Understanding the "Mind" through science: Taking on the challenge of visualizing "bonds" in children's group rhythm activities using hormones

In an effort to understand children's 'minds' through science, researchers are conducting novel studies that analyze the mind using biological markers.

Mitsuru Kikuchi of Kanazawa University, a Performer on the Hosoda Project under Moonshot Goal 9, is leveraging his expertise in pioneering oxytocin research to unravel the mechanisms of "bonds" formed through children's group activities. We spoke with him about the social significance and challenges of scientifically studying the "mind," based on his latest paper published online in the international journal Brain and Behavior.

Can the "Mind" change through musical activities? A new scientific challenge using hormones

Could you briefly introduce the content of the paper you recently published?

Kikuchi: This study uses biological markers, namely hormone levels, to verify the effects of group rhythmic activities in children, which have previously been discussed mainly through subjective impressions. We divided children into two groups: one consisting of friends and the other of strangers, and had them participate in a rhythmic activity called a drum circle. We measured "oxytocin" (often called the love hormone) and "cortisol" (a stress hormone) in their saliva before and after the activity. As a result, oxytocin levels rose significantly in the group of friends, while there were no major changes in cortisol. In short, the scientific data suggested that for changes in the "mind," such as "bonds" or "connection," it may not just be about what you do, but who you do it with.

What methods have been used to measure, analyze, and study changes in feelings such as "it was fun because we all played rhythm together"?

Kikuchi: For example, music activities and workshops are often described through personal experience as being "good." Methods for capturing invisible things like the psychological feeling of "drumming together is fun" or "it gives me energy" have mainly relied on subjective data such as surveys and interviews. However, there are two challenges with these subjective assessments.

First, adults and even children (once they reach elementary school age) have a sense of social "appearance," meaning they distinguish between their true feelings and what is socially expected. Someone might answer "it was fun" even if they didn't really feel that way. Relying solely on subjective indicators can lead to extreme results where "everyone is the same," making real differences hard to see.

The second point is that what we "feel" is composed of at least a two-layered structure: the "subjective experience of the mind" and the "response of the body." There are views that "emotions are born from the body" and "the mind triggers bodily responses," and both influence each other. Rather than explaining it through just one side, it is important to take a two-layered approach that incorporates bodily responses alongside subjective reports.

So you decided to use "saliva" to measure hormones such as oxytocin and cortisol as biological indicators of the body's response. Why is that?

Kikuchi: The most significant reason was practical constraints. When measuring biological indicators at schools or where children's activities take place, we cannot simply employ a method that requires long preparation, complex equipment, or invasive procedures like blood sampling, which place a burden on children. It was important that the measurement be quick, painless, easy, and under the same conditions for everyone. In this sense, saliva-based hormone measurement was a very practical choice, as it is less burdensome and requires only the collection of saliva in a test container.

What was the reason for choosing hormones over other methods like heart rate or brain waves?

Kikuchi: There are other methods like heart rate monitors or accelerometers. However, heart rate monitors require attaching sensors to the body, which raises issues regarding "private zones" (body parts that should not be shown to or touched by others), especially with children. To target many children in a school setting, the hurdles regarding setup, time, and ethics are higher than one might imagine. While it might be possible in a setting where you can spend time one-on-one, saliva-based hormone measurement was the best way to turn group activities into data in a short period of time. This was primarily for practical reasons. However, we are also considering the use of wristwatch pulse wave meters and accelerometers in the future.

There are many different types of hormones. Why did you choose these two?

Kikuchi: Cortisol, which can be measured relatively easily and stably from saliva, has long been used as a stress indicator. Oxytocin is also a hormone that has been shown worldwide to be involved in bonding, "bonds," "attachment," and "trust." However, the challenge is that oxytocin levels in saliva are very low and extremely difficult to measure. Innovations in technology, equipment, and procedures are essential for accurate measurement, and there are not many facilities that can actually measure it stably.

