vol.38 Using the Latest Analytical Technologies to Decipher the Design of the Brain’s Operating Principles

The Department of Histology and Cytology is a historic department with its roots in Anatomy III, which was established when the Hokkaido University School of Medicine was first established. In 2020, Professor Toshihiko Iwanaga, who was responsible for the department, retired and Professor Fumino Fujiyama was appointed as his successor. In addition to Professor Fujiyama, whose primary research focus is on central nervous circuits, Associate Professor Hiromi Iwanaga and Lecturer Junko Kobayashi have been part of the department since Professor Toshihiko Iwanaga’s tenure. Associate Professor Iwanaga works on mechanoreceptors that detect rodent whisker movement and teeth meshing, while Lecturer Kobayashi conducts research on the functional morphology of sugar chains and lectins.

“In my clinical practice as a neurologist, I began to wonder why patients with Parkinson’s disease and Huntington’s chorea have difficulty moving as they wish. Conversely, the question we should be asking is, ‘Why are we able to move as we wish?’ I entered the field of basic research to answer this question,” says Professor Fujiyama.

Dopamine neurons, which cause Parkinson’s disease, control not only motor functions but also higher brain functions such as reward-based reinforcement learning. However, the neural circuits of the brain are extremely complex, with all of the elements including sensation, movement, cognition, and emotion functioning while simultaneously influencing each other, making it difficult to grasp the overall picture of the brain and decipher the design that serves as the operating principle.

In the group that studies the central nervous system, Assistant Professor Fuyuki Karube, Postdoctoral Fellow Yasuharu Hirai, and doctoral program student Fuko Kadono, who transferred from Doshisha University with Professor Fujiyama, are analyzing the cortex-basal ganglia-thalamus loop in the central nervous system field using various approaches.
“Morphology and other static approaches have the advantage of being able to pursue precision. By combining this with dynamic approaches such as electrophysiology and optogenetics, we believe we can comprehensively elucidate a fundamental image of the brain. Based on the accurate maps thus obtained, we hope to contribute to the elucidation of the pathology and therapeutic application of neurodegenerative diseases in which specific neuronal systems are damaged,” says Professor Fujiyama.
As a planning group receiving a Grant-in-Aid for Transformative Research Areas (A) ‘Cell type census of adaptive neuronal circuits: biological mechanisms of structural and functional organization (Adaptive Circuit Census, ACC)’ in FY 2021 and as part of a four-country group selected for a HFSP Research Grant in 2022, they are working to further develop their national and international collaborations.

Graduate student Fuko Kadono is also enrolled in the Graduate Course: Developmental Brain Science (DBS) at the Research and Education Center for Brain Science, along with the doctoral program at the Graduate School of Medicine, where she is experiencing systematic lectures and practical training, and is elucidating the special neural regions in the basal ganglia and their input/output, a theme she has been pursuing since her master’s program.
“There is a specific structure in the striatum of the cortex-basal ganglia-thalamus loop. I am working to elucidate the mechanisms related to the input/output of two types of cells with acceleration and braking functions. I became fascinated in research on the nervous system at university and chose Professor Fujiyama’s laboratory because I wanted to know how far I could go to figure it out. I am committed to giving it my all in this department until I achieve satisfactory results,” says Kadono.