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Berger Dauxère A, Montagne G, Serres JR. Honeybees Use Multiple Invariants to Control Their Altitude. INSECTS 2023; 14:313. [PMID: 37103128 PMCID: PMC10146580 DOI: 10.3390/insects14040313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 02/28/2023] [Accepted: 03/16/2023] [Indexed: 06/19/2023]
Abstract
How do bees perceive altitude changes so as to produce safe displacements within their environment? It has been proved that humans use invariants, but this concept remains little-known within the entomology community. The use of a single invariant, the optical speed rate of change, has been extensively demonstrated in bees in a ground-following task. Recently, it has been demonstrated that another invariant, the splay angle rate of change, could also be used by bees to adjust their altitude. This study aims to understand how bees use these invariants when they are available simultaneously. This issue has been addressed using an experimental setup providing discordant information to bees. We have shown that when the two invariants were available, bees performed ground-following tasks relying primarily on optical speed rate of change. Conversely, when optical speed rate of change was less easily accessible, splay angle rate of change was prioritized, unless the bees perceive danger. Taken together, these results illustrate how the joint use of several invariants allows bees to produce adaptive behaviors.
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2
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Egelhaaf M. Optic flow based spatial vision in insects. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2023:10.1007/s00359-022-01610-w. [PMID: 36609568 DOI: 10.1007/s00359-022-01610-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 12/06/2022] [Accepted: 12/24/2022] [Indexed: 01/09/2023]
Abstract
The optic flow, i.e., the displacement of retinal images of objects in the environment induced by self-motion, is an important source of spatial information, especially for fast-flying insects. Spatial information over a wide range of distances, from the animal's immediate surroundings over several hundred metres to kilometres, is necessary for mediating behaviours, such as landing manoeuvres, collision avoidance in spatially complex environments, learning environmental object constellations and path integration in spatial navigation. To facilitate the processing of spatial information, the complexity of the optic flow is often reduced by active vision strategies. These result in translations and rotations being largely separated by a saccadic flight and gaze mode. Only the translational components of the optic flow contain spatial information. In the first step of optic flow processing, an array of local motion detectors provides a retinotopic spatial proximity map of the environment. This local motion information is then processed in parallel neural pathways in a task-specific manner and used to control the different components of spatial behaviour. A particular challenge here is that the distance information extracted from the optic flow does not represent the distances unambiguously, but these are scaled by the animal's speed of locomotion. Possible ways of coping with this ambiguity are discussed.
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Affiliation(s)
- Martin Egelhaaf
- Neurobiology and Center for Cognitive Interaction Technology (CITEC), Bielefeld University, Universitätsstraße 25, 33615, Bielefeld, Germany.
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3
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Serres JR, Morice AHP, Blary C, Miot R, Montagne G, Ruffier F. Floor and ceiling mirror configurations to study altitude control in honeybees. Biol Lett 2022; 18:20210534. [PMID: 35317623 PMCID: PMC8941389 DOI: 10.1098/rsbl.2021.0534] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
To investigate altitude control in honeybees, an optical configuration was designed to manipulate or cancel the optic flow. It has been widely accepted that honeybees rely on the optic flow generated by the ground to control their altitude. Here, we create an optical configuration enabling a better understanding of the mechanism of altitude control in honeybees. This optical configuration aims to mimic some of the conditions that honeybees experience over a natural water body. An optical manipulation, based on a pair of opposed horizontal mirrors, was designed to remove any visual information coming from the floor and ceiling. Such an optical manipulation allowed us to get closer to the seminal experiment of Heran & Lindauer 1963. Zeitschrift für vergleichende Physiologie47, 39-55. (doi:10.1007/BF00342890). Our results confirmed that a reduction or an absence of ventral optic flow in honeybees leads to a loss in altitude, and eventually a collision with the floor.
