Labile or stable: opposing consequences for memory when reactivated during waking and sleep.

Area of Science:

• Neuroscience
• Cognitive Psychology

Background:

• Memory consolidation is a dynamic process involving reconsolidation.
• Reactivation during wakefulness is thought to transiently destabilize memories.
• Memory reactivation during slow-wave sleep (SWS) is linked to sleep's consolidating effects.

Purpose of the Study:

• To investigate if memory reactivation during SWS also leads to transient destabilization.
• To compare the effects of memory reactivation during SWS versus wakefulness on memory stability.
• To explore the neural correlates of memory reactivation in different brain states.

Main Methods:

• Human participants underwent memory reactivation using odor cues during SWS or wakefulness.
• Memory stability was assessed using an interference task post-reactivation.
• Functional magnetic resonance imaging (fMRI) was employed to examine brain activity.

Main Results:

• Reactivation during wakefulness destabilized memories, as predicted.
• Reactivation during SWS immediately stabilized memories, enhancing resistance to interference.
• fMRI showed distinct activation patterns: SWS reactivation engaged hippocampal and posterior cortical regions, while wakefulness reactivation involved prefrontal areas.

Conclusions:

• Memory reactivation serves different functions depending on the brain state (sleep vs. wakefulness).
• Reactivation during SWS actively stabilizes memories, contrasting with destabilization during wakefulness.
• Neural activity patterns differ significantly between sleep- and wake-dependent memory reactivation.