A map for the sense of smell
Evolution has structured flies with an energy-efficient olfactory system


Date:
January 31, 2022
Source:
University of California - San Diego
Summary:
Our sensory systems provide us with immediate information about
the world around us. Researchers have created the first sensory map
for smell. The map details how the fruit fly's olfactory receptor
neurons, the components that sense smell, are organized within
the insect's sensory hairs.



FULL STORY ==========================================================================
The distinctive smell of a flower... the unmistakable aroma of
coffee... the dangers linked with inhaling smoke fumes. Sensory systems
have evolved to provide us with immediate, finely tuned information
about the world around us, whether they are colors processed through
our visual system or certain pitches interpreted through our hearing.


==========================================================================
This barrage of information is processed by our sensory
systems. Scientists have uncovered maps that depict how sensory neurons
are arranged based on their function to effectively process such
information. This kind of functional map, however, had not yet been
identified for the sense of smell. University of California San Diego researchers have now described such a smell sensory map in fruit flies. On
the surface of fly antennae, where odorous chemicals are detected, the scientists have discovered how the fly olfactory system is organized,
and why.

This new map was published in the Proceedings of the National Academy
of Sciences by a team lead by graduate student Shiuan-Tze Wu from the laboratory of Biological Sciences Associate Professor Chih-Ying Su. The
study details how the fly's olfactory receptor neurons, the components
that sense smell, are organized within the sensory hairs.

"We are constantly being bombarded by hundreds of odorous chemicals in
our environment," said Su, the corresponding author of the study. "We
have described a peripheral mechanism that has allowed the fly to make
sense of such overwhelmingly complex stimuli." The researchers provide evidence that the fruit fly's olfactory system, which Su described as
simple yet elegant, is structured to give the insect the ability to
make quick assessments of odors in an unusual way that circumvents
synaptic communication, which is metabolically expensive. Rather,
the insect's olfactory receptor neurons (ORNs) communicate through
electrical interactions with nearby ORNs. This offers an energy-saving, "metabolically cheap" way to process "meaningful odor blends without
involving costly synaptic computation," the researchers note in the paper.

The study describes how compartments with two ORNs are arranged to detect
cues with opposite meanings for the fly. Such cues either promote or
inhibit certain behaviors -- to quickly and efficiently assess complex
odors in their environment.

"This arrangement provides a means to both evaluate and shape the countervailing sensory signals relayed to higher brain centers for
further processing," according to the paper.

In this study, the Su lab collaborated with UC San Diego Neurobiology
Assistant Professor Johnatan Aljadeff, who built a mathematical model
which explains how electrical interactions help in extracting relevant information.

"In asking questions about the functional meaning of this organization,
we found that nature has chosen a specific way of structuring this sensory assay," said Aljadeff. "If we can understand the principle of this type
of processing, there could be future engineering applications." Aljadeff
is funded by a Defense Advanced Research Projects Agency (DARPA) Young
Faculty Award to investigate such questions.

Wu, the first author of the study, is proud to be part of the team that
made this fundamental discovery. He marvels at the elegance of the system
by which fly ORNs compute countervailing cues and points to parallels
in the way that visual systems contrast color shades to help us perceive
the difference between red and green, for example.

The full author list is: Shiuan-Tze Wu, Jen-Yung Chen, Vanessa Martin,
Renny Ng, Ye Zhang, Dhruv Grover, Ralph Greenspan, Johnatan Aljadeff
and Chih-Ying Su.

========================================================================== Story Source: Materials provided by
University_of_California_-_San_Diego. Original written by Mario
Aguilera. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Shiuan-Tze Wu, Jen-Yung Chen, Vanessa Martin, Renny Ng, Ye Zhang,
Dhruv
Grover, Ralph J. Greenspan, Johnatan Aljadeff, Chih-Ying Su. Valence
opponency in peripheral olfactory processing. Proceedings of the
National Academy of Sciences, 2022; 119 (5): e2120134119 DOI:
10.1073/ pnas.2120134119 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/01/220131110515.htm

--- up 8 weeks, 2 days, 7 hours, 13 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)