Summary findings on narcolepsy

(A) Summary of findings from fMRI studies in narcolepsy. During winning on a gambling task, activity is reduced in the bilateral nucleus accumbens and the ventromedial prefrontal cortex, and activity is increased in the putamen and inferior lateral frontal cortex. During an encoding and recognition task, there is more deactivation within the default mode network. In response to the presentation of humorous images, decreased activation is present in the right hypothalamus, medial prefrontal cingulate cortex, nucleus accumbens, and hypothalamus. Increased activity is present in the right inferior frontal gyri and amygdala. (B) Summary of findings from PET and SPECT studies in narcolepsy. During sleep, activity in temporoparietal regions of the cortex and cerebellum is increased; perfusion within parietal regions is increased during REM sleep. During wakefulness, there is decreased perfusion in the brainstem, cerebellum, caudate nucleus, subcallosal gyrus, and cingulate gyrus extending along the corpus callosum. Glucose metabolism is decreased in the parahippocampal gyrus, bilateral paracentral areas, bilateral hypothalami, thalamic nuclei, and frontal-parietal cortices. Hypermetabolism is present in the anterior and midcingulate cortex, the right cuneus, and the lingual gyrus. (Contributed by Dr. Nathan Cross and Dr. Florence Pomares.)