How computer network models could help us better understand our sense of smell

A person wafts the smell coming from a pan of food cooking on a stove.
Researchers at VCU, the University of Arkansas and Southern Methodist University are testing how the brain distinguishes exhaled odors that originate in the mouth. (Getty Images)

The sense of smell plays an important role in how we perceive food and drink flavors, largely due to odors that originate in the mouth and enter the nose via the back of the throat in a process called retronasal olfaction.

Cheng Ly, Ph.D.
Cheng Ly, Ph.D.

A team of researchers from the University of Arkansas, Virginia Commonwealth University and Southern Methodist University has received a $922,531 grant from the National Science Foundation to gain a better understanding of how this process works.

The researchers will combine direct measurements of the brain in action with computer simulations of airflow through the nose and neural networks. They will test the hypothesis that different forces on the nose caused by reversing airflow through the nasal cavity are responsible for how the brain distinguishes exhaled retronasal odors from inhaled odors.

Cheng Ly, Ph.D., associate professor in the Department of Statistical Sciences and Operations Research in the VCU College of Humanities and Sciences, is one of three co-principal investigators on the grant, along with Woodrow Shew, Ph.D., at the University of Arkansas and Andrea Barreiro, Ph.D., at Southern Methodist University.

Ly, an expert in computational neuroscience focusing on the variability, or fluctuations, of cortical neural network activity and dynamics with sensory inputs, recently discussed his role in the study.

Why is it important to understand how retronasal olfaction works?

Retronasal olfaction (sensing smells that originate in the back of the throat) is important because it happens while eating. So understanding this better could have broad implications for the obesity epidemic because we know smells are strongly tied to appetite and food taste, as well as regulating eating behaviors.

As part of the study, you will be developing computer model neural networks. What will that entail and how will that fit within the larger study?

Except for a few brain imaging studies, there is little known about how we sense smells retronasally. We have exciting unpublished data where some brain cells selectively respond to retronasal odors. To fully understand this (and many other open questions), we need to use computational and mathematical modeling because current experimental tools cannot probe all of the possible attributes that shape retronasal olfaction.

There are currently no computer network models of retronasal olfaction. In this project, we will develop new models to explain the data and make predictions about how pharmacologically blocking certain synaptic connections changes retronasal olfaction. We hope to validate predictions with new data collected from the other co-principal investigators on this grant. The experimental and modeling components of this project are closely tied together.

Retronasal olfaction is important because it happens while eating. So understanding this better could have broad implications for the obesity epidemic because we know smells are strongly tied to appetite and food taste, as well as regulating eating behaviors.

What inspired your interest in studying this topic?

My whole research career has been dedicated to computational/mathematical neuroscience because I like attacking problems from different angles, and many sub-disciplines tie in to this type of research. Making progress on understanding how the brain senses stimuli requires using tools from applied math, computing, biophysics, statistics, signal processing, electrophysiology, etc. I'm especially fascinated by randomness; unlike other systems or machines, the brain activity responds differently to the same stimuli, and appears to be very “noisy.” This complexity is better understood with theoretical and computational models.

Anything else you'd like to add?

I'm thankful for previous funding by the Simons Foundation that funded my travels that led to this collaboration. I feel very fortunate to work on such interesting research, especially being a first-generation college student growing up in an immigrant family that escaped the Cambodian civil war in the late 1970s. Life is good.

Subscribe to VCU News

Subscribe to the VCU News newsletter at newsletter.vcu.edu and receive a selection of stories, videos, photos, news clips and event listings in your inbox every Monday and Thursday.