ECR Spotlight is a series of interviews with early-career authors from a selection of papers published in Journal of Experimental Biology and aims to promote not only the diversity of early-career researchers (ECRs) working in experimental biology during our centenary year but also the huge variety of animals and physiological systems that are essential for the ‘comparative’ approach. Kazuki Yoshino-Hashizawa is an author on ‘ The distress context of social calls evokes a fear response in the bat Pipistrellus abramus’, published in JEB. Kazuki is a PhD student in the lab of Shizuko Hiryu and Kohta I. Kobayasi at the Graduate School of Life and Medical Sciences, Doshisha University, Japan, investigating decision-making processes via vocal communication with a focus on emotion and/or individuality.

Kazuki Yoshino-Hashizawa

Describe your scientific journey and your current research focus

I studied electronic engineering for 7 years at a college of technology (‘Kosen’, a unique Japanese institution of higher education). During my studies at Kobe City College of Technology, I conducted research on the technology for simulating acoustic space and how humans perceive three-dimensional sounds with Associate Professor Yoshiki Nagatani. While there, I learned about the ability of bats to understand space through ultrasonic echoes, and I developed a deep interest in this field. Therefore, I decided to continue my research as a graduate student under Professor Shizuko Hiryu in Doshisha University, who is an expert in bat echolocation in Japan. This is a complete change from the engineering research I had done before, such as numerical calculations, programming and circuit design. Instead, I was able to spend much more time interacting with animals. As I was observing bats for experiments, I was also fascinated by their communication. Within their communication, the bats seemed to have different expressions such as anger, fear and being unmotivated sometimes. Based on these observations, I'm focusing on their vocal communication and reactions as my PhD research with Shizuko and Professor Kohta I. Kobayasi. I'm also currently doing research as part of a fellowship at the Japan Society for the Promotion of Science. I would like to study how the emotions and individuality of bats affect their vocal communication.

How would you explain the main finding of your paper to a member of the public?

What would you do if you saw a lion biting another person? Some of you may attack the lion with courage, or some may escape to a safe place, or some may freeze in fear. The decision-making process would rely on your internal states. Bats also have a response mechanism toward danger. Echolocating bats primarily use sound information to navigate at night. Therefore, they are good model animals for conducting hearing research. Most Japanese house bats showed a freezing response upon hearing a distress call from conspecifics in our experiment. In addition, their heart rate increased when hearing a distress call. Incidentally, bats didn't show heart rate increases when the stimulus consisted of many distress calls, but they showed heart rate increases in the context where the distress call was produced only once in a while. In other words, they recognized the situation from the distress context. Therefore, our results suggest that the bats will freeze based on their fear state when facing the distress of conspecifics.

What are the potential implications of this finding for your field of research?

Currently, rodents and songbirds are the dominant animal models of vocal communication in the field of animal psychophysiology – there are very few animal psychophysiological studies using bats as a model animal. In this study, we applied a psychological paradigm, the auditory oddball task, to bats for the first time. We found that their heart rate varied more in response to the context of the social call than to the surprise effect of the acoustic presentation. It would be very significant if this approach could be used not only in conventional animal models but also in bats, which have a decision-making mechanism based on sound information. We hope that animal psychophysiological research using vocal communication in bats will continue to develop.

A Japanese house bat (Pipistrellus abramus) on the wall of our laboratory.

A Japanese house bat (Pipistrellus abramus) on the wall of our laboratory.

If you had unlimited funding, what question in your research field would you most like to address?

The first thing I would do is to build a facility to breed bats. Currently, especially in Japan, there are very few environments where it is possible to study bats while keeping them in captivity. Although much of the research on bats is extremely unique, the research environment is still inadequate. An environment where we can study the fascinating behaviors exhibited by various bats will yield many research results. Although it is important to know about their ecology in the wild, I am interested in physiological and psychological research using bats as model animals. For example, I think research on the individuality/personality of bats is very interesting. Even when bats of the same species are in the same environment, they often exhibit different behaviors. There are many factors involved in the decision-making process surrounding behavior, and I would like to clarify part of this problem by combining neurophysiological measurements and behavioral–psychological methods.

What changes do you think could improve the lives of early-career researchers, and what would make you want to continue in a research career?

Financial support for living expenses is important. A healthy life is probably the most basic and important condition for researchers, especially the ECRs, who are working hard to learn more about research and building new research environments. I think that a stable income and moderate refreshments would be effective to allow ECRs to do even better work. For now, I feel that ECRs are not receiving a stable salary. Particularly in Japan, many PhD students have to take out loans to pay their tuition. The general public still think that PhD students are just students, not researchers. I have had acquaintances asking me, ‘How long are you going to stay as a student?’ and ‘Why aren't you working?’. I am fortunate to be able to do research while receiving money, because Doshisha University waives tuition fees for my doctoral course, and I have also won a fellowship. But most of my ECR friends at other universities are not financially well off. In such a situation, they will be more preoccupied with life than with great ideas for research. I believe that financial support will improve the research ability of ECRs.

What's next for you?

I'm currently enjoying my research and I can continue my research for a few years at Doshisha University in Japan. My next position is still not decided, and I'm eagerly searching for a post-doc position. I'm not good at English, but I would like to do my next research with overseas researchers.

Kazuki Yoshino-Hashizawa’s contact details: Graduate School of Life and Medical Sciences, Doshisha University, 1-3 Tatara-Miyakodani, Kyotanabe, Kyoto 610-0394, Japan.

E-mail: kyoshino@ultrasonics.jp

Yoshino-Hashizawa
,
K.
,
Nishiuchi
,
Y.
,
Hiragochi
,
M.
,
Kihara
,
M.
,
Kobayasi
,
K. I.
and
Hiryu
,
S.
(
2023
).
The distress context of social calls evokes a fear response in the bat Pipistrellus abramus
.
J. Exp. Biol.
226
,
jeb246271
.