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Affiliation(s)
| | | | - Constance Blary
- Aix Marseille Univ, CNRS, ISM, Marseille, France
- CEFE UMR 5175, CNRS - Université de Montpellier - Université Paul-Valéry Montpellier - EPHE - 1919 route de Mende, 34293 Montpellier cedex 5, France
| | - Romain Miot
- Aix Marseille Univ, CNRS, ISM, Marseille, France
- XTIM SAS, 77 rue de Lyon, 13015 Marseille, France
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4
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Berger Dauxère A, Serres JR, Montagne G. Ecological Entomology: How Is Gibson's Framework Useful? INSECTS 2021; 12:1075. [PMID: 34940163 PMCID: PMC8703479 DOI: 10.3390/insects12121075] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/23/2021] [Revised: 11/25/2021] [Accepted: 11/26/2021] [Indexed: 11/17/2022]
Abstract
To date, numerous studies have demonstrated the fundamental role played by optic flow in the control of goal-directed displacement tasks in insects. Optic flow was first introduced by Gibson as part of their ecological approach to perception and action. While this theoretical approach (as a whole) has been demonstrated to be particularly suitable for the study of goal-directed displacements in humans, its usefulness in carrying out entomological field studies remains to be established. In this review we would like to demonstrate that the ecological approach to perception and action could be relevant for the entomologist community in their future investigations. This approach could provide a conceptual and methodological framework for the community in order to: (i) take a critical look at the research carried out to date, (ii) develop rigorous and innovative experimental protocols, and (iii) define scientific issues that push the boundaries of the current scientific field. After a concise literature review about the perceptual control of displacement in insects, we will present the framework proposed by Gibson and suggest its added value for carrying out research in the field of behavioral ecology in insects.
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Affiliation(s)
- Aimie Berger Dauxère
- The Institute of Movement Sciences, Aix Marseille University, CNRS, ISM, CEDEX 07, 13284 Marseille, France; (J.R.S.); (G.M.)
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5
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Motion cues from the background influence associative color learning of honey bees in a virtual-reality scenario. Sci Rep 2021; 11:21127. [PMID: 34702914 PMCID: PMC8548521 DOI: 10.1038/s41598-021-00630-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 10/13/2021] [Indexed: 11/21/2022] Open
Abstract
Honey bees exhibit remarkable visual learning capacities, which can be studied using virtual reality (VR) landscapes in laboratory conditions. Existing VR environments for bees are imperfect as they provide either open-loop conditions or 2D displays. Here we achieved a true 3D environment in which walking bees learned to discriminate a rewarded from a punished virtual stimulus based on color differences. We included ventral or frontal background cues, which were also subjected to 3D updating based on the bee movements. We thus studied if and how the presence of such motion cues affected visual discrimination in our VR landscape. Our results showed that the presence of frontal, and to a lesser extent, of ventral background motion cues impaired the bees' performance. Whenever these cues were suppressed, color discrimination learning became possible. We analyzed the specific contribution of foreground and background cues and discussed the role of attentional interference and differences in stimulus salience in the VR environment to account for these results. Overall, we show how background and target cues may interact at the perceptual level and influence associative learning in bees. In addition, we identify issues that may affect decision-making in VR landscapes, which require specific control by experimenters.
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Bergantin L, Harbaoui N, Raharijaona T, Ruffier F. Oscillations make a self-scaled model for honeybees' visual odometer reliable regardless of flight trajectory. J R Soc Interface 2021; 18:20210567. [PMID: 34493092 PMCID: PMC8424324 DOI: 10.1098/rsif.2021.0567] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Honeybees foraging and recruiting nest-mates by performing the waggle dance need to be able to gauge the flight distance to the food source regardless of the wind and terrain conditions. Previous authors have hypothesized that the foragers’ visual odometer mathematically integrates the angular velocity of the ground image sweeping backward across their ventral viewfield, known as translational optic flow. The question arises as to how mathematical integration of optic flow (usually expressed in radians/s) can reliably encode distances, regardless of the height and speed of flight. The vertical self-oscillatory movements observed in honeybees trigger expansions and contractions of the optic flow vector field, yielding an additional visual cue called optic flow divergence. We have developed a self-scaled model for the visual odometer in which the translational optic flow is scaled by the visually estimated current clearance from the ground. In simulation, this model, which we have called SOFIa, was found to be reliable in a large range of flight trajectories, terrains and wind conditions. It reduced the statistical dispersion of the estimated flight distances approximately 10-fold in comparison with the mathematically integrated raw optic flow model. The SOFIa model can be directly implemented in robotic applications based on minimalistic visual equipment.
