The Applied Cognitive Neuroscience Research Unit (representative: Professor Ippeita Dan in the Faculty of Science and Engineering), in the Center for Research and Development Initiatives, in joint research with Jichi Medical University and Kyoto Sangyo University, in a world-first, has succeeded in developing a method to measure cerebral blood flow reactions from the cerebral cortex surface with direct light, and represent brain activity in the form of a high precision two-dimensional map.
Up until now, multiple light sources and photo-sensors have been placed on the surface of the scalp, and technology called optical topography, which shows, in a two-dimensional image, the distribution of cerebral blood flow on the brain’s surface using information from the sensors, has been applied. But with a spatial resolution of about 2cm (in the case of placing a 3cm lattice probe), there was the possibility of signal intrusion from extracerebral skin tissue. On the other hand, using the successfully developed direct optical topography method, multiple light sources and photo-sensors were placed on the surface of the brain at 5mm intervals, and with a high accuracy of approximately 3mm, it was possible to separate brain activity from different locations.
In this experiment, electric shocks were applied to different parts (upper, middle and lower) of the nose of an anesthetized miniature pig during craniotomy. In this case, it was determined that brain neurons are active in different locations of the brain’s somatosensory areas (front, centre, rear at about 8mm intervals). After examining the location of brain neurons, taking measurements with the direct optical topography method, the existence of cerebral blood reactions were verified in the locations of brain’s somatosensory areas in response to the position of electric shocks to the nose.
In the past, even if there were examples of cerebral blood flow change from the cerebral cortex that we wanted to measure, such as identifying speech areas by having craniotomy patients speak, they were difficult to coordinate. However, there is hope that the direct optical topography technology that we developed will respond to such demands. In the future we will conduct basic experiments on miniature pigs with the aim of realizing clinical application where brain functions can be monitored during human neurosurgical procedures.
Results of this research were published in the online version of US science journal NeuroImage (January 11).
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