The Role of the Amygdala in Dreaming

Numerous neuroimaging studies have strongly implicated the amygdala in dreaming. Various neuropsychological dream theories propose roles for the amygdala in dreaming (particularly in the generation of dream affect), however little empirical research on its function in dreaming exists. Urbach Wiethe Disease is a very rare genetic condition which leads to calcification of the amygdala over time. Analyzing the dream reports of patients with Urbach Wiethe Disease (UWD) provides a unique opportunity to assess the role of the amygdala in dreaming. The threat simulation theory (TST) suggests that the biological function of dreams is to allow humans to practice effectively escaping from threatening situations in safety. The amygdala, which is pivotal to fear conditioning, is thought to play a central role in this process. This study assessed the dream reports of eight adult UWD patients with fully calcified amygdala bilaterally in order to examine dream affect and various other qualities of dreaming, as well as certain hypotheses specifically based on the TST. It was also necessary to refine and develop certain quantitative dream coding techniques. Results indicate only small differences between the dreams of the UWD group and a control group on various measures, including intensity of negative and positive affect and the prevalence of nightmares. These findings echo the results of the one existing study examining dream affect in UWD patients and begin to contradict the view that the amygdala has a principal role in the generation of dream affect. The results particularly seem to undermine the TST.