Naked Science Forum
Life Sciences => Physiology & Medicine => Topic started by: Julia Ravey on 08/11/2021 15:59:16
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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?
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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'.
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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.
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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
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Hello Julia Ravey & Welcome to the Forum!
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Thanks Paul for an intriguing question.
👍
So...in short, what is the Fate of all those Brains stored at ALCOR?
🧠
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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?
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Some parts of the brain act like memory storages.
Please show me the bits that rotate at 300 RPM.
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So the severed head must still contain the memory.
Unless the freezing process killed it via ice crystal growth.
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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.
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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.
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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.
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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
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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!
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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.
I am pleased to see that you have followed my suggestion to stop talking about CDs and DVDs.
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Nobody looks Smart & Good in the process of making someone else look Bad & Dumb!
Nobody here knows who I am, so there's no real point in me trying to look clever (or dumb, come to think of it).
But I do like to think that I sometimes make the site more correct.
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Nobody looks Smart & Good in the process of making someone else look Bad & Dumb!
Nobody here knows who I am, so there's no real point in me trying to look clever (or dumb, come to think of it).
But I do like to think that I sometimes make the site more correct.
You did not quite get the Reference, Again!
Perhaps I'm wasting my time here.
Ps - What good is Knowledge, if it makes one Rude & Arrogant.
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I am pleased to see that you have followed my suggestion to stop talking about CDs and DVDs.
I brought the CD as counter example for the assertion in the OP that preserving memory requires sending of electrochemical messages.
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.
Technically, reading the data written on a CD doesn't need to rotate it at 300 rpm. You can go as slow as you like.
If cost and practicality are not concerned, we can move the optical head in 2D while the CD is stationary. It's even possible, at least in principle, to read the CD using extremely high resolution photosensor, just like how smartphones read QR codes.
Come to think of it, even solid state drives don't work exactly like how brains work.
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You can go as slow as you like.
With one exception; the speed can't be zero.
Unless, of course you turn to from a serial to a parallel device and have a separate sensor look at each pit on the disk. It would probably be easier to multiplex those sensors in some way. As you say, a way to do this would ab a very high resolution camera.
If you did that, you would have something that looked a lot more like a SS drive.
And it would also look a lot more like the human brain.
that preserving memory requires sending of electrochemical messages.
In the human brain, it does.
If you are looking for an electronic analogy dram looks less bad than sram.
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Pardon me, but This is sounding less & less of Physiology & Medicine...
& More & more off of Technology & Geek Speak!
Ps - Yea, i think i get this one now too.
🙏
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In biological brain, it's mostly about connections between neurons.
Possibly, especially in the hippocampus, which is sort of short term memory. The synapses need to be further strengthened by immediate exercise of the pathways. In this manner it would seem that important things might be remembered later on, and unimportant things promptly forgotten.
Long term memory has to work in at least a somewhat different manner, because it needs to be more non-volatile as you put it. Some childhood memory may not have been accessed in decades, yet it is in there, more firmly even than more recent memories, as evidenced by Alzheimer patients who steadily forget their lives in reverse order, with the oldest memories being the last to go.
The connections, or rather the information contained in the strength of those connections, seems to vanish before actual death, as evidenced by memory loss from people revived from oxygen deprivation. This is evidence, but not hard evidence, that memories become irretrievable before death occurs, at least by the subject. Perhaps a hypothetical molecular scan might still find vestiges of the state of those failed connections despite their lack of functionality to the damaged brain. Information in theory cannot be destroyed, so past state can be constructed in principle.
I don't think Heisenberg's uncertainty prevents a scan of a person. You don't much care about momentum or exact quantum state of anything, just sufficiently detailed state at a given moment. And molecular detail is probably an overkill, but a scan down to the cellular level is not enough.
So now you have state of a dead being, complete with probable description of connections that might have been not too long ago. Nobody can read that, so you need to somehow print that state on a brain that's in a different (live) state, sort of like transferring an odometer reading from a crashed car onto a replacement model built with all the wear and tear of the car just before the crash. It's a poor analogy because a car isn't something that can be dead. Only damaged. One presumes that an undamaged biological being would be alive, but nobody has ever built one, however crude.
Also, we're talking death of the system, which is different than cellular death. People are alive in more than one way, and the death of one way is not necessarily the death of the other. Organ transplants would not work if they were biologically dead, despite their being taken from dead people.
