Biological Models of Associative Learning

Virtually all species of animals demonstrate the capacity to acquire and retain new information or modify behavior through experience, which indicates that learning and memory are the sine quo non of survival. Contemporary psychological and biological studies recognize that memory is not a single cognitive entity but rather can be divided into multiple informational systems—such as learning to ride a bicycle or speak a second language—subserved by different brain structures. In order to probe the neural and molecular mechanisms of memory, however, it is a prerequisite to identify the site(s) of a memory trace (an engram). Classical or Pavlovian conditioning, in which an animal learns a predictive relationship between two or more stimuli and is considered the basic building block of learning and memory, is a model system for neurobiological studies of learning and memory because it provides an important advantage over other more complex forms of learning. In classical conditioning the environmental stimuli (inputs) are well defined and can be precisely controlled, and the behavioral response (output) is discrete and accurately assessed. This chapter presents two well-investigated basic associative paradigms: eyeblink conditioning and fear conditioning. Keywords: amygdala; cerebellum; eyeblink conditioning; fear conditioning; learning and memory