# The perception of odor blends and mixtures: Modulation, Inhibition and Enhancement of Olfactory Receptors alters perception of complex blends

> **NIH NIH R01** · COLUMBIA UNIV NEW YORK MORNINGSIDE · 2024 · $339,140

## Abstract

Project Summary/Abstract
This is a continuation of an existing program funded by an RO1 that seeks to understand fundamental
questions about the nature of the olfactory stimulus and its discrimination by primary sensory receptors, in
order to better grasp the nature of the signal being forwarded to the brain. We supplement the standard
organic chemistry approach to odor classification with one that includes a biological perspective based in
principles of medicinal chemistry pioneered in the pharmaceutical industry and drug development. This allows
us to not only consider physical chemical characteristics of molecules but also how they interact with the many
olfactory receptors. This work, like much of olfactory cellular studies, utilized monomolecular stimuli to probe
receptor function. However the olfactory system is usually confronted with complex stimulus blends of
between tens and hundreds of components. To better understand the complexity of mixture discrimination we
have begun utilizing a novel microscopic technique, SCAPE – that allows us to visualize large numbers of
individual neurons in an intact tissue with single cell temporal and spatial resolution. Preliminary data from that
work showed a remarkable and unexpected degree of inhibition and enhancement of responses by one
component of the mixture on other components of the mixture. This raises a fundamental issue in olfactory
discrimination as there appears to be considerable interaction between stimuli at the primary receptor, raising
crucial questions about how the brain perceives and manages signals that differ depending on the presence of
particular odors in a blend. It appears that many, if not all, odors can act as either an agonist or antagonist at
different receptors. Thus depending on whether or not an antagonist to odor X, for example, exists in the
blend, the signal from odor X will appear different to the brain. This level of complexity is unusual in sensory
systems where signal processing of this sort occurs in the brain not the primary receptors. Understanding
higher brain processing olfactory signals will require a greater understanding of the initial events at primary
receptors. The olfactory code is more than the additive contributions of the olfactory receptors.

## Key facts

- **NIH application ID:** 10744182
- **Project number:** 5R01DC013553-10
- **Recipient organization:** COLUMBIA UNIV NEW YORK MORNINGSIDE
- **Principal Investigator:** Stuart J Firestein
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $339,140
- **Award type:** 5
- **Project period:** 2014-07-15 → 2024-11-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10744182

## Citation

> US National Institutes of Health, RePORTER application 10744182, The perception of odor blends and mixtures: Modulation, Inhibition and Enhancement of Olfactory Receptors alters perception of complex blends (5R01DC013553-10). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10744182. Licensed CC0.

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