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The connections, or rather the information contained in the strength of those connections, seems to vanish before actual death, as evidenced by memory loss from people revived from oxygen deprivation. This is evidence, but not hard evidence, that memories become irretrievable before death occurs, at least by the subject.
Another way to look at it, is that it's oxygen deprivation, and not death itself, which destroys memory. The problem can be resolved if we can find a way to make someone die without causing oxygen deprivation.
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Christof Koch - How does Memory Work?
We all wish for better memories. But how are memories stored? For all our neuroscience, we still do not know even the level in the brain where memories are stored—from inside neurons to long brain circuits. We do know that the synapses between neurons in the brain are critical, but how those chemical changes mean a specific memory remains a mystery.
Interesting finding : One experiment found Jennifer Aniston neuron in a patient.
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The connections, or rather the information contained in the strength of those connections, seems to vanish before actual death, as evidenced by memory loss from people revived from oxygen deprivation. This is evidence, but not hard evidence, that memories become irretrievable before death occurs, at least by the subject.
Another way to look at it, is that it's oxygen deprivation, and not death itself, which destroys memory. The problem can be resolved if we can find a way to make someone die without causing oxygen deprivation.
So, the answer to the op comes back to how we define death. If it requires irreversible destruction of someone's memory, then the answer would be no. In pre-modern societies, it can simply means stoppage of breath or heart beat. Because they simply have no way to reverse those.
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If it requires irreversible destruction of someone's memory, then the answer would be no
There is no definition of death that has anything to do with memories.
The answer to the question is simply when you are dead you are dead, so of course there are no memories. For instance I do not think Newtons skeleton has memories.
Now if the question is about the existence of 'life after death', like a human soul or something then it is a philosophical or religious question, not a science question.
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So, the answer to the op comes back to how we define death.
This definition seems to change over time. It usually means 'non-functional beyond the point of healing', which changes as technology improves to the point of reviving somebody who would previously have been considered dead.
The problem can be resolved if we can find a way to make someone die without causing oxygen deprivation.
Can you think of one? I mean, doctors are known for saying that actual cause of death is never from heart failure, drowning, cancer, or whatever. It's always lack of oxygen to the brain that finishes you off. This of course isn't strictly true. A grenade going off by your head will surely kill you before the oxygen deprivation even begins, but it isn't going to leave the memories intact.
If it requires irreversible destruction of someone's memory, then the answer would be no.
But per my prior post, is the destruction irreversable? The guy has lost them, but is it lost to somebody doing a scan? It's not like anybody can look at the scan data (even of a live person) and know what his memories are/were. How might one glean memories from such data, scanned from a person dead enough that they're gone to him.
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The problem can be resolved if we can find a way to make someone die without causing oxygen deprivation.
Simple.
Blow their brains out with a shotgun.
Plenty of access to oxygen.
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There is no definition of death that has anything to do with memories.
Do you think that memory is a biological function?
Death is the permanent, irreversible cessation of all biological functions that sustain a living organism.[1] Brain death is sometimes used as a legal definition of death.[2] The remains of a previously living organism normally begin to decompose shortly after death. Death is an inevitable, universal process that eventually occurs in all living organisms.
https://en.wikipedia.org/wiki/Death
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The problem can be resolved if we can find a way to make someone die without causing oxygen deprivation.
Simple.
Blow their brains out with a shotgun.
Plenty of access to oxygen.
How would you collect the memory then?
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if we can find a way to make someone die without causing oxygen deprivation.
Someone who is on a heart/lung machine will not suffer oxygen deprivation.
But if their brain is still intact, they are not legally dead.
I think the scanning process is a major problem.
- With current technology, if you could get a "fresh" brain, to make a complete map of the connections between cells (whether that be chemical, mechanical, protein structures, etc) on a scale of a synapse would require infusing it with antifreeze, cryogenically freezing it, and slicing it into extremely thin slices. These could be infused with a suitable stain and scanned into a computer with a microscope, to be reassembled as a digital 3D model.
- With a fantastic extension of current technology, one could image a super-resolution MRI machine that could obtain a non-destructive synapse-level scan of a whole brain. But that won't come soon (as I understand it, this would require an incredibly powerful magnetic field, and lots of processing power)!
