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Dyakova, O., Rångtell, F. H., Tan, X., Nordström, K. & Benedict, C. (2019). Acute sleep loss induces signs of visual discomfort in young men. Journal of Sleep Research, 28(6), Article ID e12837.
Open this publication in new window or tab >>Acute sleep loss induces signs of visual discomfort in young men
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2019 (English)In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 28, no 6, article id e12837Article in journal (Refereed) Published
Abstract [en]

Acute sleep loss influences visual processes in humans, such as recognizing facial emotions. However, to the best of our knowledge, no study till date has examined whether acute sleep loss alters visual comfort when looking at images. One image statistic that can be used to investigate the level of visual comfort experienced under visual encoding is the slope of the amplitude spectrum, also referred to as the slope constant. The slope constant describes the spatial distribution of pixel intensities and deviations from the natural slope constant can induce visual discomfort. In the present counterbalanced crossover design study, 11 young men with normal or corrected-to-normal vision participated in two experimental conditions: one night of sleep loss and one night of sleep. In the morning after each intervention, subjects performed a computerized psychophysics task. Specifically, they were required to adjust the slope constant of images depicting natural landscapes and close-ups with a randomly chosen initial slope constant until they perceived each image as most natural looking. Subjects also rated the pleasantness of each selected image. Our analysis showed that following sleep loss, higher slope constants were perceived as most natural looking when viewing images of natural landscapes. Images with a higher slope constant are generally perceived as blurrier. The selected images were also rated as less pleasant after sleep loss. No such differences between the experimental conditions were noted for images of close-ups. The results suggest that sleep loss induces signs of visual discomfort in young men. Possible implications of these findings are discussed.

Keywords
aesthetical pleasantness, amplitude spectrum, natural scene statistics, psychophysics, total sleep deprivation
National Category
Neurosciences
Identifiers
urn:nbn:se:uu:diva-380990 (URN)10.1111/jsr.12837 (DOI)000495679200026 ()30815934 (PubMedID)
Funder
Swedish Research Council, 2012-4740Swedish Research Council, 2015-03100Novo Nordisk, NNF14OC0009349
Available from: 2019-04-03 Created: 2019-04-03 Last updated: 2019-12-05Bibliographically approved
Dyakova, O., Müller, M. M., Egelhaaf, M. & Nordström, K. (2019). Image statistics of the environment surrounding freely behaving hoverflies. Journal of Comparative Physiology A. Sensory, neural, and behavioral physiology, 205(3), 373-385
Open this publication in new window or tab >>Image statistics of the environment surrounding freely behaving hoverflies
2019 (English)In: Journal of Comparative Physiology A. Sensory, neural, and behavioral physiology, ISSN 0340-7594, E-ISSN 1432-1351, Vol. 205, no 3, p. 373-385Article in journal (Refereed) Published
Abstract [en]

Natural scenes are not as random as they might appear, but are constrained in both space and time. The 2-dimensional spatial constraints can be described by quantifying the image statistics of photographs. Human observers perceive images with naturalistic image statistics as more pleasant to view, and both fly and vertebrate peripheral and higher order visual neurons are tuned to naturalistic image statistics. However, for a given animal, what is natural differs depending on the behavior, and even if we have a broad understanding of image statistics, we know less about the scenes relevant for particular behaviors. To mitigate this, we here investigate the image statistics surrounding Episyrphus balteatus hoverflies, where the males hover in sun shafts created by surrounding trees, producing a rich and dense background texture and also intricate shadow patterns on the ground. We quantified the image statistics of photographs of the ground and the surrounding panorama, as the ventral and lateral visual field is particularly important for visual flight control, and found differences in spatial statistics in photos where the hoverflies were hovering compared to where they were flying. Our results can, in the future, be used to create more naturalistic stimuli for experimenter-controlled experiments in the laboratory.

