Brain activity patterns may 'tag' experiences for later memory-making during sleep

A recent study published in PLOS Biology suggests that the brain may tag experiences during learning to better consolidate them into long-term memories during sleep. Most people do not remember every experience they've had; the brain selectively consolidates some experiences for memory while discarding others. To investigate how the brain selects experiences for later memory consolidation, researchers collected data from 31 participants using electroencephalography (EEG) to measure brain activity patterns.

Participants learned object-word pairs and were tested immediately and after a two-hour break, with half of the participants allowed to sleep while the other remained awake. The study found that word-object pairs associated with theta oscillations between 3-8 Hz during learning were more likely to be remembered after sleep compared to wakefulness.

Theta activity during learning was also linked to stronger coupling between slow neural oscillations and sleep spindles, which correlated with better memory performance after sleep. While the study only examined memory after two hours, researchers suggest that theta oscillations may serve as a mechanism for the brain to identify experiences to consolidate into memories during sleep.

The authors note that understanding how the brain determines what to remember and what to forget remains a mystery, but these findings offer new insights into the brain processes behind memory consolidation and may contribute to understanding and treating mental health conditions such as depression.