Navigational brain cells that help sense direction are as electrically active during deep sleep as they are during wake time and have visual and vestibular cues to guide them. Such information could be useful in treating navigational problems, among the first major symptoms of Alzheimer's disease and other neurological disorders.
Researchers at NYU Langone Medical Center found that head direction neurons continued to code for the “virtual” direction of their gaze during sleep. In fact, during Rapid Eye Movement (REM) sleep—a stage known for intense dreaming activity in humans and during which brain electrical activity is virtually indistinguishable from wake—the ‘needle’ of the brain compass in the mice surprisingly moved at the same speed than observed during wake. During slow-wave periods of sleep, it showed a 10-fold acceleration of activity, as if the mice turned their head 10 times faster than during the time they were awake.