# *Drosophila* Behavior & Optogenetics

## Background & Goals

### *Drosophila* as a model in neuroscience

With just over 100,000 neurons but incredible genetic tractability, the fruit fly is an important model organism in neuroscience. About 65% of human disease-associated genes have a homolog in *Drosophila melanogaster* (Ugur et al., 2016). Like many model organisms, fruit flies are easy to reproduce, cheap, and easy to take care of in a lab. On top of that, they've been studied for more than a century. *Drosophila* have been used to study learning, memory, vision, sleep, addiction, courtship, and aggression, among many other behaviors.

In these labs, we'll aim to characterize the gustatory, ethological, and locomotor behavior of transgenic fruit flies, solving a few mysteries along the way.

### What's coming up

This module spans **two days** of lab:

- **[Day 1: The Case of the Mislabeled Fly Vials](Day1.md)** — three behavioral assays (proboscis extension reflex, ethological observation, and locomotor tracking) to characterize an unknown transgenic line.
- **[Day 2: The Case of the Missing Methods](Day2.md)** — design your own optogenetic experiment to figure out what the genetically modified neurons control.

### In these labs you will:

- Operationalize and quantify the behavior of a fruit fly
- Use a computer vision program to track locomotor behaviors
- Identify different types of transgenic flies used for neuroscience research
- Design an optogenetic experiment to interrogate neural circuit function

### Relevant references

Al-Anzi, B., Tracey, W. D., & Benzer, S. (2006). Response of *Drosophila* to wasabi is mediated by *painless*, the fly homolog of mammalian TRPA1/ANKTM1. *Current Biology* 16(10): 1034–1040.

Chen, Y.-C. D., & Dahanukar, A. (2020). Recent advances in the genetic basis of taste detection in *Drosophila*. *Cellular and Molecular Life Sciences* 77(6): 1087–1101.

Devineni, A. V., & Heberlein, U. (2009). Preferential ethanol consumption in *Drosophila* models features of addiction. *Current Biology* 19(24): 2126–2132.

Mandel, S. J., Shoaf, M. L., Bostwick, J. R., Combs, D. J., Trudeau, V. L., & Johnson, E. C. (2018). Behavioral aggression is regulated by *Drosophila* CCAP signaling. *Frontiers in Neural Circuits* 12: 45.

Nakamura, M., Baldwin, D., Hannaford, S., Palka, J., & Montell, C. (2002). Defective proboscis extension response (DPR), a member of the Ig superfamily required for the gustatory response to salt. *Journal of Neuroscience* 22(9): 3463–3472.

Trisal, S., VijayRaghavan, K., & Ramaswami, M. (2023). The proboscis extension reflex assay for evaluating taste responses in *Drosophila*. *Bio-protocol* 13(20).

Ugur, B., Chen, K., & Bellen, H. J. (2016). *Drosophila* tools and assays for the study of human diseases. *Disease Models & Mechanisms* 9(3): 235–244.