Pavlov (1927) was the first to describe acquisition of classical conditioning. After repeating the tone-food (CS-US) pairings a number of times, he observed that the dogs began to salivate (the CR) before the food was delivered. At the beginning, he observed that only the food presentation elicited salivation (the UR).
This definition excludes changes that might oc… Conditioning (psychology), The process of closely associating a neutral stimulus with one that evokes a reflexive response so that eventually the neutral stimulus alone will ev… Learning, Learning can occur in a variety of manners. Learning is defined as a relatively permanent change in behavior as a result of experience. Critical neural structures for this form of learning include the amygdala, certain nuclei of the thalamus, and the cingulated area of the cerebral cortex.] But until the animal first moves to avoid the shock, the training is Pavlovian. The focus in this entry is on active avoidance, where the animal can make a response (e.g., locomotion) when a CS occurs to avoid a shock US. It describes an example of instrumental learning, where the animal can influence the outcome, unlike classical conditioning. The article on NEURAL SUBSTRATES OF AVOIDANCE LEARNING is included in this book in part for contrast. As in freezing, the amygdala plays a critical role. Much of the circuitry for the startle response and fear potentiation of the response has been identified. Presentation of the light CS enhances the startle response to the acoustic stimulus. This CS is then given together with a loud acoustic stimulus that elicits behavioral startle response. Here a light CS is paired with shock to establish conditioned fear to the light. Another productive method to study learned fear is F ear -P otentiated S tartle. However the hippocampus also becomes critically important in learned freezing to context. Here it appears that critical components of the fear memory are stored in a region of the amygdala. The most widely used behavioral index of F ear C onditioning is freezing. Here, the amygdala, prefrontal cortex, and cerebellum are all involved. A major component of fear learning is classical conditioning of C ardiovascular R esponses. The amygdala plays a key role in all aspects of fear conditioning. Elsewhere in this book, NEURAL SUBSTRATES OF EMOTIONAL MEMORY provides an overview of fear learning, where a neutral CS is paired with an aversive, emotionally arousing US such as shock. The cerebellum and its associated brainstem circuitry is the necessary and sufficient circuit for this form of learning however, the hippocampus also becomes important in the trace procedure. The second entry in this section, on conditioning of D iscrete B ehavioral R esponses, uses eyeblink conditioning as the prototypic example (tone CS, corneal airpuff US). Although contiguity of the CS and US is necessary for learning, the contingency between them, the probability that the CS will predict the occurrence of the US, is critically important. The CS must precede the US for learning to occur in the delay procedure the CS and US co-terminate in the trace procedure the CS offset occurs prior to the onset of the US.
The salivation UR elicited by the meat powder came to be elicited by the bell, the CR. In Pavlov's original experiments with dogs, a bell (CS) was paired with meat powder in the mouth (US). As a result of pairing, the CS comes to elicit a conditioned response (CR). [ Classical or Pavlovian conditioning, first described by Ivan Pavlov (see PAVLOV, IVAN ), is a procedure where a neutral stimulus such as a light or sound (conditioned stimulus, CS) is presented together with an unconditioned stimulus (US) that elicits a behavioral response (UR). NEURAL SUBSTRATES OF CLASSICAL CONDITIONING