Apr 30 2018

Keeping Brains Alive Outside the Body

Researchers at Yale report (at a meeting – not yet published) that they were able to keep pig brains alive for up to 36 hours after the pigs were decapitated. They acquired the pig head from a slaughterhouse, and experimented on them about 4 hours after death. This research is a long way from an alive “brain in a jar” but it does raise some early ethical questions.

First the technical stuff, with the caveat that the study is not yet published in the peer-reviewed literature so some details are sparse. We know the researchers experimented on pig heads. The report does not say explicitly whether the brains were completely removed from the skulls or not, but they did have access to the brain itself so it was at least exposed if not removed. They attached a series of pumps to the blood vessels and pumped oxygenated blood through them. They also used drugs to prevent the brains from swelling, and the researchers say these drugs would also prevent some brain cell activity (they are channel blockers).

They used brain-surface EEG to record electrical brain activity and – there was none. The pig brains were flat-line. But when they later dissected the brain tissue there was cellular activity for up to 36 hours.

This is clearly a baby step in the direction of maintaining a living brain outside of a body. Four hours after death is a long time, and there would certainly already be a lot of cellular death by that point. If the goal (and this wasn’t their goal) is to maintain a fully functional extracorporeal brain, then it would need to be hooked up to external blood flow within minutes of death, not hours. You can’t just get pig heads from the slaughterhouse.

But there is no theoretical reason why this would not work. If the brains were kept oxygenated throughout the process, and they were hooked up to an external system that fed oxygenated blood with managed CO2 levels and a supply of glucose (basically normal arterial blood), there is no reason why the cells could not survive for a long time. There are likely to be many technical hurdles here, but as a thought experiment it seems plausible.

This research raises several questions – could such a brain be conscious, what us the utility of this research, and what are the ethical implications?

The first question is perhaps the easiest to answer – almost definitely yes. If the brain were fed sufficient oxygen and glucose and was kept in a sufficient metabolic environment, there is no reason why it could not be conscious. Just like we can get a heart to beat outside the body, we could get a brain to be conscious outside the body.

It’s difficult to imagine what that experience would be like, but it would certainly be extreme sensory deprivation, with no sensory input at all. The brain does have a tendency to essentially hallucinate, to make up its own virtual sensory input when it is so completely deprived. So is is interesting to think about what the experience would be like. It is also within the realm of possibility that such a brain would experience intense neuropathic pain. That would not be a good thing.

We could infer the activity of the brain with EEG. If it displayed normal awake electrical activity, it seems reasonable to conclude that the brain is awake. But of course we would have no way of communicating with the brain, so we could not know what the experience is actually like. Communication would require some brain-machine-brain interface, which is theoretically possible but it would be hard to know where to even begin with a disembodied brain.

It’s possible a person could have the brain-machine interface before their brain is removed. They could be trained to operate external devices (robot limbs, computer interface) just with their thoughts. Such an interface could then remain intact after the brain is removed. However, I don’t know how you would train a brain to use such an interface without any preexisting sensory feedback.

What function would this line of research have? The researchers speculate (and this is speculation) that living intact animal brains could be useful for some types of research. That makes sense, although I would like to see some specific protocols. Treatments for neurological diseases could be tested on brains without having to worry about their effects on the rest of the body. Mapping networks in the brain also require a nearly intact brain for those networks that are wide-ranging.  So research applications is a plausible idea, but we would need to explore some specifics.

The application that most people probably think about is keeping a person alive after the death of their body. Perhaps a healthy brain could live for additional decades inside a robot body, for example. Again – there is no theoretically reason why this would not work. However, we are a very long way away from the technology necessary. Just keeping the brain alive and fully functional would be a challenge. But then we would need to interface that brain with sufficient sensory input and motor output, and also deal with any other phenomena that emerge. There are bound to be a few curve balls with such a technology. It’s hard to know what the experience would feel like, and how to fix it if it is extremely negative.

It would also be extremely challenging to develop this technology, because how will we ethically perform the experiments needed to advance the technology prior to the technology being advanced? Even conducting such research on non-human primates would have ethical concerns.

And this brings us to the final question – what are the ethics of this technology. That is a long conversation, but as a starting point I think we can agree on the premise that a living conscious human brain is a human and should be afforded the rights and protections of a human. Right now the law does not accommodate this concept. A brain outside the body is considered tissue, without any rights. But the brain is unique because of its potential to be conscious. It needs special protections.

On that issue, Nature recently published an editorial about the ethics of experimenting on human brain tissue. I think the statement goes a bit far – I am not worried about bits of human neural tissue in a petri dish. But it does recognize the special status of human brains and is a good starting point for developing the relevant ethics and regulations.

We probably don’t have to really worry about any applications of this technology for several decades, but now is precisely the time to start worrying about. We need to anticipate possible ethical considerations, and have the conversation before the prospect of a living brain in a jar becomes a reality.

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