# Characterizing motor control and variability at the single-cell level in larval Drosophila

> **NIH NIH F31** · UNIVERSITY OF CHICAGO · 2021 · $46,036

## Abstract

ABSTRACT
Variability in the muscle activations used for movement is a fundamental feature of neural control of movement.
Changes to motor variability are associated with aging and motor disease, but motor variability's behavioral
consequences are unclear. In order to causally test the role of motor variability in behavior, we need to
manipulate sources of motor variability, but few such sources have been empirically identified. The objective of
this proposal is to build a new model system for investigating motor variability — Drosophila melanogaster
larvae — and use it to experimentally
variability in muscle activation timings
identify sources of motor variability. I will test the central hypothesis that
arises from the motor system's continuous adjustment to feedback from
ongoing and recent movements, and that proprioceptive feedback changes motor variability by adjusting
muscle activation timings from cycle to cycle. I single out proprioception as a strong candidate source of motor
variability, as proprioception is necessary for normal phase relationships and amplitude of the movements used
in locomotion. Aim 1 asks “What features of body posture affect variability in muscle activation timings?”
Specifically, I will test the working hypothesis that during Drosophila larval crawling, postural variables (e.g.,
segment lengths and inter-segmental angles) contribute to and will predict stride-by-stride variation in muscle
activation timing. This will provide correlative evidence for or against the central hypothesis. This Aim will also
test other, non-mutually-exclusive, hypotheses for sources of motor variability, and enable future experimental
tests of these hypotheses.
Aim 2 asks “How does loss of proprioceptive feedback change timing and variability
of muscle activations?” Specifically, I will test the working hypothesis that proprioceptive feedback changes the
extent and structure of motor variability by adjusting muscle activation timings from stride to stride. This will
causally test the central hypothesis. It will also provide insight into how proprioceptive information informs
motor control and regulates motor variability, and into potential behavioral consequences of this variability. In
this proposal, I use calcium imaging in intact, crawling larvae; I use precise genetic tools to acutely silence
proprioceptive neurons while imaging muscle activity during locomotion; and I model the variability of muscle
activation timing as a function of many potentially informative features, including postural variables. Completion
of the experiments in this proposal will have two major impacts: 1) I expect to identify a source of variability that
will ultimately allow for probing the strategic role of motor variability in behavior. 2) I also expect to establish a
tractable model system for motor research in which to manipulate specific cell types or neural circuit
architectures and test their functions in control of movement or motor variability. Thes...

## Key facts

- **NIH application ID:** 10235437
- **Project number:** 1F31NS118835-01A1
- **Recipient organization:** UNIVERSITY OF CHICAGO
- **Principal Investigator:** Marie R Greaney
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $46,036
- **Award type:** 1
- **Project period:** 2021-04-01 → 2023-09-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10235437

## Citation

> US National Institutes of Health, RePORTER application 10235437, Characterizing motor control and variability at the single-cell level in larval Drosophila (1F31NS118835-01A1). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10235437. Licensed CC0.

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