　The purpose of this homepage is to introduce the results of our research conducted at NEC Fundamental Research Laboratories and Ritsumeikan University.

The natural world is a world where order and disorder, stability and instability coexist. How does order and stability come from a chaotic world? This is an important research subject in the natural sciences. For example, in water vapor, many water molecules move randomly, but when the temperature is lowered, the water vapor becomes water and finally ice, and a regular structure appears. There are also various stable structures that are different from ice, such as snowflakes. On the other hand, if you look at the biological world, you will encounter a completely different order and stability. In the case of humans, the fertilized egg, which is a combination of sperm and egg, continues cell proliferation and continuously grows into infants and adults. It looks like a stable structure in short-term observations. However, this is not the case with long-term observations. Nevertheless, human organization and functions are maintained, and a state that can be called dynamic order and dynamic stability is realized. Obviously, it is different from the static order and static stability of the material world.

Originally I was a physicist, but I was also interested in brain function. So, if I had the opportunity, I also wanted to study life sciences. Around 1995, I happened to find a diagram of the life cycle of cellular slime molds in a book entitled "Molecular Biology of Cells". I still remember it was very shocking.

Cellular slime mold is a type of unicellular amoeba. However, when starving, many amoebas gather to form animal-like slugs that move around freely and then transform into fruiting bodies. And a part of the fruiting body becomes a spore. The spores scattered on the ground sprout and return to the original amoeba. It takes only 24 hours from amoebae aggregation to sporulation. The anterior part of the slug functions like the brain in multicellular animals. However, splitting one slug into two will reshape two smaller slugs. This means that the tip, where brain function is expected, is also newly formed in each slug. In other words, cellular slime mold can be said to be a type of autonomously dispersed biological system. Furthermore, the number of amoebas that make up slugs varies greatly from 100 to 10000.

It is expected that the above-mentioned characteristics of cellular slime molds will be a strength for quantitative model research and will greatly promote the elucidation of brain function. In multi-particle systems, orders of magnitude change in the number of particles in a single system can significantly change the qualitative properties of the system. Therefore, the flexibility of slugs, which can change the number of constituent cells by 10 times or 100 times, is very useful for testing the theory.

This is why I chose Dictyostelium discoideum, a cellular slime mold, as a model organism for brain and systems biology research.