Anxious : Using the Brain to Understand and Treat Fear and Anxiety (9781101619940) by Ledoux Joseph

Author:Ledoux, Joseph
Language: eng
Format: epub
Publisher: Penguin USA
Published: 2015-06-18T00:00:00+00:00

COGNITION IN EXPOSURE THERAPY

An important difference between exposure and extinction that needs special highlighting is that in exposure therapy the measure most used to gauge treatment effects is the client’s self-report of a reduction in feelings of fear (or anxiety) in the presence of the threat stimulus or situation. By contrast, in a typical study of threat extinction, the effects of stimulus repetition are measured as a reduction in behavioral or physiological responses. Although it is common for researchers studying either humans or animals to state that extinction reduced “fear,” the fact is that the goal of the study is usually to determine whether behavioral or physiological responses have been affected. A decrease in freezing in a rat or a change in some physiological response, such as skin conductance (a measure of perspiration) in humans, does not indicate that the conscious feeling of fear has been reduced—as I’ve pointed out, studies in humans have shown that the degree of fear measured behaviorally or physiologically often does not coincide with self-reports of subjective feelings.68

Because extinction alters the propensity of the threat CS to activate defensive circuits, it is tilted toward changing implicit processes. Exposure therapy adds layers of top-down cognition, such as reappraisal, to this process and assesses progress based on self-report. Experiments that have examined the neural basis of emotion regulation in healthy human participants are revealing. For example, as noted in the last chapter, studies by Liz Phelps and colleagues using extinction or other emotion regulation training techniques to implicitly change physiological responses implicated the medial prefrontal cortex,69 whereas studies by James Gross, Kevin Ochsner, and their colleagues using top-down reappraisal strategies to change self-reported emotion found that the lateral prefrontal cortex played a more significant role.70

I will explain why these and other differences between extinction and exposure are significant by discussing a popular form of exposure therapy called prolonged exposure.71 This method is based on emotional processing theory, as proposed by Edna Foa and Michael Kozak.72 The basic concept of prolonged exposure therapy is that fearful feelings must be elicited and sustained during repeated exposure until fear reduction occurs, allowing disconfirmation of false belief about the irrationally feared object or situation’s ability to cause harm. If fear is not fully activated, it will not fully extinguish, and problems will continue.

Foa and Kozak built on Peter Lang’s idea that fear is represented in the brain in the form of fear structures, or schemas,73 similar to Aaron Beck’s notion of automatic thoughts and beliefs being represented in schemas. (Recall that schemas are also part of the psychological construction theory of emotion, and my theory described in Chapter 8.) This was an elaboration of Lang’s earlier idea that fear and anxiety could be accounted for in terms of response systems. The fear structure is viewed as a program (in the sense of a computer program) for escaping or avoiding danger and includes several kinds of stored propositions: It includes propositions about threats—when the threat signal (CS) occurs, a bad thing (US)

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