Q&A: Can We Preserve Our Brains After Death?

brain comp chip SS

As promised, here’s the first-ever official Connectome Q&A! We’ve been getting lots of incoming questions on our Facebook and Twitter pages – some of them on the technical side; others of the more “general interest” variety. Most of these questions require pretty involved answers – and it’s important to me that each of them gets the full treatment it deserves.

So for today’s Q&A, I’ve decided to focus on just one question. That doesn’t mean we’ve forgotten the others, though – we keep everything archived, and we’ll be doing plenty more Q&As in the future. So keep sending those neuroscience queries and article requests our way.

And now, let’s get into today’s question!     —Ben

 

Q. “What is the best current method to preserve a connectome or whole brain – cryonics, vitrification, chemical brain preservation or something else?”     Ivan Smirnov, via Facebook

 

A. There are actually two different questions here: 1) “What’s the best way to preserve a brain?” and 2) “What’s the best way to preserve all the information in a brain?” There’s also a third question that’s sorta implied by the first two: “Is it possible to preserve a person’s ‘self’ by preserving that person’s connectome?” Let’s take these questions one-by-one.

When it comes to preserving brain tissue, the most successful and widely used technique available today is cryopreservation: cooling a brain to sub-zero temperatures, which stops all biological processes. Techniques like slow programmable freezing (SPF), along with cryoprotectant chemicals, can protect cells from being damaged by freezing. In fact, laboratories around the world use CPF and cryoprotectants to preserve living cells and organs – and even whole animals – for later resurrection.

A technique that shows some promise for the near future is neurovitrification, which transforms the water in living neural issue into a glass-like solid, allowing cells to be frozen with minimal damage. Though vitrification preserves many organs quite well, we’re still years away from being able to freeze and resurrect a mammalian brain – let alone a human one. In theory, a perfected neurovitrification technique would preserve living neurons right down to the molecular level, locking every atom of every synapse in place.

That kind of lockdown would be crucial for preserving and resurrecting a brain, because most information in the brain is stored not in physical connections, but in electrochemical communication networks that shift and morph from moment to moment. Keeping those synaptic molecules in place would be the only way to resurrect a brain without “wiping its hard drive.” For the same reason, it’d be vital (no pun intended) to preserve a brain before its owner had died; once those neurons have stopped firing, most of the brain’s stored information is lost forever.

Early brain preservation experiments didn’t always go as planned. (image credit: kosy790am.com)

This brings us to another approach: preserving the information encoded in a brain’s connectome. The idea here is that if we can understand precisely how the brain encodes various kinds of information, we could record and save a digital “copy” of its connectome – perhaps without having to map the location of every molecule in every synapse – and, helpfully, without having to freeze a living person (possibly ending his/her life and thus defeating the whole point).

To understand how a connectome does what it does, efforts like the Human Connectome Project, the Whole Brain Catalog and the Open Connectome Project aim to produce functional simulations of brain activity at all scales. Before we can build a digital copy of a connectome, we need to understand exactly what needs to be copied, and how it’s supposed to work.

Connectome naysayers claim that even this won’t be enough. They draw comparisons between the Human Connectome Project and its earlier cousin, the Human Genome Project (HGP). Although the HGP has led to plenty of breakthroughs, we’re still a long way from understanding what most of our genes actually do. And whereas a human genome has about 3,000,000,000 (3 billion) base pairs, a human connectome may involve as many as 100,000,000,000,000 (one hundred trillion) synaptic connections – all of them constantly transforming and exchanging information with their neighbors. At the very least, we’re going to need some major innovations in computing power, and a vastly expanded program of data-gathering, before we can simulate an entire human connectome at the synaptic level.

Of course, none of this tells us anything about whether preserving a person’s connectome or brain – even flawlessly – will preserve that person’s mind/self/individuality. Sebastian Seung, one of the big brains behind the Human Connectome Project, has called the question of immortality “the only truly interesting problem in science and technology.”

We know that some animals, such as frogs and salamanders, can be frozen for long periods, thawed, and awakened to keep going about their amphibian business. So far, though, no one’s been able to do this with a mammal – so it’s unclear whether it’d be possible to resurrect your dog or cat, spunky personality and all. (Unsurprisingly, that hasn’t stopped wealthy pet owners from putting Rover on ice just in case.)

As with the connectome mapping projects, the problem with preserving a personality is that no one knows exactly what needs to be preserved: living nerve cells, positions of neurotransmitter molecules, and/or certain kinds of neurochemically encoded data might all be necessary pieces of the puzzle.

