抄録
In recent years, techniques have been developed for estimating internal electrical sources in the human brain from measurements of magnetic fields (MEG). In this study, we investigate how to estimate spatially distributed sources, since this information is important for analyzing the higher functions of the human brain. We used a 64-channel whole-head-type SQUID system to record MEG activities evoked by visually cognitive tasks. Three kinds of stimuli were presented: English words, nonsense words, and random dot patterns. Spatially distributed internal sources with latencies between 320 and 420 ms were estimated by using the sub-optimal least-squares subspace scanning technique. The estimated sources were located in the frontal region for random-dot stimuli, the left temporal region for nonsense-word stimuli, and the right postero-temporal region in addition to the other regions for English-word stimuli.
