Head – Body coordination in Drosophila melanogaster

Event Abstract Back to Event Spatial vision in insects: How visual information processing is facilitated by an active flight and gaze strategy Martin Egelhaaf1*, Roland Kern1 and Jens P. Lindemann1 1 Bielefeld University, Neurobiology & CITEC, Germany Flying insects, such as blowflies and bees rely on the image flow on their eyes (“optic flow”) solving spatial tasks as diverse as collision avoidance and local navigation, i.e. localizing a previously learnt inconspicuous goal on the basis of landmark cues. In free flight flies and bees exhibit characteristic behavioural actions to shape the dynamics of the optic flow. By employing a saccadic flight and gaze strategy they squeeze rotations into brief and rapid turns leaving most of the flight time for various types of translational prototypical movements. Separation of rotational and translational optic flow components by a behavioural strategy is reasonable , since only the optic flow component induced by translations contains information about the relative distance of environmental structures from the animal. By combined electrophysiological analysis and model simulations we analyzed how during rotational and translational self-motion information about the spatial layout and the textural properties of both experimenter-designed and natural environments are represented at the different processing stages of the visual motion pathway. Only two major conclusions shall be mentioned here: (1) during intersaccadic translational flight, the mechanisms of local motion detection segregate in a computationally cheap way natural sceneries into their depth structure: nearby objects pop out in the activity profile of retinotopic arrays of local motion detectors, whereas more distant structures evoke only negligible responses. (2) Even after spatial pooling of local motion signals by the dendritic trees of the wide-field cells in the lobula complex of flies and bees, these distance dependent response modulations persist. Hence, these neurons, which are traditionally conceived as rotation sensors being involved in mediating compensatory optomotor responses, provide information about the spatial properties of the environment. In conclusion, the neural processing of spatial information in flies and bees is greatly facilitated by their saccadic flight and gaze strategy. This active vision strategy enables the nervous system to solve apparently complex spatial vision tasks in a computationally parsimonious way. Thus, by making use of the closed action–perception loop in a smart way, insects with their tiny brains are capable of performing extraordinarily well even on extremely fast timescales of some ten milliseconds. Acknowledgements The work in our lab is supported by the Deutsche Forschungsgemeinschaft (DFG) Keywords: motion vision, Spatial Vision, Optic Flow, collision avoidance, navigation, fly, Honeybee, Bumblebee, Flight control Conference: International Conference on Invertebrate Vision, Fjälkinge, Sweden, 1 Aug - 8 Aug, 2013. Presentation Type: Oral presentation preferred Topic: Motion vision Citation: Egelhaaf M, Kern R and Lindemann JP (2019). Spatial vision in insects: How visual information processing is facilitated by an active flight and gaze strategy. Front. Physiol. Conference Abstract: International Conference on Invertebrate Vision. doi: 10.3389/conf.fphys.2013.25.00044 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 25 Feb 2013; Published Online: 09 Dec 2019. * Correspondence: Prof. Martin Egelhaaf, Bielefeld University, Neurobiology & CITEC, Bielefeld, D-33501, Germany, martin.egelhaaf@uni-bielefeld.de Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Martin Egelhaaf Roland Kern Jens P Lindemann Google Martin Egelhaaf Roland Kern Jens P Lindemann Google Scholar Martin Egelhaaf Roland Kern Jens P Lindemann PubMed Martin Egelhaaf Roland Kern Jens P Lindemann Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Reproduction is costly and individual decisions about when and how much to invest in reproduction will relate to potential benefits in terms of offspring survivorship or mating success. For those organisms that can reproduce more than once, individuals should invest relatively more in reproduction when the potential benefits are high. If females gain directly or indirectly from choosing attractive, highly ornamented males, then it could be predicted that females mated to these males should invest more in reproduction. Here we report the first test of this prediction for a lekking species, peafowl (Pavo cristatus), in which males do not provide resources for offspring, and females prefer to mate with those males that possess the most elaborate trains. We find that peahens randomly mated to males that vary in the degree of ornament produce more eggs for those peacocks with more elaborate trains. We could find no evidence to support the possibility that this difference arises as a result of difference between males in their ability to fertilize eggs.

Why are voluntary head movements in cervical dystonia slow?

Amplitudes of head movements during putative eye-only saccades

Previous work (Reynolds and Gross 1992) has demonstrated that mate choice enables female guppies, Poecilia reticulata , to obtain heritable benefits (‘good genes’) for their offspring. It is not yet known whether males also signal their functional fertility, that is, their viability as fathers, to female guppies. Our study tested the hypothesis that a male9s behaviour reveals characteristics of his ejaculate. We uncovered a strong correlation between display rate and sperm number in male guppies derived from two wild Trinidadian populations. This result indicates that information on the functional fertility of potential mates is available to females. However, our investigation also found a significant relationship between the frequency of sneaky mating and sperm number. Female guppies in wild populations, particularly those experiencing a high predation regime, are constantly subjected to sneaky mating attempts. As the males responsible for these sneaky matings have highest reserves of sperm they may have the capacity to undermine female choice. The implications of these findings for sperm competition are discussed.

