Local motion detectors are required for the computation of expansion flow-fields.

Tabea Schilling,Alexander Borst

doi:10.1242/bio.012690

Abstract

ABSTRACTAvoidance of predators or impending collisions is important for survival. Approaching objects can be mimicked by expanding flow-fields. Tethered flying fruit flies, when confronted with an expansion flow-field, reliably turn away from the pole of expansion when presented laterally, or perform a landing response when presented frontally. Here, we show that the response to an expansion flow-field is independent of the overall luminance change and edge acceleration. As we demonstrate by blocking local motion-sensing neurons T4 and T5, the response depends crucially on the neural computation of appropriately aligned local motion vectors, using the same hardware that also controls the optomotor response to rotational flow-fields.

Highlights

Silencing T4 and T5 neurons genetically, we found that information from local motion circuits is essential for both the avoidance and the landing response
Whenever an animal moves or something else is moving in the environment relative to it, visual motion occurs on the retina
A typical collision avoidance response to a bar expanding at a constant velocity of 180 deg/s is shown in Fig. 1B: After a brief latency the animals attempted to turn away as long as the stimulus was presented

Summary

Introduction

Whenever an animal moves or something else is moving in the environment relative to it, visual motion occurs on the retina. We first characterized the avoidance and landing response of tethered flying flies using different expanding stimuli. Looming stimuli can induce two different behaviors in flying flies dependent on the position of the stimulus.

Results

Conclusion