Neurobiological Analysis of Plasticity: Learning and Memory

我们如何学会保护自己免受接近危险的伤害？研究这种学习的最古老的范式之一是经典的巴甫洛夫条件反射。在经典的条件反射中，两个刺激一起重复出现，一个是有机体通常会避免的(无条件刺激)，另一个是不会的(中性刺激)，最终导致有机体试图避免中性刺激。之前的中性刺激已经获得了一种价值--它已经变成了条件。巴甫洛夫认为，条件反射所必需的新联系发生在大脑皮层，这是大脑中专用于思考和感知的部分。令人惊讶的是，汤普森博士和他的学生们已经证明，条件反射的发生需要的是小脑而不是大脑皮层的回路。在这次更新他的NSF拨款时，他将使用新开发的可逆失活方法来证明新的联系实际上是在小脑中形成的。然后，他将使用各种复杂的神经生物学技术来确定这些新记忆的存储机制。研究人员很有可能是第一个描绘出哺乳动物大脑中完整的信息存储电路的人。他们的工作将进一步加深我们对人类学习和记忆的理解，也将对人工神经网络和教学机器的设计者有用。

How do we learn to protect ourselves from approaching danger? One of the oldest paradigms for studying this kind of learning is classical Pavlovian conditioning. In classical conditioning, the repeated presentation of two stimuli together, one that the organism normally would avoid (the unconditioned stimulus), and one that it does not (the neutral stimulus), leads eventually to the organism trying to avoid the neutral stimulus. The previously neutral stimulus has acquired a value -- it has become conditioned. Pavlov thought that the new associations necessary for conditioning occur in the cerebral cortex, that part of the brain devoted to thinking and perception. Dr. Thompson and his students have shown, surprisingly, that circuits in the cerebellum, not the cerebral cortex, are necessary for conditioning to take place. In this renewal of his NSF grant, he will use newly developed reversible inactivation methods to demonstrate that the new associations are actually formed in the cerebellum. He will then use a variety of sophisticated neurobiological techniques to determine the mechanisms by which these new memories are stored. The investigators have a good chance of being the first to delineate a complete information storing circuit in the mammalian brain. Their work will further our understanding of human learning and memory and will be also useful to designers of artificial neural nets and teaching machines.***//