# Targeting of sensory axons in the olfactory bulb

> **NIH NIH R01** · UNIVERSITY OF PENNSYLVANIA · 2021 · $489,639

## Abstract

PROJECT SUMMARY/ABSTRACT
The objective of this proposal is to understand how the first elements of olfactory circuitry are correctly wired
together during embryonic development. Odorant sensing neurons project axons from the olfactory epithelium
to the olfactory bulb in the brain. Each olfactory sensory neuron in the epithelium chooses a single odorant
receptor to express from a very large gene repertoire. Remarkably, all of the sensory neurons that have
chosen the same odorant receptor to express extend axons that converge together in specific reproducible
locations within the olfactory bulb. This research proposal addresses how olfactory sensory axons so precisely
locate their specific targets in the brain. This project takes advantage of the relative simplicity of the zebrafish
olfactory system and its developmental and experimental accessibility to study the guidance of sensory
neurons between the olfactory epithelium and the bulb. In the first aim, the hypothesis that transcription factors
coordinately direct the expression of particular odorant receptors and axonal guidance receptors will be tested.
This should help determine how certain groups of odorant receptors and guidance receptors are expressed
together in the same sensory neurons. In the second and third Aims, axonal guidance molecules that direct the
axons of olfactory sensory neurons to their specific targets in the olfactory bulb will be identified and
characterized in mutant embryos. Thus far, this project has identified 12 signaling proteins that contribute to
olfactory sensory axon guidance. As this project identifies additional guidance molecules, their specific
functions in selective fasciculation, axon branch selection, and target field recognition will be studied in detail.
These studies are building a systems level understanding of how an important functional circuit is assembled
during development. This knowledge will be essential in the formulation of therapies for the regeneration and
repair of olfactory circuitry in anosmic patients.

## Key facts

- **NIH application ID:** 10170317
- **Project number:** 5R01DC012854-09
- **Recipient organization:** UNIVERSITY OF PENNSYLVANIA
- **Principal Investigator:** JONATHAN A RAPER
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $489,639
- **Award type:** 5
- **Project period:** 2013-07-08 → 2023-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10170317

## Citation

> US National Institutes of Health, RePORTER application 10170317, Targeting of sensory axons in the olfactory bulb (5R01DC012854-09). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10170317. Licensed CC0.

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