Neural Cartography

This first article doesn't sound like the cartography I came here for, but it's in the title so...

Researchers present insight into the neural cartography of smell

Oct 2022, phys.org

https://medicalxpress.com/news/2022-09-insight-neural-cartography.html

Honestly I'm unclear as to what this means; the endoplasmic reticulum has some mediating influence on the neural computations that turn olfactory receptor stimulus into the olfactory perception of a specific odorant?

"It is mind-blowing," said Dr. Lomvardas, also a professor of neuroscience and of biochemistry and molecular biophysics at Columbia's Vagelos College of Physicians and Surgeons. "This system found a way to create a genetically encoded, hard-wired means of transforming randomly-chosen receptor identity to a very precise target in the olfactory bulb."

Perhaps, olfactory neurons are not alone in the way endoplasmic reticulum stress organizes their wiring with downstream neurons. "If it turns out that all neurons do this, this discovery could help us understand much more about the brain," said Shayya.

via Mind, Brain and Behavior Zuckerman Institute at Columbia University:  Hani J. Shayya et al, ER stress transforms random olfactory receptor choice into axon targeting precision, Cell (2022). DOI: 10.1016/j.cell.2022.08.025

https://dx.doi.org/10.1016/j.cell.2022.08.025

Image credit: AI Art - Number Two Number One - 2022

Here's another article that makes reference to "maps" but isn't actually about navigation...

Mapping the path from smell to perception

Nov 2022, phys.org

https://medicalxpress.com/news/2022-10-path-perception.html

"The last frontier of sensory neuroscience"

Because previous studies of the olfactory cortex failed to find any logical organization among neurons there, many neuroscientists suspected information about odors was relayed randomly through the brain. But those studies examined connectivity patterns of just a few dozen neurons.

DNA-based brain-mapping technologies charting the way sensory information is routed between olfactory-processing parts of the brain including the olfactory bulb, which receives sensory information from the nose, the primary smell-processing hub called the piriform cortex, and several other brain regions that receive inputs from the olfactory bulb.

via Cold Spring Harbor Laboratory: Yushu Chen et al, High-throughput sequencing of single neuron projections reveals spatial organization in the olfactory cortex, Cell (2022). DOI: 10.1016/j.cell.2022.09.038

https://dx.doi.org/10.1016/j.cell.2022.09.038

And finally, a little something about how we use olfaction to navigate...

Flies smell the motion of odors and use it to navigate, study finds

Nov 2022, phys.org

https://phys.org/news/2022-11-flies-motion-odors.html

Flies can sense the direction of moving odor packets themselves, not just the wind.

Cool study design: They genetically modified fly antennae to detect light, then created fictive odor packets out of light and watched how the flies responded to these signals in both windless and windy environments.

via QBio Institute at Yale: Nirag Kadakia et al, Odour motion sensing enhances navigation of complex plumes, Nature (2022). DOI: 10.1038/s41586-022-05423-4

https://dx.doi.org/10.1038/s41586-022-05423-4

On Olfactory Navigation

I purposely read this book Supernavigators (2019) hoping to get some snippets on using our sense of smell to find things, and I wasn't disappointed. 

Humans were led to a random location within a room diffused with two odors. After brief sampling and spatial disorientation, they had to return to this location. Humans located the target with higher accuracy in the olfaction-only condition than in the control condition and showed higher accuracy than chance. 

-Jacobs, L.F.; Arter, J.; Cook, A.; and Sulloway, FJ. (2015). "Olfactory orientation and navigation in humans," PLOS 'One, 10(6), e0129387. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4470656/

Note there are two different versions of olfactory navigation -- one where you track an odor to its source (this relies heavily on bilateral input, aka stereo-olfaction) and the other, much more common for modern-day humans, is when you identify a place by its odor. We usually have our eyes open, and being the ocularcentric creatures that we are, we are likely to use visual cues and not even realize the odor-identity of a place. 

But it doesn't stop here, the rabbit hole continues, and this one goes all the way back to the golden days of behavioral science, when rats told us everything we wanted to know about ourselves: 

This report is ultimately based on rat experiments, with the "men" part being only conjecture by the researcher; and he concedes, "My argument will be brief, cavalier, and dogmatic. For I am not myself a clinician or a social psychologist. What I am going to say must be considered, therefore, simply as in the nature of a rat psychologist's ratiocinations offered free.

*Ratiocinations are another word for thoughts that also happens to remind the reader that we're talking about rats (he italicized the rat in ratiocinations).

The "mapmaking" happens during what they call "Vicarious Trial and Error" or "VTE'" and described as "the hesitating, looking-back-and-forth, sort of behavior which rats can often be observed to indulge in at a choice-point before actually going one way or the other." If you're not a scientist, you can probably just call it "thinking."

via Berkeley Labs: Tolman, E.C. (1948). "Cognitive maps in rats and men," Psychological Review, 55(4), p.189.

https://web.csulb.edu/~cwallis/382/readings/482/tolman.%20cognitive_maps_in_rats_and_men.1948.html

Image taken from the Silver Bible of Interior Design Standards

And with that, let us not forget that olfaction is the first sense. Before all the other ways we sense our environment, bacteria and fungi were using chemotaxis, detecting and navigating their way through a world of chemical gradients. The essay at the end of Hidden Scents, called "Olfactory Space and n-Dimensionality" tells the story of the primordial eukaryote as it chemo-taxis its way through evolution, past the multi-cellular organism, the chordata (animals with vertebrate), and eventually to the big-brained, smooth-skinned monkeys that we are today.

