
Smell helps the brain form memories during sleep - prostoalex
https://www.medicalnewstoday.com/articles/smell-helps-the-brain-form-memories-during-sleep#Sleep-and-memory
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ohazi
There are a tiny handful of smells (perhaps 3) that I encounter very rarely
(maybe once every few years), and for whatever reason, they bring back
childhood memories of a particular place more vividly than just about any
other form of recall I've ever experienced.

It's always the same smells, and it's always the same place, and it's happened
enough times that I dont think I'm imagining it, and _nothing_ else does this.

Has anyone else experienced something like this?

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joveian
Pierre Gloor's book _The Temporal Lobe and Limbic System_ has an excellent
discussion of this pages 316-318. I'll try to type it in by hand and stick it
on pastebin later since it is unfortunately a rare out of print book (Google
Books has it but it seems to show much less text these days than it used to).
Gloor suggest that because low level olfaction is not able to distinguish
parts of a smell it is more heavily associated with context than other senses.
He notes a study where recognition of olfactory cues are not as immediately
reliable as visual or auditory cues but there is very little decay over time
of that recognition ability in olfaction while visual and auditory cues are
recognized no better than chance after 3 months. He compares the Proust
description to electrical stimulation of the amygdala in an epilepsy patient
and suggests that particularly strong memories may be amygdala assisted recall
(and notes that similarly vivid recall can happen with other senses but seems
to be less common).

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joveian
Ok, took a bit longer than I expected to get to it but here it is:

[https://pastebin.com/UKdMz5zJ](https://pastebin.com/UKdMz5zJ)

I think he overstates the inability to pick out individual smells (presumably
from later processing comparing them with memories). Also, I seem to do at
least as well recalling odors as I do recalling images, but mostly that is
because I am unusually bad at recalling images. I don't think this really
affects the overall argument all that much.

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jerzyt
I once had a dream of being in a ballroom of a fancy hotel, and the smell was
overpowering. I was thinking that there must have been a murder and they've
bleached the carpet. Turns out, my wife was already taking a shower and used a
new brand of shampoo. I couldn't stand the smell of it. Somehow,
contemporaneous reality entered my dream, rather than a memory of a past
event.

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keenmaster
This can have implications for skill and knowledge acquisition. Imagine if a
different smell is released for every new branch of activity you perform on a
computer or digital device (memorizing an anatomy text, playing a new keyboard
concerto, learning to code Python, watching finance lectures). At night, you
wear an EEG headband connected to a scent machine which releases scents
connected with the activities of the day. The more important the task, the
more you are exposed to the corresponding scent (kind of like spaced
repetition but with smell).

Here are some questions I have in light of the study, assuming it can be
replicated:

\- Is this technique biased towards certain types of knowledge, such as
tangible, locational knowledge as opposed to abstract skill acquisition?

\- Can a certain smell be over-saturated with knowledge, such that it becomes
less effective for knowledge reinforcement? If so, can the “saturation point”
be predicted using measurable variables?

\- Does this technique only work for many discrete pieces of knowledge, or
does it also work for branches of knowledge? (in the example of the finance
lecture, there might be 30 major discrete facts throughout the lecture, but
they can be bucketed into three major concepts - it might only be practical to
use three scents).

\- Are more recent associations with a scent significantly more salient to the
brain than older ones, or do we subconsciously cycle through the old
associations with roughly equal weight?

\- Can we synthesize related knowledge sets by broadcasting multiple scents
simultaneously?

I am fascinated by the possibilities here. We are advanced primates after all.
Our brains are “designed” for more basic things than most of what we do.
Paradoxically, it seems possible to supercharge the abstract by engaging the
primordial. Brb, I’m buying wallflowers at Bed Bath and Beyond.

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flippyhead
Interesting fact: the nerves in your nose for smelling are the only part of
your brain that is in direct contact with the outside world. Ancient stuff!

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chewz
Source: [https://www.cell.com/current-
biology/fulltext/S0960-9822(20)...](https://www.cell.com/current-
biology/fulltext/S0960-9822\(20\)30171-8)

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2sk21
I wonder if this also has some bearing on Alzheimer's. My father who has a
notoriously bad sense of small developed Alzheimer's a few years ago.

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ohazi
I've also heard that lack of / loss of sense of smell and Alzheimer's are
correlated.

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Parakeet-App
pretty cool