Place, publisher, year, edition, pages
Springer, 2019
Keywords
Free flight behavior, Hoverfly, Image statistics, Modelling, Vision
National Category
Ecology
Identifiers
urn:nbn:se:uu:diva-381316 (URN)10.1007/s00359-019-01329-1 (DOI)000471951300009 ()30937518 (PubMedID)
Funder
Swedish Research Council, 2012-4740Stiftelsen Olle Engkvist Byggmästare, 2016/348Australian Research Council, DP170100008Australian Research Council, DP180100144Australian Research Council, FT180100289
Available from: 2019-04-08 Created: 2019-04-08 Last updated: 2019-08-07Bibliographically approved
Nicholas, S., Supple, J., Leibbrandt, R., Gonzalez-Bellido, P. T. & Nordström, K. (2018). Integration of Small- and Wide-Field Visual Features in Target-Selective Descending Neurons of both Predatory and Non-Predatory Dipterans. Journal of Neuroscience, 38(50), 10725-10733
Open this publication in new window or tab >>Integration of Small- and Wide-Field Visual Features in Target-Selective Descending Neurons of both Predatory and Non-Predatory Dipterans
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2018 (English)In: Journal of Neuroscience, ISSN 0270-6474, E-ISSN 1529-2401, Vol. 38, no 50, p. 10725-10733Article in journal (Refereed) Published
Abstract [en]

For many animals, target motion carries high ecological significance as this may be generated by a predator, prey or potential mate. Indeed, animals whose survival depends on early target detection are often equipped with a sharply tuned visual system, yielding robust performance in challenging conditions. For example, many fast-flying insects use visual cues for identifying targets, such as prey (e.g. predatory dragonflies and robberflies) or conspecifics (e.g. non-predatory hoverflies), and can often do so against self-generated background optic flow. Supporting these behaviors, the optic lobes of insects that pursue targets harbor neurons that respond robustly to the motion of small moving objects, even when displayed against syn-directional background clutter. However, in diptera, the encoding of target information by the descending neurons, which are more directly involved in generating the behavioral output, has received less attention. We characterized target selective neurons by recording in the ventral nerve cord of male and female predatory Holcocephala fusca robberflies and of male non-predatory Eristalis tenax hoverflies. We show that both species have dipteran target-selective descending neurons (dTSDNs) that only respond to target motion if the background is stationary or moving slowly, moves in the opposite direction, or has un-naturalistic spatial characteristics. The response to the target is suppressed when background and target move at similar velocities, which is strikingly different to the response of target neurons in the optic lobes. As the neurons we recorded from are pre-motor, our findings affect our interpretation of the neurophysiology underlying target-tracking behaviors.SIGNIFICANCE STATEMENTMany animals use sensory cues to detect moving targets that may represent predators, prey or conspecifics. For example, birds of prey show superb sensitivity to the motion of small prey, and intercept these at high speeds. In a similar manner, predatory insects visually track moving prey, often against cluttered backgrounds. Accompanying this behavior, the brains of insects that pursue targets contain neurons that respond exclusively to target motion. We here show that dipteran insects also have target selective descending neurons in the part of their nervous system that corresponds to the vertebrate spinal cord. Surprisingly, and in contrast to the neurons in the brain, these pre-motor neurons are inhibited by background patterns moving in the same direction as the target.

National Category
Neurosciences
Identifiers
urn:nbn:se:uu:diva-367332 (URN)10.1523/JNEUROSCI.1695-18.2018 (DOI)000452854200013 ()30373766 (PubMedID)
Note

P.T.G.-B. and K.N. contributed equally to this work.

Available from: 2018-11-30 Created: 2018-11-30 Last updated: 2019-12-17Bibliographically approved
Nicholas, S., Thyselius, M., Holden, M. & Nordström, K. (2018). Rearing and Long-Term Maintenance of Eristalis tenax Hoverflies for Research Studies.. Journal of Visualized Experiments (135), Article ID e57711.
Open this publication in new window or tab >>Rearing and Long-Term Maintenance of Eristalis tenax Hoverflies for Research Studies.
2018 (English)In: Journal of Visualized Experiments, ISSN 1940-087X, E-ISSN 1940-087X, no 135, article id e57711Article in journal (Refereed) Published
Abstract [en]

With an estimated 6000 species worldwide, hoverflies are ecologically important as alternative pollinators to domesticated honeybees. However, they are also a useful scientific model to study motion vision and flight dynamics in a controlled laboratory setting. As the larvae develop in organically polluted water, they are useful models for investigating investment in microbial immunity. While large scale commercial breeding for agriculture already occurs, there are no standardized protocols for maintaining captive populations for scientific studies. This is important as commercial captive breeding programs focusing on mass output during peak pollination periods may fail to provide a population that is consistent, stable and robust throughout the year, as is often needed for other research purposes. Therefore, a method to establish, maintain and refresh a captive research population is required. Here, we describe the utilization of an artificial hibernation cycle, in addition to the nutritional and housing requirements, for long term maintenance of Eristalis tenax. Using these methods, we have significantly increased the health and longevity of captive populations of E. tenax compared to previous reports. We furthermore discuss small scale rearing methods and options for optimizing yields and manipulating population demographics.

