Finding Behavioral Motifs in Fly Trajectories

Abstract

Patterns of locomotor activity of a freely moving organism can help characterize its behavioral phenotypes. To infer behavior from such activity in Drosophila melanogaster, we use a real-time image acquisition system to track the movement of multiple flies in three dimensions. When dealing with fly movement trajectories, we must take into account that similar movement patterns can be expressed in different orientations and speeds. In this paper, we present methods to transform the three-dimensional fly movement trajectories into a space that is translation, rotation, scale and timescale invariant. We then propose an approach motivated by sequence alignment to detect similar movement patterns from fly trajectories in order to infer specific behaviors. We demonstrate the accuracy of the methods and highlight their usefulness in studies aimed at characterizing behavioral phenotypes.