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.***//