National Category
Ecology
Identifiers
urn:nbn:se:uu:diva-352619 (URN)10.3791/57711 (DOI)000444372200127 ()29863660 (PubMedID)
Funder
Australian Research Council, DP170100008Australian Research Council, DP180100144Stiftelsen Olle Engkvist Byggmästare, 2016/348
Available from: 2018-06-06 Created: 2018-06-06 Last updated: 2018-11-15Bibliographically approved
Thyselius, M., Gonzalez-Bellido, P., Wardill, T. & Nordström, K. (2018). Visual approach computation in feeding hoverflies. Journal of Experimental Biology, 221(10), Article ID jeb.177162.
Open this publication in new window or tab >>Visual approach computation in feeding hoverflies
2018 (English)In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 221, no 10, article id jeb.177162Article in journal (Refereed) Published
Abstract [en]

On warm sunny days, female hoverflies are often observed feeding from a wide range of wild and cultivated flowers. In doing so, hoverflies serve a vital role as alternative pollinators, and are suggested to be the most important pollinators after bees and bumblebees. Unless the flower hoverflies are feeding from is large, they do not readily share the space with other insects, but instead opt to leave if another insect approaches. We used high-speed videography followed by 3D reconstruction of flight trajectories to quantify how female Eristalis hoverflies respond to approaching bees, wasps and two different hoverfly species. We found that, in 94% of the interactions, the occupant female left the flower when approached by another insect. We found that compared with spontaneous take-offs, the occupant hoverfly's escape response was performed at similar to 3 times higher speed (spontaneous take-off at 0.20.05 m s(-1) compared with 0.55 +/- 0.08 m s(-1) when approached by another Eristalis). The hoverflies tended to take off upward and forward, while taking the incomer's approach angle into account. Intriguingly, we found that, when approached by wasps, the occupant Eristalis took off at a higher speed and when the wasp was further away. This suggests that feeding hoverflies may be able to distinguish these predators, demanding impressive visual capabilities. Our results, including quantification of the visual information available before occupant take-off, provide important insight into how freely behaving hoverflies perform escape responses from competitors and predators (e.g. wasps) in the wild.

Keywords
Approach, Foraging behavior, Looming stimuli, Motion vision, Retinal size, Target detection
National Category
Ecology
Identifiers
urn:nbn:se:uu:diva-351233 (URN)10.1242/jeb.177162 (DOI)000438913100016 ()29720383 (PubMedID)
Available from: 2018-05-22 Created: 2018-05-22 Last updated: 2018-09-27Bibliographically approved
Dyakova, O. & Nordström, K. (2017). Image statistics and their processing in insect vision. Current Opinion in Insect Science, 24, 7-14
Open this publication in new window or tab >>Image statistics and their processing in insect vision
2017 (English)In: Current Opinion in Insect Science, ISSN 2214-5745, Vol. 24, p. 7-14Article, review/survey (Refereed) Published
Abstract [en]

Natural scenes may appear random, but are not only constrained in space and time, but also show strong spatial and temporal correlations. Spatial constraints and correlations can be described by quantifying image statistics, which include intuitive measures such as contrast, color and luminance, but also parameters that need some type of transformation of the image. In this review we will discuss some common tools used to quantify spatial and temporal parameters of naturalistic visual input, and how these tools have been used to inform us about visual processing in insects. In particular, we will review findings that would not have been possible using conventional, experimenter defined stimuli.

