# Neural Circuit Mechanisms Underlying Dynamic Stimulus Selection

> **NIH NIH DP2** · UNIVERSITY OF CALIFORNIA SANTA BARBARA · 2020 · $2,332,500

## Abstract

Project Summary/Abstract
Imagine a baseball outfielder tracking a fly ball. To catch it successfully, the player must not get
distracted by a passing bird, even if it has a similar size and apparent motion similar to the ball. This
is a challenging example of stimulus selection and maintenance in the presence of distractors, but
we all do this sort of task every moment. Yet how brains internally represent multiple objects and
coordinate activities across diverse neural populations to perform the selection process has
remained elusive. In mammalian brains, the sheer number, complex projections and distribution of
neurons involved in stimulus selection processes (e.g., attention) make it challenging to visualize all
their connections to one another and decipher the dynamics of the network.
 The fruit fly Drosophila melanogaster will naturally orient to (select) and track (maintain selection
of) an object among many in a virtual reality arena, a behavior influenced by the fly’s navigation
system. This unambiguous readout in a numerically simple brain (~150,000 neurons) provides an
unparalleled opportunity to investigate how multiple distinct populations of neurons mediate stimulus
selection and maintenance. Further, Drosophila’s rich genetic tools make it feasible and
straightforward to reproducibly label and manipulate the same population of neurons from animal to
animal in physiological experiments.
 The proposed studies build a quantitative understanding, at the microcircuit level and ultimately
across multiple neural populations, of: (1) how an animal’s selection of a stimulus among many
manifests across multiple levels of visual processing, (2) how the stimulus selection decision
impinges on information processing in the upstream visual neurons, and, finally, (3) how internal
brain states such as hunger and locomotion modulate stimulus selection.
 This proposal describes a novel and powerful experimental approach. We will use multi-color
two-photon calcium imaging to record the activity of distinct neuronal populations that constitute the
fly's navigation system while monitoring the fly’s flight behavior in a virtual reality arena. The
technique we will develop also incorporates simultaneous, high resolution (spatial and temporal)
optogenetic stimulation, which allows us to probe multi-population neural dynamics and interactions
with single-cell resolution. We will develop single-cell level computational models and test how the
population activity of visual (ring) neurons and feedback from landmark-selective (compass) neurons
interact with each other and the fly’s internal states. This project's successful execution will provide
the first concrete understanding of multi-population dynamics underlying stimulus selection.

## Key facts

- **NIH application ID:** 10002827
- **Project number:** 1DP2EY032737-01
- **Recipient organization:** UNIVERSITY OF CALIFORNIA SANTA BARBARA
- **Principal Investigator:** Sung Soo Kim
- **Activity code:** DP2 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $2,332,500
- **Award type:** 1
- **Project period:** 2020-09-30 → 2025-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10002827

## Citation

> US National Institutes of Health, RePORTER application 10002827, Neural Circuit Mechanisms Underlying Dynamic Stimulus Selection (1DP2EY032737-01). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/10002827. Licensed CC0.

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