from the rose-by-any-other-name-smells-as-sweet-unless-there-are-a-bunch-of-them dept.
The delicate fragrance of jasmine is a delight to the senses. The sweet scent is popular in teas, perfumes and potpourri. But take a whiff of the concentrated essential oil, and the pleasant aroma becomes almost cloying. Indeed, part of the flower's smell comes from the compound skatole, a prominent component of fecal odor.
Our sense of smell is clearly a complex process; it involves hundreds of different odorant receptors working in concert. The more an odor stimulates a particular neuron, the more electrical signals that neuron sends to the brain. But researchers at UC Santa Barbara discovered that these neurons actually fall silent when an odor rises above a certain threshold. Remarkably, this was integral to how the brain recognized each smell. "It's a feature; it's not a bug," said Matthieu Louis, an associate professor in the Department of Molecular, Cellular, and Developmental Biology.
The paradoxical finding, published in Science Advances, shakes up our understanding of olfaction. "The same odor can be represented by very different patterns of active olfactory sensory neurons at different concentrations," Louis said. "This might explain why some odors can be perceived as very different to us at low, medium and very high concentrations. Consider for instance the smell of a ripe banana from a distance (sweet and fruity) versus up-close (overpowering and artificial)."
[...] Scientists thought that neurons would effectively max out above certain odor concentrations, at which point their activity would plateau. But the team led by Louis' graduate student, David Tadres, found the exact opposite: Neurons actually fall silent above a certain level, with the most sensitive ones dropping off first.
[...] Having certain sensory neurons drop out as others join in might help preserve the distinction between odors at high concentrations. And this could prove important for survival. It might prevent poisons and nutrients that share certain compounds from smelling alike when you take a big whiff of them.
It could also have consequences for how we perceive odors. "We speculate that removing successive high-sensitivity olfactory sensory neurons is like removing the root of a musical chord," Louis said. "This omission of the root is going to alter the way your brain perceives the chord associated with a set of notes. It's going to give it a different meaning."
Journal Reference:
David Tadres, Philip H. Wong, Thuc To, et al., Depolarization block in olfactory sensory neurons expands the dimensionality of odor encoding, Sci Adv, 2022. DOI: https://doi.org/10.1126/sciadv.ade7209
(Score: 2) by DannyB on Wednesday February 15, @08:12PM
I would prefer that an implementation not place an artificial limit in the olfactory censors. Instead, do any input limiting during the analysis of the meaning of those inputs from the censers.
How often should I have my memory checked? I used to know but...
(Score: 3, Interesting) by Anonymous Coward on Wednesday February 15, @10:17PM
From the linked article (which I found excellent--thanks to the submitter!):
That is some fancy lab work, to get electrodes into fruit fly larvae! I'll guess this experiment fits in the "very hard to duplicate" category--how many labs are there that can do that kind of micro-sensing?
Something similar happened with this old paper, "What the frog's eye tells the frog's brain" https://hearingbrain.org/docs/letvin_ieee_1959.pdf [hearingbrain.org] "In this paper, we analyze the activity of single fibers in the optic nerve of a frog."
Jerry Lettvin told the story of several labs trying to repeat his results but failing on the instrumentation side, likely because they didn't have an EE as part of the team.
(Score: 1) by Runaway1956 on Wednesday February 15, @11:56PM
I suppose this explains why working on a pig farm is bearable. Eventually, you overload the pig shit sensors, and they stop reporting in.
Abortion is the number one killed of children in the United States.