They're using graphene sensors, they're using combinatorial coding, they're looking at the timing of the coding via the epithelium and not the spatial organization, and perhaps the most interesting finding, that good smells and bad smells are processed in a totally different way. And I'm sure artificial noses will have no problem telling the difference between good and bad smells; random note of interest, wild roses, which smell like an intoxicating combination of armpits and vaginas, is not just good, it's great, and I'll bet that would be really confusing to an electronic nose robot that's never had sex before.
Anyway, then they're looking real carefully at common chordata ancestors and insects alike for clues to how and where our olfactory genetic legacy came from.
But finally, we may now have the first ever odor map of the epithelium; only took a few hundred years of curiosity.
Image credit: Oxalic acid crystals during precipitation - James Dvorak - 1975 Nikon Photomicrography Competition 1st Place [link]
Lab-boosted olfactory receptor reveals new insights about how our sense of smell works
Oct 2025, phys.org
Researchers tweaked the C-terminal domains of ORs, resulting in increased OR cell-surface expression and sensitivity (100-fold improvement), and allowing them to "de-orphanize" several ORs, finding matching ligands for them.
via Givaudan the fragrance company: Roger Emter et al, Decoding human olfaction by high heterologous expression of odorant receptors detecting signature odorants, Current Biology (2025). DOI: 10.1016/j.cub.2025.09.041
AI-powered electronic nose detects diverse scents for health care and environmental applications
Apr 2025, phys.org
While conventional electronic noses (e-noses) have already been deployed in areas such as food safety and gas detection in industrial settings, they struggle to distinguish subtle differences between similar smells or analyze complex scent compositions.The research team was inspired by the biological mechanism known as combinatorial coding, in which a single odorant molecule activates multiple olfactory receptors to create a unique pattern of neural signals.The novel electronic nose uses a laser to process a thin carbon-based material (graphene) and incorporates a cerium oxide nano catalyst to create a sensitive sensor array. This single-step laser fabrication method eliminates the need for complex manufacturing equipment and enables high-efficiency production of integrated sensor arrays.
via Convergence Research Advanced Centre for Olfaction at Daegu Gyeongbuk Institute of Science and Technology: Hyeongtae Lim et al, Intelligent Olfactory System Utilizing In Situ Ceria Nanoparticle-Integrated Laser-Induced Graphene, ACS Nano (2025). DOI: 10.1021/acsnano.5c03601
AI model mimics brain's olfactory system to process noisy sensory data efficiently
May 2025, phys.org
Never heard this analogy before, good one: In this study, the Cornell researchers discovered exactly how the outer layers of the biological system — the olfactory epithelium and the outer layer of the olfactory bulb — perform computations that "create a firewall between the world and the brain."
Next, this development seems to focus on what I will call time instead of space, i.e., we aren't trying to figure out the sensory epithelial map of odor receptors because that doesn't really seem to matter much; instead we are now looking at the timing of the receptor or neuronal activity:
The researchers' work on the olfactory system has also yielded theoretical insights regarding spike-phase coding in the brain — a method by which neurons transmit information by tightly regulating the timing of their communication pulses. This common energy-conservation strategy, it is now clear, can also be leveraged for stable learning and regularization in practical scenarios where data can be noisy and scarce.
So look out for this:
"It suggests interesting parallels to recent work on quantization-aware training in machine learning..."
via Cornell Department of Psychology's Computational Physiology Lab and the AI for Science Institute: Roy Moyal et al, Heterogeneous quantization regularizes spiking neural network activity, Scientific Reports (2025). DOI: 10.1038/s41598-025-96223-z
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| Crystal of ascorbic acid - Richard B. Young - 1976 Nikon Photomicrography Competition 11th Place [link] |
Nonlinear neural network model reveals how fly brains reduce odor complexity
Jun 2025, phys.org
This is ultimately about dimension reduction - which is a way of reducing the complexity of sensory data coming into our brains.
A relatively simple nonlinear model known as t-distributed stochastic neighbor embedding (t-SNE) has been developed."The original t-SNE isn't biologically plausible — it's an engineering method rather than a neural network. We rewrote the algorithm so that it mimicked a biological neural network."The model consisted of three layers, each of which corresponded to specific groups of neurons in the fly brain. It also incorporated dopamine-dependent Hebbian plasticity — the concept that the connection between two neurons will become stronger if they fire at the same time in the presence of dopamine.
via RIKEN Center for Brain Science: Kensuke Yoshida et al, A biological model of nonlinear dimensionality reduction, Science Advances (2025). DOI: 10.1126/sciadv.adp9048
Fruity fly study uncovers neural circuits for sensing the pleasantness or unpleasantness of odors
Oct 2025, phys.org
Researchers developed a method of recording the activity of all neurons in each brain region of the fruit fly by combining two-photon microscopy and optogenetic cell labeling, and by building a connectome model. The model predicted that unpleasant odors were represented by feedforward excitation of neurons across the lateral horn region, while pleasant odors were derived from additional local inhibition.The most unexpected result was that the pleasantness and unpleasantness of odors are computed in circuits that are not only separate from each other, but also distinct in connectivity motifs. This means that in terms of the circuit, "good" is not simply the opposite of "bad".
