NEUROLOGICAL STUDIES

这项工作的总体目标是加深我们对 脑细胞活动的变化与由 神经学正常人类的大脑功能活动，以及 血流和新陈代谢的变化。每个人都同意休息 大脑有氧代谢葡萄糖作为其主要能量来源。论 在此基础上，假设大脑活动的变化将是 伴随着血液发光、葡萄糖利用和 耗氧量。这让人大吃一惊，当你与 正电子发射断层扫描(PET)，以前在本 方案项目[福克斯，1986#18][福克斯，1988#19]，揭示了 葡萄糖利用和血流不伴随氧气的变化 消费。这一重要的观察不仅催化了一次 对这些关系的评估也提供了生理上的 人脑磁图的基本原理 磁共振成像(MRI)。尽管人们对功能的巨大兴趣 大脑的图谱，围绕着我们对这些的理解的不确定性 功能性引起的代谢和循环变化。这个项目 讨论了与这一理解有关的两个核心问题。首先，做 血流量的变化超过了耗氧量的变化 保持足够的组织氧气。为了回答这个问题，我们建议 检查血流反应作为氧气供应的函数。第二, 如果葡萄糖被利用，但只被代谢成乳酸，为什么组织不 乳酸水平足以反映糖酵解的增加？要回答这个问题 我们提出的问题是确定乳酸从大脑中流出是否 在职能活动增加的领域提供便利。这些实验 将提供关于大脑关系的有价值的新信息 神经学正常的脑功能活动对能量代谢的影响 人类和更可靠的脑功能成像的科学基础 宠物和功能性核磁共振检查。

The overall objective of this work is to further our understanding of the relationship between changes in brain cellular activity, caused by the functional activity of the brain in neurologically normal humans, and changes in blood flow and metabolism. Everyone agrees that the resting brain metabolizes glucose aerobically as its main source of energy. On the basis it was assumed that changes in the activity of the brain would be accompanied by parallel changes in blood glow, glucose utilization and oxygen consumption. It came as a considerable surprise when work with positron emission tomography (PET), supported previously under this program project [Fox, 1986#18][Fox, 1988#19], revealed parallel changes in glucose utilization and blood flow unaccompanied by changes in oxygen consumption. This important observation has not only catalyzed a re- evaluation of these relationships but also provided the physiological rationale for functional mapping of the human brain with magnetic resonance imaging (MRI). Despite the immense interest in functional mapping of the brain, uncertainty surrounds our understanding of these functionally-induced metabolic and circulatory changes. This project addresses two central questions concerning that understanding. First, do the changes in blood flow exceed those of oxygen consumption simply to maintain adequate tissue oxygen. To answer this question we propose to examine blood flow responses as a function of oxygen availability. Second, if glucose is used but only metabolized to lactate, why don't tissue lactate levels adequately reflect the increased glycolysis? To answer this question we propose to determine whether lactate egress from brain is facilitated in areas of increased functional activity. These experiments will provide valuable new information on the relationship of brain functional activity to brain energy metabolism in neurologically normal humans and a sounder scientific basis for functional brain imaging with PET and fMRI.