ABSTRACT
The workings and purpose of sleep and dreaming have long been shrouded in mystery. A major scientific goal is to shed the light of modern neurobiology on the inner mechanisms of the brain during sleep and wakefulness. In recent years, new methods of functional brain imaging have made it possible to literally see what happens in the living brain, particularly in people, as they sleep and dream or deal with sleep deprivation. The emerging technologies of functional brain imaging include positron emission tomography (PET), functional magnetic resonance imaging (FMRI), magnetic resonance spectroscopy (MRS), and older methods such as xenon-133 (133Xenon), single photon emission computerized tomography (SPECT), and Doppler measures of arterial blood flow. These brain-imaging methods can be associated, in some conditions, with topographic EEG, magneto-encephalography (MEG), or other ways of assessing localized cerebral activity.