Understanding the selective pressures shaping the number of offspring per breeding event is a key area in the study of life-history strategies. However, in species with parental care, costs incurred in offspring production, rather than rearing, have been largely ignored in both theoretical and empirical studies until relatively recently. Furthermore, the few experimental studies that have manipulated production costs have not yet teased apart effects that operate via the parental phenotype from effects on the quality of the resulting young. To examine whether increased egg production influences parental brood rearing capacity independently of effects operating via egg quality, we experimentally increased egg production in gulls and then examined their capacity to rear a control clutch. We found that the capacity of parents to rear the control brood was substantially reduced solely as a consequence of having themselves produced one extra egg. The paradox that, in many species, parents apparently aim for fewer young per breeding event than the experimentally and theoretically demonstrated optimum, has partly arisen from the failure to take into account the constraints imposed by production costs.

We investigated coordinated saccadic eye and head movements following predictive horizontal visual targets at - 30° by applying transcranial magnetic stimulation (TMS) over the cerebellum before the start of the gaze movement in 10 young subjects. We found three effects of TMS on eye-head movements: 1. Saccadic latency effect. When stimulation took place shortly before movements commenced (75-25 ms before), significantly shorter latencies were found between predictive target presentation and initiation of saccades. Eye latencies were significantly decreased by 45 ms on average, but head latencies were not. 2. Gaze amplitude effect. Without TMS, for the 60° target amplitudes, head movements usually preceded eye movements, as expected (predictive gaze type 3). With TMS 5-75 ms before the gaze movement, the number of eye movements preceding head movements by 20-50 ms was significantly increased ( p < 0.001) and the delay between eye and head movements was reversed ( p < 0.001), i.e. we found eye-predictive gaze type 1. 3. Saccadic peak velocity effect. For TMS 5-25 s before the start of head movement, mean peak velocity of synkinetic eye saccades increased by 20-30% up to 600°/s, compared to 350-400°/s without TMS. We conclude that transient functional cerebellar deficits exerted by means of TMS can change the central synkinesis of eye-head coordination, including the preprogramming of the saccadic pulse and step of a coordinated gaze movement.

A male Drosophila melanogaster deposits many more sperm in a female's bursa copulatrix than are stored in her ventral receptacle or paired spermathecae soon after copula has ended. The remaining sperm are expelled by the female. These observations suggest a sexual conflict over the processes involved in sperm storage. We used genetically manipulated flies to study the role of the central nervous system in sperm storage. Flies with female bodies but masculinized nervous systems, or isolated female abdomens, stored significantly fewer sperm than did control females. Furthermore, compared with control flies, there were relatively more sperm in the ventral receptacle and relatively fewer in the spermathecae. These results suggest that the female nervous input counteracts the male's attempts to force sperm into the ventral receptacle during copula and promotes active transport of sperm to the spermathecae during and after copula. The female is clearly a very active partner in influencing processes involved in sperm competition, especially as only stored sperm can be used later to fertilize eggs. To our knowledge, this is the first study to show directly the involvement of the female nervous system in sperm storage.

The role of compensatory eye and head movements for gaze stabilization in the unrestrained frog

Sperm competition is widespread and influences both male investment in spermatogenic tissue and ejaculate characteristics. Sperm competition models assume trade-offs between sperm size and number, although such trade-offs may be difficult to detect. This study examines the effects of sperm competition risk on the sperm production characteristics of the freshwater snail Viviparus ater. In this prosobranch, females mate frequently and store sperm, generating sperm competition. Males produce two sperm morphs, fertile eupyrene sperm and non-fertilizing oligopyrene sperm. Non-fertilizing sperm may play a role in sperm competition and therefore, like fertilizing sperm, the number produced could vary relative to sperm competition risk. In addition, trade-offs between sperm number and sperm size may be expected. We manipulated the sex ratio of sexually mature snails and found the presence of rivals affected the ratio of oligopyrene/eupyrene sperm males produced. In experimental and natural populations, the number of oligopyrene sperm produced, but not the number of eupyrene sperm, was significantly higher when the sex ratio was male biased. Testis mass did not vary between experimental treatments. We also found a negative relationship between the number and size of oligopyrene sperm produced, which is consistent with evolutionary models of sperm competition, and is, to our knowledge, the first intraspecific demonstration of a trade-off between these traits.

Eight participants were presented with auditory or visual targets and then indicated the target's remembered positions relative to their head eight seconds after actively moving their eyes, head or body to pull apart head, retinal, body, and external space reference frames. Remembered target position was indicated by repositioning sounds or lights. Localization errors were found related to head-on-body position but not of eye-in-head or body-in-space for both auditory (0.023 dB/deg in the direction of head displacement) and visual targets (0.068 deg/deg in the direction opposite to head displacement). The results indicate that both auditory and visual localization use head-on-body information, suggesting a common coding into body coordinates--the only conversion that requires this information.

