Song, Z., Zhou, Y. and Juusola, M.I. orcid.org/0000-0002-4428-5330 (2016) Random photon absorption model elucidates how early gain control in fly photoreceptors arises from quantal sampling. Frontiers in Computational Neuroscience, 10. 61. ISSN 1662-5188
Abstract
Many diurnal photoreceptors encode vast real-world light changes effectively, but how this performance originates from photon sampling is unclear. A 4-module biophysically-realistic fly photoreceptor model, in which information capture is limited by the number of its sampling units (microvilli) and their photon-hit recovery time (refractoriness), can accurately simulate real recordings and their information content. However, sublinear summation in quantum bump production (quantumgain-nonlinearity) may also cause adaptation by reducing the bump/photon gain when multiple photons hit the same microvillus simultaneously. Here, we use a Random Photon Absorption Model (RandPAM), which is the 1st module of the 4-module fly photoreceptor model, to quantify the contribution of quantum-gain-nonlinearity in light adaptation. We show how quantumgain-nonlinearity already results from photon sampling alone. In the extreme case, when two or more simultaneous photon-hits reduce to a single sublinear value, quantum-gain-nonlinearity is preset before the phototransduction reactions adapt the quantum bump waveform. However, the contribution of quantum-gain-nonlinearity in light adaptation depends upon the likelihood of multiphoton-hits, which is strictly determined by the number of microvilli and light intensity. Specifically, its contribution to lightadaptation is marginal (≤1%) in fly photoreceptors with many thousands of microvilli, because the probability of simultaneous multi-photon-hits on any one microvillus is low even during daylight conditions. However, in cells with fewer sampling units, the impact of quantum-gain-nonlinearity increases with brightening light.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2016 Song, Zhou and Juusola. This is an open-access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. |
Keywords: | photoreceptor; light adaptation; Random Photon Absorption Model (RandPAM); sublinear summation; quantum-gain-nonlinearity; photon sampling; multi-photon-hits |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Science (Sheffield) > School of Biosciences (Sheffield) > Department of Biomedical Science (Sheffield) |
Funding Information: | Funder Grant number BIOTECHNOLOGY AND BIOLOGICAL SCIENCES RESEARCH COUNCIL (BBSRC) BB/H013849/1 BIOTECHNOLOGY AND BIOLOGICAL SCIENCES RESEARCH COUNCIL (BBSRC) BB/M009564/1 JANE & AATOS ERKKO FOUNDATION NONE LEVERHULME TRUST (THE) RPG-2012-567 BIOTECHNOLOGY AND BIOLOGICAL SCIENCES RESEARCH COUNCIL (BBSRC) BB/F012071/1 BIOTECHNOLOGY AND BIOLOGICAL SCIENCES RESEARCH COUNCIL (BBSRC) BB/D001900/1 |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 22 Jun 2016 09:48 |
Last Modified: | 11 Jul 2016 12:12 |
Published Version: | http://dx.doi.org/10.3389/fncom.2016.00061 |
Status: | Published |
Publisher: | Frontiers Media |
Refereed: | Yes |
Identification Number: | 10.3389/fncom.2016.00061 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:100808 |