NEUROLOGICAL STUDIES

这项工作的总体目标是进一步了解 脑细胞活动的变化之间的关系，引起的 神经正常人的大脑功能活动，以及 血液流动和新陈代谢的变化。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。上 在此基础上，人们假设大脑活动的变化将是 伴随着血液发光、葡萄糖利用和 耗氧量当我和一个 正电子发射断层扫描（PET），以前在此支持 计划项目[福克斯，1986#18][福克斯，1988#19]，揭示了平行的变化， 葡萄糖利用率和血流无氧变化 消费这一重要发现不仅促进了一场重新... 这些关系的评价，但也提供了生理 用磁共振技术对人脑进行功能性测绘的基本原理 磁共振成像（MRI）。尽管人们对功能性的 大脑的映射，不确定性围绕着我们对这些的理解， 功能性诱导的代谢和循环变化。这个项目 解决了有关这种理解的两个核心问题。一是做 血液流动的变化超过了氧气消耗的变化， 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可用性的函数。第二、 如果使用葡萄糖，但仅代谢为乳酸，为什么组织 乳酸水平充分反映了糖酵解的增加？回答这个 我们提出一个问题，以确定乳酸从大脑中排出是否是 在增加功能活动的领域提供便利。这些实验 将为研究大脑与神经系统之间的关系提供有价值的新信息。 神经系统正常人脑能量代谢的功能活动 人类和一个健全的科学基础，功能性脑成像， PET和功能磁共振成像

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.