Neuroimaging of dreaming: state of the art and limitations.

During the last two decades, functional neuroimaging has been used to characterize the regional brain function during sleep in humans, at the macroscopic systems level. In addition, the topography of brain activity, especially during rapid eye movement sleep, was thought to be compatible with the general features of dreams. In contrast, the neural correlates of dreams remain largely unexplored. This review examines the difficulties associated with the characterization of dream correlates. ἓν οἶδα ὅτι οὐδὲν οἶδα Σωκράτης (The only thing I know is that I know nothing) Socrates.