The organization of honeybee ocelli: Regional specializations and rhabdom arrangements

Ribi, Willi A.; Warrant, Eric J.; Zeil, Jochen

doi:10.1016/j.asd.2011.06.004

Cited by 39 publications

(76 citation statements)

References 61 publications

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“…This difference suggests independence between the two systems, which would also explain previous behavioral observations that the immediate color corrections in changing illumination conditions do not fit with the time course for physiological chromatic adaptation (1). Furthermore, ocellar ventral retinas are innervated by two small neurons termed S neurons (25,26).…”

Section: Significancementioning

confidence: 89%

“…processes (25), ocelli provide underfocused images (26), have large apertures or field of view, and possess two spectrally different photoreceptor classes containing AmUVop and AmLop2 opsins (27), with peak absorption at 335-360 and 499-500 nm, respectively (28,29), in their skyward-facing ventral retinas (26). Interestingly, the ocellar long-wavelength opsin differs from the corresponding opsin present in the compound eye (AmLop) (27).…”

Section: Significancementioning

confidence: 99%

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Improved color constancy in honey bees enabled by parallel visual projections from dorsal ocelli

Garcia

Hung

Greentree

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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How can a pollinator, like the honey bee, perceive the same colors on visited flowers, despite continuous and rapid changes in ambient illumination and background color? A hundred years ago, von Kries proposed an elegant solution to this problem, color constancy, which is currently incorporated in many imaging and technological applications. However, empirical evidence on how this method can operate on animal brains remains tenuous. Our mathematical modeling proposes that the observed spectral tuning of simple ocellar photoreceptors in the honey bee allows for the necessary input for an optimal color constancy solution to most natural light environments. The model is fully supported by our detailed description of a neural pathway allowing for the integration of signals originating from the ocellar photoreceptors to the information processing regions in the bee brain. These findings reveal a neural implementation to the classic color constancy problem that can be easily translated into artificial color imaging systems.daylight | insect | vision | neuron tracing | von Kries C olor constancy allows natural and artificial visual systems to solve the challenge of maintaining the color sensation of an object despite changes in the illumination. Color constancy requires the visual system to discount an unknown illumination function, when the only available information to a sensor may be the total response of the different photoreceptors present in the visual system (1).Color constancy by chromatic adaptation is classically modeled by assuming a set of scalar coefficients that adjust the sensitivity of the different sensors responsible for color vision depending on the particular ambient light conditions (2, 3). The chromatic effect produced by variation of the spectral power distribution (SPD) of daylight is explained by differences in the ratio of long to short wavelengths observed at different conditions of daylight (4). This variability is constrained, potentially making possible the recovery of SPD from a limited number of sensor responses and simplifying color constancy solutions (5). Indeed, it is possible to reconstruct the entire SPD for different phases of daylight with just two functions summarizing daylight variability at short (<550 nm) and long (>550 nm) wavelengths (6). However, visual targets often present complex shapes and textures and are illuminated by variable intensity, spectrally mixed illumination, potentially requiring the use of contextual information for achieving color constancy (7,8). Chromatic adaptation is thus thought unlikely to be the sole mechanism enabling constancy (8, 9), and different cortical or other neural processing mechanisms seem important for reliable color vision (10, 11). Considering human vision, color processing involves multistage neural representations from V1 to V4 and the frontal cortex, and although V4 neurons seem critical for automatic color constancy operations (11-14), subsequent neural processing stages have been implicated (15).Although this evidence suggests ...

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Section: Significancementioning

confidence: 89%

Section: Significancementioning

confidence: 99%

Improved color constancy in honey bees enabled by parallel visual projections from dorsal ocelli

Garcia

Hung

Greentree

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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“…Anatomically, the cross-sections of ocellar rhabdoms in many hymenopteran insects are straight and are formed by microvilli from two photoreceptors that are positioned opposite to each other. This arrangement and the fact that the rhabdom sheets do not twist along their length indicates that they are likely to be polarization sensitive (Kral, 1978;Ribi et al, 2011;Zeil et al, 2014). A recent study of the particular alignment of elongated rhabdoms in the three ocelli of orchid bees has provided further evidence for the possible involvement of ocelli in the detection of polarized skylight (Taylor et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

