[Julia Ravey (OP)]

Paul has written in to us to ask:

"How long after death have we lost our memory? If one is dead there are no electrochemical messages being sent around. I remember once seeing something about the face of a murderer being in the eye of a victim, but it may have just been science fiction."

What do you think?

[Bored chemist]

I remember once seeing something about the face of a murderer being in the eye of a victim, but it may have just been science fiction.

I'm not sure if it's exactly "science fiction" but it was a Victorian myth.
In reality the "image" would persist for very little time; my guess would be microseconds- maybe milliseconds.
It's also not clear how you would "read" it.

The myth led to some murderers stabbing out the eyes of their victims- a practice which did nothing to help them, but which added to the distress of the bereaved.

[Origin]

How long after death have we lost our memory?

All evidence indicates your memories die with you.

I remember once seeing something about the face of a murderer being in the eye of a victim, but it may have just been science fiction.

Yes, that was science fiction.

[hamdani yusuf]

If one is dead there are no electrochemical messages being sent around.

Static memories don't need messages being sent around. Think of a CD/DVD.

[Bored chemist]

If one is dead there are no electrochemical messages being sent around.

Static memories don't need messages being sent around. Think of a CD/DVD.

And then stop thinking of CD/ DVD because they are not really how the brain works.

[hamdani yusuf]

If one is dead there are no electrochemical messages being sent around.

Static memories don't need messages being sent around. Think of a CD/DVD.

And then stop thinking of CD/ DVD because they are not really how the brain works.

Some parts of the brain act like memory storages. That's the topic of this thread.
If the brain can be frozen quickly enough, it's possible to restore the brain functionality in the future, including memory. It has been done experimentally with small mammals, like hamster.
Otherwise, it will deteriorate pretty quickly. CD and DVD deteriorate too, but at much slower rate.

[Origin]

Some parts of the brain act like memory storages. That's the topic of this thread.

And those memories vanish at the time of death.

If the brain can be frozen quickly enough, it's possible to restore the brain functionality in the future, including memory. It has been done experimentally with small mammals, like hamster.

If that could work it would be because the animals were not dead.  If you die you go bye-bye, that means all thoughts and memories go bye-bye.

[hamdani yusuf]

Some parts of the brain act like memory storages. That's the topic of this thread.

And those memories vanish at the time of death.

If the brain can be frozen quickly enough, it's possible to restore the brain functionality in the future, including memory. It has been done experimentally with small mammals, like hamster.

If that could work it would be because the animals were not dead.  If you die you go bye-bye, that means all thoughts and memories go bye-bye.

It's a technical problem. Let's say that the technology is advanced enough to scan and record all molecules of the hamster, and then restore it to the original state before it was properly killed. Does it ever die?

In the frozen hamster case, in principle you can cut off its head, so some of us will say that it's dead. But its head is in the same state with the frozen hamster who hasn't its head cut off. So the severed head must still contain the memory.

[Halc]

If that could work it would be because the animals were not dead.

It's a technical problem. Let's say that the technology is advanced enough to scan and record all molecules of the hamster, and then restore it to the original state before it was properly killed. Does it ever die?

If you're scanning a live hamster, then sure, you get one (or many as you want) new live hamsters, complete with memories, by (instantly) 3D printing some molecules in the exact same state. Whether the original scanned hamster is still alive or not is irrelevant.

In the frozen hamster case, in principle you can cut off its head, so some of us will say that it's dead.

A severed head is not dead. If not frozen, it soon will be without decent life support.

So the severed head must still contain the memory.

Even not frozen. People with severed heads have been known to still look around and/or attempt to speak, but the loss of blood pressure tends to make one lose consciousness in a few seconds. Death takes place several minutes later. The memories are lost before death takes place, as evidenced by those who have been revived from sufficiently near-death states.

- - -

In support of Paul's query, some memories are stored apparently as chemicals. I remember an experiment where they taught some flatworms to perhaps run a maze or some task requiring memory. Then they ground them up and fed the slurry to other flatworms. The flatworms that ate this stuff were able to better perform the task on first try than those that ate similar food without the 'memories'.

[hamdani yusuf]

A severed head is not dead. If not frozen, it soon will be without decent life support.

When will you declare something as dead?

The memories are lost before death takes place, as evidenced by those who have been revived from sufficiently near-death states.

