In memory of Dr. Tsutomu Nakada

Dr. Tsutomu Nakada, who founded the Niigata University Brain Research Institute's Center for Integrated Human Brain Science and remained active as a project professor at the Brain Research Institute after his retirement, passed away on July 1, 2018. We would like to express our sincere condolences to Dr. Nakada as we reflect on the irreplaceable years we spent together with him.

Dr. Nakada graduated from the Faculty of Medicine at the University of Tokyo in 1976 and moved to the United States in 1978 after clinical training at the University of California and the University of Stanford, where he served as an assistant professor and professor in the Department of Neurology at the University of California, and then moved to Niigata University in 1996 as a professor in the Brain Research Institute. In 2002, he established the Center for Integrated Human Brain Science, and served as the Director of the Center. In addition, he was a tenured professor at the University of California, and continued his clinical teaching and research in the United States, and led an extremely busy life, dividing his time between Japan and the United States.

As a pioneer of biomedical molecular imaging using magnetic resonance imaging (MR), he succeeded in detecting and imaging brain FDG by 19F-MRI using fluorodeoxyglucose in the 1980s, and has since left behind world-recognized research on MRS, fMRI, and other brain applications. His research interests are not only in clinical neurology and neuroscience, but also in information technology, philosophy and history, and he has made significant achievements in each field.

Among them, he has spent his life analyzing the hydrodynamics of the brain. When he was a student at the University of Tokyo's School of Medicine, he wondered why general anesthesia causes loss of consciousness, and was inspired by a paper by Linus Pauling, which he came across in the library, and developed his research under the hypothesis that the dynamics of water in the brain tissue is involved in the creation of consciousness. This led to the Vortex Theory1), 2), which is hypothesized to be deeply related to the phenomena exhibited by water molecules. After that, he continued to pursue the dynamics of water molecules in the brain in both physiological and pathological states, and the results of his various studies were published in his posthumous review article, "Fluid Dynamics Inside the Brain Barrier: Current Concept of Interstitial Flow, Glymphatic Flow, and Cerebrospinal Fluid Circulation in the Brain "3).

After returning to Japan, he developed and introduced the world's first 3T whole-body MRI scanner, and studied brain morphology and function, and then developed and introduced the world's first 3T longitudinal MRI scanner, ISSORAR, and Japan's first ultra-high-field 7TMRI scanner, and then developed MR microscopy to visualize living human geriatric units and study brain fluid dynamics. He has been at the forefront of neuroscience, for example, by elucidating the role of aquaporin 4, a water channel protein, in the brain's hydrodynamics and function.

As one of his students, the thing I will remember most about him since I first joined him in the U.S. 25 years ago is his commitment to the free and active management of his research organization. With the slogan "Research is meaningless unless it is fun," he always had a perpetual enthusiasm for research and discussion with the staff, which I still remember as if it were only yesterday. He was always very strict in his daily research, but behind his strictness was a kindness that cared for each and every one of us, and above all, he was a researcher who was never too hard on himself.

The great legacy he left us has left a great mark on the progress of MRI technology. His legacy will undoubtedly continue to be carried on by the many disciples who were trained by him. We would like to express our deepest respect for his achievements and our gratitude to him for his guidance over the years and pray that he may rest in peace.

References

• 1. Nakada T. Vortex Model of the Brain: The Missing Link in Brain Science? in Nakada T eds. Integrated Human Brain Science, Elsevier :2000: 3-22
• 2. 中田力著、いちたすいち、紀伊国屋書店:2001 (in Japanese)
• 3. Nakada T, Kwee IL : Fluid Dynamics Inside the Brain Barrier: Current Concept of Interstitial Flow, Glymphatic Flow, and Cerebrospinal Fluid Circulation in the Brain. Neuroscientist. 2018:1073858418775027. doi: 10.1177/1073858418775027.