# Using functionally-defined glomeruli to probe circuit function in the mammalian olfactory bulb

> **NIH NIH R01** · UTAH STATE HIGHER EDUCATION SYSTEM--UNIVERSITY OF UTAH · 2021 · $384,690

## Abstract

PROJECT SUMMARY
 We seek to better understand how the brain processes olfactory information by focusing on how circuits
of the olfactory bulb control two fundamental aspects of sensory processing: the relationship between sensory
input and olfactory bulb output as a function of stimulus intensity, and tuning of response specificity by lateral
inhibition. Models of how olfactory bulb circuits mediate these operations exist, but generating and testing
rigorous predictions from them has been limited by a lack of understanding of how circuits are organized with
respect to olfactory bulb glomeruli. Glomeruli represent individual odorant receptors and so constitute the
fundamental unit of information processing at this stage.
 Our strategy is to overcome this gap by, first, better defining the functional map of odor 'space' across
glomeruli of the dorsal olfactory bulb. To achieve this we will functionally define glomeruli in terms of the
odorants to which they have maximal sensitivity as well as their relative sensitivities across a carefully-selected
odorant panel, yielding the first `odor sensitivity' map of the dorsal olfactory bulb and allowing for the rapid and
reliable identification of individual glomeruli across animals. We will use these data to uncover new insights into
the organization of glomerular odor maps and to generate a public resource for further exploration by the
neuroscience community. We will next use this knowledge to rigorously test alternative models for how specific
circuits shape the input-output functions of the olfactory bulb by comparing intensity-response functions of
sensory inputs and glomerular outputs and by selectively removing particular interneuron types from the
olfactory bulb network. We will also test alternative models for how inhibitory connections between different
glomeruli are organized and how they may be shaped by odor experience, using odorants that selectively
activate different combinations of identified glomeruli.
 Our experimental strategy builds on innovative approaches that are key to achieving a new level of
understanding of how odor representations are transformed by olfactory bulb circuits. First, we are able to
repeatedly identify and target many glomeruli across the dorsal olfactory bulb using a small number of
diagnostic odorants and to efficiently map responses to many odorants in a single experiment. Second, we are
able to selectively image from sensory inputs to glomeruli, projection neuron outputs from glomeruli, or both
simultaneously, allowing us to precisely characterize input-output transformations by olfactory circuits.
 Finally, we will develop an improved model of the olfactory bulb network that is highly constrained by
experimental data and which should lead to new insights into how this network alters odor representations and
enable new predictions that can be tested with further circuit manipulations or behavioral assays.

## Key facts

- **NIH application ID:** 10241984
- **Project number:** 5R01NS109979-04
- **Recipient organization:** UTAH STATE HIGHER EDUCATION SYSTEM--UNIVERSITY OF UTAH
- **Principal Investigator:** DALE M WACHOWIAK
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $384,690
- **Award type:** 5
- **Project period:** 2018-09-30 → 2023-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10241984

## Citation

> US National Institutes of Health, RePORTER application 10241984, Using functionally-defined glomeruli to probe circuit function in the mammalian olfactory bulb (5R01NS109979-04). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10241984. Licensed CC0.

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