DURHAM, N.C., Jan. 19 (UPI) -- Researchers at North Carolina's Duke University have detected signals in areas of the brain during sleep that reveal the process of consolidating memory.
According to the researchers, their findings offer important evidence that extensive regions of the brain are involved in processing memories during a particular form of sleep, called slow-wave sleep.
The findings lay to rest previous doubts that sleep enables consolidation of newly acquired memories, and also establishes roles for both slow-wave sleep and rapid eye-movement sleep in memory consolidation. Slow-wave sleep is a deep, dreamless sleep, and REM sleep is associated with dreaming.
The findings were published Monday in the online Public Library of Science (www.plos.org).
In their study, the researchers placed about 100 infinitesimal recording electrodes in the brains of rats, in four regions involved in memory formation and sensory processing.
The researchers next exposed the rats to four kinds of novel objects in the dark and analyzed brain signals from the rats before, during and after their exploration for several days across natural sleep-wake cycles.
Analyses of those signals revealed "reverberations" of distinctive brain wave patterns up to 48 hours after the experience.
