Limbic Fitness and The Aging Brain

We all know that memory function decreases as we age. One of the ways in which this is evidenced is in the correlation between how much our eyes move and the brain activity that comes with it. You see grandpa's eyes skipping around the room, from one face to another, but he isn't recording any of it. (Exaggeration of course, depends how old he is, and his mental capacity.)

It's normal for people of all ages that the more we look at the same thing, the less and less brain activity there is in our memory-forming hippocampus. But in older folks, they can dart their eyes all over the place, and yet generate no information about what they see. No matter how many times they look at a thing, it can remain unfamiliar.

Despite the fact that smell is typically associated with airtight bear-trap memories, we can experience similar diminishing effects with our sense of smell. The relationship is so intimate that our olfactory perception is used to forecast dementia decades in advance.

It is certainly possible that your 60-year old self can be transported 50 years into the past by the mere wisp of familiar a molecule. But your 110-year old self will be less likely to transport so swiftly back to your 60's - the older we get, the less robust the memory-complex formed by each sensation.

This is covered pretty thoroughly in Hidden Scents. Olfaction, the limbic system and our episodic memory form a powerful complex of stored experience. But this system works less and less as we age-out of episodic memory and begin to rely more regularly on semantic memory for our day to day activities.

Episodic memories, i.e., the collection of feelings in your body during a particular episode in your life, are very powerful when recalled. Ironically, they cannot be recalled at will. They must come to us from outside, unlocked by a face, a voice, or a smell. The name of a friend from first grade doesn't do it. The smell of the inside of your first lunchbox, that'll do it.

You're way less likely to be brought to tears at the re-smelling of your first new car (if you were to somehow recreate that, or be so lucky as to be exposed to it later in life). Your dad's first new car - the one you got to ride in when you were 8 - smelling that might get emotional.

Notes:

Link between what we see and how we remember 'breaks' as we get older

Oct 2018, phys.org

Zhong-Xu Liu et al, Age-related changes in the relationship between visual exploration and hippocampal activity, Neuropsychologia (2018). DOI: 10.1016/j.neuropsychologia.2018.07.032

Image source - link

On the Science of Vintage Thrift Store Smells

Jolie Kerr wrote a book about how to clean stuff real good. In fact, she’s a cleaning expert.

Her blog is about getting the drool crust off your kids’ stuffed animals and analyzing Karate Kid’s waxing technique.

Not sure if it has something to do with the preoccupation with smell, but I am also a bit crazy about cleaning things. Let’s continue.

She knows some people in the cleaning industry, like Proctor & Gamble. They own all the cleaning products like Tide etc. She sent them some thrift store retro-wear to get a headspace analysis, which means they put your old clothes/my new clothes into a smelling machine to see what they’re made of, scent-wise. The results show that most of the odors come from us, as in our body oils. Not much of a surprise. Sorry if that's a let-down, but I'm not sure what you were expecting.

Here’s how they describe these anthropogenic aromas: Sweet, sour, oily, herbal, fatty, whiskey, nutty, cheesy, sweaty, stinky feet, fermented, bready.

More surprising is the environmental smells that came from gasoline, car exhaust, dry cleaning, solvents, perfume, etc.

She then goes on to explain how to clean these smells out of your clothes, because she’s a cleaning expert after all. I, on the other hand, came just for the smells.

Smell words related to thrift stores:

Vintage

Grandma’s attic

Musty

Decay

Funky

Whiff of wool

Hint of cigarette smoke

A life well-lived

(the smell of old people – nonenal)

Post Script:

Check out this very informative post about the smells that come from your body, in case that’s something you’ve always wanted to know more about:

Anthropogenic Aroma Compounds

Notes:

Getting to the Bottom of ‘Thrift Store Smell’

Jun 2018, The New York Times

Lo Fi Biometric Data

Missing Florida woman found after she bottled her scent

July 2017, BBC

Yes it’s true – you can swab your armpits, put that swab in a jar for the next twenty years, and eventually use it to find yourself amidst your own sliver alert (a public alert system for missing persons in the US).

If you haven’t read the 1985 olfactory crime thriller Perfume, you might not think the same thing when you read headlines like this. In the story, the main character with the nose of steel wraps bodies in a cocoon of fat-laced paper, absorbing the victim’s unique scent, and concentrating it into a kind of olfactive mind control substance that allows him to shapeshift his own persona while committing more crimes or just turning an entire town into an orgy.

Anyway, in the same era where employers are chipping their workers, and face rec algorithms are so good they can be used with as much accuracy as a fingerprint, it’s cool to see such simple methods for finding missing persons.

