Species-Specific Flight Styles of Flies are Reflected in the Response Dynamics of a Homolog Motion-Sensitive Neuron.

Bart R H Geurten,Roland Kern,Martin Egelhaaf

doi:10.3389/fnint.2012.00011

Abstract

Hoverflies and blowflies have distinctly different flight styles. Yet, both species have been shown to structure their flight behavior in a way that facilitates extraction of 3D information from the image flow on the retina (optic flow). Neuronal candidates to analyze the optic flow are the tangential cells in the third optical ganglion – the lobula complex. These neurons are directionally selective and integrate the optic flow over large parts of the visual field. Homolog tangential cells in hoverflies and blowflies have a similar morphology. Because blowflies and hoverflies have similar neuronal layout but distinctly different flight behaviors, they are an ideal substrate to pinpoint potential neuronal adaptations to the different flight styles. In this article we describe the relationship between locomotion behavior and motion vision on three different levels: (1) We compare the different flight styles based on the categorization of flight behavior into prototypical movements. (2) We measure the species-specific dynamics of the optic flow under naturalistic flight conditions. We found the translational optic flow of both species to be very different. (3) We describe possible adaptations of a homolog motion-sensitive neuron. We stimulate this cell in blowflies (Calliphora) and hoverflies (Eristalis) with naturalistic optic flow generated by both species during free flight. The characterized hoverfly tangential cell responds faster to transient changes in the optic flow than its blowfly homolog. It is discussed whether and how the different dynamical response properties aid optic flow analysis.

Highlights

Flies perform complex aerobatic maneuvers with a brain composed of less than a million neurons
In this article we describe the relationship between locomotion behavior and motion vision on three different levels: (1) We compare the different flight styles based on the categorization of flight behavior into prototypical movements
In this study we address the following two questions: (1) In which way are the differences in the flight styles of Eristalis and Calliphora reflected in their optic flow? (2) Are there any characteristic differences between the responses of ventral centrifugal horizontal (vCH) cells in both species that indicate adaptations in the motion vision pathway to process species-specific optic flow?

Summary

Introduction

Flies perform complex aerobatic maneuvers with a brain composed of less than a million neurons. We analyze the consequences of these differences for the neural representation of optic flow in the visual system Both animals segregate their flight trajectories into short fast rotations, called saccades, they differ much with respect to translational motion between these saccades (Schilstra and van Hateren, 1999; van Hateren and Schilstra, 1999; Braun et al, 2010; Geurten et al, 2010). This flight style has been interpreted, despite the differences in the translational sections, to facilitate the acquisition of spatial information (Land, 1999; Schilstra and van Hateren, 1999; Boeddeker et al, 2005; Kern et al, 2006; Braun et al, 2010; Geurten et al, 2010)

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