Tracking Freely Walking Flies: A Method to Assess Locomotion in Drosophila

Abstract

Source: Sun, M. and Chen, L. L. A Novel Method to Model Chronic Traumatic Encephalopathy in Drosophila. J. Vis. Exp. (2017).

This video describes how to track freely walking flies to assess their general locomotion ability. The featured protocol demonstrates the assay's setup and data analysis using video tracking software.

Protocol

This protocol is an excerpt from Sun and Chen, A Novel Method to Model Chronic Traumatic Encephalopathy in Drosophila, J. Vis. Exp. (2017).

1. Video-assisted Movement Tracking

1. Fill a 6-cm-diameter Petri dish with transparent silicon elastomer to make the tracking arena. Leave a 3 mm space between the silicon and the dish lid to allow the flies to walk freely but not fly.
2. Anesthetize four flies from either the sham or treated group each time and place them in the arena. Leave the flies at 22 °C for 1 h.
3. Position a Charge-Coupled Device (CCD) camera above the arenas and record for 5 min.
4. Analyze the recorded movement trajectories using Ctrax software (freely available from Caltech). Export the tracked data in a programming language (e.g., Matlab)-compatible format and analyze the data based on distance traveled per frame. Calculate the mean walking distance for each fly and combine it with all other recorded flies/group to obtain a mean cumulative distance travelled by the population of files in the same group.

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
60 mm Petri Dishes	Fisher Scientific	FB0875713A	Used as a tracking arenas
Flow Regulator	Genesee Scientific	59-122WC
Fine Brush	Genesee Scientific	59-204
Flypad	Genesee Scientific	59-114
Sylgard Silicone Elastomer	Dow Corning	4019862
CCD Camera	Microsoft	HD-5000
Ctrax Walking Fly Tracker	Caltech	Ctrax 0.2.11
MATLAB Image Processing Toolbox	MATLAB	R2015b