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Affiliation(s)
| | - Nesrine Harbaoui
- Aix-Marseille University, CNRS, ISM, Marseille, France.,CRIStAL Laboratory, CNRS UMR, 9189, University of Lille, 59650 Lille, France
| | - Thibaut Raharijaona
- Aix-Marseille University, CNRS, ISM, Marseille, France.,Université de Lorraine, Arts et Métiers Institute of Technology, LCFC, HESAM Université, 57070 Metz, France
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7
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Bertrand OJN, Doussot C, Siesenop T, Ravi S, Egelhaaf M. Visual and movement memories steer foraging bumblebees along habitual routes. J Exp Biol 2021; 224:269087. [PMID: 34115117 DOI: 10.1242/jeb.237867] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 04/06/2021] [Indexed: 11/20/2022]
Abstract
One persistent question in animal navigation is how animals follow habitual routes between their home and a food source. Our current understanding of insect navigation suggests an interplay between visual memories, collision avoidance and path integration, the continuous integration of distance and direction travelled. However, these behavioural modules have to be continuously updated with instantaneous visual information. In order to alleviate this need, the insect could learn and replicate habitual movements ('movement memories') around objects (e.g. a bent trajectory around an object) to reach its destination. We investigated whether bumblebees, Bombus terrestris, learn and use movement memories en route to their home. Using a novel experimental paradigm, we habituated bumblebees to establish a habitual route in a flight tunnel containing 'invisible' obstacles. We then confronted them with conflicting cues leading to different choice directions depending on whether they rely on movement or visual memories. The results suggest that they use movement memories to navigate, but also rely on visual memories to solve conflicting situations. We investigated whether the observed behaviour was due to other guidance systems, such as path integration or optic flow-based flight control, and found that neither of these systems was sufficient to explain the behaviour.
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Affiliation(s)
- Olivier J N Bertrand
- Department of Neurobiology and Cognitive Interaction Technology Center of Excellence (CITEC) , Bielefeld University, D-33501 Bielefeld, Germany
| | - Charlotte Doussot
- Department of Neurobiology and Cognitive Interaction Technology Center of Excellence (CITEC) , Bielefeld University, D-33501 Bielefeld, Germany
| | - Tim Siesenop
- Department of Neurobiology and Cognitive Interaction Technology Center of Excellence (CITEC) , Bielefeld University, D-33501 Bielefeld, Germany
| | - Sridhar Ravi
- Department of Neurobiology and Cognitive Interaction Technology Center of Excellence (CITEC) , Bielefeld University, D-33501 Bielefeld, Germany.,School of Engineering, RMIT University, Melbourne, VIC 3083, Australia
| | - Martin Egelhaaf
- Department of Neurobiology and Cognitive Interaction Technology Center of Excellence (CITEC) , Bielefeld University, D-33501 Bielefeld, Germany
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8
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Migdał P, Murawska A, Bieńkowski P, Berbeć E, Roman A. Changes in Honeybee Behavior Parameters under the Influence of the E-Field at 50 Hz and Variable Intensity. Animals (Basel) 2021; 11:ani11020247. [PMID: 33498413 PMCID: PMC7909437 DOI: 10.3390/ani11020247] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 01/13/2021] [Accepted: 01/18/2021] [Indexed: 12/27/2022] Open
Abstract
EM-fields come from both natural and anthropogenic sources. This study aimed to investigate changes in honeybee behavior parameters under the influence of an electric field at 50 Hz and variable intensity. Bees were exposed for 1 h, 3 h, or 6 h to the following artificial E-field intensities: 5.0 kV/m, 11.5 kV/m, 23.0 kV/m, or 34.5 kV/m. Bees in the control group were under the influence of an E-field <2.0 kV/m. Six basic behaviors were selected for bee observation (walking, grooming, flight, stillness, contact between individuals, and wing movement). Our research shows the impact of bee exposure time on behavioral change within groups. Exposure for 3 h caused a decrease in the time that bees spent on behaviors and in the number of occurrences. After 6 h, the parameters increased within the groups, as was the case with 1 h exposure. This may indicate that there is a behavioral barrier that allows the pattern to normalize for some time.
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Affiliation(s)
- Paweł Migdał
- Department of Environment Hygiene and Animal Welfare, Wroclaw University of Environmental and Life Sciences, 25 C.K. Norwida St., 51-630 Wroclaw, Poland; (A.M.); (E.B.); (A.R.)
- Correspondence: ; Tel.: +48-71-3205864
| | - Agnieszka Murawska
- Department of Environment Hygiene and Animal Welfare, Wroclaw University of Environmental and Life Sciences, 25 C.K. Norwida St., 51-630 Wroclaw, Poland; (A.M.); (E.B.); (A.R.)
| | - Paweł Bieńkowski
- Telecommunications and Teleinformatics Department, Wroclaw University of Science and Technology, 27 Wybrzeze, Wyspianskiego St., 50-370 Wroclaw, Poland;
| | - Ewelina Berbeć
- Department of Environment Hygiene and Animal Welfare, Wroclaw University of Environmental and Life Sciences, 25 C.K. Norwida St., 51-630 Wroclaw, Poland; (A.M.); (E.B.); (A.R.)
| | - Adam Roman
- Department of Environment Hygiene and Animal Welfare, Wroclaw University of Environmental and Life Sciences, 25 C.K. Norwida St., 51-630 Wroclaw, Poland; (A.M.); (E.B.); (A.R.)
