局所脳循環よりみた脳機能活動—特に閉眼安静時ならびにtalking test時のrCBFパターンについて

BRAIN FUNCTIONAL ACTIVITY AS REVEALED BY REGIONAL CEREBRAL BLOOD FLOW:WITH SPECIAL REFERENCE TO rCBF PATTERNS AT REST AND DURING TALKING TEST

I．はじめに

　最近の人間脳における局所脳循環regional cerebralblood flow （以下rCBFと略す）の研究により，局所脳機能活動とrCBFあるいは脳代謝が密接な関係にあることが知られるようになり^{3,5,13,19,20）}，種々の脳機能活動と局所脳循環代謝の関係が次第に解明されつつある。

　これらに対する現在までの報告をみると，大きく分けて1）随意運動（Voluntary movement）時，2）精神機能活動（Mental activity）時のrCBFならびに脳代謝の研究に2分される。前者に関しては，Olesen¹⁰，Ro—land and Larsen¹⁷，Raicheら^13），Ingvar and Schwartz^2）の報告があり，それらによればcontralateral hand，foot,mouth等の随意運動時あるいはtactile discrimi—nationで反対側大脳半球のsensori-motorcortexの機能解剖部位に各々一致したrCBFまたは局所脳代謝の増加を認めている。後者に関しては，Ingvar and Ris—berg^1），Ingvar^5），Risberg and Ingvar^15）は覚醒，睡眠，speech,reading,abstract thinking等のmental eventsにおけるrCBFパターンがactivationのタイプにより各々異なる様相を呈し，それらはmotor movementによるrCBF増加のパターンと明らかに区別されることを報告している。

Using a dynamic multi-detector gamma camera and intracarotid Xe-133 injection method the acti-vation as revealed by changes of rCBF (regional cerebral blood flow) was studied at rest and during talking test. The patients underwent rCBF

studies, in all cases, have right-handedness and have no neurological deficits. The results obtained from this series is as follows :

1) In the resting state with closed eyes, the widespread increased activities of 10-30% above the hemispheric mean flow was seen in frontal region on both hemispheres. Contraversely, the decreased activities was seen in temporal region and in parietal region.

2) The results obtained from double rest studies with 20 minutes of intervals showed a tendency of decrease of mean flow in right hemisphere, and showed almost unchanged flow in left hemisphere. Such rCBF alteration seemed to be related to neither changes of MABP nor changes of Pco,.

3) In the talking test, an unchanged mean flow in both hemispheres was disclosed, when the flow value was compaired with that of resting state.

4) In addition to unchanged mean CBF, focal relatively high activation was localized in upper frontal region, sensorimotor mouth area, mid-sylvian region and in posterior sylvian region. The pattern of activation was rather similar in both hemispheres, but which was a little more widespread and diffuse in the right than in the left hemisphere.

5) This pattern of rCBF coincides rather well to a well-known concept that the different forms of aphasia have been decided by different regions of focal impairement.