By Sherry Wang
Reconsolidation theory states that the reactivation of memories destabilizes them unless they are reconsolidated within a certain amount of time. A study by Susanne Diekelmann shows that memory reactivation actually serves different purpose when we are awake and when we are asleep. Apparently memory reactivation during slow wave sleep results in an immediate stabilization while reactivation during wakefulness still results in destabilization. Diekelmann and her lab reactivated memories by presenting subjects with odors, and used fMRI technology to image the brain during reactivation. Participants in this study learned during the evening in the presence of an experimental odor in order to establish a connection between the odor and the material being learned.
During slow wave sleep, the participants were presented with the odor and then awoken a few minutes later to be started learning an interference object location task. Reactivating memories using the presented odor during waking lead to a reduced ability to recall the original object location task when interference preceeded. Using the fMRI, they found that reactivation during slow wave sleep activated hippocampal and posterior cortical regions whereas reactivation during wakefulness activated activated prefrontal cortical areas. Their findings indicate that the reactivations of memory traces have opposite effects on memory during slow wave sleep and awake times.
This study makes me think about Jim Carey in Sunshine of the Spotless Mind, where he undergoes a procedure while sleeping to erase all of his memories of his ex-girlfriend. While this plot seems totally unrealistic, it may be something that will be plausible in the future. But according to this study, wouldn't it be more effective to try and erase memories while people are awake? Imagine. What would the world be like if we could selectively choose the things we want to remember and those we want to be erased from our lives? We build our personalities and choices off of previous experiences, and learn from our mistakes. If we erase our mistakes, aren't we just likely to make them again? I mean Jim Carey went looking for his ex-girlfriend again in the movie.
For more information or to read this study check out "Labile or Stable: Opposing Consequences for Memory While Reactivated during Waking and Sleep" in Nature Neuroscience.
Sherry Wang, Andrew L Varnell, Donald C Cooper (2011). Think while you sleep! NeuroCloud