Italian scientists 'show how we remember dreams' 'Theta waves' key to recollection

(ANSA) - Rome - Italian scientists have found out how we remember dreams.



A team from Rome, L'Aquila and Bologna universities discovered that people will recall their dreams only if they experience a certain sort of electrical oscillation during the well-known phase of sleep associated with rapid eye movements (REM).



"Only if the cerebral cortex is flooded with slow oscillations called theta waves will the person have any recollection of his dreams when he wakes up," said the coordinator of the study, Luigi De Gennaro of Rome's La Sapienza university.



According to the experts, whose work has been published in the US Journal of Neuroscience, the same phenomenon is at work when, while awake, we form solid memories of events that are "more real" to us than others.



This mechanism is called 'episodic memory'.



"When you ask someone to remember important facts or situations," De Gennaro said, "the presence of electrical oscillations in the frontal cortex makes the recollection possible.



"If that does not happen, the memory of the event will apparently be lost forever".



The study also demonstrates something that was hitherto not thought possible, that dreams are formed outside the phase of REM sleep.



"But here the mechanism is different," De Gennaro said.



"In short, we don't really know why we recall or forget dreams, but we have finally identified how we recall or forget them". The discovery came a few months after another breakthrough on dreams by the same group.



In October De Gennaro's team said they had managed to pinpoint areas in the brain that enable people to remember vivid dreams.



"We've found the parts of the amigdala and hippocampus that are linked to bizarre and intense dreams, the ones people remember," De Gennaro told the journal Human Brain Mapping.



In that study, the Italian scientists used the latest neuro-imaging techniques to get down to the "deep microstructures" in the two key brain areas.



"We think we've cracked why some people never remember their dreams and others have such a detailed memory you might almost call it film-like," De Gennaro said.



"It was possible to show that the volumetric and ultrastructural parameters of the two deep nuclei of the brain predict the qualitative aspects of every individual's dreams".