Circuit Mechanisms Underlying Chromatic Encoding in Drosophila Photoreceptors

Heath, Sarah; Christenson, Matthias P.; Oriol, Elie; Saavedra-Weisenhaus, Maia; Kohn, Jessica; Behnia, Rudy

doi:10.1016/j.cub.2019.11.075

Cited by 54 publications

(105 citation statements)

References 61 publications

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“…To detect and distinguish wavelength cues, the output of two or more photoreceptors with different spectral sensitivities must be compared. This colour-opponency system has been well explored in vertebrates but only more recently has insect colour opponency been characterised, using Drosophila as the model 1 , 2 . Drosophila melanogaster is fast becoming the model for insect colour vision due to the wide range of genetic tools available.…”

Section: Introductionmentioning

confidence: 99%

The spectral sensitivity of Drosophila photoreceptors

Sharkey

Blanco

Leibowitz

et al. 2020

Sci Rep

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Drosophila melanogaster has long been a popular model insect species, due in large part to the availability of genetic tools and is fast becoming the model for insect colour vision. Key to understanding colour reception in Drosophila is in-depth knowledge of spectral inputs and downstream neural processing. While recent studies have sparked renewed interest in colour processing in Drosophila, photoreceptor spectral sensitivity measurements have yet to be carried out in vivo. We have fully characterised the spectral input to the motion and colour vision pathways, and directly measured the effects of spectral modulating factors, screening pigment density and carotenoid-based ocular pigments. All receptor sensitivities had significant shifts in spectral sensitivity compared to previous measurements. Notably, the spectral range of the Rh6 visual pigment is substantially broadened and its peak sensitivity is shifted by 92 nm from 508 to 600 nm. We show that this deviation can be explained by transmission of long wavelengths through the red screening pigment and by the presence of the blue-absorbing filter in the R7y receptors. Further, we tested direct interactions between inner and outer photoreceptors using selective recovery of activity in photoreceptor pairs.

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Section: Introductionmentioning

confidence: 99%

The spectral sensitivity of Drosophila photoreceptors

Sharkey

Blanco

Leibowitz

et al. 2020

Sci Rep

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“…The study of motion vision in Drosophila is usually carried out using blue light for visual stimulation, which offers an adequate wavelength range for Rh1derived visual responses that sits outside of the PMT's detection range. For the use of spectrally diverse stimuli, a workaround method was developed whereby the visual stimulus delivery occurs during the two-photon scanner fly-back period 26,27 . This approach, however, is limited by the discontinuous nature of the visual stimulus, which could introduce aliasing problems with moving patterns, but also reduces the microscope photon collection time thereby reducing the imaging sensitivity (this particularly affects calcium indicators with slow temporal responses).…”

Section: Discussionmentioning

confidence: 99%

“…It is less clear, however, why these flies lose their increased sensitivity to green light uniquely in this layer structure. If the shift in response properties is caused by the photoreceptor terminals, green light should inhibit R7 activity 26,27 , resulting in decreased sensitivity in the red-eye flies expressing all functional opsins while maintaining unaffected high sensitivity in the orange-eye strain. Our data appears to suggest layer-specific shifts in spectral response properties in the medulla corresponding to projection regions of photoreceptor terminals.…”

Section: Discussionmentioning

confidence: 99%

“…Our setup overcomes many limitations that have hindered the study of colour vision and the integration of visual modalities in Drosophila. Going forward, it will serve as a highly versatile tool to further recent breakthroughs in the field 26,27 and unravel the neural circuitry underlying spectral processing. 44 was achieved using the GAL4/UAS expression systems 55 .…”

Section: Discussionmentioning

confidence: 99%

“…The overall picture of colour vison in Drosophila is being pieced together with improved knowledge of photoreceptors, candidate cells involved in circuitry, and colour-guided behaviour [22][23][24][25][26][27][28] , but much still remains to be characterised. The long-standing dogma advocates that the motion and colour vision processing streams are neatly separated, with R1-R6 providing input to the motion detection pathway and R7-R8 providing input to the colour vision pathway 22,[29][30][31] .…”

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A novel setup for simultaneous two-photon functional imaging and precise spectral and spatial visual stimulation in Drosophila

Feord

Wardill

2020

Sci Rep

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Motion vision has been extensively characterised in Drosophila melanogaster, but substantially less is known about how flies process colour, or how spectral information affects other visual modalities. To accurately dissect the components of the early visual system responsible for processing colour, we developed a versatile visual stimulation setup to probe combined spatial, temporal and spectral response properties. Using flies expressing neural activity indicators, we tracked visual responses in the medulla, the second visual neuropil, to a projected colour stimulus. The introduction of custom bandpass optical filters enables simultaneous two-photon imaging and visual stimulation over a large range of wavelengths without compromising the temporal stimulation rate. With monochromator-produced light, any spectral bandwidth and centre wavelength from 390 to 730 nm can be selected to produce a narrow spectral hue. A specialised screen material scatters each band of light across the visible spectrum equally at all locations of the screen, thus enabling presentation of spatially structured stimuli. We show layer-specific shifts of spectral response properties in the medulla correlating with projection regions of photoreceptor terminals.

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Morphology and spectral sensitivity of long visual fibers and lamina monopolar cells in the butterfly Papilio xuthus

Wakita,

Shibasaki,

Kinoshita

et al. 2024

J of Comparative Neurology

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Extensive analysis of the flower‐visiting behavior of a butterfly, Papilio xuthus, has indicated complex interaction between chromatic, achromatic, and motion cues. Their eyes are spectrally rich with six classes of photoreceptors, respectively sensitive in the ultraviolet, violet, blue, green, red, and broad‐band wavelength regions. Here, we studied the anatomy and physiology of photoreceptors and second‐order neurons of P. xuthus, focusing on their spectral sensitivities and projection terminals to address where the early visual integration takes place. We thus found the ultraviolet, violet, and blue photoreceptors and all second‐order neurons terminate in the distal region of the second optic ganglion, the medulla. We identified five types of second‐order neurons based on the arborization in the first optic ganglion, the lamina, and the shape of the medulla terminals. Their spectral sensitivity is independent of the morphological types but reflects the combination of pre‐synaptic photoreceptors. The results indicate that the distal medulla is the most plausible region for early visual integration.

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Circuit Mechanisms Underlying Chromatic Encoding in Drosophila Photoreceptors

Cited by 54 publications

References 61 publications

The spectral sensitivity of Drosophila photoreceptors

The spectral sensitivity of Drosophila photoreceptors

A novel setup for simultaneous two-photon functional imaging and precise spectral and spatial visual stimulation in Drosophila

Morphology and spectral sensitivity of long visual fibers and lamina monopolar cells in the butterfly Papilio xuthus

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