Dynamic structure of locomotor behavior in walking fruit flies.

Alexander Y Katsov,Limor Freifeld,Mark Horowitz,Thomas R Clandinin,Seppe Kuehn

doi:10.7554/elife.26410

Alexander Y Katsov, Limor Freifeld + Show 3 more

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https://doi.org/10.7554/elife.26410

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Abstract

The function of the brain is unlikely to be understood without an accurate description of its output, yet the nature of movement elements and their organization remains an open problem. Here, movement elements are identified from dynamics of walking in flies, using unbiased criteria. On one time scale, dynamics of walking are consistent over hundreds of milliseconds, allowing elementary features to be defined. Over longer periods, walking is well described by a stochastic process composed of these elementary features, and a generative model of this process reproduces individual behavior sequences accurately over seconds or longer. Within elementary features, velocities diverge, suggesting that dynamical stability of movement elements is a weak behavioral constraint. Rather, long-term instability can be limited by the finite memory between these elementary features. This structure suggests how complex dynamics may arise in biological systems from elements whose combination need not be tuned for dynamic stability.

Highlights

Behaving animals can act as quickly as their nervous systems allow, as slowly as their environments fluctuate, or over intervals determined by some task
Classical ethological studies examined different stereotyped, goal-driven behaviors including feeding, courtship rituals, aggressive encounters, and escape sequences (Tinbergen, 1963). Many of these behaviors consisted of recognizable movements that often occurred in characteristic sequences. These movements were inferred to be the fundamental units of behavior, and their modularity suggested a modular organization in neural control (Tinbergen, 1950; Simmons and Young, 2010)
We identified patterns in movement dynamics from body velocity time series using an iterative Independent Components Analysis (ICA) procedure, and defined unique or interchangeable behavior components from their occurrence statistics

Summary

Introduction

Behaving animals can act as quickly as their nervous systems allow, as slowly as their environments fluctuate, or over intervals determined by some task. Behaviors may change quickly to avoid predators, slowly to adjust to seasons, or at the intervals of locomotor steps, song phrases, or nest-building stages. Many of these behaviors consisted of recognizable movements that often occurred in characteristic sequences. These movements were inferred to be the fundamental units of behavior, and their modularity suggested a modular organization in neural control (Tinbergen, 1950; Simmons and Young, 2010). Animals can adjust their movements in both discrete and graded ways.

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