ポジトロン断層法(PET)による心の動きの画像化 Imaging of Mind using Positron Emission Tomography

ポジトロン断層法(PET)を用いた脳血流画像法によれば、脳活動を三次元的に画像化できる。本報告は脳活動抽出の信頼性を向上させるための画像解析法、特に、三次元脳標準化法と統計的推定法について述べる。本研究で用いた脳波-PET相関解析法は、脳波における特定の周波数帯の出現と関連する脳部位の抽出に有用で、意識、ないし、こころの探求に応用できる可能性がある。本研究では、気功を取りあげ、気功中の脳活動を普通人の安静時と対比して検討した。気功師において低周波数脳波(12Hz以下)の出現が海馬、扁桃体等の大脳辺縁系の活動を伴うことが明かとなった。

Qigong is a type of meditation originating in Chiena and shares some common features with yoga and zen Buddhism. Our aim was to introduce scientific imaging technology in order to describe this unique state of mind by simultaneous recording of positron emission tomography and EEG. Regional cerebral blood flow (rCBF) images obtained by using [15O] water were transformed onto the Talairach-Tournoux's coordinate using brain standardization techniques. A statistical analysis of regional cross correlation between rCBF and EEG frequency fractions was examined to identify possible brain regions which related to qigong meditation. Eight right-handed normal subjects who served as a control compared with eight qigong professionals. The slow EEG waves (the delta) accompanied a general reduction of rCBF at resting condition and vice versa. The results of the control subjects document the effects of psychological tension or relaxation in rCBF during PET measurements. EEG slow waves in the qigong professionals on the contrary, accompanied increases in rCBF in deep brain structures. The right amygdala correlated with both EEG theta and alpha and the left hippocampus with delta. No remarkable positive correlation was found in the necortices as a whole. These results support that qigong meditation is a state of mind that departs from ordinary thoughts traveling into the depth of consciousness.