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Aging brains blend memories together instead of just forgetting them

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Re: Aging brains blend memories together instead of just forgetting them

#41
Worth keeping in mind also is that memories are not a reliable facsimile of objective reality.

Instead, they are selective representations of parts of a subjective experience. It also means that memories aren’t static, but shift over time and can even be imagined.

Re: Aging brains blend memories together instead of just forgetting them

#42

This comes as absolutely no surprise to me -- my mother was recently transferred into memory care, and the changes to her memories are definitely showing some interesting changes. The foremost was that her new "apartment" is shared with one other person, gives off a bit of a dorm room vibe. First day, she was talking about how excited she was to be going back to school and seeing her boyfriends again(?!). I said, "Oh…

It's hard to write this, but before my grandmother died about 45 years ago, it felt like she'd lost almost all her memories, but was easy to take care of. She was in her late 80's.

My mom & aunt took yearly turns keeping her in their homes. If you kept her away from the stove, she still seemed quite happy helping fix her own breakfast, taking her meds, etc. Give her a warm washrag after, and she'd wipe down the table and then proceed to putter all around the kitchen, wiping and straightening. She preferred cartoons on TV (easier to see, I guess), and was always glad to fold clean towels or clothes, if she had the chance.

Once, she actually recognized me, and remembered my name. It was a very precious 5 minute chat, but then the memories were gone. Still, I'll always remember her that way, because it was just like how I remembered her, when I was a child.

Re: Aging brains blend memories together instead of just forgetting them

#43
post #42

This comes as absolutely no surprise to me -- my mother was recently transferred into memory care, and the changes to her memories are definitely showing some interesting changes. The foremost was that her new "apartment" is shared with one other person, gives off a bit of a dorm room vibe. First day, she was talking about how excited she was to be going back to school and seeing her boyfriends again(?!). I said, "Oh…

It's hard to write this, but before my grandmother died about 45 years ago, it felt like she'd lost almost all her memories, but was easy to take care of. She was in her late 80's. My mom & aunt took yearly turns keeping her in their homes. If you kept her away from the stove, she still seemed quite happy helping fix her own breakfast, taking her meds, etc. Give her a warm washrag after, and she'd wipe down the table…

Man, that makes me happy. I'm guessing your grandmother was a very upbeat, happy person who dealt with change well. My mother's the opposite, so now every little thing going wrong is the end of the world. It's rough, but I also get to see these moments where I can see how she was when I was little/before I was born, and those are moments that I do really enjoy.

Re: Aging brains blend memories together instead of just forgetting them

#44

I wonder how much of this is directly related to age (biological aging), and how much is just someone's brain becoming "full" due to more memories getting added every year? It seems that memories must be stored as embeddings with single multi-neuron assemblies (cortical columns?) storing multiple embeddings as a kind of contents-addressable memory that is able to keep memories distinct due to the very high dimensiona…

The brain does not have the Von Neumann bottleneck. Unlike most current digital systems, the brain doesn’t have a separate memory registry it needs to pull from. Engrams, that is, the physical trace of a memory, are not stable through life. They start out in the hippocampus, but as the stimulus recedes in time without reinforcement, it moves away. No evidence exists though that the memory is encoded in one set of cel…

This is really fascinating. The actual mechanisms of the human mind are distinct from computer systems, yet there are some parallels.

There are some hints that increased memory access times scale with the amount of information the brain has stored vs the more typical narrative that aging decreases the capabilities of the brain.

> Our results indicate that older adults'; performance on cognitive tests reflects the predictable consequences of learning on information-processing, and not cognitive decline. We consider the implications of this for our scientific and cultural understanding of aging.

[0] https://pubmed.ncbi.nlm.nih.gov/24421073/

Re: Aging brains blend memories together instead of just forgetting them

#45

I wonder how much of this is directly related to age (biological aging), and how much is just someone's brain becoming "full" due to more memories getting added every year? It seems that memories must be stored as embeddings with single multi-neuron assemblies (cortical columns?) storing multiple embeddings as a kind of contents-addressable memory that is able to keep memories distinct due to the very high dimensiona…

The brain does not have the Von Neumann bottleneck. Unlike most current digital systems, the brain doesn’t have a separate memory registry it needs to pull from. Engrams, that is, the physical trace of a memory, are not stable through life. They start out in the hippocampus, but as the stimulus recedes in time without reinforcement, it moves away. No evidence exists though that the memory is encoded in one set of cel…

> The brain does not have the Von Neumann bottleneck

Obviously not, which is why I didn't say it did!

