News Release 

New insights into how the brain perceives and processes odors

Scientists probe the neural basis of rodents' keen sense of smell

Society for Neuroscience

CHICAGO -- New research makes advances in understanding how smells are perceived and represented in the brain. The findings were presented at Neuroscience 2019, the annual meeting of the Society for Neuroscience and the world's largest source of emerging news about brain science and health.

Olfactory cues provide essential information for finding food, navigation, predator avoidance, and social interactions, among other functions. Yet our understanding of how the brain perceives and processes smells lags behind our understanding of the neural basis of other senses, such as vision.

Today's new findings show that:

  • Neurons in early odor-processing areas of mice respond quickly to dynamic features of airborne odors, which may help the brain track sources of odor molecules in complex environments (Suzanne Lewis, University of Washington).
  • Fast sniffing can improve the ability of mice to focus on the most relevant information about an odor to track its source (Roman Shusterman, University of Oregon Institute of Neuroscience).
  • In mice, odors can serve as landmarks to guide navigation by increasing the number of cells that show location-specific activity in the hippocampus, a brain area important for spatial navigation (Walter Fischler, Columbia University).
  • By mapping neuronal connections using DNA sequencing, scientists uncovered the building blocks of an olfactory circuit in mice that appears to send odor information to multiple different brain areas (Yushu Chen, Cold Spring Harbor Laboratory).
  • Individual scents are represented in the brains of mice by timed sequences of cell activation, in which both the cells activated and the order in which they are turned on are important (Dmitry Rinberg, New York University Langone Health).

"The sense of smell is one of the last mysteries in sensory neuroscience," said Alexander Fleischmann, PhD, a professor at Brown University who studies sensory perception and behavior. "This research advances our understanding of how the brain perceives, represents and navigates a complex olfactory environment."

This research was supported by national funding agencies including the National Institutes of Health and private funding organizations. Find out more about olfaction and other senses on BrainFacts.org.

Related Neuroscience 2019 Presentation
Minisymposium: Sensory Circuits for Vision and Smell: Integrating Molecular, Anatomical, and Functional Maps
Tuesday, Oct. 22, 8:30 - 11:00 a.m., Room S105

Olfaction Press Conference Summary

  • Advances in research are adding to our understanding of how the brain perceives, represents and processes smells to guide behaviors such as navigation and finding resources.

Processing of Intermittent Odor Plumes Through Population Activity Between Glomerular Networks in the Mouse Olfactory Bulb
Suzanne Lewis, slewis4@uw.edu, Abstract 399.21

  • Tracking the source of an odor is challenging due to the complex ways that airborne odors travel through the environment.
  • To determine which properties of an airborne odor plume may be important for locating its source, researchers observed brain activity in mice as the strength of an odor changed over time.
  • Researchers observed high levels of neural activity in the initial odor-processing brain region, the olfactory bulb, after a rapid change in the strength of an odor.
  • Computer simulations of three-dimensional odor flow show how this rapid information could be used by a simulated searcher to track odors in complex environments, work that could guide the development of next-generation robotic noses.

Active Sampling Optimizes Processing of Fluctuations in Odor Concentration
Roman Shusterman, roma.shusterman@gmail.com, Abstract 399.19

  • A faster rate of sniffing improves how well mice can track the source of an odor, suggesting that the olfactory system is able to use dynamic sensory information.
  • Neural activity in the olfactory bulb of mice responds to rapid changes in odor concentrations but not unchanged levels in consecutive sniff cycles.
  • Fast sniffing helps the brain filter out irrelevant information, improving the animal's ability to locate an odor source more efficiently.

The role of Olfactory Landmarks in Place Cell Formation and Navigation
Walter Fischler, wmf2107@columbia.edu, Abstract 663.18

  • The hippocampus, a brain area important for spatial navigation, combines information about odors and movement through space to create a memory of a journey.
  • Mice can recognize odors as spatial landmarks and use them to improve navigation toward a goal location.
  • Such landmarks increase the number of neurons in the hippocampus that act as "place cells," which show location-specific activity and are thought to help to create a cognitive map of space.

The Logic of Olfactory Bulb Outputs Revealed by High-Throughput Single-Neuron Projection Mapping Using Sequencing
Yushu Chen, yuchen@cshl.edu, Abstract 399.27

  • Many of the properties of odor molecules that are important for perceiving smells and how they are represented by circuits in the brain are poorly understood.
  • In mice, researchers mapped neuronal connections that convey odor information from the olfactory bulb to the rest of the brain.
  • The researchers used a new technique called MAPseq, which uses DNA sequencing to quickly map the projections of thousands of neurons in a single animal.
  • The olfactory bulb appears to send different information about odors separately to different groups of brain areas, which may allow the information to be processed in multiple ways and drive different behaviors.

Mapping Olfactory Codes to Perceptual Spaces With Synthetic Optogenetic Odors
Dmitry Rinberg, rinberg@nyu.edu, Abstract 635.04

  • In a specially engineered strain of mice, smell circuits in the brain can be switched on and off by shining light on the cells.
  • Researchers combined mathematical modeling and experiments with these mice to identify the combination of olfactory cells that are responsible for representing a specific scent.
  • They found that each smell is not only represented by which cells become activated but also the order in which those cells are turned on, meaning that scents are registered in the brain through timed sequences of cell activation.

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About the Society for Neuroscience

The Society for Neuroscience is the world's largest organization of scientists and physicians devoted to understanding the brain and nervous system. The nonprofit organization, founded in 1969, now has nearly 37,000 members in more than 90 countries and over 130 chapters worldwide.

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