Researchers have even documented sleep-like behavior in cultures of glial and neural cells. By increasing the number of electrophysiological measurements we use to characterize sleep states, the homology between sleep-like states in culture and sleep in intact animals becomes stronger.
© CATHERINE DELPHIA
Mammalian sleep is characterized by several stages, typically measured using an electroencephalogram (EEG), which involves the recording of brain activity from an array of electrodes on the scalp. Rapid-eye movement (REM) sleep, the stage during which vivid dreams occur, is characterized by EEG waves similar to those observed during waking. High-amplitude delta waves (0.5–4 Hz) occur at the deepest stage of non-REM, or slow-wave, sleep. Both the presence and amplitude of these delta waves are used to characterize sleep in whole animals. When treated with ...