Then that leads to the next problem: how do you interpret this mass of data?
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The problem can be resolved if we can find a way to make someone die without causing oxygen deprivation.
Simple.
Blow their brains out with a shotgun.
Plenty of access to oxygen.
How would you collect the memory then?
Do you think the memory would still be there?
Is the memory not a combination of complex structural and chemical aspects?
And, if it is, do you not think that the process of death would also destroy those complex patterns?
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Can you think of one? I mean, doctors are known for saying that actual cause of death is never from heart failure, drowning, cancer, or whatever. It's always lack of oxygen to the brain that finishes you off.
Is it the lack of oxygen to the brain that finishes you off, or is it the follow up reactions that destroy the molecular configuration of the brains? The frozen experimental hamster had no access to oxygen. Some naturally frozen frogs don't either.
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Do you think the memory would still be there?
Is the memory not a combination of complex structural and chemical aspects?
And, if it is, do you not think that the process of death would also destroy those complex patterns?
Some chunk of the brain may still intact. But you need to act quickly preserving and reading it before it deteriorates.
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Do you think the memory would still be there?
Is the memory not a combination of complex structural and chemical aspects?
And, if it is, do you not think that the process of death would also destroy those complex patterns?
Some chunk of the brain may still intact. But you need to act quickly preserving and reading it before it deteriorates.
I'm not sure that's possible.
The distributed nature of the brain lead me to think that you need essentially all of it to decode any of it.
Both "life" and "memory" are dependent on the proper organisation of the brain's chemistry and structures.
A baby has life, but no memory.
To me that suggests that the requirement for "life" is easier to meet than the requirement for "memory".
If I'm right then it's likely that any disruption to the brain which extinguished "life" would also destroy "memory".
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You need to distinguish between "memory", the combination of hardware and software that permits storage and recall of data, and "memories" - the data within that system. There is no doubt that babies contain the hardware and bootstrap software, but are pretty much devoid of content.
So we move on to the nature of memory. In the realm of artificial memory we use a combination of static and dynamic memory hardware, and various forms of compression and regeneration software. It is arguable that we can segment the workings of the human brain in the same way.
The development of the hippocampus in London taxi drivers has been noted and implies that longterm memory is to some extent a hardware/static element. At the other end of the scale most people can remember a 7-digit phone number for long enough to dial it, but I get the impression from watching the development of pilots' radio communication that eight or nine digits is quite a feat until you acquire some "compression software" by experience: all civilian VHF frequencies begin with 1 and although communication frequencies are allocated in 8.33 kHz steps, the display is deliberately "fudged" to the nearest 5 kHz, sea level barometric pressure is usually between 900 and 1300 kPa, transponder codes are 4-digit octal (0-7 only)....so your longterm memory says you don't need to keep the whole instruction in your short-term memory to execute it.
Most people can sing back one line of a jazz song (usually 8 or 12 bars, sometimes 16) and that is the essence of leading a crowd chorus, but to recall a whole verse or an entire 3 minute number needs lots of repetition for a beginner. An experienced musician however seems to develop some compression-decompression mechanism that allows adequate recall of an arrangement you may have only played once, years ago. Note "adequate": like a video image, something can get lost in the CODEC process, but the joy of live performance is to fill in the gaps!
So my simplistic analogy is that short-term memory, like dynamic RAM, needs to be refreshed or compressed and transferred to something more akin to static RAM. To pursue the analogy to an extreme, interruption of the refresh process would destroy the contents of dynamic RAM but static RAM decays much more slowly. Evidence? Many people with head trauma never recall the previous two minutes or so, but gradually reconfigure the stuff about names and addresses. Thus we might conclude that longterm memory involves fairly permanent chemical changes that in principle could be detected in a nonfunctional brain, even if we have no idea how to decode them.
Considering how "memory techniques" work, I guess a lot of the CODEC business is done by association and probability, which may account for witness statements often being plausible but contradictory. It also explains the difference between learned language, where we consciously study the formalised structure of a foreign tongue, and language acquired by immersion. The former often gives us a good "passive vocabulary", particularly if we can recognise similarities or have studied a common root language (like Latin) and can read a newspaper or follow a conversation, but "active vocabulary", the ability to respond in Klingon without compiling the sentence in English and translating it, is much harder to acquire after the age of five.
