2019 Fiscal Year Annual Research Report
Relationship of color and polarization information in the butterfly lamina
| Project/Area Number |
18F18807
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| Research Institution | The Graduate University for Advanced Studies |
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Principal Investigator |
蟻川 謙太郎 総合研究大学院大学, 先導科学研究科, 教授 (20167232)
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| Co-Investigator(Kenkyū-buntansha) |
ILIC MARKO 総合研究大学院大学, 先導科学研究科, 外国人特別研究員
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| Project Period (FY) |
2018-11-09 – 2021-03-31
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| Keywords | Intracellular recording / Insect / Vision / Lamina / Spectral sensitivity / Spectral opponency / Papilio xuthus / Modelling |
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| Outline of Annual Research Achievements |
We have successfully made a new 21 channel LedSynth device, and used it to measure physiological properties of photoreceptors (PR) and lamina monopolar cells (LMC) in the Papilio xuthus butterfly brain. The new and improved device allows for better spectral control of the stimulating light and thus increases the details for distinguishing between different cell types (PR and LMC). Using this better dataset, we were able to further our mathematical model for lateral inhibition in the lamina, producing a better prediction of response amplitude (positive and negative, relative to the baseline resting membrane potential) based on the spectral composition of the stimulating light and the estimated synaptic connections between cells. On the foundation of this model we calculated the distribution of possible spectral sensitivities of cells depending on the composition of neighboring ommatidial types. Our modeled results show, that the effect of lateral inhibition is mostly due to intraommatidial inhibition. The model is a simplified representation of the real-life situation and of course the modeled predictions will have to be tested experimentally before any conclusions can be made.
Unfortunately, the merger of a LedSynth with a DLP projector proved to be unsuccessful for the lack of light intensity when projecting on to a screen. We thus continued the experiments by positioning the light source in discrete angular steps around the on-axis position and mapped receptive fields of PRs and LMCs. This data needs to be further analyzed.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
We successfully tested the potential merger of a LedSynth with a DLP device and concluded that the output intensity is unfortunately not sufficient for the type of experiments we were interested in. Based on that, we continued measuring the receptive fields with a goniometrically movable point source, which produced useful data for lateral inhibition modeling. The obtained data has been used to further the mathematical model for predicting lateral inhibition effect. We have also modeled the theoretical effect of different neighboring ommatidial types and evaluated the effects of intra- and interommatidial inhibition. Additionally, we made a 21 channel LedSynth device that allows us to measure the physiological properties in a fast and spectrally rich manner. We were able to continue our research project towards obtaining combined physiological and anatomical data for photoreceptors (PRs) and lamina monopolar cells (LMCs) with injecting neurobiotin and its successful visualization under a microscope. The method has proven to be difficult, but nevertheless we were able to establish a protocol which produces results. The next step is to change the labeling to visualize the dendritic arborization of cells and the layered structure of the medulla simultaneously.
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| Strategy for Future Research Activity |
The next step in figuring out the effect of lateral inhibition and neural processing that is taking place in the lamina is to see how the physiologically measured properties coincide with the anatomical structures, how a specific signal is being transmitted further down the visual system. We have started experiments with injecting neurobiotin for cell labeling. The end goal is to produce double staining showing the dendrite arborization of PRs and LMCs in the layers of the medulla, which can be seen by staining cell nuclei. We plan on using a confocal microscope with antibody-bound fluorescent dye. We will mainly focus on the dye injection experiments to produce a solid foundation for connecting physiologically measured characteristics of PRs and LMCs and their connectivity profiles in the lamina and medulla. In the meantime, we will analyze data and prepare results for publications and start writing up the manuscripts for publication of our findings in peer-reviewed journals and on conferences.
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