Cryonics and the importance of body to cognition

No idea about what's raised in the standard literature.

For practical purposes, the key question here is not how important the non-brain body is to cognition, but how much of the variation among individuals is explained by differences in bodies vs. differences in brains.

If the variation due to body differences is sufficiently negligible, then the "personality extraction" process can be done with just the brain, and uploaded into a standard body (whether biological or mechanical or digital or energetic or what-have-you), and the resulting person will be a "close enough" match to the original.

If not, then the resulting person won't be a close enough match.

Personally, I suspect that most people vastly overestimate the precision-of-duplication required to be a close enough match for practical purposes. I suspect the differences in cognition caused by the loss of original somatic context will be swamped by, for example, the differences caused by the original social context.

Of course, if one wants to drop the practical stance and instead ask metaphysical questions about whether it's "really the same person" without the original body, then different issues are salient... of course, that's true even with the original body. I have trouble seeing the point of that, though.

I'm not an expert on cryonics, but it seems obvious to me that simulating the body (to the level of detail needed to support cognition) is orders of magnitude easier than simulating the brain. Do you think a more substantial response than this is needed?

I agree that the state of one's body changes cognition quite a bit. Still, if someone becomes a quadriplegic or acquires locked-in syndrome, we don't consider them to be dead or a different person. And compared to extracting a mind from a cryopreserved brain, rebuilding a (simulated or real) body from memories and DNA isn't that hard.

If people are given a chance of either dying or having an arm amputated and replaced with a high-quality prosthetic limb, I'm having a great deal of trouble imagining people who will choose death, all else being equal.

If the question is between losing all four limbs and death, it becomes a bit trickier. Being a quadruple amputee is a big drop in quality of life with current prosthetic technology, and if no prosthetics whatsoever are going to be available, people might justifiably choose death instead. But we already have good enough prosthetics for the below the knee/elbow case that I wouldn't hesitate to take the amputation then, and it shouldn't take unimaginable technology to provide reasonably good complete limb prostheses.

I imagine most people haven't worked through such an extrapolation into the case of a brain in an entire prosthetic body. Will they still keep the aversive intuition if they do?

I think the DNA of the neurons is very important. The production of hormones e.g. is of course very relevant for character of a person. This is definitely not stored in the connectome. Hormones are created in the brain and different organs of the body.

The production of neurotransmitter depends on genes too and is therefore not represented by the connectome alone.

We should assume that the character of a person would change a lot if the body is exchanged. On the other hand, memory and knowledge could still be very similar.

I recall thinking about this as a possible objection to whole brain emulation in general – specifically in the context of a Hansonian singularity.

Strangely, I've never seen a response. It seems as if transhumanist folks and embodied cognition folks don't interact much with each other.

I would be very surprised if information in the brain were insufficient to reconstruct a (simulation of a) subjectively indistinguishable body. (You also have genetic information, but the brain should be sufficient.)

I thought the point of Lakoff et al. was that cognition is shaped by genetically encoded and/or learned physiological metaphors, not that the body plays much of an active role in cognition, let alone that it stores enough long-term state that its loss would be a severe problem for cryonics. The existence of mentally normal quadruplegics falsifies strong forms of the latter claim, though I have heard claims that paralysis dulls emotion.

Oh, here I thought this was going to be about glial cells. But I suppose if you freeze the head, and can already do neural reconstruction, that shouldn't be a much harder problem. This also possibly falls under TheOtherDave's point.

If you change the sensory equipment you change the person. Blinding, othe handicaps do that, but you can also tack on new sensory. Like a compass. But is not that still better than not being?

It would be awesome to stay alive, even if the body needs a make over.

without a body the brain won't 'work', the brain is very much linked to the rest of the body, the fiction that we only need the head to 'reanimate' a person back to normal is just that, fiction.

wei Dai:"rebuilding/simulating the body to the level of detail needed to support cognition" yes,but how complex is the nervous system? which wire connects to which, or is that not important? seems to me that you're oversimplifying..

I haven't seen it raised as a "standard" objection, but it has occurred to me quite a few times as a problem with the head-only approach.