Single Photon Signals And Transduction In An Insect Eye

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Sen Mot -

signals to the central nervous system All stimuli represent forms ofenergy. Sensation involves con­ verting this energy to a change in the membrane potential of sensory receptorcells and thereby regulating the output ofac­ tion potentials to the central nervous system (eNS). Sensory Pathways We'llbegin ourconsideration ofsensorysystems with the sen­

(Published 14 February 2006)

Photon Fig. 1.Olfactory and visual transduction in vertebrate (5, 9, 33), insect (33, 34), lobster (33), and nematode (23). Activation of OR or rhodopsin leads to activation of a G protein; the Gα subunit activates various targets. The arthropod scheme for insect olfaction has

Neural Image Enhancement Allows Honeybees to See at Night

compromises both spatial and temporal resolution, the improved photon capture enhances vision sufficiently for bees to discriminate coarse images in moonlight. This explains how bees and many other insects can adopt a nocturnal lifestyle despite having an eye design typical of a day-active insect

Static and Dynamic Adaptation of Insect Photoreceptor

insect photoreceptors. The final stage is a static quadratic function. The model fitted current and voltage responses of isolated single photoreceptors from three different insect species with reasonable fidelity when they were stimulated by naturalistic time series having wide bandwidth and contrast, over a light intensity range of >1:10. 4

Relating information capacity to a biophysical model for

eye to the photoreceptors. Absorption of photons activates photo-sensitive pigments in the photoreceptor cells. The activated pigments trigger a cascade of biochemical reactionswhichproduce messengeramolecules.Thesemessengerscauseionchannels in the photoreceptor membrane to open. The open channels provide a membrane

Contrast Gain, Signal-to-Noise Ratio, and Linearity in

Previous studies of insect phototransduction have shown that long contrast steps elicit nonlinear responses (see Laughlin, 1989). This is mostly due to increasing compres- sion (i.e., reduction of the amplitude) of photoresponses to light increments as the

Light Adaptation in Drosophila Photoreceptors: I. Response

responses is limited by the photon shot noise. Amplifi-cation of single photon responses into individual de-tectable events leads to noisy voltage responses, whose slow speed is set by the slow rate of the transduction re-actions and matches the filter properties of the photo-receptor membrane. Such low frequency signaling

50 lecture presentation 0 -

evolved in invertebrates: the compound eye and the single-lens eye. Compound eyes are found in insects and crustaceans and consist of up to several thousand light detectors called ommatidia. Compound eyes are very effective at detecting movement. Compound eyes Rhabdom (a) Fly eyes Crystalline cone Lens (b) Ommatidia Ommatidium Photoreceptor Axons Cornea m

Visual Transduction: Microvilli Orchestrate Photoreceptor

transduction machinery shape response dynamics and information coding properties at both low and high light intensities. The insect compound eye collects light through an array of small lenses that together sample visual information across space [2]. In Diptera, each of these unit eyes, the ommatidia, contains eight photoreceptors that

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photoreceptor cell is able to detect a single photon (~ 2 eV) and generates an information the brain receives from the physical environment. In the retina, a Photons in the visible range (X = 0.4 t0 0.7 ;r)pr0vide the main source of ABSTRACT PLACE : Auditorium TIME :11.00 hours to 12.00 hrs DATES : March 4, 5, 6,1985

Distinct roles of light-activated channels TRP and TRPL in

In insect photoreceptors, absorption of a photon by a visual pigment molecule triggers a cascade of biochem-ical reactions culminating in opening of cationic chan-nels belonging to the TRP (transient receptor potential) superfamily (Hardie, 2014). Until recently, these light-activated channels were identified and studied ex-

Stark trade-offs and elegant solutions in arthropod visual

A structure that can direct light through total internal reflection. In insect rhabdoms,this is facilitated by the relatively high internal refractiveindex comparedwiththesurroundingtissue,allowingrhabdomstofunctionlike fiber-optic cables. Microsaccade Small, involuntary movement of the eye or head. Ommatidia

Marc Chabre, Grenoble - Europhysics News

visual information in the insect brain must therefore be of a totally different type from that of the image processing in our brain. Here we shall restrict our­ selves to the vertebrate eye. The photoreceptor cells are the key element of the whole visual system, in which photon fluxes are converted into signals amenable to neuronal analysis.

Biomimetically Inspired Algorithm for Noise Reduction in

Photoreceptors act as a transduction mechanism by which incoming photons are registered as electrical signals of proportional amplitude. This should sound familiar as it is the same (biomimetic) concept applied by the NVG photocathode. Under low light conditions, photoreceptors in the eye suffer from the same noise contamination as the

Legend for the front cover illustration

42. Signal transduction in SynGAP mutant mice 45 43. Activation of Ca2+/calmodulin-dependent protein kinase II (CaMKII) by concentrations of Ca2+ and

Circuit Mechanisms Underlying Chromatic Encoding in

transduction takes place. Photoreceptors project their axons to the medulla where synaptic in-teractions occur. (B E) NorpA, an essential component of the photo-transduction cascade, was restored in norpA blind fliesinindividualphotoreceptortypes(RhXdenoting Rh3/4/5/6). This allowed for

RESEARCH ARTICLE Open Access Cellular elements for seeing

conditions when the rate of photons arriving in the eye is small. While several studies on vision of nocturnal insects have been published [25], a detailed characterization of the biophysical properties of photoreceptors has not been previously performed in any dark-active insect. Our earl-ier investigations have revealed several peculiar features

Microbial and Animal Rhodopsins: Structures, Functions

specialized GPCRs, capable of detecting single photons as a physical stimulus.21 Because the 11-cis-retinal ligand is covalently bound within the retinal-binding pocket of the receptor, photon absorption and the ensuing retinal cis → trans isomerization convert an inactivating ligand (the inverse agonist

Nonlinear mechanisms for gain adaptation in locust

1985) or even single (Grzywacz and Hillman, 1985) photonshavebeentransduced. Inaddition, thefirst-order Wiener kernel of the photoreceptor response has been shownto beaffected bybackground light intensity (Kus-ter and French, 1985), an effect which can only be explained bynonlinear mechanisms. In this paper we return to the analysis of insect

Current Biology 18 2008 Elsevier Ltd All rights reserved

ual photons (photon bumps). Such recordings also reveal a much larger photon bump amplitude in Megalopta s photo-receptors (1.8 6 0.4 mV) compared to those of Lasioglossum (0.9 6 0.2 mV) (Figures 1A and 1B). This indicates that photo-receptor responses to single photons in the nocturnal M. gen-

Impact of Rearing Conditions and Short-Term Light Exposure

accomplish the required recordings, the experiments from a single photoreceptor lasted typically 30 min. Light stimulation and data analysis Photoreceptors were stimulated with light from a small field (5° as seen by the fly) generated by a high-intensity green LED with a peak wavelength of 525 nm (Marl Optosource) that was driven by a

A biomimetic fly photoreceptor model elucidates how

A standard digital camera cannot capture the whole range of light intensities in a natural scene with a single exposure. A, fine details of the ground are lost with a short exposure. B, longer exposures produce white blobs in the picture due to saturation. C, the eyes can enhance detailed signals in the dark, and oppose saturation in bright light.

University of Groningen Vision, pigments and structural

A simple (single-chambered or camera-type) eye consists of a single optical system (a pinhole and/or a lens) that serves the whole photoreceptor array. In a compound eye, the sensor array is broken into units the ommatidia, each having its own optical system and a