Izawa, Eiichi



Faculty of Letters, Department of Humanities and Social Science (Human Relations) (Mita)



Related Websites

Career 【 Display / hide

  • 2002.04

    JSPS doctal research fellow/ Graduate School of Bioagricultural Sciences, Naogya University

  • 2004.04

    JSPS Post-doctal research fellow/ Graduate School of Human relations, Keio University

  • 2006.01

    慶應義塾大学文学研究科 准教授(有期)(魅力ある大学院教育イニシアティブ)

  • 2008.04

    慶應義塾大学社会学研究科 准教授(有期)(人文グローバルCOE”論理と感性に関する先端的教育研究拠点”)

  • 2012.04

    慶應義塾大学 論理と感性のグローバル研究センター, 共同研究員

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Academic Background 【 Display / hide

  • 1999.03

    Nagoya University, School of Science, Department of Physics

    University, Graduated

  • 1999.04

    Nagoya University, 大学院生命農学研究科, 生物機構・機能科学専攻

    Graduate School, Completed, Master's course

  • 2001.04

    Nagoya University, Bioagricultural Sciences, Biological Mechanisms and Functions

    Graduate School, Completed, Doctoral course

Academic Degrees 【 Display / hide

  • 博士(農学), Nagoya University, Coursework, 2003.03


Research Areas 【 Display / hide

  • Humanities & Social Sciences / Experimental psychology (Animal Psychology)

  • Neuroethology


Books 【 Display / hide

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Papers 【 Display / hide

  • Measurement of urinary mesotocin in large-billed crows by enzyme-linked immunosorbent assay.

    Seguchi A. Mogi K. Izawa E-I

    Journal of Veterinary Medical Science 84   520 - 524 2022.05

    Joint Work, Corresponding author, Accepted

  • Socio-ecological correlates of neophobia in corvids.

    Miller R, Lambert ML, Frohnwieser A, Brecht KF, Bugnyar T, Crampton I, Garcia-Pelegrin E, Gould K, Greggor AL, Izawa E-I, Kelly DM, Li Z. Luo Y, Luong LB, Massen JJM, Nieder A, Reber SA, Schiestl M, Seguchi A, Sepehri P, Stevens JR, Taylor AH, Wang L, Wolff LM, Zhang Y, and Clayton NS

    Current Biology (Current Biology)  32 ( 1 ) 74 - 85 2022.01

    Research paper (scientific journal), Joint Work, Accepted,  ISSN  09609822

     View Summary

    Behavioral responses to novelty, including fear and subsequent avoidance of novel stimuli, i.e., neophobia, determine how animals interact with their environment. Neophobia aids in navigating risk and impacts on adaptability and survival. There is variation within and between individuals and species; however, lack of large-scale, comparative studies critically limits investigation of the socio-ecological drivers of neophobia. In this study, we tested responses to novel objects and food (alongside familiar food) versus a baseline (familiar food alone) in 10 corvid species (241 subjects) across 10 labs worldwide. There were species differences in the latency to touch familiar food in the novel object and novel food conditions relative to the baseline. Four of seven socio-ecological factors influenced object neophobia: (1) use of urban habitat (versus not), (2) territorial pair versus family group sociality, (3) large versus small maximum flock size, and (4) moderate versus specialized caching (whereas range, hunting live animals, and genus did not), while only maximum flock size influenced food neophobia. We found that, overall, individuals were temporally and contextually repeatable (i.e., consistent) in their novelty responses in all conditions, indicating neophobia is a stable behavioral trait. With this study, we have established a network of corvid researchers, demonstrating potential for further collaboration to explore the evolution of cognition in corvids and other bird species. These novel findings enable us, for the first time in corvids, to identify the socio-ecological correlates of neophobia and grant insight into specific elements that drive higher neophobic responses in this avian family group. Video abstract: [Figure presented]

  • Scalable representation of time in the hippocampus

    SHIMBO Akihiro, Izawa E-I., Fujisawa Shigeyoshi

    Science Advances 7 ( 6 ) eabd7013 2021.02

    Research paper (scientific journal), Joint Work, Accepted

     View Summary

    Hippocampal “time cells” encode specific moments of temporally organized experiences that may support hippocampal functions for episodic memory. However, little is known about the reorganization of the temporal representation of time cells during changes in temporal structures of episodes. We investigated CA1 neuronal activity during temporal bisection tasks, in which the sets of time intervals to be discriminated were designed to be extended or contracted across the blocks of trials. Assemblies of neurons encoded elapsed time during the interval, and the representation was scaled when the set of interval times was varied. Theta phase precession and theta sequences of time cells were also scalable, and the fine temporal relationships were preserved between pairs in theta cycles. Moreover, theta sequences reflected the rats' decisions on the basis of their time estimation. These findings demonstrate that scalable features of time cells may support the capability of flexible temporal representation for memory formation.

  • Sex-specific effects of cooperative breeding and colonial nesting on prosociality in corvids.

