Adult-born neurons strengthen memories during sleep in mice

Learning-associated neurons that form in the adult mouse brain must get reactivated during rapid eye movement (REM) sleep for new memories to stick.

The fact that dreaming occurs during REM suggests that this stage of sleep may be important for memory processing and consolidation.

Now, a University of Tsukuba–led team has shown that adult-born neurons inside a region of the hippocampus known as the dentate gyrus become activated after a learning experience and that they are then reactivated during the mice’s next phases of REM sleep.

Using optogenetic techniques, the researchers then modulated neuronal activity during REM sleep —. Any perturbation caused the mice to forget their fears, suggesting that these neurons are critical to memory replay and consolidation.

If validated in the human brain, these findings could help scientists develop new treatments for people with memory disorders.