Cell: A neural map of the sense of smell

Each glomere receives signals from its own subset of olfactory neurons, which are randomly distributed in the animal's nose, but they all detect odors
in the same way.
Since the 1990s, researchers have known that every subpopulation of olfactory neurons carries a uniquely shaped receptor protein (thanks to a process based on random genes) that specifically targets different odor molecules
.

This raises a neuroscience puzzle: How does each randomly distributed olfactory detection cell in the nose send a signal to a specific glomere within the olfactory bulb? It's like 50 friends scattered across the city who came to the same apartment
without knowing the address at first.
Somehow, they were born to know where
to go.

Key insights into how olfactory systems can achieve wiring accuracy seem to be just around the corner
.
In a study published in the journal Cell, a team led by Zuckerman Institute principal investigator Stavros Lomvardas, Ph.
D.
, and M.
D.
candidate Hani Shayya speculated about the central tissue process
between the snout sensory cells of mice and their glomerular targets in the brain's olfactory bulb.

At the heart of their discovery lies in the shape of each receptor protein, as they have a unique 3D shape
in the endoplasmic reticulum (ER), a tubular component of the cell.
The shape of each protein is determined by a unique sequence of
its amino acid composition.

The researchers found that each amino acid sequence puts some level of pressure on the endoplasmic reticulum (imagine stuffing all sorts of things into a sock
).
These varying degrees of endoplasmic reticulum pressure are like a scale setting, and the way in which they are not clear is clear
.

Each setting triggers a gene-directed process through which sensory cells effectively direct their axons (through patterns of "guiding molecules") to target glomeruliis within the olfactory bulb
.
In this way, each subset of sensory cells with the same shape of the receptor protein eventually projects its axons onto the
exact same glomeruli.
Without this receptor-glomerular mapping, roses may smell like rotten eggs and vice versa
.

"It's so exciting," Dr.
Lomvardas said, "that the system has found a way to create a way to code, hard-link genes that translate randomly selected receptor identities into very precise targets
in the olfactory bulb.
" ”

He noted that neurodegenerative diseases, including Alzheimer's and Parkinson's, often involve olfactory deficits
early in the disease.
This, he said, suggests that early detection of high-precision connection disruptions in olfactory systems may become "clinically important
.
"

Shayya points to another tempting possibility
.
Perhaps, olfactory neurons are not unique
in the way endoplasmic reticulum stress connects with downstream neurons.
Shayya said: "If it turns out that all neurons do this, this discovery will help us learn more about the brain
.
"

essay

ER stress?transforms random olfactory receptor choice into axon targeting precision