# The Functional Role and Neural Basis of Rapid Turns in Olfactory Search Behavior

> **NIH NIH R01** · CALIFORNIA INSTITUTE OF TECHNOLOGY · 2024 · $1,204,096

## Abstract

Summary
When searching their environment for food, animals often switch from making random changes in direction to
reflexively orient upstream when they smell an attractive odor, followed by rhythmic turns when they lose the
plume. Random changes in direction are traditionally interpreted as manifestation of a stochastic search process.
In this proposal, we test new hypothesis for the role of these random turns: animals turn deliberately to gather
information before and after they change direction—allowing them to compute important internal and external
state parameters such as wind direction, wind speed, ground speed, and altitude that they cannot directly
measure. This idea is theoretically feasible based on the principle of observability, a powerful concept we borrow
from control theory and informatics that is critical in the design of autonomous vehicles; here, we apply it to
address fundamental questions in neuroscience. To do so, we exploit the natural behavior of flies, which execute
rapid turns (called body saccades) as they search during flight. Our research program exploits state-of-the-art
experimental techniques pioneered in the labs of team members, which we will leverage with genetic techniques
and the rapidly emerging connectome databases available to the fly community—an integrated approach that
has already provided our team with a solid foundation for our proposed effort. From wind tunnel experiments we
have discovered that hungry flies execute a brief, stereotyped turn when they first experience an odor stimulus,
which we postulate they use to estimate ambient wind direction and speed before either executing an upwind
surge, or initiating a circling behavior in still air. From physiology experiments, we discovered a small network of
identified cells that serve as command neurons for generating spontaneous saccades (DNa0X and DNb01) and
another, specialized neuron that regulates their execution during flight (VS041). These preliminary results
provide a strategic entry point for our proposed work, which is separated into four Specific Aims:
(1) Test whether DNa0X and DNb01 are responsible for saccades that mediate olfactory search.
(2) Identify upstream regulators of the saccade generating circuits responsible for the olfactory search behavior.
(3) Determine the role of spontaneous saccades in gathering information.
(4) Develop circuit-inspired, agent-based predictive models of olfactory search
This effort to elucidate the circuitry that controls both stimulus-evoked and spontaneous turns during olfactory
search and test their potential role in information-gathering links the ethologically important behavior of olfactory
search across spatial and temporal scales—from the transient responses of individual neurons to the long flight
trajectories of whole animals as they search for food. While not widely used in systems neuroscience, we believe
that the concept of observability will provide a major conceptual advance in understanding...

## Key facts

- **NIH application ID:** 10877451
- **Project number:** 1R01NS136988-01
- **Recipient organization:** CALIFORNIA INSTITUTE OF TECHNOLOGY
- **Principal Investigator:** Bingni Wen Brunton
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $1,204,096
- **Award type:** 1
- **Project period:** 2024-09-05 → 2029-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10877451

## Citation

> US National Institutes of Health, RePORTER application 10877451, The Functional Role and Neural Basis of Rapid Turns in Olfactory Search Behavior (1R01NS136988-01). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10877451. Licensed CC0.

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