【TED】记忆的产生和丢失
中英文稿
回想一个生动的回忆， 好了吗？ 好的，现在，想想三周前你午餐吃了什么？ 这个回忆可能就不是那么栩栩如生了吧， 为什么会这样呢？ 为什么我们会记住一些事情， 而忘却另外一些事情？ 为什么记忆最终会一点一点地褪色？ 让我们首先来看一下，记忆是如何产生的。 当你经历什么事情的时候，比如拨电话号码。 这个体验会被转化成一种脑电波脉冲， 这种脉冲快速地沿着神经网络前进。 信息首先到达短期记忆处理中心， 这是一个存储几秒钟到 几分钟记忆的区域。 然后，体验通过海马体等区域被转成长期记忆， 最终保存到大脑几个记忆储存区域。 大脑里的神经元在专门的站点连接， 这些站点运用被称为突触的 特殊的神经传递。 如果两个神经元重复连接，一件重要的事情就会发生： 这两个神经元之间的连接就会变得更加有效率， 这个过程被称为长时程增强效应。 它被认为是体验被储存到长期记忆中的原理，
但是，怎么有些记忆会丢失呢？ 年龄是一个影响因素。 随着我们年龄的增大， 神经元突触开始衰退和变弱， 这影响了我们读取记忆的难易程度。 科学家们有几个原理 解释了这种退化背后的原因。 从真正的大脑萎缩开始， 海马体每十年失去了5%的神经元， 当时你80岁的时候，你一共失去了20%的神经元， 这导致了神经传递产物的下降， 比如，对学习和记忆至关重要的乙酰胆碱， 这些改变可能影响了 人们读取那些存储的信息。 年龄也影响了我们产生记忆的能力， 当我们集中精力的时候， 当我们完全投入的时候， 当信息对我们来说非常重要的时候， 深刻的记忆就会生成。 当年纪变大，精神和身体的 健康问题就变得越来越多， 干扰我们注意力的集中度， 也因此成为了我们记忆的小偷。
另一个引发记忆力问题的原因是长期的压力， 当我们长期面对超负荷的工作和个人压力， 我们的身体会报警。 这个反应是源于我们身体为保证 能在危机中生存而设计的生理机制， 因为压力而产生的化学物质 帮助身体调动能量和增加警戒。 但是，长期的压力让我们的 身体里的这些化学物质泛滥了， 导致脑细胞的流失和 制造新脑细胞能力的衰弱， 从而影响了我们记住新信息的能力。 抑郁是另一个罪犯， 40%的抑郁的人更容易有记忆力问题。 低水平的 激起兴奋神经传递的血清素， 可能让抑郁的人更不关注新信息。 抑郁的另一个症状， 是沉浸在过去悲伤的事件中出不来， 这导致他们很难关注现在发生的事情， 影响了存储短期记忆的能力。 与抑郁紧密联系的“ 孤立 ” 是另一个记忆的小偷， 一个哈佛大学公共健康学院的研究发现， 在六年时间里， 拥有更高的社会融合能力的老人 记忆衰退较慢。 虽然确切的原因还不清楚， 但专家推测， 社会交往使我们的大脑得到了锻炼。 就像肌肉力量的训练一样， 我们必须使用我们的大脑， 不然就有可能失去它。
不过不要绝望， 你可以用下面的几个步骤， 去帮助你的大脑保存记忆。 首先，确保你坚持锻炼， 增加血液回流大脑是有益的。 然后好好吃饭， 你的大脑需要所有的正确的营养物来保持功能正常。 最后，给你的大脑一些锻炼， 让你的大脑应对新的挑战， 比如学习一门新的语言， 这是最好的保持你记忆力的方法之一。
Think back to a really vivid memory. Got it? Okay, now try to remember what you had for lunch three weeks ago. That second memory probably isn't as strong, but why not? Why do we remember some things, and not others? And why do memories eventually fade? Let's look at how memories form in the first place. When you experience something, like dialing a phone number, the experience is converted into a pulse of electrical energy that zips along a network of neurons. Information first lands in short term memory, where it's available from anywhere from a few seconds to a couple of minutes. It's then transferred to long-term memory through areas such as the hippocampus, and finally to several storage regions across the brain. Neurons throughout the brain communicate at dedicated sites called synapses using specialized neurotransmitters. If two neurons communicate repeatedly, a remarkable thing happens: the efficiency of communication between them increases. This process, called long term potentiation, is considered to be a mechanism by which memories are stored long-term, but how do some memories get lost? Age is one factor. As we get older, synapses begin to falter and weaken, affecting how easily we can retrieve memories. Scientists have several theories about what's behind this deterioration, from actual brain shrinkage, the hippocampus loses 5% of its neurons every decade for a total loss of 20% by the time you're 80 years old to the drop in the production of neurotransmitters, like acetylcholine, which is vital to learning and memory. These changes seem to affect how people retrieve stored information. Age also affects our memory-making abilities. Memories are encoded most strongly when we're paying attention, when we're deeply engaged, and when information is meaningful to us. Mental and physical health problems, which tend to increase as we age, interfere with our ability to pay attention, and thus act as memory thieves. Another leading cause of memory problems is chronic stress. When we're constantly overloaded with work and personal responsibilites, our bodies are on hyperalert. This response has evolved from the physiological mechanism designed to make sure we can survive in a crisis. Stress chemicals help mobilize energy and increase alertness. However, with chronic stress our bodies become flooded with these chemicals, resulting in a loss of brain cells and an inability to form new ones, which affects our ability to retain new information. Depression is another culprit. People who are depressed are 40% more likely to develop memory problems. Low levels of serotonin, a neurotransmitter connected to arousal, may make depressed individuals less attentive to new information. Dwelling on sad events in the past, another symptom of depression, makes it difficult to pay attention to the present, affecting the ability to store short-term memories. Isolation, which is tied to depression, is another memory thief. A study by the Harvard School of Public Health found that older people with high levels of social integration had a slower rate of memory decline over a six-year period. The exact reason remains unclear, but experts suspect that social interaction gives our brain a mental workout. Just like muscle strength, we have to use our brain or risk losing it. But don't despair. There are several steps you can take to aid your brain in preserving your memories. Make sure you keep physically active. Increased blood flow to the brain is helpful. And eat well. Your brain needs all the right nutrients to keep functioning correctly. And finally, give your brain a workout. Exposing your brain to challenges, like learning a new language, is one of the best defenses for keeping your memories intact.
