Research

My goal is to understand animal behavior as a system. Using copulation behavior in Drosophila melanogaster as a model, I work in parallel on two fronts: identifying the neural circuits that control this behavior, and developing analysis systems that detect behavior on the fly and intervene in real time. Truly understanding behavior requires four perspectives—causation, ontogeny, survival value, and evolution—yet each has traditionally been pursued separately, in its own field. By combining the tools of neuroethology and informatics, I propose “Systems Ethology” as a framework that connects the four.

Research Topics

Neural mechanisms of copulation behavior in Drosophila

I study the neural circuits that control copulation behavior in the fruit fly Drosophila melanogaster. Drosophila is well suited as a model for the neural basis of behavior: it has a central nervous system, an extensive genetic toolkit, a short generation time, easy husbandry, and stereotyped behavioral patterns. Although the connectivity between neurons in the brain has now been mapped almost in full, what each of those neurons actually does remains largely unknown, leaving ample room to work backward from behavior to circuits. I have shown that the mechanosensitive channel Piezo and the neurons expressing it contribute to the stability of the copulation posture and thereby to reproductive success. I am currently investigating the neural mechanisms that control the timing of ejaculation during copulation.

→ For more, see the blog post “Why are flies used in research?“

Real-time behavioral intervention systems

I develop real-time behavioral intervention systems that trigger a device the instant an animal performs a particular behavior. Conventional behavioral analysis has centered on offline analysis of recorded video, but detecting a behavior as it happens and applying optogenetic manipulation at that moment allows a far more direct approach to the relationship between behavior and neural activity. I have reported a method that uses pose estimation to detect the onset of copulation in real time and control a laser accordingly, as well as a method that uses the object detection algorithm YOLO to recognize copulation behavior itself and intervene. Defining behavior through object detection is robust as the number of animals increases, is largely insensitive to animal orientation, and runs quickly; it can also capture behaviors that are difficult to resolve with pose estimation. On the other hand, it is poorly suited to tracking behavioral sequences or identifying individuals, so the two approaches complement each other.

→ For more, see the blog post “What exactly is YORU, a new object-detection-based behavioral analysis tool?“

Systems Ethology

Ethology has long been guided by Niko Tinbergen’s four questions: causation, ontogeny, survival value, and evolution. In practice, however, each has been pursued separately within its own field, with everything outside the immediate focus treated as a black box. Systems Ethology is a framework that places the notion of the “system” at the center as a common language linking these perspectives. Behavior is treated as the output of a system, and the components handling its inputs and processing are defined as the behavioral system. A behavioral system can be viewed at multiple levels—organism, neuron, molecule—and understanding it demands crossing those levels, yet no single study can capture the whole. That is precisely why I believe we need a venue where approaches and findings can be shared across disciplines. I proposed this framework at SWARM2024 in September 2024, where I organized an Organized Session, and I am currently preparing to launch a Systems Ethology research group in Japan.

→ For more, see the blog post “What exactly is Systems Ethology?“

Tools Developed

Publications and Awards

Papers, proceedings, conference presentations, and review articles are listed on the Publications page; awards, grants, and scholarships are listed on the Awards and Grants page.

Presentation Materials

From GitHub basics to code management and publishing your code alongside a paper (PDF) (updated January 15, 2024)

Presentation slides on how to use Git and GitHub. I walk through how to actually work with GitHub in practice, and the steps involved in making your code available alongside a published paper.