather certain that we know enough about brains to confindently say that all the higher functions of the central nervous system quite definitely reside in the brain, and specifically in the neocortex, not in the spinal cord or anywhere else.

There is a reason I said "identity" with the quotes, not higher functions. I have no doubt a well funded enough project can transplant a human brain into a different body and "weld" the nervous systems to restore basic cognitive and motor functions in the next few decades.

What I mean by identity is an understanding of how "you" as a person are formed by phenomena emerging from very complex biological system. For example, I have a very bad feeling in my stomach when I do something I am ashamed of. I'm 99% certain that the neurons in my stomach have little to do with this feeling and it's "all in my head," but we really know for certain how our brain chemistry, our mood, our reactions are shaped by the chemical and hormonal functions of the rest of the body? You are, afterall, combining two separate genetic lines, is there no possibility for a neural rejection like graft-versus-host?

I will grant that transplants get us into weird territory. It was just in the last decade or so when the first larynx transplant was done did we learn that the recipient has his original voice restored and doesn't gain that of the donor's. The outcome was really in question at the time.

Perhaps the new body does feed back some changes into the brain, but overall we still have a cortex with the original memories, etc as a starting point.

And weird territory is what humanity is all about :)

Do you have a link to the larynx transplant paper? That sounds fascinating. I was actually more thinking about very understood practical lines like I know my personality is drastically different (according to friends) on certain medications. With the role even common hormones like testosterone have and the various feedback loops that could come down to the genetics of body cell lines, I can't imagine a person's personality not changing, at least in a time/environment dependent way. Seasonal depressive disorders come to mind, as those seem to have partially somatic causes.

Another interesting question is to what degree does the body (i.e. muscle memory) assist or modify how memories are "pulled up" and processed? Perhaps there will be random unavoidable "corruptions" in the fusing process that result in the signals for stimuli changing (i.e. sensitivity to heat and cold is probably somatic) and the brain pulling up inappropriate emotions or responses?

Is it still your identity if chemical mismatches change your interpretation of your memories over the long term or are you now a hybrid that, due to the transplant, has the extreme fortune of experiencing life and even epistemology in an entirely different way?

What I'm saying is that the head is an element in the set of parts called the body. The head is a body part. It isn't separate from the body, it is intertwined with it. Identity isn't totally centered in the brain (at least from what we can tell so far).

I am my brain. That is most of what I am.

If my brain gets seated onto a new body, you could say that my head was transplanted onto the new body, but it would be inaccurate to say that I received a head transplant.

That's a bold assumption. You don't really know how much of your personality is based on reactions from your gut (spleen, heart, etc).

People have had just about all major organs south of the brain replaced individually by either machines or biological transplants. (Can anyone identify one that hasn't?) And I don't think anyone's ever seriously claimed that such people have had their identity changed in any meaningful sense. Unless you have a very complicated hypothesis about multiple organs in the abdomen effecting personality in a weird redundant way--where losing one of them doesn't change your identity but loosing many does--the evidence is overwhelming that everything we think of as "identity" is in the brain.

Of course various hormones change personality traits, and many of those are governed or heeded below the neck. Trivially, testosterone.

I think you underestimate the effect body changes can have on one's identity. "identity change due to trauma" will find you plenty to think about, for example http://www.centerforpos.org/Positive/POS-Research/Papers/Pap... "Matthew, a professional ‘cellist, damaged two tendons in his shoulder. […] he felt “a kind of total emptiness and utter exhaustion that really was literally sapping my will to live.” At the centre of this emptiness lay the question, “Who am I now?""

http://biomed.brown.edu/Courses/BI108/BI108_2003_Groups/Hand...: "In addition, assessments should be made of their body-image adaptation after amputation, impact of amputation on their identity and relationships"

http://www.athealth.com/consumer/disorders/traumaeffects.htm...: "Survivors may have problems with identity when PTSD symptoms change important aspects of a person's life such as relationships or whether the person can do his or her work well."

http://www.nbmtlink.org/resources_support/spg/spg_appearance...: "Every time I look in the mirror, I see someone different than the person I knew during my life before transplant."

Is all of that in the brain? In some sense: yes, but bodily changes do change how you think about yourself, and that is one definition/aspect of 'personality' (http://en.wikipedia.org/wiki/Identity#Personal_conception_an...)

All of these effects are smaller and of the same type as you might get from life events (like PTSD, or divorce). But that doesn't mean that "you are your marriage" in anything like the same sense as "you are your brain".

I don't disagree, and I'm excited about these new developments - but continuity-of-consciousness would continue even if I had my bowel ripped out. This is not the case if I had my brain ripped out.

On the other hand, people with radical brain surgery still think they're the same person, putting aside cases like Phineas Gage.

On the gripping hand, even though transferring my brain and its shell to a different body will still maintain my memories, and continuation-of-consciousness and transferring everything neck-down won't, if the person with my guts-and-spleen acts more like me, and the person with my head on their shoulders acts more like the guy whose anus it's attached to acts more like them, perhaps it could be said that we really did switch, despite the memories.

I dunno, try reading Machine Man by Max Barry. The protagonist would only partially agree.

If calling it a body transplant bothers you because you don't think the definition of body works with that, then call it a "torso and limb transplant" or something. "head transplant" is absurd.

What problems? If it's Frank's head then after the operation you still have Frank.

Worry about identity when someone invents a partial brain transplant or something crazy like that.

That depends. If you're grafting Frank's head onto Mr Stein's body, you get...

Well. Moving right along.

