20 research outputs found
A Novel Interception Strategy in a Miniature Robber Fly with Extreme Visual Acuity
Our visual system allows us to rapidly identify and intercept a moving object. When this object is far away, we base the trajectory on the target's location relative to an external frame of reference [1]. This process forms the basis for the constant bearing angle (CBA) model, a reactive strategy that ensures interception since the bearing angle, formed between the line joining pursuer and target (called the range vector) and an external reference line, is held constant [2-4]. The CBA model may be a fundamental and widespread strategy, as it is also known to explain the interception trajectories of bats and fish [5, 6]. Here, we show that the aerial attack of the tiny robber fly Holcocephala fusca is consistent with the CBA model. In addition, Holcocephala fusca displays a novel proactive strategy, termed "lock-on" phase, embedded with the later part of the flight. We found the object detection threshold for this species to be 0.13°, enabled by an extremely specialized, forward pointing fovea (âŒ5 ommatidia wide, interommatidial angle ÎÏ = 0.28°, photoreceptor acceptance angle ÎÏ = 0.27°). This study furthers our understanding of the accurate performance that a miniature brain can achieve in highly demanding sensorimotor tasks and suggests the presence of equivalent mechanisms for target interception across a wide range of taxa.This work was funded by the Air Force Office of Scientific Research (FA9550-15-1-0188 to P.T.G.-B. and K.N. and FA9550-15-1-0068 to D.G.S.), an Isaac Newton Trust/Wellcome Trust ISSF/University of Cambridge Joint Research Grant (097814/Z/11/Z) to P.T.G.-B., a Biotechnology and Biological Sciences Research Council David Phillips Fellowship (BBSRC, BB/L024667/1) to T.J.W., a Royal Society International Exchange Scheme grant to P.T.G.-B. (75166), a Swedish Research Council grant (2012-4740) to K.N., and a Shared Equipment Grant from the School of Biological Sciences (University of Cambridge, RG70368)
Fly Photoreceptors Encode Phase Congruency
More than five decades ago it was postulated that sensory neurons detect and selectively enhance behaviourally relevant features of natural signals. Although we now know that sensory neurons are tuned to efficiently encode natural stimuli, until now it was not clear what statistical features of the stimuli they encode and how. Here we reverse-engineer the neural code of Drosophila photoreceptors and show for the first time that photoreceptors exploit nonlinear dynamics to selectively enhance and encode phase-related features of temporal stimuli, such as local phase congruency, which are invariant to changes in illumination and contrast. We demonstrate that to mitigate for the inherent sensitivity to noise of the local phase congruency measure, the nonlinear coding mechanisms of the fly photoreceptors are tuned to suppress random phase signals, which explains why photoreceptor responses to naturalistic stimuli are significantly different from their responses to white noise stimuli
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Research data supporting "A novel interception strategy in a miniature robber fly with extreme visual acuity"
Highlights
âą Holcocephala fusca robber flies capture prey with a constant bearing angle strategy
âą The approach is proactively altered to âlock-onâ on to prey within 29 cm distance
⹠The retina spatial resolution is 0.28°, but the object detection threshold is 0.13°
âą The flyâs stereopsis range is estimated to be ~26 cm
eTOC blurb
Robber flies are aerial predators. Here, Wardill and Fabian et al. show that the tiny robber fly Holcocephala fusca attacks a detected prey reactively, but proactively changes its speed and direction when the prey is within 30 cm. They also show that the very small object detection threshold of 1.3Âș is supported by a striking visual fovea
Data included here is the supplemental data figures and main figures. As the raw dataset is over 10 TB it cannot be offered here or elsewhere. Please contact the authors for obtaining such volumes of data
Hawks steer attacks using a guidance system tuned for close pursuit of erratically manoeuvring targets
An Unexpected Diversity of Photoreceptor Classes in the Longfin Squid, Doryteuthis pealeii
jYCaMP: an optimized calcium indicator for two-photon imaging at fiber laser wavelengths
Femtosecond lasers at fixed wavelengths above 1,000ânm are powerful, stable and inexpensive, making them promising sources for two-photon microscopy. Biosensors optimized for these wavelengths are needed for both next-generation microscopes and affordable turn-key systems. Here we report jYCaMP1, a yellow variant of the calcium indicator jGCaMP7 that outperforms its parent in mice and flies at excitation wavelengths above 1,000ânm and enables improved two-color calcium imaging with red fluorescent protein-based indicators