抄録
We examined magnetoencephalography (MEG) coherence in the five bands (theta, alpha1, alpha2, beta1, and beta2) while the subjects were performing two different calculation tasks: (i) single-digit subtraction, and (ii) double-digit subtraction. MEG signals were recorded using a whole-head SQUID system. Five healthy males participated. Coherence was used to provide a functional measurement of corticocortical communication. The results showed that coherence in the alpha2 (10∼12.5 Hz) band significantly decreased with increasing memory load during mental calculation tasks. Secondly, in the beta2 (19∼30 Hz) band, significant increase of coherence with increasing memory load during calculation tasks was obtained between regions of left frontal dominance. This result agrees with that obtained in a preliminary study. The results showed that coherence in the beta2 band between regions of left hemisphere dominance significantly increased with increasing memory load during verbal working memory tasks. Therefore, this finding leads to a conclusion that information processing in mental calculation is necessarily a verbal working memory process.