>If it's Frank's head then after the operation you still have Frank.

according to police database of fingerprints - not, according to DNA - depends of where it is sampled from and even after that - what would be a DNA say in saliva, blood?

Can't you already screw up DNA testing with a marrow transplant? And fingerprints can change too.

It's not a head transplant, it's a body transplant.

I imagine it'll be easier eventually to simply move the head to an android body.

One benefit of this is avoiding many sources of cancer, since there would be a whole lot less cell-machinery to go wrong. To me, this seems like the most obvious (though drastic) means of life-extension.

What would we do with all the spare android heads then? :P

Put them back on our abandoned human bodies so as to allow the machines to fully integrate and understand the human experience as a defense against them misunderstanding our collective craziness and rising up to destroy us. :)

I agree. This is way, way more likely than human transplants, for a dozen reasons. And to be honest, it could be done in a few years. Moving around using the body would be relatively easily accomplished but expression via tapping the spinal cord... not so easy.

Sounds like Avatar B to me!

http://2045.com/

I wonder how to deal with the issue of nutrition and digestion (some sort of synthetic digestive system?), which would be necessary to sustain the brain. Also, how would the head perceive hunger and thirst?

Previous HN Discussion: https://news.ycombinator.com/item?id=5956301 And the technical details: http://www.surgicalneurologyint.com/article.asp?issn=2152-78...

this seems to be thought experiment on throwing together of the old experiment on monkey head transplanting technicalities and the recent discoveries about PEG and some other compounds stopping the typical inflamation process that makes spine cord cuts into unrestorable connection breaks.

That begs a question - why wouldn't before head transplant we'd try to transplant a piece of spine (one or few vertebrae) with a cord to the people with traumatic damages of the spine (like bullet or some sport injuries)?

You just have identified the primary reason why this entire head transplant thing is badly thought-out fiction right there: we haven't mastered reconnecting nerves yet. At least not reliably and not on that scale.

Hasn't it been shown that the body, especially the gastrointestinal system, has a huge effect on cognitive function? I wonder if a procedure like this is possible without dramatically changing the personality of the subject.

Has it? I have never seen anything to that effect. Do you have any reading on the subject?

It certainly can affect your moods and drives, but it's feedback, not origination. If such a procedure were in fact carried out successfully (and I have grave doubts about that) the person may certainly have different habits when it comes to eating, tiring, and so on, but they wouldn't suddenly start liking spicy food or jazz.

Well... there are a couple of reports of heart transplants suddenly changing one taste for soccer team so... I am not so sure about that.

I guess it might relate to hormonal response or something.

Here's the only important sentence:

Connection of a spinal cord from the head of one creature to the body of another has never been attempted even in animals, so Canavero’s paper must be taken as an exercise in speculation.

Not quite ever it's been done with dogs.

https://www.youtube.com/watch?v=lICXAFFxWgk

edit: I guess that's part 1 of the procedure, there is another video of the transplant. There are pictures of it too https://www.google.com/search?q=russian+soviet+transplant+do...

Has anyone sat down and tried to itemise all the taboos this would break?

I don't consider myself especially squeamish, bit this concept creeps the hell out of me!

I don't see why it should be an issue in a world where we already do transplants. It is just more of the same, an iteration, albeit a very impressive advance.

Are you creeped out by the idea of an arm transplant?

Was there no resistance to the first organ transplants ? I bet many people weren't willing to allow it or even benefit from it.

Heart transplants caused a lot of upset at first, because folk beliefs about the heart as the seat of the soul still lingered.

Here's a short story on a similar subject, the ethics of a brain transplant. Won a Hugo in 1973. http://docs7.chomikuj.pl/1852561988,PL,0,0,Frederik-Pohl---T... Ignore the first 2 paragraphs. Its the end of an introduction by Issac Asimov from an anthology of Hugo winners.

Some people appear to be trying to use rational arguments to persuade me that I shouldn't feel creeped out.

You'll fail. Rational arguments reach an entirely different part of my brain.

Please try this on a monkey first. Show me a monkey with a transplanted head and we'll talk.

http://vimeo.com/20230127

Sweet I'm putting my head onto a baby's body next week I'll totally own the other kids in chess club this time through school!

I'm no bioethicist, but there seem to be several ethical problems with your plan.

https://www.youtube.com/watch?v=KDqh-r8TQgs

https://en.wikipedia.org/wiki/Experiments_in_the_Revival_of_...

This could be the way to go in the future if you have any major incurable trouble, so long as it's below the neckline... it's a whole new spin on attaining immortality. Of course, heads too must die some day, but this certainly would push your runway out quite a bit.

There is a related video http://vimeo.com/20230127 (14min) with an interview of Robert White and some footage of animals head transplants in the 70s.

How would you like to be the guy on the waiting list who gets the call?

"Mr. Doe, we have a suitable donor. Be at the hospital in 30 minutes so we can decapitate you before this corpse goes bad."

Nit: isn't "first-ever" kind of redundant, since "now possible" necessarily implies it wasn't possible before?

Gives new meaning to brushing your teeth.

Now we need to figure out how to grow bodies with no brains.

All I can think is this is one step closer to Futurama's Head in a Jar. ;)

Shouldn't this be called "body transplantation", instead?

I wonder what kind of quality of life the new body would provide.

"The Head of Professor Dowell" vs. reality ;)

AT a $13 million dollar cost, that's a barrier to entry... I'll take SuperMan's body please...

http://www.tv.com/shows/lois-and-clark-the-new-adventures-of...

Reply on news.ycombinator.com