LeDoux, Joseph E. “Emotions: A View through the Brain."

In his second essay for this volume, “Emotions: A View through the Brain,” Joseph E. LeDoux provides an argument for his claim that the scientific investigation of emotion requires a distinction between emotional behavior or associated physiological responses and the subjective feelings experienced by humans. Emotional behavior can be understood by the evolutionist in terms of the function it serves in human and animal life. Emotional feelings must be seen as secondary since emotional behavior is present in organisms that do not have the capacity for conscious awareness. LeDoux defines emotional feelings as a result of sophisticated brains being aware of their own activities - in this case, being aware that an emotion system, such as the fear system, is activated. The problem of explaining emotional feelings is a part of the single problem of the explanation of consciousness. However, different emotional behavior or response systems may involve different brain mechanisms. Here LeDoux is critical of the “limbic-system” theory, a theory that sought to identify a single set of brain structures involved in all emotional responses.

LeDoux summarizes in more detail here the results of research on fear conditioning in rats (see above), and notes that studies of the effects of damage to the amygdala in humans, as well as fMRI studies, show that the amygdala is the key to the fear-conditioning system in humans, as well. However, the association of fear not with the original stimulus but with the environmental context in which the stimulus was encountered appears to depend on the hippocampus.

The persistence of learned fear responses is obviously valuable for survival. However, the inability to inhibit unwarranted fear responses can have devastating consequences, as in phobias and post-traumatic stress disorder. Thus, research on the probable role of neocortical areas in extinction of fear responses may be of great value in treating these disorders.

Less is known about other basic emotion such as anger or joy; it remains to be seen whether the amygdala is involved in these as well. Far less is known about “higher-order” emotions such as jealousy. And, as mentioned above, an account of emotional feelings awaits an adequate account of consciousness in general. However, LeDoux notes that working memory receives a greater number and variety of inputs in the presence of an emotional stimulus than otherwise, due to the variety of neural pathways involved; he speculates that this excess stimulation is what adds the affective charge to representations in working memory that we associate with felt emotions.

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