Biological complexity: how we smell odors; very well (Introduction)

by David Turell , Sunday, April 12, 2020, 21:27 (1474 days ago) @ David Turell

More studies on odor identification:

https://www.sciencedaily.com/releases/2020/04/200409141541.htm

"The cells in the nose that detect smells each have one of a wide range of different sensors, or receptors; humans, for example have up to 400 different types of these receptors. For a pure, single odor, only the cells whose receptors are sensitive to that odor will become active, sending a code to the brain that it can identify as that odor. But for more complex mixtures of odors, this code would become increasingly complex to interpret.

"The researchers expected to see that the cells activated by mixtures of odors would be equivalent to adding together responses to individual odors. In fact, they found that in some cases an odor can actually turn off a cell's response to another odor in a mixture; in other cases, a first odor could amplify a cell's response to a second odor.

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"The team's data challenged the traditional view that the brain makes sense of a mixture of scents by figuring out all of the individual components. It confirmed what perfumers have long known: combining different scents can create a certain experience on its own, essentially becoming an entirely new scent that can provide a completely different experience.

"'We were excited to find that these changes in the code happened in the nose, before signals even get to the brain," said Lu Xu, a doctoral candidate in the Firestein lab and the co-first author of today's study. "We think that these effects could help us to detect and identify a much larger range of odors and mixtures than a simple additive code could convey."

"'Our results showed that scent molecules can both activate and deactivate receptors, masking other scents not by overpowering them, but by changing the way cells respond to them," said Dr. Hillman, who is professor of biomedical engineering at Columbia School of Engineering and Applied Science. "These findings could actually be very useful, for example to make better air fresheners that actually block out any unwanted smells."

"'These results are also exciting because we didn't expect that this kind of receptor could be enhanced or suppressed in this way," added Dr. Firestein. "Being able to change the way a receptor responds to one substance is very important for drug development. Our studies in the nose actually shed new light on possible ways to modulate the response of other cell types that might be involved in disease.'"

Comment: A very complex system which does a lot of sorting in the olfactory bulb before sending signals to the brain. This is one area where the specialization of humans changed nothing.