Neuron New Technology Unlocks Hard-to-Study 'Sense of Smell'

Since its discovery more than 100 years ago, neurons known as clustered cells in the brain's olfactory bulb have been difficult to study
.
The distance between clustered cells and other neurons, known as monastic cap cells, is too close, limiting the ability to analyze the activity of
each neuron.
By utilizing fluorescent genetic markers and new optical imaging techniques, neuroscientists at Cold Spring Harbor Laboratory (CSHL) were able to compare neuronal activity
.

CSHL Associate Professor Florin Albeanu and Assistant Professor Arkarup Banerjee found that clustered cells are better at recognizing odors
than monk cap cells.
They found that clustered cells are essential for helping the brain process one of two parallel neural circuits with different odor signatures
.
These findings help explain how the brain receives sensory information
that affects behavior and mood.

The researchers exposed the rats to different concentrations of a variety of odors, from fresh mint to sweet bananas
.
They tracked neural activity in both cell types at the same time and found that clustered cells were superior to monk cap cells
.
They identify odors faster and better
.
They also captured a wider range of concentrations
.
While this reveals a new role for clustered cells, it also leads to a new unanswered question
.
"If clustered cells are really better at recognizing odors, what is the function of monk cap cells?" Albeanu said
.

Albeanu and Banerjee believe that monk hat cells enhance important odors
.
They are part of a neural feedback loop that can help animals distinguish priorities, for example, food or the smell
of a predator.
In contrast, clustered cells are part of a second feedback loop that helps deal with odor intensity and recognition
.
This can guide the animal to locate the odor
in the environment.
Banerjee explains: "If you can't tell if it's high [intensity] or low [intensity], then you can't track the smell
.
If you can't tell the difference, there's no way to know if you're really closer to the source of the
smell.
”

These two neural circuits offer new explanations
for how the brain processes sensory information.
Going forward, the new genetic and optical imaging tools used by the CSHL team, including postdoc Honggoo Chae and graduate student Marie Dussauze, could uncover more underrated neurons involved in sensory processing
.

Long-range functional loops in the mouse olfactory system and their roles in computing odor identity