What would be required to allow a human brain to function for thousands of years?

Question

Could a human brain be kept functioning (thinking, alive, etc.) for thousands of years by use of some sort of machine or technology by the machine preserving the brain? What would such a machine have to do in order to prevent the brain from deteriorating over time?

Some parameters:

• It can be put to sleep to help preserve it at times. Perhaps a hibernation type of sleep.
• It has to preserve all of the brain’s functionality, not just some of it.
• It can be converted into a computer brain so long as it doesn’t replace the original person with a new person (it has to preserve everything about the person’s brain that makes them the person that they are).

Answer 1

Sure, it's easy

To make it a little bit of a challenge, let's not say "nanites."

First of all you've got to deal with the effects of aging: shortened telomeres, cancers, natural loss of neurons and connections, buildup of damaging molecules such as lead or prions.

Many of these things can be done if you assume you can genetically edit the human as an embryo, so the changes spread to all the cells in the brain. The problem of shortening telomeres in particular can be solved by this method. (In fact, cancers solve this problem by chance all the time!)

Naturally, if you genetically engineer a person so their telomeres don't get shorter, they're going to get a lot more cancers. More genetic engineering for a stronger cancer-fighting immune system would help for solving this. You would also want active monitoring: place the brain in some sort of advanced scanner that regularly scans the brain at high resolution and detects cancers as they are just forming. Couple this with some highly advanced cancer-fighting technology. Perhaps the technology involves sampling the cancer with a needle and rapidly and automatically developing a vaccine from the sample, so the immune system can fight it naturally. Perhaps the technology involves using magnetic fields to very precisely maneuver tiny capsules full of chemotherapy drugs through the bloodstream to where the nascent cancer is. Perhaps the technology involves rapidly analyzing cancer samples and synthesizing a custom drug that binds only and exactly to the mutant cancer cells. A combination of methods would work better than any one alone.

Next you need to solve the problem of the natural loss of neurons and synapses that occurs over time. Genetic engineering would again be your go-to; you'd need to engineer the brain so that it gradually replaces the lost neurons with new ones. You could supplement this by injecting stem cells exactly where they are needed, so they could grow into new neural tissue.

The gradual buildup of prions and other damaging molecules is a tough one. Genetic engineering, of course, could provide the brain with better self-cleaning abilities. Custom drugs could be used to bind to the damaging molecules and break them down. But gunk has a way of building up in nooks and crannies, of which the brain has a whole lot. Perhaps the only way to solve this in the long term would be to continually replace small portions of the brain: periodically just suction out a cubic millimeter of brain tissue, gunk and all, and plant some new stem cells there. Over a hundred years the whole brain would be replaced, bit by bit, and the gunk older than that would be cleared away.

And done, now your brain doesn't physically age! All that's left is the psychology of living a thousand years.

How about the buildup of excess memories, to the point the brain cannot function? Already solved! As the brain gets replaced one cubic millimeter at a time, old, undesired memories go with it, unless they are important enough memories to be frequently refreshed and rebuilt.

Now how do you stop the brain from going crazy from ennui over the centuries? You've got to somehow keep refreshing its sense of childlike wonder and joy. A few gentle shocks from implanted electrodes to the right brain regions twice a day ought to cover it.

Easy!

Answer 2

It's very hard for human brains stored in what is the state of the art containment vessel, vulgarly called human body, to be kept fully functional for 100 years.

Dementia, various diseases, slowing of reflexes, ageing, all take a toll on the brain functionality, progressively making it working worse and worse.

Whatever might do what you ask, is going to be doing much more than simply supplying the brain with nutrients and stimuli and removing wastes. It has to manage somehow to contrast ageing, via what as of today can be only called magic, intended in the Clarkean sense.

Answer 3

Cryostasis

Slow and controlled freezing (to avoid ice crystal formation leading to cell death) has been considered plausible in science fiction for generations. It may or may not really be possible for an adult human, or for hundreds of years, but it seems to work ok for bugs and many organisms of a few cells or less over time spans of a few years, it doesn't contradict anything we know about science, and it uses principles that are well understood, which makes it good enough for realistic science fiction. It was probably most famously used in Futurama to get Fry to the future.

Special Relativity

If you have a sufficiently outrageous power supply, an outrageous pile of reaction mass, and a really good shield to keep from being sandblasted out of existence by interstellar space dust, you can keep a human alive for their 100 years or so of life in their frame while a thousand years go by at home. Boost the traveler into frame with a relative velocity near the speed of light, then turn around and boost them into another frame with the opposite relative velocity, then turn around a third time and boost them back into the home base frame for a nice soft landing. This is the Twin Paradox. It would absolutely, positively work... if you had a space ship that could do it, which is probably a fantasy. It was used in Speaker for the Dead to get Ender Wiggin to the future.

Answer 4

First, you will need to keep the brain in an apparatus that keep it constantly well-nourished, oxygenated and also removes wastes from the outside environment. Most people die when this fails, since a failure, a trauma or a disease in the lungs, heart, kidneys, liver, intestines, infections, etc. can lead to improper nourishment and oxygenation in the brain or to the build-up of dangerous levels of toxic substances inside it.

Also, the apparatus should keep the brain well-protected from the outside environment, preventing head injuries, head traumas, gunshots, concussions, infections and entrance of toxins.

There is still the problem from diseases in the brain itself, like cancer, dementia, alzheimer and stroke. Cancers and strokes could be prevented if the brain is constantly scanned by the apparatus and is able to perform precise micro-brain surgeries when something wrong is detected.

About dementia and alzheimer, possibly a steam-cell therapy could be used to replace lost areas of the brain with new neurons and glial cells.

A bad side-effect could be that as the old brain has its life prolonged indefinitely and parts of it are continuously being replaced, when it reaches the age of, let's say, 600, it is likely that > 99.9% already have been replaced and the person would probably not remember anything from before the implantation, it will say:

"After so many centuries, I can't recall how my father or my mother were other than through photos or videos, I don't remember my infancy, nor my teen years, nor when my children born, it was a so long time ago that it was simply lost to the time. I simply can't remember anything anymore from before my brain was inserted into this apparatus centuries ago and even for some time after that. The best that I can do now is to ask the computer to give me those very old information. However, in the past, I could recall all those things, even for many years after being inserted here. Well, this is the price to pay, otherwise, I wouldn't live those centuries and I would be dead instead. And I surely lived good centuries and still want to live some more centuries for sure".

Further, in this apparatus, since the brain is not limited anymore by the size of the skull nor by its energetic needs, you could make it grow larger and possible much more intelligent by strategically implanting steam-cells or even mature neurons and glial cells. But, nobody knows yet for sure how to do this right. Do it wrongly and those cells will either do no useful job at all or they will harm the brain's mind by making confusion, insanity, aches, epilepsy or who-knows-what-else.