# Olfactory tubercle circuits involved in odor valence assignment

> **NIH NIH F32** · HARVARD UNIVERSITY · 2020 · $69,306

## Abstract

Project Summary
How sensory stimuli acquire emotional tags based on behavioral experience is a subject of vital
importance in neuroscience, but has been difficult to study due to the complex brain circuits involved in
this process. I propose that olfaction may be an ideal system in which to interrogate this question due to
the direct interface of olfactory bulb projections and dense dopaminergic input in a ventral basal ganglia
structure, the olfactory tubercle. Furthermore, this evolutionarily conserved stream of olfactory
information to limbic brain regions like the olfactory tubercle may be the basis of a proposed exceptional
capacity of odors to evoke positive or negative emotional responses. I plan to first dissect the function of
olfactory tubercle circuits in odor-valence assignment in a classical conditioning task by using
microendoscopy to perform calcium activity imaging of single D1-type or D2-type dopamine receptor
expressing neurons in the olfactory tubercle. I will then ablate dopamine terminals in the olfactory
tubercle locally with the use of 6-hydroxydopamine, and assess the changes in the odor and outcome
evoked activity in the same neuronal types in the absence of dopamine input. Secondly, I will develop a
novel behavioral assay in order to test the hypothesis that learned odor associations result in odor
preferences that are uniquely strong as compared to stimulus-outcome associations with stimuli of
another sensory modality (audition). To do so, I will first identify odor and sound stimuli of similar
discriminability for mice and then use these stimuli in a classical conditioning task. After stimulus-outcome
training, the preference of the mice for the stimuli used in classical conditioning will be assessed in a
preference test. Finally, I will test the causal role of the olfactory tubercle in odor-outcome learning and
in the development of odor preferences with the use of bilateral lesions of the olfactory tubercle.
Together, the proposed research is likely to contribute significantly to our understanding of (1) the
processes underlying valence assignment to sensory stimuli, (2) the functional circuit mechanisms of the
olfactory tubercle, an understudied brain region, and (3) the behavioral phenomenon of odor-evoked
emotional responses and associated brain circuits.

## Key facts

- **NIH application ID:** 9979629
- **Project number:** 5F32DC017891-02
- **Recipient organization:** HARVARD UNIVERSITY
- **Principal Investigator:** Nuné Martiros
- **Activity code:** F32 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $69,306
- **Award type:** 5
- **Project period:** 2019-07-01 → 2022-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9979629

## Citation

> US National Institutes of Health, RePORTER application 9979629, Olfactory tubercle circuits involved in odor valence assignment (5F32DC017891-02). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/9979629. Licensed CC0.

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