Flexible Memory Consolidation Requires Sleep

Subjects learned a list of words and then were either sleep-deprived for 24 hours or allowed to maintain their normal sleeping habits.

According to research presented at the Associated Professional Sleep Societies SLEEP 2011 meeting in Minneapolis, getting some sleep allows for flexibility in recently formed memories. This flexibility is necessary for the adaptive consolidation of memories, putting them into context and integrating them with what you already know. Sleep deprivation, on the other hand, insulates new memories, making them isolated and rigid, which is not an adaptive format for the integration of new information.

Professor Lynn Nadel and his colleagues in the Psychology Department at the University of Arizona investigated the role of sleep deprivation in the formation and updating of memories. They found that during the process of reconsolidation, a reminder or cue returns an initial memory to a labile state, making it susceptible to new information that can become incorporated into the original memory.

In the study, subjects learned a list of words and then were either sleep-deprived for 24 hours or allowed to maintain their normal sleeping habits. The subjects were then either given a reminder or no reminder and asked to learn a second set of words. The next day, they were given recall and recognition tasks.

Those in the sleep-deprived group showed lower intrusion rates compared to the rested control group, meaning that their memory of the list of words was not susceptible to interference from the words in the second list. They scored the same as controls in the recall task, indicating that there was no problem with consolidation of the first set of words, but an inability to update their memories with new information.

The researchers reported that “without sleep, memory traces remain insulated and isolated, unable to be modified. This generation of flexibility may be crucial for the process of reconsolidation. Thus, sleep is likely crucial for healthy consolidation and subsequent reconsolidation.”

 

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