Post Script

 The conversation on my last date led to her revealing to me the secret techniques of pet detectives (yes they exist). Her cat escaped from her apartment, and never having been outside the apartment, could not figure out how to get back in. Turns out that what a pet detective does is have you piss in a bottle, then spill that bottle outside the front door to your apartment. It’s not enough that your neighbors will complain, but certainly enough that your cat will recognize it as a sign of home, and begin hanging out around where you spilled your piss, and eventually you will be reunited. (And probably because this is what I end up talking about on dates, I’m still single, no pet detective necessary to solve that one.)

image source: shutterstock

Getting Old Stinks

World’s first – We developed technology to prevent “Nonenal” (component for a body odor in older people)

Shiseido successfully developed completely new technology that prevents body odor in the middle-aged and old people through joint research with Takasago International Corporation. Now we are in the aging society, more people are bothered by “body odor unique to middle-aged and old people”. Shiseido focused on the change in the body odor caused by aging and discovered “nonenal” which is an odor component that is found in many middle-aged and older people and the level of which increases with age. -source: Shiseido

Although, this isn’t the first time this has hit the news:

It Stinks: The Smell of Aging: Japanese researcher's discovery that older men emit a pungent body odor hit a nerve with the populace. Now companies have jumped in with products to mask the offending scent. July 14, 1999. Mark Magnier, Los Angeles Times.

“Shoji Nakamura, whose million-dollar nose is reputedly able to distinguish among some 2,000 different odors, says he first noticed a distinctive smell among middle-aged and older men in 1987 and spent the next decade thinking about it.

"I'm very interested in body odor," he says.

“Now, after painstaking research, Shiseido has acted on Nakamura's evident insight. This September, the company will unveil what it says is the world's first product line of shampoos, powders and air fresheners designed to block, cover and otherwise obscure the unique smell of growing old.”

-source: latimes

Perhaps I belabor this point, but once again I can’t resist. There is something quite different between the skin of Asians and that of Caucasians. White people have more body odor, because they have more of the glands that produce body odor hiding under their skin.

Aside, they also smell like cheese, according to the Vietnamese soldiers who could sniff them out of the jungle. They also smell “like wet dogs,” according to Google’s predictive search algorithm circa 2014 – you can no longer test this; the script must’ve changed; personally I think it was a very typical semantic conflation between wet dog, which is a very specific smell, and wet hot dogs, which actually has something to do with cheese, or at least I’m willing to bet. I’m not an expert here, only an enthusiast.

And to complete the run, the first result for “why do ____ people smell like” went like this:

Why do white people smell like wet dog?

Why do black people smell like crayons?

Why don’t Asian people smell? (I swear, it would rearrange your question to produce this)

And when it came to ‘Indian people,’ the question would get so rearranged that it just isn’t worth adding it to the list. Again, the scripts have changed since, and in 2017 there is no way in hell Google would allow that to happen. Sorry, wish I screenshotted that little piece of anthropological gold.

Back to the point; I bring this up about Asian people having less body odor because it makes it seem more obvious that a Japanese man would be trying to quell old-people odor and not simply (armpit) body odor. Anyway, thanks Shiseido, for reminding me of my inevitable end.

[After some further research]
Then again, in total contrary, check out this study by  Johan Lundstrom, a neuropsychologist at the Monell Chemical Senses Center in Philadelphia (Monell is one of the premier institutes for olfactory research). They had a whole bunch of people put handkerchiefs under their arms overnight, and then, after cutting-up and mixing the samples of similar people, they put the smell samples in corresponding jars for willing participants to investigate.

Conclusion: "It turned out that the underarm odor of 75-to-95-year-olds was judged to be less intense and far more pleasant than the scent of either young or middle-aged adults. The most intense — and perhaps not coincidentally, the most unpleasant — odor came from 45-to-55-year-old men. Women in that age group, on the other hand, produced the most pleasant smell of everyone who wore the underarm pads.

"On the whole, men generally smelled worse than women, but that distinction disappeared in old age, the researchers found.

"As you grow older, you smell more and more like a woman," Lundstrom said. That is due to changes in men's hormone levels as they age. "It's almost as if you're going back to what happened before puberty." source: latimes

Anyway, totally to the contrary of the things mentioned via Shiseido. But, kind of reinforcing the Asian body odor/Asian smell scientist theory.

-image source: Shiseido

POST SCRIPT

More Old Folks Stuff –

Old Folks Jokes

Limbic Signal, 2016

Instant Grandpa

Limbic Signal, 2016