In other words, what works for frogs and salamanders may or may not work for mammals like us. It’s unclear whether what we call a “self” is correlated with stable body temperature, or even with a cerebral cortex – for example, there’s some evidence that octopi may have a form of self-awareness, and they’re ectothermic and have very different neural wiring from vertebrates.

It’s also very unlikely that one day in vertebrate evolution, the “self” just popped into being – more likely, self-awareness arose gradually out of the interactions among many self-referential circuits of brain activity; the same goes for personalities, emotions, hopes, fears, and all the other vaguely defined ghosts that haunt our machinery.

What this implies is that the processes of understanding, disassembling and reverse-engineering the “self” are going to be very gradual ones. It’s likely that we’ll spend decades studying correlations between neural activity and subjective experience before we understand exactly how they correlate – which means that for the foreseeable future, the only one who’ll know for certain whether a resurrected brain contains “the true-blue you” will be …well… you.

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2 Responses to “Q&A: Can We Preserve Our Brains After Death?”

  1. Luke Parrish says:

    This article makes a good effort but distorts a key point of cryonics, which is that if the connectome is sufficient (or the connectome plus some additional biochemical data that remains present in the brain) we probably *can* get people back from a vitrified state who happen to currently be regarded as “dead” by contemporary clinical criteria. This is because “most of the brain’s information” which is being lost in that case is meaningless noise.

    I’m not sure where you got the idea that it is realistic to get a connectome from a still-living person (which is what it sounds like you are saying). To get a viable connectome, you would almost certainly need to cool and perfuse the person, arrest their metabolism completely, and bring them to a vitreous (or worse — fixed) state, before it becomes realistic to map out their connectome in any detail.

    However I do see what you are going for in distinguishing different types of preservation. It’s a noble goal to break it down, but vastly more complicated than anyone seems to think it is. Here are the layers as I see them (sorted by tech/progress level):

    1) Contemporary cryonics under currently realistic conditions — patients must be already dead by clinical criteria (implying heavy neural damage from the agonal phase of death unless this is a fresh case of cardiac arrest). May not constitute true (information-theoretic) death because we are uncertain about the role that future technology can expand to fill in this regard. It may be that dying of Alzheimer’s with a long painful dying phase is not too bad for future science to sort out. Even so, agonal death can cause perfusion impairment which can make perfusion pointless in individual cases. Out of practical necessity, this kind of cryonics plays the role of mortician in contemporary society, however it does not see itself that way but rather as a life-saving endeavor with uncertain results.
    2) “Best possible case” contemporary tech cryonics — controlled deanimation in a specialized clinical setting designed to optimize the conservation of information by measurable metrics like perfusion quality, cooling rates, etc. Only likely to be legally practicible in jurisdictions where assisted suicide is already allowed, but technically falls under the category of life-preserving medicine (in intent, irrespective of results, which would still be uncertain — though more likely to work than in #1).
    3) Relatively advanced tech cryonics where the brain is routinely preserved with no discernible structural or biochemical damage. Mammalian brains examined under similar conditions could perhaps be demonstrated to retain memories and personality traits by dissection and connectome analysis. Most scientists (in an ideal world where scientists are apolitical) would consider this a valid medical procedure to save the lives of the terminally ill. The endorsement of scientists on the matter may or may not be enough to get it legalized as a permortem/medical treatment in many jurisdictions.
    4) True “suspended animation” where patients can demonstrably be preserved and brought back with minimal damage levels. I would expect in the early phases for this to be a very rough process involving “hardening” the body beforehand with complex and invasive pretreatments like heat conductive (e.g. carbon nanotube) implants, and gene therapies to guard against chilling injury. Gene therapy could also be used to introduce nonpenetrating cryoprotectants like the sugar trehalose directly into the neurons. This is decades away, but not outside the realm of what we know to be possible.
    5) Very good suspended animation which reliably preserves the whole body and does not require substantial gene therapy and difficult surgery. This is more the theoretical realm and includes speculative things like embedding the tissue in special polymers that form a room temperature glass but can be dissolved with a not-too-toxic solvent, or using special field effects to wick away the heat very quickly and thus achieve “kinetic” vitrification without requiring toxic cryoprotectants.

    Even this description still blurs some important distinctions. For example, between the third and fourth levels there are points where animal trials work but human trials don’t. Also, we could consider that human brains might be brought back to consciousness in controlled environments, making #3 equivalent in some respects to #4 and #5. Furthermore, there are scan/digital upload based scenarios which some consider more likely/lower tech than #4.

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