[hamdani yusuf]

In support of Paul's query, some memories are stored apparently as chemicals. I remember an experiment where they taught some flatworms to perhaps run a maze or some task requiring memory. Then they ground them up and fed the slurry to other flatworms. The flatworms that ate this stuff were able to better perform the task on first try than those that ate similar food without the 'memories'.

Any configuration of matter is a potential information storage. Some are volatile like RAM, some others are non-volatile like Flash drive. In biological brain, it's mostly about connections between neurons.

The brain simmers with activity. Different groups of neurons (nerve cells), responsible for different thoughts or perceptions, drift in and out of action.

Memory is the reactivation of a specific group of neurons, formed from persistent changes in the strength of connections between neurons. But what allows a specific combination of neurons to be reactivated over any other combination of neurons?

The answer is synaptic plasticity. This term describes the persistent changes in the strength of connections – called synapses – between brain cells. These connections can be made stronger or weaker depending on when and how often they have been activated in the past. Active connections tend to get stronger, whereas those that aren’t used get weaker and can eventually disappear entirely.

A connection between two neurons becomes stronger when neuron A consistently activates neuron B, making it fire an action potential (spike), and the connection gets weaker if neuron A consistently fails to make neuron B fire a spike. Lasting increases and decreases in synaptic strength are called long-term potentiation (LTP) and long-term depression (LTD).

Changing the strength of existing synapses, or even adding new ones or removing old ones, is critical to memory formation. But there is also evidence that another type of plasticity, not directly involving synapses, could be important for memory formation. In some parts of the adult brain, such as the important memory structure known as the hippocampus, brand new neurons can be created in a process called neurogenesis. Studies in older mice have shown that by increasing neurogenesis in the hippocampus, memory can be improved. In humans, exercise has been shown to increase the volume of the hippocampus – suggesting new neurons are being created – and at the same time improve performance in memory tasks.

https://qbi.uq.edu.au/brain-basics/memory/how-are-memories-formed

[Zer0]

Hello Julia Ravey & Welcome to the Forum!
🙏
Thanks Paul for an intriguing question.
👍

So...in short, what is the Fate of all those Brains stored at ALCOR?
🧠

[Bored chemist]

It's a technical problem. Let's say that the technology is advanced enough to scan and record all molecules of the hamster,

Why would we say that, given that we know the uncertainty principle makes it impossible?

[Bored chemist]

Some parts of the brain act like memory storages.

Please show me the bits that rotate at 300 RPM.

[Bored chemist]

So the severed head must still contain the memory.

Unless the freezing process killed it via ice crystal growth.

[hamdani yusuf]

It's a technical problem. Let's say that the technology is advanced enough to scan and record all molecules of the hamster,

Why would we say that, given that we know the uncertainty principle makes it impossible?

Because of variation tolerance for preservation of identity. A hamster now isn't exactly the same as it was a few seconds ago. We still call it the same hamster.

[hamdani yusuf]

Some parts of the brain act like memory storages.

Please show me the bits that rotate at 300 RPM.

Why? a solid state drive doesn't need to rotate.

[hamdani yusuf]

So the severed head must still contain the memory.

Unless the freezing process killed it via ice crystal growth.

The condition is assumed to be well controlled just like the experiment where they successfully brought back the hamster after being frozen.

[evan_au]

some memories are stored apparently as chemicals

Some memories are stored mechanically, in "spines" on nerve cells.
- It is conceivable that these spines could be scanned for a short time after the nerve cells to which they were attached had died.
See: https://en.wikipedia.org/wiki/Dendritic_spine

Of course, translating patterns of neurons into anything we can understand is one of the major unsolved problems in biology - and the subject of several international research projects.
See: https://en.wikipedia.org/wiki/BRAIN_Initiative

Re Flatworm learning experiment: If you ran across a lot of dead people, that might inspire you to learn more quickly, too

[Zer0]

If one is dead there are no electrochemical messages being sent around.

Static memories don't need messages being sent around. Think of a CD/DVD.

And then stop thinking of CD/ DVD because they are not really how the brain works.

It's a Pity you understand the Equivalence Principle but Failed to grasp such a Simple Reference from the User.

Ps - I'll just Repeat what i muttered in another OP.
Nobody looks Smart & Good in the process of making someone else look Bad & Dumb!