The neocortex is an outgrowth of the nose-brain, and not the other way around, and therefore olfaction can be a useful model for understanding the n-dimensional information network in which our brains operate. The world is typically understood as a 3-dimensional space, but in fact, from the perspective of the brain, we are navigating and interacting with an infinitely-dimensional information space. 

 

Hyper Dimensions in Olfactory Space

Artwork by Alex Grey

The title of this post is named after an article about categorizing smells, although it would work just as well as the title of a work of science fiction. It's from last August 2018, so it's old news by now; but that title isn't getting old anytime soon.

Probing the interconnected-ness of odors, and sketching a map of an omnicategorical odor network, the article starts out with a basic premise.

Let's say the olfactory system is designed to warn us of poisons in the environment. But a poison could be many chemicals, or a chemical we've never encountered before. So it would be necessary for the odors of those chemicals to be classified not by features intrinsic to the chemicals themselves, but by the likelihood of their co-occurrence with other chemicals. You can't be born with a database of chemicals to recognize and avoid. So instead, the hypothesis here is that an odor is only identified in its relationship to the other odors it's with.

This idea, at least to my ears, sounds really similar to the way statistical correlation text analysis can determine whether a piece of writing was written by a robot or not. (Also called visual forensics.)

It's way easier to visualize, so I'm taking these three images from the paper itself:

In the above 3 images, the first is a chunk of text written by a robot (most of the words are green, with a few yellows sprinkled in), the second is a real New York Times article (only half is green, the rest is yellow, with some red, and a sprinkle of purple) and the third picture is a clip from "the most unpredictable human text ever written", James Joyce's Finnegan's Wake (the colors green, yellow, red, purple are all evenly distributed about the page).

Green words are very predictably the next word. Yellow words are less likely to show up after the word they show up after. And red and purple are for when the next word is something you absolutely did not expect.

Because text-writing algorithms today use a statistical correlation program based on a compendium of written language (so they know what words typically occur together, and can therefore sound more like a normal person) the output of such algos will tend to look like the topmost image with all green words. Very predictable. The algos can't think for themselves, they can't "come up with" new stuff, and they can't be unpredictable. The whole point of writing an algorithm to do this is to prescribe what it's going to do in advance, i.e., it's predictable.

Bringing this back to olfaction, unfortunately there isn't a compendium of odor associations such as a Bible for smells or an encyclopedia for volatile organic compounds in nature. Furthermore, even if there were, we would need to augment it with a companion encyclopedia of the odors in the anthroposphere, because your supermarket isn't "nature" and yet it organizes a whole lot of our daily scentscape. One day though.

Notes:

Hyperbolic geometry of the olfactory space.

Yuansheng Zhou, Brian H. Smith, Tatyana O. Sharpee

Science Advances  29 Aug 2018: Vol. 4, no. 8, eaaq1458

DOI: 10.1126/sciadv.aaq1458

http://advances.sciencemag.org/content/4/8/eaaq1458

Catching a Unicorn with GLTR: A tool to detect automatically generated text.

Hendrik Strobelt and Sebastian Gehrmann. Association for Computational Linguistics: Proceedings of the 57th Annual Meeting of the Association for Computational Linguistics: System Demonstrations. Florence, Italy. July 2019. DOI:10.18653/v1/P19-3019

http://gltr.io

Subjective Cartography

Where you at? I’m at 5-spice, north of Orange Peel.

Can city 'smellfies' stop air pollution?

Mar 2017, BBC

The image I have above is from NYC 2011, but Kate McLean nonetheless. And now she’s going even further with her work. Artist and designer Kate McLean from Canterbury Christ Church University is now using her smellmaps to indicate pollution emissions. At the nexus, however, is language – that is, the words used to describe these places. I cut a piece here from the BBC article because it emphasizes this is the most interesting part, for me. For the project as well, it’s a serious point to consider.

“Clicking on a street on the London map allows you to zoom in and see how people have described the area, using terms related to emissions, nature, food, animals or waste.

“So where people have tagged pictures with words including "cars" or "petrol" or "exhaust", these would be classified as emissions-related in the system and the map would show more red.

“But can something built on people's subjective impressions of what they're smelling bear any relationship to objective data on air quality?

"Some people might say you're using social media, it's biased so you're just capturing most of the hipsters in East London," said Daniele Quercia, the computer scientist from Bell Labs who led the study.

So, for example, what happens if a bunch of Londoners come to New York and do this? What does the '5-spice' neighborhood of NYC smell like to a Londoner? And can we compare those maps? Now we’re talking.

On Space and Place

Confused John Travolta

The hypothalamus is called the seat of social behavior. The hippocampus is the thing that knows where you are, your internal GPS. Together, these brain parts, along with your olfactory system, of course, influence all of your decisions. Everything we do is dependent on where we are (or where we think we are) and who we’re with (or who we think…). Olfactory data informs these things. Places and the smell of those places are centrally located both in the memory and in the motivating, motility actuating parts of us. The emotions that drive us are informed by the smells of the places we are in.

This new report shows that there may be very specific cells that can tell who’s house you’re in. (The experiment is on male mice and other male’s habitats.) They’re looking to use this to help people with social disorders, like autism, schizophrenia, depression, and social anxiety. Anyway, this just points to the use of olfactory studies to help with larger social problems.

Smell tells intruder mice how to behave

phys.org, Jun 2016