The effect of alteration of glucose use on brain function

长期以来，葡萄糖一直被认为是大脑的必需燃料，尽管人们并不完全理解为什么会这样。大脑葡萄糖供应的障碍会导致大脑功能受损，昏迷，最终死亡。因此，人体拥有严格的调节系统，以将血糖水平维持在设定的限度内。在某些情况下，当血糖水平经常低于正常水平时，大脑会通过增加大脑对葡萄糖的摄取来进行补偿，从而保持正常的葡萄糖供应，尽管血糖浓度低于正常水平。在这些情况下，包括糖尿病低血糖意识不清、厌食和饥饿，警告低血糖的正常激素系统被绕过。然而，尽管大脑的葡萄糖供应正常，但大脑的表现仍然受到不利影响。大脑的电活动发生变化，反应时间变慢，警觉性降低。这意味着，尽管大脑有正常的葡萄糖供应，但葡萄糖的使用方式不同，这些差异影响了大脑的功能表现。本研究的目的是确定：1.在低血糖无意识状态下，葡萄糖的使用有何变化？2.这些变化如何影响大脑的表现？这项工作的意义在于1.增加我们对葡萄糖在大脑中的作用的了解，2.增加我们对大脑如何工作的了解，3.增加我们对糖尿病、厌食症和饥饿等疾病中为什么会出现认知障碍以及这种损害是否可逆的理解。4.开发一种相对较新的技术--功能磁共振波谱技术，用于研究生化和认知性脑疾病。

Glucose has long been accepted as the mandatory fuel for the brain although it is not fully understood why this is so. Impairment of the glucose supply to the brain results in impairment in brain functions, coma and ultimately death. As a result the body possesses rigid regulatory systems to maintain blood glucose levels within set limits. In certain conditions where blood glucose levels frequently drop below normal, the brain compensates by increasing the uptake of glucose into the brain thus keeping the glucose supply normal despite lower than normal blood glucose concentrations. In these conditions, which include diabetic hypoglycaemia unawareness, anorexia and starvation, the normal hormonal systems warning of low blood glucose are bypassed. However, despite normal glucose supply to the brain, the performance of the brain is still adversely affected. The electrical activity of the brain changes, reaction times slow, and vigilance is decreased. This implies that, despite the brain having a normal supply of glucose, the glucose is being used differently and that these differences affect the functional performance of the brain. The AIMS of this study are to determine: 1. How does the use of glucose vary in the hypoglycaemia unawareness state? 2. How do these variations effect the performance of the brain? The SIGNIFICANCE of this work lies in 1. Increasing our understanding of the role of glucose in the brain, 2. Increasing our understanding of how the brain works, and, 3. Increasing our understanding of why cognitive impairment occurs in disorders such as diabetes, anorexia and starvation and whether this impairment is reversible. 4. Developing application of a relatively new technique, functional magnetic resonance spectroscopy, for use study of biochemical and cognitive brain disorders.