Retrograde Amnesia for Trace Fear Conditioning

大脑如何从环境中提取信息，并将这些信息存储为记忆，这是行为神经科学中一个基本但尚未回答的问题。 在人类和其他动物中，与记忆最密切相关的大脑结构是海马体。 对这一大脑区域的损伤会导致健忘症或记忆丧失，这在所有哺乳动物中都有许多共同特征。 本项目侧重于其中两个共性。 一种是海马损伤前不久获得的记忆丢失，但更早的记忆仍然存在。 这种记忆丧失的模式被称为时间分级逆行性遗忘症。 在对大鼠进行通常不会忘记的任务训练后，在不同时间对海马体进行非常精确的损伤，从而检查大鼠的逆行性遗忘。 这项任务是恐惧条件反射，老鼠对先前预测会受到短暂轻微电击的刺激表现出情绪反应。海马损伤导致的健忘症的另一个特征是，某些类型的记忆丢失，而其他类型的记忆则完全幸免。 例如，如果海马损伤的人被教导一种新的运动技能，如网球，他们打网球的能力将不断提高，但他们将没有打网球的记忆。他们记得如何玩，但却不记得他们玩过。 我们将研究这种选择性记忆丧失的一种形式。 如果音调预示着休克，海马损伤可能会也可能不会导致对音调和习得情绪之间关系的遗忘。 如果音调和电击在时间上重叠，海马体就不需要了。 然而，如果在音调终止和电击开始之间有一段短暂的时间，海马体对记忆是必不可少的。 这种类型的条件反射被称为痕迹条件反射，海马损伤后的痕迹条件反射的逆行性遗忘将被检查。痕迹条件反射的遗忘是不寻常的，因为它不同于其他形式的记忆，海马是需要的。 通常，海马损伤的大鼠对空间位置或由几种不同成分组成的刺激的记忆有问题。 在这个项目中，它将确定是否逆行性遗忘的痕迹条件反射和复杂的配置源于相同或不同的功能的海马。 还将确定改变正常动物学习痕迹条件反射的能力的各种操作是否可以减轻痕迹条件反射的遗忘症。 通过研究和对比这些形式的记忆，希望能准确地找到海马体从经验中提取的东西，并更精确地定义遗忘症中丢失和保留的东西。

How the brain extracts information to from the environment and stores that information as a memory is a fundamental but unanswered question in behavioral neuroscience. The brain structure that is most intimately associated with memory in humans and other animals is the hippocampus. Damage to this brain area produces amnesia, or loss of memory, that shares many features in all mammals. This project focuses on two of these commonalties. One is that memories that were acquired shortly before hippocampal damage are lost but older memories remain. This pattern of memory loss is called temporally graded retrograde amnesia. Retrograde amnesia in rats will be examined by making very precise damage to the hippocampus after various times after rats are trained on a task that is not normally forgotten. The task is fear conditioning, where rats show an emotional reaction to stimuli that have previously predicted that they will receive a brief mild electric footshock.Another feature of the amnesia that stems from hippocampal damage is that certain types of memories are lost and others are completely spared. For example, if people with hippocampal damage are taught a new motor skill like tennis, their tennis playing ability will continual improve but they will have no memory of ever playing tennis. They remember how to play without being able to remember that they played. One form of this selective memory loss will be examined. If a tone predicts shock, hippocampal lesions may or may not cause amnesia for the relation between tone and the learned emotion. If the tone and shock overlap in time the hippocampus is not necessary. However, if a brief period of time is placed between tone termination and shock onset the hippocampus is necessary for memory. This type of conditioning is called trace conditioning and retrograde amnesia for trace conditioning following hippocampal damage will be examined.Amnesia for trace conditioning is unusual because it differs from other forms of memory for which the hippocampus is needed. Usually rats with hippocampal damage have problems with memory for spatial locations or for stimuli that are composed of several different components. In this project it will be determined whether retrograde amnesia for trace conditioning and complex configurations stem from the same or different functions of the hippocampus. It will also be determined if various manipulations that alter the ability of normal animals to learn trace conditioning can alleviate the amnesia for trace conditioning. By investigating and contrasting these forms of memory it is hoped to find exactly what the hippocampus is extracting from experience and more precisely define what is lost and preserved in amnesia.