The Body/Brain Connection in the Conditioned Fear Response

What takes place physiologically when we experience or believe we are in a threatening or dangerous situation? We already know that our bodies often react with abdominal distress, dizziness, shortness of breath, sweating, and increase in heart rate and breathing, but what are the neural (brain) mechanisms that cause these bodily reactions? These are some of the questions we would like to explore in this article.

As for our friend in the car, she was apparently experiencing a "normal reaction to a threatening situation," or she would not have displayed the physiological (physical) symptoms she did when the car she was in crossed that particular part of town. Additionally, since fear that automatically recurs in a familiar situation is a conditioned response, we would also like to focus on those "fear pathways" specifically in this article. We will demonstrate how the "lessons" people learn from their traumatic experiences are yet another example of Pavlovian fear conditioning.

How fear conditioning takes place in typical Pavlovian (classical) conditioning

Classical fear conditioning is simply a procedure where a neutral stimulus (called the CS, the conditioned stimulus) is paired with an aversive (unpleasant) stimulus (the US, the unconditioned stimulus) such as a shock. Typically, a tone or a bell is paired with the aversive stimulus (the aversive stimulus can also be an event, which is often the case with trauma survivors). After as few as one or two pairings, the subject will associate the aversive US with the tone, and "long-lasting changes become established in the brain as a result" (LeDoux, 1998). These responses become so "hardwired" in the brain that the changes come to elicit new autonomic responses that the individual did not exhibit previously. These changes are also observed behaviorally when fear-provoking stimuli are encountered. Such responses tend to literally become second nature. The now conditioned CR(s) (conditioned responses) can be elicited with only a cue that does not need to be on a conscious level at all in order for it to be effective. In the case of your friend in the opening scenario, for example, the cue could be any kind of reminder of a traumatic event that took place her past experience. If indeed she was passing through a part of town where such an event had occurred it would explain her physiological and psychological reactions, whether she was conscious of them or not.

This is one example of how Pavlovian fear conditioning

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