“…A recent study of the particular alignment of elongated rhabdoms in the three ocelli of orchid bees has provided further evidence for the possible involvement of ocelli in the detection of polarized skylight (Taylor et al, 2015). In contrast, the cross-sections of ocellar rhabdoms in the nocturnal bee Megalopta are not straight (Ribi et al, 2011) and the ocellar photoreceptors have indeed been found not to be polarization sensitive (Berry et al, 2011). The polarization sensitivity in ocelli has been suggested not only to provide celestial compass information but also to improve segmentation of the horizon line by enhancing contrast for the control of head attitude, particularly around roll and pitch axes (Zeil et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Regional differences in the preferred e-vector orientation of honeybee ocellar photoreceptors

Ogawa

Ribi

Zeil

et al. 2017

Journal of Experimental Biology

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In addition to compound eyes, honeybees (Apis mellifera) possess three single-lens eyes called ocelli located on the top of the head. Ocelli are involved in head-attitude control and in some insects have been shown to provide celestial compass information. Anatomical and early electrophysiological studies have suggested that UV and blue-green photoreceptors in ocelli are polarization sensitive. However, their retinal distribution and receptor characteristics have not been documented. Here, we used intracellular electrophysiology to determine the relationship between the spectral and polarization sensitivity of the photoreceptors and their position within the visual field of the ocelli. We first determined a photoreceptor's spectral response through a series of monochromatic flashes (340-600 nm). We found UV and green receptors, with peak sensitivities at 360 and 500 nm, respectively. We subsequently measured polarization sensitivity at the photoreceptor's peak sensitivity wavelength by rotating a polarizer with monochromatic flashes. Polarization sensitivity (PS) values were significantly higher in UV receptors (3.8± 1.5, N=61) than in green receptors (2.1±0.6, N=60). Interestingly, most receptors with receptive fields below 35 deg elevation were sensitive to vertically polarized light while the receptors with visual fields above 35 deg were sensitive to a wide range of polarization angles. These results agree well with anatomical measurements showing differences in rhabdom orientations between dorsal and ventral retinae. We discuss the functional significance of the distribution of polarization sensitivities across the visual field of ocelli by highlighting the information the ocelli are able to extract from the bee's visual environment.

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“…It requires that the microvilli are parallel and the rhabdomere is as straight as possible (Ribi et al, 2011). In the X-shaped rhabdomes of archaeognathan ocelli, parts of two almost perpendicular arms are formed by each of the four receptor cells (Fig.…”

Section: Functional Role Of the Ocellimentioning

confidence: 99%

The ocelli of Archaeognatha (Hexapoda): Functional morphology, pigment migration and chemical nature of the reflective tapetum

Böhm

Pass

2016

Journal of Experimental Biology

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The ocelli of Archaeognatha, or jumping bristletails, differ from typical insect ocelli in shape and field of view. Although the shape of the lateral ocelli is highly variable among species, most Machiloidea have sole-shaped lateral ocelli beneath the compound eyes and a median ocellus that is oriented downward. This study investigated morphological and physiological aspects of the ocelli of Machilis hrabei and Lepismachilis spp. The lightreflecting ocellar tapetum in M. hrabei is made up of xanthine nanocrystals, as demonstrated by confocal Raman spectroscopy. Pigment granules in the photoreceptor cells move behind the tapetum in the dark-adapted state. Such a vertical pigment migration in combination with a tapetum has not been described for any insect ocellus so far. The pigment migration has a dynamic range of approximately 4 log units and is maximally sensitive to green light. Adaptation from darkness to bright light lasts over an hour, which is slow compared with the radial pupil mechanism in some dragonflies and locusts.

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The organization of honeybee ocelli: Regional specializations and rhabdom arrangements

Cited by 39 publications

References 61 publications

Improved color constancy in honey bees enabled by parallel visual projections from dorsal ocelli

Improved color constancy in honey bees enabled by parallel visual projections from dorsal ocelli

Regional differences in the preferred e-vector orientation of honeybee ocellar photoreceptors

The ocelli of Archaeognatha (Hexapoda): Functional morphology, pigment migration and chemical nature of the reflective tapetum

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