via RIKEN Center for Brain Science: Makoto Someya et al, Distinct circuit motifs evaluate opposing innate values of odors, Cell (2025). DOI: 10.1016/j.cell.2025.08.032
Hagfish olfactory genes hint at ancient origins of vertebrate sense of smell
Dec 2025, phys.org
Recall the hagfish is something like the lapmprey; it's what happens when a fish first becomes a mammal; it's got fins but they're used like legs, and it's got the same nose-brain parts of a fish, but it smells air as well as water, so that's new, phylogenetically speaking. (And the water part of smells is in the TAAR trace amine-associated receptors, which if my memory serves correct do not contain burnt smells, because you can't burn things underwater. And as for the vomeronasal, those aren't supposed to be working for humans so we don't look at those.)
The researchers' findings reveal that certain olfactory receptor gene families have undergone substantial lineage-specific diversification, suggesting that the vertebrate common ancestor likely possessed a broader and more complex olfactory repertoire than previously proposed.In vertebrates, four major receptor families mediate olfaction; these include olfactory receptors (ORs), vomeronasal type 1 receptors (V1Rs), vomeronasal type 2 receptors (V2Rs), and trace amine-associated receptors (TAARs). However, the evolutionary origin and early diversification patterns of these receptor classes remain poorly understood.In this study, the researchers examined the hagfish genome for genes linked to ORs. In total, they identified 48 OR genes, two V1R genes, a surprisingly large set of 135 V2R genes, and no TAAR gene.Notably, the presence of true V2Rs in hagfish overturns the long-standing assumption that these receptors evolved only in jawed vertebrates.Conversely, the results of this study suggest that functional V2Rs were already present in the common ancestor of all vertebrates and that they subsequently diversified in a lineage-specific manner.
via University of Tsukuba: Hirofumi Kariyayama et al, Hagfish olfactory repertoire illuminates lineage-specific diversification of olfaction in basal vertebrates, iScience (2025). DOI: 10.1016/j.isci.2025.114118
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| Crystals in quenched steel in a matrix of austenite - Harlan H. Baker - 1977 Nikon Photomicrography Competition 7th Place [link] |
Insect-inspired robot tracks odors even with only one working 'antenna'
Mar 2026, phys.org
I'm just here to say it's funny how they don't use the beating wings method, the one just discovered in the past year, for enriching the air sample with a better representation of the ambient air from less sensors (one lost antennae).
Bio-inspired robotic system can locate odor sources even if one of its two sensors fails: The silkmoth Bombyx mori utilize a bilateral pair of antennae to enable accurate localization of an odor source. But if one antenna is lost, they use the positional angle of their head to dynamically integrate odor location information.
via National Institute of Informatics, Tohoku University: Shunsuke Shigaki et al, Insect-inspired adaptive behavioral compensation strategy against olfactory sensory deficiency for robotic odor source localization, npj Robotics (2026). DOI: 10.1038/s44182-026-00080-5
Scientists create first-ever 'smell map' of the nose's smell receptors
Apr 2026, phys.org
(This is a very, very big deal in the smell science world)
The team discovered that unlike what scientists had long believed, the neurons expressing these receptors have a high degree of spatial organization: They form horizontal stripes based on receptor type from the top of the nose to the bottom."Our results bring order to a system that was previously thought to lack order, which changes conceptually how we think this works."Moreover, the researchers established that the receptor map in the nose matches up with smell maps in the olfactory bulb of the brain, providing clues about how information moves from the nose to the brain.Maps have long existed that describe how receptors in the eye, ear, and skin are organized to capture and interpret auditory, visual, and touch information—and scientists have figured out how these maps correspond with those inside the brain.However, "Olfaction has been the one exception; it's the sense that has been missing a map for the longest time."
(Again, very big deal)
In their new study, the researchers combined single-cell sequencing and spatial transcriptomics techniques to examine around 5.5 million neurons in more than 300 individual mice. The first technique allowed them to identify which smell receptors were expressed by neurons in the nose, and the second let them determine the locations of those receptors."This is now arguably the most sequenced neural tissue ever, but we needed that scale of data in order to understand the system."They discovered that the neurons are organized into tight, overlapping, horizontal stripes from the top of the nose to the bottom based on the type of smell receptor they express. This highly organized receptor map was consistent across the mice and mirrored the organization of smell maps in the brain, just like researchers have observed in vision, hearing, and touch.
via Blavatnik Institute at Harvard Medical School: A spatial code governs olfactory receptor choice and aligns sensory maps in the nose and brain, Cell (2026). DOI: 10.1016/j.cell.2026.03.051
Also: Spatial Organization and Detection of Social Odors in Mouse Primary Olfactory System, Cell (2026). DOI: 10.1016/j.cell.2026.03.053. www.cell.com/cell/fulltext/S0092-8674(26)00389-2
