The 19th (2019) Yamazaki-Teiichi Prize Winner Measurement Science and Technology
Development of wearable optical topography systems for the imaging of brain functions and its social implementation
| Winner | ||
|---|---|---|
| Atsushi Maki | ||
| History | ||
| Mar. 1988 | Graduated from Faculty of Science and Technology, Keio University | |
| Mar. 1990 | Completed Graduate School of Faculty of Science and Technology, Keio University | |
| Apr. 1990 | Joined Central Research Laboratory, Hitachi Ltd. | |
| Mar. 1997 | Received a Doctorate (Engineering), Keio University | |
| Apr. 2010 | New Business Development Office, Hitachi, Ltd. Research & Development Group | |
| Apr. 2013 | Center for Exploratory Research, Hitachi, Ltd. Research & Development Group | |
| Present | ||
| Winner | ||
|---|---|---|
| Masashi Kiguchi | ||
| History | ||
| Mar. 1981 | Graduated from the Department of Physics, School of Science, Osaka University | |
| Apr. 1983 | Completed School of Science, Graduate School of Science, Osaka University | |
| Apr. 1983 | Joined Hitachi, Ltd. | |
| Aug. 1985 | Hitachi, Ltd. Research & Development Group | |
| Mar. 1995 | Received a Doctorate (Science), Osaka University | |
| Apr. 2019 | Rejoined Hitachi, Ltd. | |
| Present | ||
| Winner | ||
|---|---|---|
| Hiroki Sato | ||
| History | ||
| Mar. 1998 | Graduated from College of Liberal Arts, International Christian University | |
| Mar. 2000 | Completed Graduate School of Arts and Science, College of Arts and Science, the University of Tokyo | |
| Apr. 2000 | Joined Hitachi, Ltd. | |
| Mar. 2006 | Received a Doctorate (Engineering), Keio University | |
| Apr. 2018 | Professor, Ph. D., Department of Bioscience and Engineering, College of Systems Engineering and Science, Shibaura Institute of Technology | |
| Present | ||
Reason for award
Dr. Maki and his colleagues succeeded in the development of the optical topography system for non-invasive imaging of brain activities in the cerebral cortex for the first time in the world. They have further expanded this development and succeeded in the development and practical implementation of wearable optical topography devices. Specifically, they have developed and put into use a hardware, performing as time-division, and switching of multiple semiconductor laser sources by single light-source-driving circuit. The wearable optical topography device has a scalp and cerebral blood flow signal separation function which enables simultaneous measurement by multiple persons. This contributes to the literature on behavioral social psychology. In addition, they developed the technique to objectively measure the depressive mood status from the activities at the site of the short-term memory, incorporating medicine, engineering and psychology.
Besides, they have contributed to the academic and social application of this measuring and evaluation technique, insurance coverage of the tests in the departments of neurosurgery (epilepsy focus test, 2003); psychiatry (aid for differential diagnosis of depressive symptoms, 2014); establishment of JEITA standard AE5010 (2012); issuance of IEC standard IEC 80601-2-71 (2015) through international cooperation with research and medical organizations and other companies.
Based on the above achievements, Dr. Maki, Dr. Kiguchi, and Dr. Sato have been awarded the 19th Yamazaki-Teiichi Prize in Measurement Science and Technology.
Background of research and development
In the 1930s, the possibility of spectroscopic measurement of the oxygenation status of hemoglobin (Hb), which is the most abundant protein in the body, was found. Maki focused on this knowledge and started the development of a new biometric technology using light in the 1990’s. He chose the brain as a measurement target among others because he thought that human information is indispensable for solving social issues in the 21st century. Beginning the research, he worked on the development of tomography, using transmitted light in conjunction with CT technology. The measurement in the brain of small animals such as mice was somehow successful, but it was completely impossible to perform measurements in the brains of large organisms like humans because of the strong interaction between the scattering and absorption of light in the body.
For the brain function measurement technique, Blood Oxygenation Level Dependent (BOLD), which is the basic principle of functional Magnetic Resonance Imaging (fMRI), was published in 1990. With this principle, it has become possible to non-invasively observe the brain activity site of man. At that time, brain function research had not caught the tide. Nevertheless, fMRI technique has greatly contributed to the development of subsequent brain researches.