National Category
Neurosciences
Research subject
Neurology
Identifiers
urn:nbn:se:uu:diva-329430 (URN)10.1016/j.cois.2017.08.002 (DOI)000417020600004 ()
Funder
Swedish Research Council, 2012-4740Stiftelsen Olle Engkvist Byggmästare, 2016/348
Available from: 2017-09-15 Created: 2017-09-15 Last updated: 2018-03-12Bibliographically approved
Nordström, K., Dahlbom, J., Pragadheesh, V., Ghosh, S., Olsson, A., Dyakova, O., . . . Olsson, S. B. (2017). In situ modeling of multimodal floral cues attracting wild pollinators across environments. Proceedings of the National Academy of Sciences of the United States of America, 114(50), 13218-13223
Open this publication in new window or tab >>In situ modeling of multimodal floral cues attracting wild pollinators across environments
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2017 (English)In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 114, no 50, p. 13218-13223Article in journal (Refereed) Published
Abstract [en]

With more than 80% of flowering plant species specialized for animal pollination, understanding how wild pollinators utilize resources across environments can encourage efficient planting and maintenance strategies to maximize pollination and establish resilience in the face of environmental change. A fundamental question is how generalist pollinators recognize “flower objects” in vastly different ecologies and environments. On one hand, pollinators could employ a specific set of floral cues regardless of environment. Alternatively, wild pollinators could recognize an exclusive signature of cues unique to each environment or flower species. Hoverflies, which are found across the globe, are one of the most ecologically important alternative pollinators after bees and bumblebees. Here, we have exploited their cosmopolitan status to understand how wild pollinator preferences change across different continents. Without employing any a priori assumptions concerning the floral cues, we measured, predicted, and finally artificially recreated multimodal cues from individual flowers visited by hoverflies in three different environments (hemiboreal, alpine, and tropical) using a field-based methodology. We found that although “flower signatures” were unique for each environment, some multimodal lures were ubiquitously attractive, despite not carrying any reward, or resembling real flowers. While it was unexpected that cue combinations found in real flowers were not necessary, the robustness of our lures across insect species and ecologies could reflect a general strategy of resource identification for generalist pollinators. Our results provide insights into how cosmopolitan pollinators such as hoverflies identify flowers and offer specific ecologically based cues and strategies for attracting pollinators across diverse environments.

Keywords
multimodal factors, categorization, syndrome, hoverfly, multivariate
National Category
Horticulture Behavioral Sciences Biology
Identifiers
urn:nbn:se:uu:diva-328029 (URN)10.1073/pnas.1714414114 (DOI)000417806200064 ()29180408 (PubMedID)
Funder
Stiftelsen Olle Engkvist Byggmästare, 2014/254; 2016/348
Available from: 2017-08-16 Created: 2017-08-16 Last updated: 2018-02-23Bibliographically approved
Outomuro, D., Söderquist, L., Johansson, F., Ödeen, A. & Nordström, K. (2017). The price of looking sexy: visual ecology of a three-level predator–prey system. Functional Ecology, 31(3), 707-718
Open this publication in new window or tab >>The price of looking sexy: visual ecology of a three-level predator–prey system
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2017 (English)In: Functional Ecology, ISSN 0269-8463, E-ISSN 1365-2435, Vol. 31, no 3, p. 707-718Article in journal (Refereed) Published
Abstract [en]

Colour signals and colour vision play a pivotal role in intraspecific communication and predator-prey interactions. However, the costs of expressing conspicuous sexual signals at multiple trophic levels have been largely overlooked. Sexual signals can also experience character displacement in sympatric populations of closely related species, leading to potential changes in conspicuousness. We here investigate a bird-damselfly-fruit fly predator-prey system, where two closely related damselfly species have conspicuous, sexually selected wing coloration. The damselflies can occur in sympatry and allopatry, and reproductive character displacement in the coloration size has been previously reported. We quantify the damselfly wing reflectance from replicated sympatric and allopatric populations, and use receptor noise models to investigate the visual discriminability of the wing coloration for the bird, damselfly and fly vision systems, against natural backgrounds. We perform electroretinograms to study damselfly eye sensitivity. We also estimate damselfly predation risk in natural populations. We find that the chromatic component of wing coloration makes males highly discriminable to the predator, but not to the prey. However, female wing coloration is predominantly cryptic for the predator and prey, and interestingly, also for male damselflies. A female being cryptic to conspecifics likely reduces male harassment. The estimates of predation risk partially support the discriminability results. We also show that there is no difference in colour vision sensitivity between the two damselfly species and sexes, and no difference in wing coloration or its discriminability between sympatric and allopatric populations. Our results suggest that sexually selected traits can be antagonistically selected by predators and prey and that this antagonistic selection can be sex-dependent: males are paying a large cost in terms of conspicuousness, while females remain mostly cryptic. Our study thus emphasizes the need for investigating visual communication at multitrophic levels since the degree of colour discriminability can differ between predators, prey and the focal species.