Problem is that unless you know a lot about the history and experiences of your dead brain, you won't be able to disentangle the hard molecular data that has been compressed and compiled by association.
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The more complicated and "embedded in the cognitive bits of the brain" memory turns out to be, the more likely it is that death erases it.
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The distributed nature of the brain lead me to think that you need essentially all of it to decode any of it.
Experiments with brain cancer patients showed that memories can be lost partially. People with amnesia may lose some of memory while retain the others.
Amnesia definition, loss of a large block of interrelated memories; complete or partial loss of memory caused by brain injury, shock, etc.
https://www.dictionary.com/browse/amnesia
Like many systems, some extent of modularity can make them more robust and less vulnerable to disruptions.
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A baby has life, but no memory.
It comes from the observation that children and adults don't remember events they experienced when they were babies. It doesn't remove the possibility that babies may have short term memories. They might just get lost when they grow up, and the memory space is overwritten by newer memory.
Babies may remember faces, or song, and relate them to events they are experiencing, such as feeling of comfort and warmth brought by their parents.
To me that suggests that the requirement for "life" is easier to meet than the requirement for "memory".
If I'm right then it's likely that any disruption to the brain which extinguished "life" would also destroy "memory".
Both are fuzzy concepts, but useful in decision making. CRISPR mechanism can be thought of as a primitive form of memory.
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The color of my eyes, my skin tone & possibly the nose that sits on my face...All bear resemblance to my Ancestors.
Can these things be also classified as Memory?
Ps - i know I'm going astray, this OP isn't about Genetics, but aren't Seeds just a bundle of memories?
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A baby has life, but no memory.
Studies have shown that even before birth, babies are picking up sounds from their mother, including the sounds of their "mother tongue".
This has been shown to affect the sounds that babies can distinguish after birth.
This is more in the speech processing part of the brain, rather than episodic memories, but I still count it as memory - it is still interconnections between neurons.
aren't Seeds just a bundle of memories?
We are certainly able to decode DNA sequences from plants, animals, ancient humans and even viruses, to an extent that was impossible in the year 1990, when the Human Genome Project was just getting underway.
- Progress during that project was exponential, with the first years devoted to improving techniques, and developing a high-level gene map that later work could fill in.
- As I understand it, after 7 years, when the planned 15-year project timetable was half used, only about 3% of the human genome had actually been decoded
- Some described it as a total waste of time, and should be abandoned
- But in fact, it was declared "finished" (for publicity purposes) 1 year ahead of schedule
- Exponential growth catches everyone by surprise!
Perhaps there will be a similar exponential progress in brain research?
See: https://en.wikipedia.org/wiki/Human_Genome_Project
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aren't Seeds just a bundle of memories?
Seeds are mainly food.
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The color of my eyes, my skin tone & possibly the nose that sits on my face...All bear resemblance to my Ancestors.
Can these things be also classified as Memory?
It's classified as information. All memory is information, but if you classify all information as memory, then there seems to be no point to having two distinct words to describe the same thing. So it seems that memory is a specific kind of information, and whether a seed constitutes memory or not depends on where you draw the line between your definitions.
So again, a dead person's memories might be gone, but the information possibly isn't, at least not right away. But there seems to be no simple way to read this information, just as you can't easily tell from a DNA molecule what sort of thing is described by it. A good biologist can get pretty close though, at least if it's something related to a life form that he's worked with before.
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aren't Seeds just a bundle of memories?
Seeds are mainly food.
You certainly aren't interested in the Art of Gardening, are You?
It's quite pleasant you know.
Helps to keep oneself calm & composed & in rhythm with nature.
Ps - Try it!
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aren't Seeds just a bundle of memories?
Seeds are mainly food.
You certainly aren't interested in the Art of Gardening, are You?
It's quite pleasant you know.
Helps to keep oneself calm & composed & in rhythm with nature.
Ps - Try it!
You seem to have muddled what they are made from with what they are for.
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So it seems that memory is a specific kind of information, and whether a seed constitutes memory or not depends on where you draw the line between your definitions.
Memory usually refers to information acquired from experience. Biology borrows the word and use it to describe similar traits for species other than humans.
Electronic engineering and computer science extend the scope further to any information which can be easily read/recalled.
But the op seems to restrict the scope to human memory.