# Genetic programs linking neuronal identity, morphology and function in a Drosophila motion detection circuit.

> **NIH NIH F32** · UNIVERSITY OF CALIFORNIA LOS ANGELES · 2020 · $38,580

## Abstract

PROJECT SUMMARY / ABSTRACT: Proper brain development requires neurons to adopt a striking diversity
of morphological characteristics that underlie specific functions, and deficits in this process are associated with
neuropsychiatric disease (1, 2). Nevertheless, the molecular determinants of neural identity and morphology
are poorly understood. The visual system of the fruit fly Drosophila is an excellent venue for investigating this
problem, owing to rich genetic tools and well-characterized neuronal cell types with specific morphological
characteristics and functions (3-6). T4 and T5 neurons of the Drosophila visual system represent a particularly
striking example of divergent morphological characteristics underlying specific functions (7-9). T4/T5 neurons
respond to visual motion of light and dark stimuli, respectively, and each is composed of four subclasses (T4a-
d and T5a-d) that respond selectively to motion in one of four cardinal directions: front to back (a), back to front
(b), upward (c), and downward (d). Remarkably, the dendrites of each class are oriented antiparallel to the
preferred direction of motion, and the axons of each class project to distinct corresponding layers of the lobula
plate neuropil. How T4/T5 neurons are distinguished from one another at a molecular level, and how this
heterogeneity is translated into specific morphologies and functions is poorly understood.
 High-throughput single cell sequencing was performed to define heterogeneity and discover molecular
determinants of identity and morphology in developing T4/T5 neurons. The data reveal multiple distinct clusters
of cells with unique gene expression profiles that are enriched in transcription factors and cell surface
molecules. This proposal will use these genetic candidates to test the hypothesis that developing T4/T5 neuron
classes exhibit distinct molecular identities, and that these identities underlie the unique morphological and
functional characteristics of these neurons. Immunohistochemistry in developing T4/T5 neurons will be used to
assign candidate expression to specific subclasses, and gene disruption will reveal the functional contribution
of molecular heterogeneity to specific morphologies. The experiments will reveal molecular principles
governing acquisition of neural identity, morphology and function that are relevant to human nature and
neuropsychiatric disease.
Training Environment: The proposal will be carried out under the mentorship of Dr. S. Lawrence Zipursky at
UCLA / HHMI. Dr. Zipursky's laboratory has discovered fundamental principles of neural identity, morphology
and connectivity (10-14), producing leading independent investigators in neurobiology for over three decades.
UCLA is a rich intellectual environment with a strong neuroscience community and opportunities for scientific
communication, collaboration and professional development. The research training plan will take full advantage
of the rich scientific and intellectual reso...

## Key facts

- **NIH application ID:** 9933811
- **Project number:** 5F32EY030025-02
- **Recipient organization:** UNIVERSITY OF CALIFORNIA LOS ANGELES
- **Principal Investigator:** Samuel Alexander LoCascio
- **Activity code:** F32 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $38,580
- **Award type:** 5
- **Project period:** 2019-06-01 → 2020-11-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9933811

## Citation

> US National Institutes of Health, RePORTER application 9933811, Genetic programs linking neuronal identity, morphology and function in a Drosophila motion detection circuit. (5F32EY030025-02). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/9933811. Licensed CC0.

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