# Predictability and hierarchy in Drosophila behavior

## TL;DR

Fruit fly behavior is organized in a hierarchical structure with multiple time scales, revealing insights into their behavioral programs and internal states.

## Contribution

The paper demonstrates hierarchical organization in the full behavioral repertoire of fruit flies using an unsupervised predictive modeling technique.

## Key findings

- Fly behavior shows multiple time scales and hierarchical structure.
- The hierarchy reflects underlying behavioral programs and internal states.
- Unsupervised methods reveal nested sub-clusters in behavioral sequences.

## Abstract

Even the simplest of animals exhibit behavioral sequences with complex temporal dynamics. Prominent amongst the proposed organizing principles for these dynamics has been the idea of a hierarchy, wherein the movements an animal makes can be understood as a set of nested sub-clusters. Although this type of organization holds potential advantages in terms of motion control and neural circuitry, measurements demonstrating this for an animal’s entire behavioral repertoire have been limited in scope and temporal complexity. Here, we use a recently developed unsupervised technique to discover and track the occurrence of all stereotyped behaviors performed by fruit flies moving in a shallow arena. Calculating the optimally predictive representation of the fly’s future behaviors, we show that fly behavior exhibits multiple time scales and is organized into a hierarchical structure that is indicative of its underlying behavioral programs and its changing internal states.