National Category
Evolutionary Biology
Identifiers
urn:nbn:se:uu:diva-315225 (URN)10.1111/1365-2435.12769 (DOI)000395347300016 ()
Funder
Stiftelsen Olle Engkvist ByggmästareSwedish Research Council, 2012-4740
Available from: 2017-02-10 Created: 2017-02-10 Last updated: 2017-11-29Bibliographically approved
Thyselius, M. & Nordström, K. (2016). Hoverfly locomotor activity is resilient to external influence and intrinsic factors. Journal of Comparative Physiology A. Sensory, neural, and behavioral physiology, 202(1), 45-54
Open this publication in new window or tab >>Hoverfly locomotor activity is resilient to external influence and intrinsic factors
2016 (English)In: Journal of Comparative Physiology A. Sensory, neural, and behavioral physiology, ISSN 0340-7594, E-ISSN 1432-1351, Vol. 202, no 1, p. 45-54Article in journal (Refereed) Published
Abstract [en]

Hoverflies are found across the globe, with approximately 6000 species described worldwide. Many hoverflies are being used in agriculture and some are emerging as model species for laboratory experiments. As such it is valuable to know more about their activity. Like many other dipteran flies, Eristalis hoverflies have been suggested to be strongly diurnal, but this is based on qualitative visualization by human observers. To quantify how hoverfly activity depends on internal and external factors, we here utilize a locomotor activity monitoring system. We show that Eristalis hoverflies are active during the entire light period when exposed to a 12 h light:12 h dark cycle, with a lower activity if exposed to light during the night. We show that the hoverflies' locomotor activity is stable over their lifetime and that it does not depend on the diet provided. Surprisingly, we find no difference in activity between males and females, but the activity is significantly affected by the sex of an accompanying conspecific. Finally, we show that female hoverflies are more resilient to starvation than males. In summary, Eristalis hoverflies are resilient to a range of internal and external factors, supporting their use in long-term laboratory experiments.

Keywords
Diet; Age; Sexual dimorphism; Circadian rhythm; Starvation
National Category
Behavioral Sciences Biology
Identifiers
urn:nbn:se:uu:diva-268566 (URN)10.1007/s00359-015-1051-2 (DOI)000367612300005 ()26610330 (PubMedID)
Funder
Swedish Research Council, 2012-4740Stiftelsen Olle Engkvist Byggmästare
Available from: 2015-12-08 Created: 2015-12-08 Last updated: 2017-12-01Bibliographically approved
Gonzalez-Bellido, P. T., Fabian, S. T. & Nordström, K. (2016). Target detection in insects: optical, neural and behavioral optimizations. Current Opinion in Neurobiology, 41, 122-128
Open this publication in new window or tab >>Target detection in insects: optical, neural and behavioral optimizations
2016 (English)In: Current Opinion in Neurobiology, ISSN 0959-4388, E-ISSN 1873-6882, Vol. 41, p. 122-128Article in journal (Refereed) Published
Abstract [en]

Motion vision provides important cues for many tasks. Flying insects, for example, may pursue small, fast moving targets for mating or feeding purposes, even when these are detected against self-generated optic flow. Since insects are small, with size-constrained eyes and brains, they have evolved to optimize their optical, neural and behavioral target visualization solutions. Indeed, even if evolutionarily distant insects display different pursuit strategies, target neuron physiology is strikingly similar. Furthermore, the coarse spatial resolution of the insect compound eye might actually be beneficial when it comes to detection of moving targets. In conclusion, tiny insects show higher than expected performance in target visualization tasks.

National Category
Neurosciences
Identifiers
urn:nbn:se:uu:diva-308754 (URN)10.1016/j.conb.2016.09.001 (DOI)27662056 (PubMedID)
Available from: 2016-11-30 Created: 2016-11-30 Last updated: 2018-01-13Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-6020-6348

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