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Hideaki Koizumi, Ph. D. Fellow, Hitachi, Ltd.
Optical topography, using light to investigate brain activity, is being used not only for diagnostics and treatment of the brain but also for research into the mechanisms of the brain, giving birth to a "Science of Humanity" that integrates natural science and the humanities.
Brain activity of a two-to-five-day-old infant hearing spoken language
(left) hearing spoken language played backwards (middle) and hearing nothing (right) Research conducted jointly with Jacques Mehler of the Scuola Internazionale Superiore di Studi Avanzati.
Topography is the charting of land features; Optical topography, an imaging technique for brain function, measures changes in blood flow using near-infrared light, a part of sunlight. The surface of the brain, or cerebral cortex, supplies freshened blood to other areas of the brain.
Blood flow to the language area, for example, increases during speaking and decreases in silence, and reflected (or absorbed) light changes with the volume of blood. Optical topography shows changes in blood flow (0.1 second increments), revealing mental processes such as thinking and calculating.
This technique is more than medical innovation; by contributing to scientific understanding of the brain, it offers unlimited possibilities for practical application in a wide range of fields.
Using a brain-machine interface, a woman moves a model train by thinking.
From the 1980s, I worked on developing MRI*1 medical measuring equipment. Optical topography grew out of improving this technology. I initially focused on changes in blood flow to show higher-level MRI images of brain function and form. This work revealed the principles of magnetic resonance angiography. We then developed an optical topography device using near-infrared light, making examinations easier and more comfortable for the subject. Measurements can be taken with a small device using semiconductors, making diagnosis easier. One effective approach: using optical topography for preliminary tests and higher-resolution MRI for closer examination.
Optical topography is now used to analyze brain activity-sensation, movement, language, memory, and so on. In 1997, we applied optical topography for identifying where epilepsy*2 originates, facilitating corrective surgery, in collaboration with Tokyo Metropolitan Police Hospital. This technology is used in brainmachine interfaces in devices such as Kokoro Gatari, used for communication by patients paralyzed with ALS (Lou Gehrig's disease).
The dawn of optical topography, letting us see inside an active brain, has opened up fields of study that integrate brain science with humanities such as ethics, religion, and philosophy. It is now possible to see brain activity in restless infants and children using a small, easily-worn probe.
In 2003, in collaborative research with a European cognitive psychologist, we discovered that a newborn can recognize its mother tongue, which caused a global sensation.*3
Looking ahead, optical topography opens up new technologies and areas of study for monitoring healthy minds in children, allowing them to become well-rounded people.
(Published in July 2007)