How might definite spatial scale be determined on the basis of monocular optic flows? The evidence for the perception of distances in depth from optic flow indicates that head motion is essential for accurate performance. Accordingly, we propose a solution that entails the use of symmetries in the physically determined form of oscillatory head trajectories. The hypothesized solution is notable in two other respects. The first is the use of a time-dimensioned optic variable (Lee, 1974). This strategy takes advantage of the fact that metric temporal scaling is preserved in optic flow. Second, somatosensory information about the amplitude of head motion is used to scale distance in intrinsic units. An alternative multimodal solution would require somatosensory information about velocity of head motion, but the evidence from studies of vestibulo-ocular reflex indicate that adequate velocity information may not be available. Finally, we discuss means for testing the proposed solution.

1. Visually guided head and body movements of restrained and freely moving mantids (Tenodera australasiae) have been studied by means of closed circuit television. Interest was concentrated on the different roles of the fovea and the periphery of the eye in controlling visuo-motor behaviour. 2. The peripheral eye is mainly responsible for the detection of novel objects (preferably potential prey) and the generation of ballistic (open-loop) saccadic head movements (Fig. 2) which bring the target image to the fovea (Figs. 3, 4, 5, 6). 3. Measurements on monocular animals show that the fovea ofeach eye is encircled by a saccade sensitive periphery (Figs. 5, 6). In other words each eye is capable of measuring any retinal position of the target image in a coordinate system whose origin is at the fovea. Based on this finding, a hypothesis, which is outlined in Sect. IV.7, suggests that the binocular coordination during fixation, tracking and distance estimation is based on the comparison of angular coordinates extracted by each eye from the position vector of the target. 4. Moving targets which have been fixated are held in the fovea either by smooth or saccadic tracking eye movements. The degree to which either tracking strategy is employed depends mainly on the features of the background, but to some extent also on the velocity of the target. 5. Targets which move against a homogeneous background are tracked by smooth eye movements (Fig. 7). Low target angular velocities are closely matched by the eye velocity. At high target speeds the head lags increasingly behind the target and saccades are periodically required to reduce the position error relative to the fovea. 6. Smooth pursuit eye movements, evoked either by a single target (Fig. 7) or a disrupted background (Fig. 8), are affected primarily by the velocity of the retinal image. While the effects of target and background are similar in this respect, they differ in others. Small objects in the foreground, subtending an angle of only a few degrees on the retina, evoke strong pursuit responses only when they resemble typical prey and project onto the fovea (Fig. 9). On the other hand, the image stabilisation of the background is a stereotyped response that can be evoked whenever a large part of the background moves across the visual field (Fig. 10a). Moreover, responses caused by a moving target in the fovea, and movements of the background in the periphery, are not combined additively (Fig. 10b). The foveal tracking response is weighted more strongly, but because the target is usually small, compared with the background, competing background motion can suppress smooth foveal tracking almost completely. 7. This limitation imposed upon the smooth pursuit system by the presence of a disrupted background (either a stripe pattern in the experimental set-up or grass and other plants in a natural setting) is avoided by the adoption of a strategy of saccadic tracking (Figs. 11, 12, 15, 16). This also applies for the tracking which immediately precedes the catching of prey (Fig. 15). Therefore, the stabilisation of the target image in place on the fovea is not a prerequisite for a successful strike. 8. Up to target angular velocities of about 100 °/s, saccadic tracking is predictive, i.e. the saccades have adequate amplitudes to bring the fovea right on target at the instant the saccade is completed (Fig. 13). This implies that the saccadic system processes not only position information of the target but velocity information as well. It is suggested that this velocity information is provided by the smooth pursuit system. Saccadic tracking would then reflect interactions of two circuits, the velocity coding circuit which in the presence of a homogeneous background also generates smooth pursuit head movements, and the position coding circuit which in the absence of target movement is able to generate saccades on its own.

The Cost of Mating

Head direction (HD) neurons fire selectively according to head orientation in the yaw plane relative to environmental landmark cues. Head movements provoke optic field flow signals that enter the vestibular nuclei, indicating head velocity, and hence angular displacements. To test whether optic field flow alone affects the directional firing of HD neurons, rats walked about on a circular platform as a spot array was projected onto the surrounding floor-to-ceiling cylindrical black curtain. Directional responses in the anterodorsal thalamus of four rats remained stable as they moved about with the point field but in the absence of landmark cues. Then, the spherical projector was rotated about its yaw axis at 4.5°/s for ∼90 s. In 27 sessions the mean drift speed of the preferred directions (PDs) was 1.48°/s (SD=0.78°/s; range: 0.15 to 2.88°/s). Thus, optic flow stimulation entrained PDs, albeit at drift speeds slower than the field rotation. This could be due to conflicts with vestibular, motor command, and efferent copy signals. After field rotation ended, 20/27 PDs drifted back to within 45° of the initial values over several minutes, generally following the shortest path to return to the initial value. Poststimulation drifts could change speed and/or direction, with mean speeds of 0.68±0.64°/s (range 0 to 1.36°/s). Since the HD cell pathway (containing anterodorsal thalamus) is the only known projection of head direction information to entorhinal grid cells and hippocampal place cells, yaw plane optic flow signals likely influence representations in this spatial reference coordinate system for orientation and navigation.