Kanazawa University, where I am based, is a pioneer in this field. We have accumulated experience in basic animal experiments, genetic modification of mice, and administering oxytocin to model animals, and have expanded that into human clinical trials, child development research, and psychiatry. Because we have created the measurement equipment and know-how from scratch, we have the advantage of being able to collect objective data in situations that are close to children's real lives, without causing pain.

Oxytocin has been attracting attention both domestically and internationally as a hormone that strengthens the bond between people. It is a representative hormone that continues to be studied to this day as a treatment for autism because of its potential. However, there are not many research communities in Japan that have reached out to field applications as we have.

Measuring the "mind" with only two types of hormones might draw some skepticism or counterarguments...

Kikuchi: That's true. It is too simple to explain all "minds" with only two hormones. There are individual differences and gaps between the reactions of the "mind" and the "body," and subjective feelings and physiological reactions often do not match. We must always be cautious and humble in our interpretations. However, even so, it creates a foundation for scientific discussion rather than having "no objective markers at all." These two hormones serve as "clues" and are interpreted in a multilayered way by combining them with subjective evaluations and behavioral data. You cannot understand everything about the mind with just two types of hormones.

Could you tell us more about the interpretation of increased oxytocin?

Kikuchi: Oxytocin is said to be involved in "attachment," "peace of mind," and "social connection," but at the same time, it may also increase as a self-healing response under strong stress, when cortisol rises. It is not necessarily limited to positive meanings and can also be considered a reaction to protect oneself in a stressful environment. Therefore, we cannot simply say "it is a good thing if oxytocin goes up," but the point of this research is that we were able to quantify physiological level changes and positive changes in the "mind" in a group activity where people cooperate and synchronize with each other in a group where no increase in cortisol was observed.

The difficulty of research is that if we seek too much reproducibility, the "natural mind" moves away

Why did you limit the elementary school students to girls this time, and why did you choose a drum circle for the music activity?

Kikuchi: In scientific research, "reproducibility," or the ability to obtain the same results no matter who, where, or when, is important. However, sociality and the "mind" are extremely diverse and chaotic. When you try to scientifically study "natural relationships," you actually tend to get different results every time.

In order to reduce "variation (confounding factors)" this time, we focused on the simple element of "only girls to avoid differences in sex and development" and "drum circles, which are easy to manipulate in content while maintaining spontaneity and bidirectionality among music." Various group activities such as singing, painting, and creative activities are also interesting, but we chose something where it was easy to control the session situation and easy to operate in the field.

On the other hand, what kind of influence is there for children who are not good at group activities or who like to be alone?

Kikuchi: This research alone cannot fully touch upon it, but people have individualities, and valuing one's own hobbies and time alone is also very important for self-esteem and peace of mind. We are not forcibly recommending group behavior. No matter how strong a child's introverted tendencies might be, they sometimes welcome a "slight connection" and share activities. The "appropriate amount" of sociality differs for each individual, but I feel that even on a small scale, it leads to great peace of mind and happiness.

It means that by doing activities together, "bonds" and "helping" behaviors are born, right?

Kikuchi: In research done overseas, there was an experiment where young children "synchronize" their bodies with adults, and behaviors involved with mutual aid increased afterward. Just like a drum circle, simply riding a rhythm spontaneously may be a "device for getting along," like dancing together in an ancient tribal society.

It may not even need to be a drum. From conducting various research, I have a feeling that even for things other than music, activities with more mutual exchanges and interactions, such as creative activities or making meals, make it easier for oxytocin to rise. Conversely, in group behaviors that follow a fixed pattern, the rise in oxytocin may be slow. I think that "minds" and "bonds" are more likely to be born from free bidirectionality and mutual influence.

Finally, could you tell us about the future direction of your research and the issues you aim to address?

We have been gradually shedding light on the "mind," an area that has tended to be talked about as something invisible, through data on hormones, the brain, and behavior. In the future, we would like to capture moments when children resonate with someone, feel secure, and demonstrate their individuality from more multifaceted perspectives. Our direction is not to simplify the "mind" but to respect its richness while connecting it to the science that will support the future of our children.