Newsstand Menu

Sniffing out the brain’s smelling power

Image of the olfactory system, sensory system used for smell
CSHL neuroscientists have discovered that a historically understudied class of neurons in the olfactory bulb, called tufted cells, seen here in cyan, play a major role in odor recognition. Image: © Design Cells - stock.adobe.com

Since their discovery over 100 years ago, neurons in the brain’s olfactory bulb called tufted cells have been difficult to study. The close proximity between tufted cells and other neurons called mitral cells, restricted the ability to dissect each individual neuron’s activity. By leveraging fluorescent genetic markers and new optical imaging technologies, Cold Spring Harbor Laboratory (CSHL) neuroscientists were able to compare the neurons’ activity.

Image of tufted and mitral cells
The images in the left column show mitral cells (top) and tufted cells (bottom) in the mouse olfactory bulb. The illustrations in the right column show how each type of neuron’s circuitry is organized in the olfactory bulb.

CSHL Associate Professor Florin Albeanu and Assistant Professor Arkarup Banerjee discovered tufted cells are better at recognizing smells than mitral cells. They’ve found tufted cells are essential to one of two parallel neural circuit loops that help the brain process different odor features. The findings help explain how the brain takes in sensory information that influences behavior and emotions.

The researchers exposed mice to various odors, from fresh mint to sweet bananas, at different concentrations. They simultaneously tracked the neural activity of the two cell types and found tufted cells outperformed mitral cells. They were faster and better at distinguishing smells. They also captured a wider range of concentrations. While this illuminated a new role for tufted cells, it also led to a new unanswered question. “If tufted cells are actually better at recognizing odors, what then, is the function of mitral cells?” said Albeanu.

Albeanu and Banerjee suggest that perhaps mitral cells are part of a neural feedback loop that helps to enhance and predict certain smells that are important for an animal to learn and to respond to throughout its lifetime. This can guide animals locating odors in the environment. Banerjee explains:

“If you can’t tell whether it’s high [intensity] versus low [intensity], then you can’t track an odor. There’s no way to know that you’re actually getting closer to the odor source if you can’t tell the difference.”

The two neural circuit loops offer novel explanations for how the brain processes sensory information. Going forward, the new genetic and optical imaging tools used by the CSHL team, that include postdoc Honggoo Chae and graduate student Marie Dussauze, can uncover more undervalued neurons involved in sensory processing.

Written by: Luis Sandoval, Communications Specialist | sandova@cshl.edu | 516-367-6826


Funding

Brain & Behavior Research Foundation, Simons Foundation, National Science Foundation, National Institutes of Health

Citation

Chae, H., et al., “Long-range functional loops in the mouse olfactory system and their roles in computing odor identity”, Neuron, September 28, 2022. DOI: 10.1016/j.neuron.2022.09.005

Stay informed

Sign up for our newsletter to get the latest discoveries, upcoming events, videos, podcasts, and a news roundup delivered straight to your inbox every month.

  Newsletter Signup

Principal Investigator

Dinu Florin Albeanu

Dinu Florin Albeanu

Associate Professor
Ph.D., Harvard University, 2008

Tags