Flight behaviour of unilaterally blinded blowflies – control of flight speed and saccadic turns
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1
Bielefeld University, Neurobiology & CITEC, Germany
Several characteristics of blowfly flight have been shown to depend on environmental features and to be controlled by optic flow (OF), the image flow across the eyes induced during self-motion of the animal. For example, both flight speed and the changes in flight direction depend on the clear space available. Most mechanisms proposed to underlie speed and direction control rely on OF information from both eyes of the animal. Then, however, blinding one eye with paint should have consequences for the free-flight behaviour of flies.
To analyse this issue we performed behavioural studies on unilaterally blinded blowflies and compared their flight performance to that of control flies in straight tunnels of different width. In contrast to what might be expected, monocular flies - as a rule of thumb - do not circle. As in non-manipulated flies flight is composed of two components, brief and fast changes in gaze direction (saccades) and intersaccadic intervals dominated by translational movements. The most obvious changes of flight of monocular flies are (i) a drastically reduced flight speed, (ii) a strong tendency to fly close to the arena wall next to the open eye, and (iii) a characteristic low angular velocity rotation offset towards the open eye in intersaccadic flight segments. More detailed analysis reveals that saccades towards the open eye are slightly smaller in amplitude and slower than saccades towards the blinded eye.
In an earlier study (Kern et al., J.Exp.Biol. 215: 2501-2514, 2012) saccade direction could be predicted correctly by up to 80% by comparing the OF generated in fronto-lateral regions on either eye during the preceding intersaccadic interval: turns were predicted to be directed away from the eye experiencing more expansion-based OF. We obtained similar prediction rates of saccade direction in monocular flies, if we compare the expansion-based OF on the open eye with an assumed constant signal originating from the blinded eye.
Velocity control in non-manipulated flies has been attributed to fronto-lateral eye regions where the intersaccadic OF was kept largely constant at a `preset` total strength across several environments. Such a mechanism also holds in monocular flies and can explain the much lower translation velocity of blinded flies, if one – again – assumes a constant signal from the blinded eye.
Acknowledgements
The work in our lab is supported by the Deutsche Forschungsgemeinschaft (DFG)
Keywords:
Flight control,
Optic Flow,
Visual Motion Processing,
fly,
collision avoidance,
Saccades,
velocity control
Conference:
International Conference on Invertebrate Vision, Fjälkinge, Sweden, 1 Aug - 8 Aug, 2013.
Presentation Type:
Poster presentation preferred
Topic:
The visual control of flight and locomotion
Citation:
Kern
R,
Lindemann
JP and
Egelhaaf
M
(2019). Flight behaviour of unilaterally blinded blowflies – control of flight speed and saccadic turns.
Front. Physiol.
Conference Abstract:
International Conference on Invertebrate Vision.
doi: 10.3389/conf.fphys.2013.25.00046
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Received:
26 Feb 2013;
Published Online:
09 Dec 2019.
*
Correspondence:
Dr. Roland Kern, Bielefeld University, Neurobiology & CITEC, Bielefeld, D-33501, Germany, roland.kern@uni-bielefeld.de