2017 Fiscal Year Research-status Report
A novel stimulus device to investigate the mechanism and function of butterfly polarisation vision
| Project/Area Number |
17K15158
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| Research Institution | The Graduate University for Advanced Studies |
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Principal Investigator |
スチュワート フィンレイ 総合研究大学院大学, 先導科学研究科, 助教 (40635893)
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| Project Period (FY) |
2017-04-01 – 2020-03-31
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| Keywords | polarization / motion vision / butterfly / insect / photoreceptor |
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| Outline of Annual Research Achievements |
I have successfully upgraded the prototype projection system that I developed previously, allowing simultaneous pixel-by-pixel control of intensity, pol-angle, pol-degree and potentially colour at refresh rates over 100Hz. I have published a primarily methodology-focused paper (Stewart et al, 2017) detailing its implementation and performance, thus establishing scientific priority for the technique. Indeed, my device has already been mentioned in a review article about the practical aspects of working on polarization vision (Foster et al, 2018).
I have gone on to investigate Papilio's polarization-based motion detection in detail, showing that they are insensitive to diagonal polarization, cannot perceive polarization independently of brightness, and are more sensitive to the polarization of green than red light. I have extended my existing model of Papilio motion vision (Stewart et al, 2015) to explain these observations, and concluded that the mechanism can be considered "monopolatic", i.e. consisting of just one pol-sensitive channel, namely the horizontal-pol-sensitive photoreceptors R3/4. Somewhat counter-intuitively, this results in a system that is in fact optimised to detect vertical polarization. I have almost finished preparing a manuscript describing this work.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
I have completed the work for the first three points of my research plan on schedule, and I intend to submit a manuscript detailing my findings on points 2 and 3 very soon.
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| Strategy for Future Research Activity |
Having rather comprehensively characterised how polarization contrast is perceived in the context of motion vision, I now intend to move away from the motion paradigm, and turn my attention to object vision (e.g. in a free-flight foraging context) as planned (research plan point 4). While I have not yet begun to devise experiments addressing this question, my motion vision findings clearly contradict Kinoshita et al's (2011) observations of foraging behaviour: they reported that vertical polarization is perceived as brighter than horizontal, while I found the opposite. This discrepancy indicates that polarization information is processed differently in different visual modalities, which encourages me that this is indeed a promising avenue for further inquiry.
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| Causes of Carryover |
Minimal expense was incurred this year because I was merely refining an existing prototype system and then carrying out experiments. In the coming year, I intend to develop a new experimental paradigm, which shall necessitate purchasing new equipment. Furthermore, I plan to replace the simple LED light engine of the projector with a "light synthesizer" in order to more finely control the spectral content of stimuli (research plan point 5). This will involve considerable expenditure on optical and electronic components.
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