    Horn L., Bugnyar T., Griesser M., Hengl M., Izawa E-I., Oortwijn T., Rössler C., Scheer C., Schiestl M, Suyama M., Taylor AH., Vanhooland L-C., von Bayern AM, Zürcher Y, Massen JJ.

    eLife (eLife)  9   e58139 - 244 2020.10

    Research paper (scientific journal), Joint Work

     View Summary

    © 2020, eLife Sciences Publications Ltd. All rights reserved. The investigation of prosocial behavior is of particular interest from an evolutionary perspective. Comparisons of prosociality across non-human animal species have, however, so far largely focused on primates, and their interpretation is hampered by the diversity of paradigms and procedures used. Here, we present the first systematic comparison of prosocial behavior across multiple species in a taxonomic group outside the primate order, namely the bird family Corvidae. We measured prosociality in eight corvid species, which vary in the expression of cooperative breeding and colonial nesting. We show that cooperative breeding is positively associated with prosocial behavior across species. Also, colonial nesting is associated with a stronger propensity for prosocial behavior, but only in males. The combined results of our study strongly suggest that both cooperative breeding and colonial nesting, which may both rely on heightened social tolerance at the nest, are likely evolutionary pathways to prosocial behavior in corvids.

  • 社会学習による行動伝播の生態学における役割

    持田浩治・香田啓貴・北條賢・高橋宏司・須山巨基・伊澤 栄一・井原泰雄

    日本生態学会誌 70   177 - 195 2020

    Research paper (scientific journal), Joint Work, Accepted

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Papers, etc., Registered in KOARA 【 Display / hide

Reviews, Commentaries, etc. 【 Display / hide

  • Salivary corticosterone measurement in large-billed crows by enzyme-linked immunosorbent assay

    Aota I., Yatsuda C., Izawa E.I.

    Journal of Veterinary Medical Science (Journal of Veterinary Medical Science)  85 ( 1 ) 71 - 75 2023

    ISSN  09167250

     View Summary

    Salivary corticosteroid measurement, as a surrogate for plasma corticosteroid levels to evaluate an animal’s stress or metabolic state, commonly used in mammals. However, the validity of salivary corticosterone (CORT) measurements in birds has not yet been reported.We aimed tomeasure salivary CORT in crows using a commercially available CORT enzyme-linked immunosorbent assay kit. An adrenocorticotropic hormone (ACTH) challenge experiment using synthetic cosyntropin, an ACTH analogue, was conducted to compare CORT level elevations between the serum and the saliva in a 10–60 min range. Both salivary and blood CORT was significantly elevated 10 min after injecting synthetic cosyntropin. The results supported the validation of salivary CORT as a surrogate for a blood CORT in crows.

  • Measurement of urinary mesotocin in large-billed crows by enzyme-linked immunosorbent assay

    Seguchi A., Mogi K., Izawa E.I.

    Journal of Veterinary Medical Science (Journal of Veterinary Medical Science)  84 ( 4 ) 520 - 524 2022

    ISSN  09167250

     View Summary

    Mesotocin (MT) is an avian homologue of oxytocin (OT). Behavioral pharmacological studies in birds have suggested the involvement of MT in socially affiliative behavior. However, investigations of peripheral MT levels associated with social behavior are lacking because non-invasive methods to measure surrogate plasma MT have yet to be established. This study aimed to measure urinary MT in crows using a commercially available OT enzyme-linked immunosorbent assay kit. Urine samples were collected after intravenous injection of MT and centrifuged to separate urine and fecal components. We found that urinary MT was significantly elevated 15–30 min after MT injection. These results validate our method for the use of urine samples for the measurement of peripheral MT levels in crows.

  • Understand the evolution of animal behaviour at the different levels: brain/body anatomy and physiology, and behavioural functions

    Ei-Ichi IZAWA

    Science IMPACT (Science Impact Ltd.)  12   70 - 72 2018

    Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media), Single Work

  • カラスから探る社会認知機能の進化 -知性に大脳“皮質”は必要か?-


    科学 (岩波書店)  79   678 - 681 2009

    Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media), Single Work

  • カラスの脳と行動から探る知性の進化


    脳21 (金芳堂)  10   355 - 359 2007

    Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media), Single Work

Research Projects of Competitive Funds, etc. 【 Display / hide

  • 絆形成がもたらす排除性孤立:鳥類3個体交渉に着目した新たな実験系の構築


    挑戦的研究(萌芽), Principal investigator

  • 内臓感受性から社会構造の理解に迫る:鳥類モデルを用いた比較心理学研究


    基盤研究(B), Principal investigator

  • 個体間の宥和関係形成を支える脳-内臓回路の比較認知神経科学研究


    MEXT,JSPS, Grant-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (B), Principal investigator

  • 身体拡張性の比較心理学


    MEXT,JSPS, Grant-in-Aid for Scientific Research, Grant-in-Aid for Challenging Research (Exploratory) , Principal investigator

  • 情動をうみだす脳と身体の協働システムの比較認知神経科学研究


    MEXT,JSPS, Grant-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (B), Principal investigator

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Courses Taught 【 Display / hide











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Memberships in Academic Societies 【 Display / hide

  • 日本動物心理学会

  • 日本動物行動学会

  • 日本鳥学会

  • 日本動物学会

  • 日本比較生理生化学会


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Committee Experiences 【 Display / hide

  • 2014.07

    理事, 日本動物心理学会

  • 2016.04

    科学技術予測センター専門調査員, 文部科学省

  • 2018.01

    評議員, 比較生理生化学会

  • 2020.10

    連携会員(第25期), 日本学術会議