Maki was inspired by fMRI research, utilizing the oxygenation status of Hb. He thought it might be possible to measure the oxygenation status of Hb with light in the outermost cerebral cortex. His research direction has greatly changed from “tomography technology” to “brain function imaging technology in a reflective configuration”.
Achievements
In 1995, Maki developed the “optical topography method” with the aim of visualizing the functional map of the cerebral cortex. Using diffuse light, he demonstrated the world’s first image measurement of human brain functions.
Optical topography is a technology for imaging the changes in blood flow accompanied by the cerebral cortex activities in the brain surface (i.e. the changes in blood oxygenated Hb and deoxygenated Hb in the cerebral tissue), using diffuse light. The square-array arrangement was devised as the most basic multi-point measuring method for realizing imaging for functional brain mapping, where irradiation points and detection points were arranged in a square array. In this arrangement, light enters from four irradiation points to one detection point. Two wavelengths should be used to measure the oxygenated Hb and deoxygenated Hb with different spectroscopic properties.
For the purpose of the research, the multi-channel lock-in technique was devised: a light source which was electrically encoded, and an output signal of a detector which -was decoded. This solved the problem in simultaneous measurement of two wavelengths at multi-points. This technique enabled multi-wavelength and multi-point simultaneous measurement in a small low-cost device and, allowed a non-invasive real-time observation of the blood flow changes associated with cerebral cortex activities.
Subsequently, Kiguchi et al. started developing a wearable optical topography device, aiming at applications for brain science in the field of health care. The three main development targets are as follows:
- （1）
- Safe reduction in size and weight of the device and power-saving technology: Development of the lock-in detection technique has realized both downsizing and high sensitivity where the time-divided pulse is further modulated at the high frequency with an appropriate wavelength laser source.
- （2）
- Scalp and cerebral blood flow separation technology: Since the depth at which light reaches depends on the distance between a light source and a detector, a new depth-wise separation algorithm has been developed by setting multiple distances between a light source and a detector.
- （3）
- Simultaneous measurement technology for multiple brains: The function to control multiple wearable optical topography devices using one PC has been developed, and the interaction between two brains was successfully observed as the first optical measurement technology for brain function.
In parallel with technology development, Maki and his colleagues have worked on applied research for social implementation of brain science. For example, in the field of brain neuroscience, they realized that measurement of language function in newborns and infants had been difficult in the past, and have contributed to the progress of developmental brain science. This has led to the social implementation of a scientific development method for educational toys for infants that nurture cognitive functions and sociality in line with the development of the brains of the infants. This is an application of brain science to the educational field in a broad sense.
In addition, Sato and his colleagues focused on the diversity of brain activities in healthy individuals and have worked on the development of mental state estimation technology, utilizing individual differences in brain activities. As a representative research achievement, they proposed a mental state measurement system, without relying on questionnaires since the prefrontal cortex activity, which is said to be closely related to human high-order functions, correlates with the mood state. In this study, they devised a method for indexing the difference between two qualitatively different brain activity signals at the same measurement site so as not to be affected by hemodynamics other than brain activities. This measurement method for brain activity signals indicates the capability of the biological measurement and estimation of mental state.
Meaning of the achievements
Currently, the taste sensor is utilized in over 400 companies, public institutions, universities, etc. With this taste sensor, it is possible to show the taste of foods in a taste map (map of taste) or radar chart composed of the basic tastes. The taste sensor successfully brought the taste sensed by the tongue to “the world seen by the eyes." This is advent of the world’s first "scale of taste." Invention and research of this taste sensor in Japan have prompted western countries to focus on research and development of electronic tongues.
In this globalized IoT era, the importance of the taste sensor is increasing more and more. A desired taste is created using AI and transmitted beyond the time and space. In the global development of foods, the characteristics of foods in each region are grasped by the taste sensor in advance. The taste sensor is now on the cusp of utilization in multiple, diverse aspects: search for a favorite taste using smartphones or tablets that register the taste data, production of foods with stable quality, manufacture of non-bitter medicines, and production of sweet foods with reduced calorie content or salty foods with reduced salt. In these days when many countries are facing the serious concerns of rapid aging and very low birthrate, the utilization value of the taste sensor will increase more and more.
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（a） Wearable optical topography （HOT-1000: NeU Corporation） |
（ｂ） Wearable optical topography （WOT-HS: NeU Corporation） |
Fig. Examples of wearable optical topography devices