Comparative Neuropsychology of Episodic Memory: Unmasking the Elements of Hippocampal Function

想象一下，你缺乏自传式记忆，记不起今天早上你做了什么，也记不起你是怎么到现在这个房间的。组织你的生活和履行你的义务肯定会很困难。然而，这正是某些大脑颞叶受损的失忆症患者所面临的情况。这也是许多科学家认为非人类动物存在的条件；他们在精神上永远“卡”在现在。对人类健忘症的研究戏剧性地揭示了一个事实，即表面上无缝的人类记忆实际上由不同的系统组成。每个记忆系统都专门处理不同的信息，包括习惯和技能、一般事实知识和第一人称自传信息。例如，人类的情景记忆含有丰富的上下文细节，这些细节可以说明它们的来源，或者它们形成的场合。当你在去年8月的一场婚礼上与一位衣着光鲜但没有刮胡子的年轻人交谈时，你可能会详细回忆起新割的草的味道。相比之下，语义记忆缺乏上下文细节。你知道狗有尾巴，但可能不记得你是在什么场合知道这个事实的。人类情景记忆和语义记忆的区别是认知神经科学的核心，并已通过行为研究、神经影像学研究和对脑损伤患者的研究相结合而确立。相比之下，我们对这些记忆系统在非人类动物中的存在程度知之甚少。事实上，许多认知科学家认为情景记忆可能是人类独有的。如果没有适当的行为测试，就不可能评估这种说法，也不可能开发出合适的动物模型来研究记忆。在美国国家科学基金会（National Science Foundation）的支持下，埃默里大学（Emory University）的罗伯特·汉普顿博士（Robert Hampton）和他的学生将开发一种新的记忆测试，能够测量非人类动物的情景记忆。具体来说，汉普顿博士将开发测试，以调查受试者是否记得他们记忆的来源，以及他们是否能回忆和识别以前经历过的图像。这些测试的表现将与其他记忆表现进行对比，并确定这些记忆类型的大脑基础。开发这些新的认知测试，并培训年轻科学家使用它们，将使未来的认知工作及其背后的生物机制成为可能。除了在人类认知的重要模型中推进我们对记忆和认知的理解外，该项目还将在许多方面产生更广泛的影响：1)研究生，包括很大比例的女学生，是研究的中心，并通过在诸如大脑意识周等活动期间访问高中来分享她们对神经科学的热情。2)每年夏天，至少有一名来自Brain项目的学生将参与提议的项目，该项目从科学领域代表性不足的群体中招募本科生。4)汉普顿博士和研究生将在亚特兰大动物园的一个认知展上进行讲解员活动，从而向公众传达他们工作的内容和兴奋之处。5)汉普顿博士和他的实验室将通过扩大他们现有的网站来分享他们的发现，该网站的目标受众是本科生。该网站的目标之一是帮助招募即将毕业的学生从事神经认知研究。

Imagine that you lacked autobiographical memory and could not recall what you did this morning or how you got to the room you are in now. It would certainly be difficult to organize your life and meet your obligations. Yet this is the situation faced by certain amnesic humans with damage to the temporal lobes of their brain. It is also the condition in which many scientists believe nonhuman animals exist; they are mentally "stuck" forever in the present. Studies of human amnesics have dramatically revealed the fact that apparently seamless human memory actually consists of distinct systems. Each memory system is specialized to process different information including habits and skills, general factual knowledge, and first-person autobiographical information. For example, human episodic memories are rich in contextual details that specify their source, or the occasion on which they were formed. One might experience detailed recollection of the smell of freshly mown grass as you talked to a well-dressed but unshaven young man at a wedding last August. By contrast, semantic memories lack contextual details. You know dogs have tails, but probably do not remember details of the occasion on which you learned this fact. The distinction between episodic and semantic memory in humans is central in cognitive neuroscience and has been established by the combination of behavioral studies, neuroimaging studies, and studies of patients with brain damage. In contrast, we know little about the extent to which these memory systems exist in nonhuman animals. Indeed many cognitive scientists argue that episodic memory may be uniquely human. It is impossible to evaluate this claim, or to develop appropriate animal models for the study of memory, without appropriate behavioral tests. With the support of the National Science Foundation, Dr. Robert Hampton and his students at Emory University will develop new memory tests capable of measuring aspects of episodic memory in nonhuman animals. Specifically, Dr. Hampton will develop tests to investigate whether subjects remember the source of their memories and whether they can recall as well as recognize previously experienced images. Performance on these tests will be contrasted with other memory performance and the brain basis for these types of memory will be determined. Development of these new cognitive tests, and training young scientists to use them, will enable future work on cognition and the biological mechanisms that underlie it.In addition to advancing our understanding of memory and cognition in an important model of human cognition, this project will also have broader impacts in a number of ways: 1) Graduate students, including a large percentage of female students, are centrally involved in the research and share their enthusiasm for neuroscience through visits to high schools during events such as Brain Awareness Week. 2) Each summer, at least one student from the BRAIN program, which recruits undergraduates from groups underrepresented in science, will work on the proposed projects. 3) Undergraduate students from Dr. Hampton's introductory psychology class are recruited annually to work in the lab through research experience programs funded by Emory College. 4) Dr. Hampton and graduate students will perform docent activities at a cognition exhibit at Zoo Atlanta, thus conveying the content and excitement of their work to the public. 5) Dr. Hampton and his lab will share their findings through expansion of their existing website, which is aimed at an undergraduate level audience. One of the goals of the website is to aid in the recruitment of graduating students to neurocognitive research.