However, if you want to identify where long-term memories are stored, then that is in the cortex, but it should go without saying that this doesn't make the cortex the storage component of a von-Neumann architecture!

> No evidence exists though that the memory is encoded in one set of cells

I'm not sure what you are trying to say.

Memories are presumably stored as embeddings - a distributed representation, and an episodic memory may well be stored as "chained together" episodic "scenes/chunks" where each chunk recalls the next.

However, a distributed representation isn't the same as a holographic one, and any redundancy may well still be localized within given cortical columns, so I think you may be wrong if you are saying that individual memories/chunks are not confined to one set of cells (some localized neural assembly such as a cortical column).

Re: Aging brains blend memories together instead of just forgetting them

#46

As a person who used to be a super genius then turned 40 and is now only a regular genius aging has been very hard to get used to.

Don’t worry. By 60 you’ll remember being a super genius again — with increasingly convincing evidence.

Re: Aging brains blend memories together instead of just forgetting them

#48

I wonder how much of this is directly related to age (biological aging), and how much is just someone's brain becoming "full" due to more memories getting added every year? It seems that memories must be stored as embeddings with single multi-neuron assemblies (cortical columns?) storing multiple embeddings as a kind of contents-addressable memory that is able to keep memories distinct due to the very high dimensiona…

The brain does not have the Von Neumann bottleneck. Unlike most current digital systems, the brain doesn’t have a separate memory registry it needs to pull from. Engrams, that is, the physical trace of a memory, are not stable through life. They start out in the hippocampus, but as the stimulus recedes in time without reinforcement, it moves away. No evidence exists though that the memory is encoded in one set of cel…

Does this mean we have unlimited memory storage?

Re: Aging brains blend memories together instead of just forgetting them

#49

I wonder how much of this is directly related to age (biological aging), and how much is just someone's brain becoming "full" due to more memories getting added every year? It seems that memories must be stored as embeddings with single multi-neuron assemblies (cortical columns?) storing multiple embeddings as a kind of contents-addressable memory that is able to keep memories distinct due to the very high dimensiona…

A fascinating story of "Patient Sh." [1], the man who did not forget.

[1] https://en.wikipedia.org/wiki/Solomon_Shereshevsky

"His memory was so powerful that he could still recall decades-old events and experiences in the smallest details. After he discovered his own abilities, he performed as a mnemonist; but this created confusion in his mind. He went as far as writing things down on paper and burning it, so that he could see the words in cinders, in a desperate attempt to forget them. Some later mnemonists have speculated that this was a mentalist's technique for writing things down to later commit to long-term memory. Reportedly, in his late years, he realized that he could forget facts with just a conscious desire to remove them from his memory, although Luria did not test this directly."

I believe that one need to have superhuman memorization abilities to have definite confusion due to too much remembered. More trivial explanation of this effect in normal ageing persons is age-related brain shrinkage.

  > Obviously the brain is not a computer,
Our brain consists of approximately 86 billions quantum computers [2] controlling tens-of-thousands chemical neural networks with at least 10 coefficients, communicating [4] using lasers [5] (coherent light is laser light).

  [2] https://www.nature.com/articles/s41598-024-62539-5
  [3] https://pmc.ncbi.nlm.nih.gov/articles/PMC11655932/
  [4] https://pmc.ncbi.nlm.nih.gov/articles/PMC12230014/
  [5] https://pubmed.ncbi.nlm.nih.gov/6204761/
Live with that. ;)

Re: Aging brains blend memories together instead of just forgetting them

#50
Being an "aging brain" myself I can totally relate to this. I've been a relatively obsessive photographer (i.e. visual diary) since digital cameras were practical, i.e. over 25 years now. 238K photos in the collection so far, and I can actually find things in it.

And I've more than once found that an anecdote I've been telling has been incorrect, precisely in a "melded memories" kind of way. It happened at this sort of gathering which were usually held for that reason so X was involved... and then finally look at the old pictures and there's no sign of X. It is literally the brain invoking "lossy compression" to make it all fit, just like certain web services that let you upload pictures without limit might reduce old ones, that hardly anyone ever looks at any more, to lower quality to limit storage bloat.

Of course any married man can confirm that this only applies to men. Women's memories are flawless. If they claim that they remember a conversation exactly, word for word, 20 years later, who's to prove them wrong?

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