抄録
In vivo NIRS is a noninvasive functional brain-mapping method that allows relatively free postures. Near-infrared light (NIR) emitted from a probe on the head surface penetrates to the brain, and is scattered back to a detector on the scalp a few cm away. The changes in the attenuation of the detected NIR reflect primarily the changes in concentration and oxygenation of hemoglobin along the optical path. Modern NIRS systems position emitter and detector probes in a rectangular lattice with a fixed probe distance of 2.5–3 cm, with the distances between the centers of the recording ("channels") being 1.75–2.1 cm. In the present study, we explored the usefulness of higher-density recording (a 0.75 cm channel distance) for improving the resolution of functional mapping. NIRS responses to finger tapping were recorded from the contralateral motor area. Although the responding channels to the tapping by the thumb and the little finger overlapped, their peak positions were different in the majority of the subjects, by about 1 cm on average. In other subjects, the barycentric positions of the activities were separated according to the fingers used, although the peak positions were same. These distances between the active centers are consistent with previous studies using fMRI or MEG. The present results suggest that the high resolution NIRS can resolve less than 1.5 cm difference in the localized activity in the brain, in spite of the spread of the NIR in the brain. [J Physiol Sci. 2008;58 Suppl:S98]