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9
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Abstract
Flies and other insects use incoherent motion (parallax) to the front and sides to measure distances and identify obstacles during translation. Although additional depth information could be drawn from below, there is no experimental proof that they use it. The finding that blowflies encode motion disparities in their ventral visual fields suggests this may be an important region for depth information. We used a virtual flight arena to measure fruit fly responses to optic flow. The stimuli appeared below (n = 51) or above the fly (n = 44), at different speeds, with or without parallax cues. Dorsal parallax does not affect responses, and similar motion disparities in rotation have no effect anywhere in the visual field. But responses to strong ventral sideslip (206° s−1) change drastically depending on the presence or absence of parallax. Ventral parallax could help resolve ambiguities in cluttered motion fields, and enhance corrective responses to nearby objects.
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Affiliation(s)
- Carlos Ruiz
- Department of Biological Sciences, Florida International University, Miami, FL 33199, USA
| | - Jamie C Theobald
- Department of Biological Sciences, Florida International University, Miami, FL 33199, USA
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10
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Lecoeur J, Dacke M, Floreano D, Baird E. The role of optic flow pooling in insect flight control in cluttered environments. Sci Rep 2019; 9:7707. [PMID: 31118454 PMCID: PMC6531491 DOI: 10.1038/s41598-019-44187-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Accepted: 05/07/2019] [Indexed: 11/23/2022] Open
Abstract
Flight through cluttered environments, such as forests, poses great challenges for animals and machines alike because even small changes in flight path may lead to collisions with nearby obstacles. When flying along narrow corridors, insects use the magnitude of visual motion experienced in each eye to control their position, height, and speed but it is unclear how this strategy would work when the environment contains nearby obstacles against a distant background. To minimise the risk of collisions, we would expect animals to rely on the visual motion generated by only the nearby obstacles but is this the case? To answer this, we combine behavioural experiments with numerical simulations and provide the first evidence that bumblebees extract the maximum rate of image motion in the frontal visual field to steer away from obstacles. Our findings also suggest that bumblebees use different optic flow calculations to control lateral position, speed, and height.
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Affiliation(s)
- Julien Lecoeur
- Laboratory of Intelligent Systems, Institute of Microengineering, École Polytechnique Fédérale de Lausanne, Lausanne, CH-1015, Switzerland.
| | - Marie Dacke
- Lund Vision Group, Department of Biology, Lund University, Lund, SE-22362, Sweden
| | - Dario Floreano
- Laboratory of Intelligent Systems, Institute of Microengineering, École Polytechnique Fédérale de Lausanne, Lausanne, CH-1015, Switzerland
| | - Emily Baird
- Lund Vision Group, Department of Biology, Lund University, Lund, SE-22362, Sweden.,Division of Functional Morphology, Department of Zoology, Stockholm University, Stockholm, SE-10691, Sweden
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11
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Frasnelli E, Hempel de Ibarra N, Stewart FJ. The Dominant Role of Visual Motion Cues in Bumblebee Flight Control Revealed Through Virtual Reality. Front Physiol 2018; 9:1038. [PMID: 30108522 PMCID: PMC6079625 DOI: 10.3389/fphys.2018.01038] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 07/12/2018] [Indexed: 11/13/2022] Open
Abstract
Flying bees make extensive use of optic flow: the apparent motion in the visual scene generated by their own movement. Much of what is known about bees' visually-guided flight comes from experiments employing real physical objects, which constrains the types of cues that can be presented. Here we implement a virtual reality system allowing us to create the visual illusion of objects in 3D space. We trained bumblebees, Bombus ignitus, to feed from a static target displayed on the floor of a flight arena, and then observed their responses to various interposing virtual objects. When a virtual floor was presented above the physical floor, bees were reluctant to descend through it, indicating that they perceived the virtual floor as a real surface. To reach a target at ground level, they flew through a hole in a virtual surface above the ground, and around an elevated virtual platform, despite receiving no reward for avoiding the virtual obstacles. These behaviors persisted even when the target was made (unrealistically) visible through the obstructing object. Finally, we challenged the bees with physically impossible ambiguous stimuli, which give conflicting motion and occlusion cues. In such cases, they behaved in accordance with the motion information, seemingly ignoring occlusion.
