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Far in the future, can there be some kind of mechanism where we can slice through a waxed brain and image every synapse, copy the neural map into a computer and find memories and personality traits from it?

Can you give some ideas about the quality of brain duplication that can be achieved through a nanometer-precise digital neural map?

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    $\begingroup$ Seeing as nanometers are a smaller unit of measurement than what brain cells are generally measured in(4-100 microns/micrometers), probably as much detail as you want. Now you just need to figure out if you are capable of capturing the brain's mental momentum. $\endgroup$
    – Lemming
    Feb 10, 2022 at 12:52
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    $\begingroup$ That's like saying that you make an accurate map of all the transistors in a turned off computer, and asking what program it was running before being turned off. You need the accurate connectome, yes; but you also need the state of each and every neuron, and that state is irretrievably lost when the brain dies. So that the "quality" of brain duplication obtained by mapping a dead brain is exactly zero. (Yes, it might be the case that brains have something analogous to persistent storage, but we don't know what that is and cannot measure it.) $\endgroup$
    – AlexP
    Feb 10, 2022 at 13:48
  • $\begingroup$ Those comments look like perfectly viable answers to me, @Lemming, AlexP $\endgroup$
    – Joachim
    Feb 10, 2022 at 13:59
  • $\begingroup$ The help center states, "To prevent your question from being flagged and possibly removed, avoid asking subjective questions where … every answer is equally valid." To avoid my VTC, can you explain how you will judge a best answer? Stack Exchange isn't a good place for fishing-for-ideas questions or brainstorming - especially when you're asking about the quality of a fictional condition dependent on a fictional technology that we have no current basis to judge at all. Why are you unable to choose for yourself what you want and move forward? Why is this not a story-based question? $\endgroup$
    – JBH
    Feb 10, 2022 at 16:36
  • $\begingroup$ It is possible to anaesthetise a person so that they have no neural activity. That they can recover from anaesthesia shows that the brain's state is stored structurally, not actively. $\endgroup$
    – Monty Wild ♦
    Feb 10, 2022 at 20:56

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No

Agree with the comments. This sounds like opening a Zip-file in Notepad to reconstruct its content. But suppose, you could measure all neurons and put them on a HDD.. even then..

A single or final state does not allow to retrieve memories

Retrieving memory requires multiple steps firing multiple neurons in sequence. Griffiths, an author on website theconversation.com states it like this,

But the hippocampus is simply too small to store every little detail of a memory. This has lead researchers to theorise that the hippocampus calls upon the neocortex – a region which processes complex sensory details such as sound and sight – to help fill in the details of a memory. The neocortex does this by doing the exact opposite of what the hippocampus does – it ensures that neurons do not fire together. This is often referred to as “neural desynchronisation”. Imagine asking an audience of 100 people for their names. If they synchronise their response (that is, they all scream out at the same time), you’re probably not going to understand anything. But if they desynchronise their response (that is, they take turns speaking their names), you’re probably going to gather a lot more information from them. The same is true for neocortical neurons – if they synchronise, they struggle to get their message across, but if they desynchronise, the information comes across easily.

https://theconversation.com/how-memories-are-formed-and-retrieved-by-the-brain-revealed-in-a-new-study-125361

Desynchronize. This is about serial events. You won't have any "memory retrieval" when you take one single snapshot, even if you can map every state accurately. You'd have to simulate the followup, without any context in the past.

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  • $\begingroup$ I didn't understand how the information would be irretrievably lost due to the decoupling of the hippocampus and the neocortex because they would actually still be paired and joined in the model. For desynchronisation issues, every kind of temporal and spatial decoding of the neurons would be possible digitally without external informations kind of like memorising in the dark with eyes closed. They decoded enigma which was encrypted where is the brain is not encrypted. $\endgroup$
    – bandybabboon
    Feb 13, 2022 at 3:16
  • $\begingroup$ @LifeInTheTrees even in the digital world, you can't expect the network to reconstruct a previous state, or enter into a new state, without any guidance. You won't know how many steps are involved in retrieving any particular memory. Any context providing further detail is lost, and you don't have full understanding of the person, prior to the attempt. Biggest issue in your scenario: post-mortem. There is no way back, nor forward. You're left with a snapshot of a dynamic process. $\endgroup$
    – Goodies
    Feb 13, 2022 at 15:28
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We'll have backups, but it will be complicated

We barely understand the brain. Neuroscience has only left the "let's touch brain regions and see what happens" phase a few decades ago. Scanners do now have resolutions of 0.1 mm, about the diameter of a neurons body. This probably has to improve by at least two orders of magnitude to allow any kind of actual monitoring and deep understanding of the activities. Additionally, a good theory of the mind won't hurt you either.

My intuition tells me that simply scanning a dead brain might not be sufficient. We aren't really made for long periods of inactivity. You might need to use generic engineering and supporting chemicals to even enable a scan. While one commenter claimed that the brains structure isn't enough to restart the "person", the cryogenic wood frog might disagree.

So just casually uploading the mind is probably out, but you can assist the backup or transmigration process in a number of ways. Genetic and chemical options might make it easier. However, I personally think digital options are quite important. Mind uploading is about crating the best possible modle of yourself. Something that functions, acts like you, is perceived by others as you and has a soul/consciousness/a sense of self (take a pick, these are probably all equivalent). Funnily enough, if the copy is you is probably going to be determined by you own beliefs. If I think a copy is a legitimate continuation of myself, it will believe and act that way. I I consider it to be a mere copy...

Going back to the digital options, you might want to use constantly active brain scanning via probes and external sensor feeds matching your perceptions and attention to train an AI. This will be used as a close partner ana assistant and if you die, it provides a valuable data point for recreating yourself.

With all that said, I view mind uploading as a Big Data project. The current state of the brain and it's encoded memories are probably necessary, but not sufficient. Especially if you are dealing with a dead brain. A live one... maybe. But historical and environmental data might be vital to the process. However, you might want to consider if a full copy is always desired. Sure, it's nice for a backup and if you want to migrate into the digital realm, but lower fidelity copies have a place as well. In Revelation Space author Alistair Reynolds differentiates Alpha (full copy), Beta ("low" fidelity copy) and Gamma (AI immitating you from behavioural data) copies.

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