Updated on 2023/10/10

写真a

 
YAMASHITA Wakayo
 
Organization
Research Field in Engineering, Science and Engineering Area Graduate School of Science and Engineering (Engineering) Department of Engineering Information Science and Biomedical Engineering Program Associate Professor
Title
Associate Professor

Degree

  • 博士(工学) ( 2009.3   鹿児島大学 )

  • 修士(工学) ( 2006.3   鹿児島大学 )

  • 工学士 ( 2004.3   鹿児島大学 )

Research Interests

  • 物体認識

  • 発達

  • 乳幼児

  • 認知科学

Research Areas

  • Humanities & Social Sciences / Cognitive science

  • Others / Others  / 視覚神経科学

  • Others / Others  / 発達

Research History

  • Kagoshima University   Associate Professor

    2022.4

  • Kagoshima University   Research Field in Engineering, Science and Engineering Area Graduate School of Science and Engineering (Engineering) Department of Engineering Information Science and Biomedical Engineering Program   Assistant Professor

    2020.4

  • Kagoshima University   Research Field in Engineering, Science and Engineering Area Graduate School of Science and Engineering (Engineering) Information Science and Biomedical Engineering Course   Assistant Professor

    2013.4 - 2020.3

Professional Memberships

  • 日本神経科学学会

    2015.10

  • Vision Science Society

    2015.10

  • 日本視覚学会

    2015.10

  • 北米神経科学学会

    2015.10

 

Papers

  • Sung-En Chien, Su-Ling Yeh, Wakayo Yamashita, Sei-Ichi Tsujimura .  Enhanced human contrast sensitivity with increased stimulation of melanopsin in intrinsically photosensitive retinal ganglion cells. .  Vision research209   108271 - 108271   2023.6International journal

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    Language:English   Publishing type:Research paper (scientific journal)  

    The intrinsically photosensitive retinal ganglion cells (ipRGCs) are known to serve non-image-forming functions, such as photoentrainment of the circadian rhythm and pupillary light reflex. However, how they affect human spatial vision is largely unknown. The spatial contrast sensitivity function (CSF), which measures contrast sensitivity as a function of spatial frequency, was used in the current study to investigate the function of ipRGCs in pattern vision. To compare the effects of different background lights on the CSF, we utilized the silent substitution technique. We manipulated the stimulation level of melanopsin (i.e., the visual pigment of ipRGCs) from the background light while keeping the cone stimulations constant, or vice versa. We conducted four experiments to measure the CSFs at various spatial frequencies, eccentricities, and levels of background luminance. Results showed that melanopsin stimulation from the background light enhances spatial contrast sensitivity across different eccentricities and luminance levels. Our finding that melanopsin contributes to CSF, combined with the receptive field analysis, suggests a role for the magnocellular pathway and challenges the conventional view that ipRGCs are primarily responsible for non-visual functions.

    DOI: 10.1016/j.visres.2023.108271

    Scopus

    PubMed

  • Tsujimura S.I., Matsumoto A., Yamashita W. .  Intrinsic Phase Difference between Cone and Melanopsin Signals in the Pupillary Pathway .  Proceedings - 2023 24th International Conference on Control Systems and Computer Science, CSCS 2023   253 - 260   2023

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    Language:Japanese   Publisher:Proceedings - 2023 24th International Conference on Control Systems and Computer Science, CSCS 2023  

    Humans have adapted to a light environment with natural light in the course of evolution. A novel light environment control system is needed to address the problems of inadequate adaptation to the modern artificial light environment. For a long time, only cone and rod cells were thought to be photoreceptors in the retina (i.e. light sensors in human), but a new photoreceptor was discovered around 2000. These photoreceptors are called melanopsin ganglion cells (ipRGCs: intrinsically photoreceptive retinal ganglion cells). However, at present, the understanding of the functions of melanopsin cells is extremely limited and little is known. For example, many people are getting more sunlight in the morning to improve their sleep quality, wearing blue light-cutting glasses or using the Night Shift function in iOS, suggesting that it is important to activate or inhibit melanopsin cells depending on the light environment, but it is necessary to understand the function of melanopsin cells in order to make appropriate decisions on when to activate or inhibit melanopsin cells. Melanopsin cells have a slower response than cones. They receive signals from classical photoreceptors, indicating that cone and melanopsin signals are integrated at the retina. In the present study, we measured the intrinsic phase difference between cone and melanopsin signals in the pupillary pathway using a silent-substitution technique. The goal of the present study was to investigate how these signals are temporally integrated. We used three different test stimuli: (i) varying melanopsin stimulation without changing L-, M-, and S-cone stimulation (melanopsin stimulus); (ii) varying L-, M-, and Scone stimulation only, without changing melanopsin stimulation (cone stimulus); and (iii) varying the radiant flux of the stimuli, without changing the spectral composition, which reduces or increases the radiant flux uniformly at all wavelengths (lightflux stimulus). Consistent with previous studies, we found a delayed pupillary response to the melanopsin stimulus. The cone signal leads the melanopsin signal by approximately 100 ms in onset constriction of the pupil response. In addition, we measured pupillary responses to the light-flux stimulus, consisting of cone and melanopsin stimuli. The timings of the melanopsin stimuli were set at variable physical phases. When we estimated the intrinsic phase difference from the first harmonic component of the pupil trace, the melanopsin signal leads the cone signal by approximately 32° and the contribution of cone signals is approximately five times greater than that of melanopsin signals at a temporal frequency of 0.5 Hz; this could be accounted for by a linear summation model of cone and melanopsin signals. These results suggest that the intrinsic phase difference between the cone and melanopsin signals is not a simple latency difference between photoreceptors at the retina. The difference in onset time of pupil constriction could be explained by the simple latency difference between cone and melanopsin photoreception, whereas the intrinsic phase difference could be explained by an integration process in the melanopsin receptive field.