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Affiliation(s)
- Elisa Frasnelli
- Department of Evolutionary Studies of Biosystems, The Graduate University for Advanced Studies, Hayama, Japan.,School of Life Sciences, University of Lincoln, Lincoln, United Kingdom
| | - Natalie Hempel de Ibarra
- Department of Psychology, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Finlay J Stewart
- Department of Evolutionary Studies of Biosystems, The Graduate University for Advanced Studies, Hayama, Japan
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12
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Linander N, Dacke M, Baird E, Hempel de Ibarra N. The role of spatial texture in visual control of bumblebee learning flights. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2018; 204:737-745. [PMID: 29980840 PMCID: PMC6096632 DOI: 10.1007/s00359-018-1274-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 06/07/2018] [Accepted: 06/19/2018] [Indexed: 11/29/2022]
Abstract
When leaving the nest for the first time, bees and wasps perform elaborate learning flights, during which the location of the nest is memorised. These flights are characterised by a succession of arcs or loops of increasing radius centred around the nest, with an incremental increase in ground speed, which requires precise control of the flight manoeuvres by the insect. Here, we investigated the role of optic flow cues in the control of learning flights by manipulating spatial texture in the ventral and panoramic visual field. We measured height, lateral displacement relative to the nest and ground speed during learning flights in bumblebees when ventral and panoramic optic flow cues were present or minimised, or features of the ground texture varied in size. Our observations show that ventral optic flow cues were required for the smooth execution of learning flights. We also found that bumblebees adjusted their flight height in response to variations of the visual texture on the ground. However, the presence or absence of panoramic optic flow did not have a substantial effect on flight performance. Our findings suggest that bumblebees mainly rely on optic flow information from the ventral visual field to control their learning flights.
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Affiliation(s)
- Nellie Linander
- Lund Vision Group, Department of Biology, Lund University, Lund, Sweden. .,Centre for Research in Animal Behaviour, Psychology, University of Exeter, Exeter, EX4 4QG, UK.
| | - Marie Dacke
- Lund Vision Group, Department of Biology, Lund University, Lund, Sweden
| | - Emily Baird
- Lund Vision Group, Department of Biology, Lund University, Lund, Sweden
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13
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Ibbotson MR, Hung YS, Meffin H, Boeddeker N, Srinivasan MV. Neural basis of forward flight control and landing in honeybees. Sci Rep 2017; 7:14591. [PMID: 29109404 PMCID: PMC5673959 DOI: 10.1038/s41598-017-14954-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 10/18/2017] [Indexed: 01/04/2023] Open
Abstract
The impressive repertoire of honeybee visually guided behaviors, and their ability to learn has made them an important tool for elucidating the visual basis of behavior. Like other insects, bees perform optomotor course correction to optic flow, a response that is dependent on the spatial structure of the visual environment. However, bees can also distinguish the speed of image motion during forward flight and landing, as well as estimate flight distances (odometry), irrespective of the visual scene. The neural pathways underlying these abilities are unknown. Here we report on a cluster of descending neurons (DNIIIs) that are shown to have the directional tuning properties necessary for detecting image motion during forward flight and landing on vertical surfaces. They have stable firing rates during prolonged periods of stimulation and respond to a wide range of image speeds, making them suitable to detect image flow during flight behaviors. While their responses are not strictly speed tuned, the shape and amplitudes of their speed tuning functions are resistant to large changes in spatial frequency. These cells are prime candidates not only for the control of flight speed and landing, but also the basis of a neural 'front end' of the honeybee's visual odometer.
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Affiliation(s)
- M R Ibbotson
- National Vision Research Institute, Australian College of Optometry, Carlton, Victoria, Australia.
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia.
| | - Y-S Hung
- National Vision Research Institute, Australian College of Optometry, Carlton, Victoria, Australia
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia
- National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH), 9000, Rockville Pike, Bldg 35 A, Bethesda, MD, USA
| | - H Meffin
- National Vision Research Institute, Australian College of Optometry, Carlton, Victoria, Australia
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - N Boeddeker
- Department of Cognitive Neuroscience, Bielefeld University, 33615, Bielefeld, Germany
| | - M V Srinivasan
- Queensland Brain Institute, University of Queensland, St Lucia, QLD 4072, Australia
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