Wednesday, February 27, 2019

Spaced Out

Because of its key role in navigation, odor-detection and spatialization go hand-in-hand. A paper from McGill's Department of Psychiatry and the Douglas Mental Health University Institute gives evidence to support this relationship.

The hippocampus, which is the central location where spatial memories are "stored," is a key part of the olfactory system. The two – space and smell – are so closely related that they can become difficult to disentangle.

There is a great philosophical essay about the ontogeny of a salamander (see Hosek and Freeman below) in which a creature develops its identity (if questionably-sentient creatures can be said to do so) by way of olfaction. This creature, as with many others, interfaces its environment primarily by smell, especially in the beginnings of its life. The decisions that it makes then are in response to olfactory information, which through iterated reinforcement forms the foundation of its self.

I was so impressed by this idea that I was compelled to write a short essay myself about space, information and dimensionality, as narrated via the odyssey of the Eukaryote evolving through the epochs to its present-day instantiation as a self-aware human. It can be read here.

On this relationship between navigation and olfaction, I am reminded of a comment I received more than once when I was first telling folks about my book on smells – "What is it about architects and smells?" I studied both architecture and olfaction, and apparently, I'm not the only one.

That was something I couldn't answer at the time; I had never heard about it. As I began to meet more people involved in an olfactory occupation, be it writing about fragrance or designing olfactory experiences, I did notice a few interdisciplinary architects scattered among them.

Now it occurs to me quite clearly – architects are not experts at navigation so much as spatial perception in general, and specifically on moving through space. Whereas the painter is concerned with the way the eyes move through two dimensions, and the sculptor thinks about eyes moving in 3-D, the architect is concerned with the moving body.

The late architect Michael Graves made this the thrust of his speech as he opened his own School of Public Architecture at New Jersey's Kean University in 2015(ish?) – he told us that in designing a building, the human scale is the only one that matters. The way we feel in a space is the primary criterion when evaluating it. If you think about it, a building is like a body for our body.

Architects don’t have to learn much about proprioception, but maybe they should. Proprioception is the feeling that we have of our own bodies, where the parts are, how they're related, what they're doing, and whether we should move them out of the way of danger. (Anybody ever see the hand-smashing phantom limb trick? This is a good example of the power of proprioception.)

As we move through a building, our proprioception recognizes and records not only our own bodies, but the “bigger body” that we're in, whether it’s a building or a backyard. Before there was such a thing as architects or buildings (i.e., before we were human), we used olfaction as a way to calibrate our proprioception, and to navigate this bigger body that we’re in.

It seems I’ve done a pretty good job of navigating myself into the part of this post that I now have no idea how to get out, so I’ll have to leave it there. Architecture and olfaction make a good pair.

Oct 2018,

Louisa Dahmani et al, An intrinsic association between olfactory identification and spatial memory in humans, Nature Communications (2018). DOI: 10.1038/s41467-018-06569-4

Hosek R J & Freeman W J (2001). Osmetic Ontogenesis, or Olfaction Becomes You: The Neurodynamic, Intentional Self and Its Affinities with the Foucaultian/Butlerian Subject. Configurations 9: 509–541.

School of Public Architecture, Kean University

BBC, 2010

Wednesday, February 20, 2019

Olfactory Remains

The picture seen here is taken from a local Arizona news source circa 2014, attached to an article citing the decrease in “migrant deaths” in the Arizona desert at that time. That data was given by Border Patrol. They say most of the deaths are caused by the heat.

But this post isn’t about migrant deaths; it’s about olfactory forensics, using one’s sense of smell to find decomposing bodies.

On the other side of the United States/Mexico border, deaths aren’t from heat, and the bodies are not of migrants. They’re people suspected to have been kidnapped by drug cartels, either for ransom, recruitment, or rivalry. Then there’s the women, who are abducted for trafficking. For whatever tragic fate befell them, their bodies are buried in a clandestine grave.

When farmers and cowboys find bones in the brush, they notify The Searchers of El Fuerte, who investigate suspected burial areas. They dig the earth, and then sniff the air. If they find bodily remains, they take them and send them for DNA testing. If a match is found, they try to inform their relatives.

It may sound primitive, but this is common practice. The human nose is the most powerful device we know of for detecting things that smell. It’s hard to believe, but it does explain why actual humans are hired to smell the fish at large industrial operations to make sure they’re fit for human consumption. It’s also why the fragrance industry employs noses. Shoot, Firmenich, who in 2017 was making 95% of the world’s supply of Hedione (which is in 95% of fragranced products) employ their own truck drivers, custodians, and administrative assistants to assure the quality of their Hedione batches. (This is because so many people have a hard time smelling it; if you’re good at detecting Hedione, no matter what your actual job, you will be asked to sniff batches.)

Back to the bodies. As flesh breaks down, it produces a molecule called Cadaverine, which smells like rotten flesh. (If you’re not sure what that smells like, try driving past exit 14 on the New Jersey Turnpike sometime around August; that should do it.)

Eventually, the cadaverine subsides, leaving other equally offensive odors. There will come a time when a deterred body no longer produces a smell at all. Until then, it is a recognizable indicator.

Dec 2018, BBC

Cadaverine has the sickly-sweet smell of rotting flesh
Limbic Signal, 2017
Limbic Signal, 2016
Sensory Psychologist Avery Gilbert features the “I Smell Dead People” installments on his blog First Nerve

Post Script:
Body Farms are places where bodies are buried under all kinds of different conditions, to be examined at various stages of decomposition, for the purpose of aiding forensic anthropology. The information learned on these body farms could be useful for solving potential crimes or missing persons cases.

The Body Farm at the University of Tennessee’s Forensic Anthropology Center

Monday, February 4, 2019

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.

Oct 2018,

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