    DOI: 10.1109/CSCS59211.2023.00047

    Scopus

  • Suzuki W, Hiyama A, Ichinohe N, Yamashita W, Seno T & Takeichi H. .  Visualization by P-flow: gradient- and feature-based optical flow and vector fields extracted from image analysis. .  Journal of the Optical Society of America A37 ( 12 ) 1958 - 1964   2020.12Visualization by P-flow: gradient- and feature-based optical flow and vector fields extracted from image analysis. Reviewed

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    Language:English   Publishing type:Research paper (scientific journal)  

  • Chien, SE., Chen, YC., Matsumoto, A., Yamashita, W., Shih, KT., Tsujimura, S., Yeh,SL. .  The modulation of background color on perceiving audiovisual simultaneity .  Vision Research172   2020.6The modulation of background color on perceiving audiovisual simultaneityReviewed

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1016/j.visres.2020.04.009

  • 山下和香代,林潤一,竹原慎太郎,王鋼 .  観察角度をまたいだ物体弁別の学習に対する内挿角画像呈示の促進作用. .  生体医工学46 ( 5 ) 514 - 521   2008.10観察角度をまたいだ物体弁別の学習に対する内挿角画像呈示の促進作用.Reviewed

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    Language:Japanese   Publishing type:Research paper (scientific journal)  

Presentations

  • 松元 明子, 山下 和香代, 辻村 誠一   錐体細胞とメラノプシン細胞へのON及びOFF刺激による明るさ知覚への影響  

    Vision  2018.1  日本視覚学会

  • 坂本 雅仁, 松崎 圭祐, 山下 和香代, 辻村 誠一   瞳孔反応の測定による錐体細胞とメラノプシン細胞間の潜時差の推定  

    Vision  2017.1  日本視覚学会

  • Yamashita Wakayo, Hayashi Junichi, Murakami Tomoki, Wang Gang   視界関連学習は挿入された視界の経験に依存する(View association learning depends on the experience of interpolated views)  

    Neuroscience Research  2006.7  エルゼビア・ジャパン(株)

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    Language:English  

  • Wang Gang, Obama Shinji, Yamashita Wakayo, Sugihara Tadashi, Tanaka Keiji   視力-不変識別は個人視力の経験に依存する(View-invariant discrimination depends on the experience of individual views)  

    Neuroscience Research  2005.7  エルゼビア・ジャパン(株)

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    Language:English  

Research Projects

  • 視覚的自然場面における人物の動き処理に関する発達過程の解明

    2021.4 - 2024.3

    科学研究費補助金  基盤研究(C)

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    Authorship:Principal investigator  Grant type:Competitive

  • Irradiance encoding process in the nonimage-forming pathway

    Grant number:17H01808  2017.4 - 2021.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)  Grant-in-Aid for Scientific Research (B)

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    Grant amount:\17420000 ( Direct Cost: \13400000 、 Indirect Cost:\4020000 )

  • Contribution of melanopsin ganglion cells to visual pathway

    Grant number:26280103  2014.4 - 2017.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)  Grant-in-Aid for Scientific Research (B)

    TSUJIMURA Sei-ichi

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    Grant amount:\14820000 ( Direct Cost: \11400000 、 Indirect Cost:\3420000 )

    In this study we have investigated how a stimulation of melanopsin ganglion cells contributes to visual pathway using several psychophysical and neurological techniques. We used a multi-primary stimulation system that enables us to stimulate each photoreceptor independently based on silent-substitution technique. In addition we have developed a multi-primary display system and measured contrast sensitivities as a function of spatial frequency.