Our Brains Smell Well When We're Asleep

So our brains are working away even while we sleep?  That's the idea behind a new study that's found that "memory of specific odors (along with many other things) depends on the ability of the brain to learn, process and recall accurately and effectively during slow-wave sleep — a deep sleep characterized by slow brain waves."

If more can be learned from better understanding of how the brain processes odors, researchers believe it could lead to novel therapies that target specific neurons in the brain, perhaps enhancing memory consolidation and memory accuracy, according to newswise.com.

Researchers showed in experiments with rats that odor memory was strengthened when odors sensed the previous day were replayed during sleep, the Web site reports. Memories deepened more when odor reinforcement occurred during sleep than when rats were awake.

When the memory of a specific odor learned when the rats were awake was replayed during slow-wave sleep, they achieved a stronger memory for that odor the next day, compared to rats that received no replay, or only received replay when they were awake.

However, when the research team exposed the rats to replay during sleep of an odor pattern that they had not previously learned, the rats had false memories to many different odors. When the research team pharmacologically prevented neurons from communicating to each other during slow-wave sleep, the accuracy of memory of the odor was also impaired.

“Our findings confirm the importance of brain activity during sleep for both memory strength and accuracy,” says one of the study's senior author. “What we think is happening is that during slow-wave sleep, neurons in the brain communicate with each other, and in doing so, strengthen their connections, permitting storage of specific information," adding that these findings are the first to demonstrate that memory accuracy, not just memory strength, is altered during short-wave sleep.