Sleep may help strengthen memory retrieval
A team of researchers at the University of York explain that sleep has a way of strengthening old and new experiences of the same memory to the same extent, thereby improving memory efficiency.
Scientific investigators also discovered that when memories are retrieved — meaning memory recall — it is updated with new data present at the time of remembering.
Apparently, the brain appears not to erase the old version of the memory. Instead, it generates and stores multiple versions of the same experience. In this way, sleep helps a person keep the “saved” experience of a memory while also allowing retention contextualized experiences, updated with new material.
Surprisingly, the storage of multiple memories of the same experience can cause similar glitches as to what occurs when we save multiple versions of a file on a P.C. and then later can’t accurately recall the differences between the file types.
The research results, conducted by York’s Sleep, Language and Memory (SLAM) Laboratory, appear in the journal, Cortex.
Lead investigator Dr. Scott Cairney of York’s Department of Psychology said, “Previous studies have shown sleep’s importance for memory. Our research takes this a step further by demonstrating that sleep strengthens both old and new versions of an experience, helping us to use our memories adaptively.
“In this way, sleep is allowing us to use our memory in the most efficient way possible, enabling us to update our knowledge of the world and to adapt our memories for future experiences.”
In this study, two different groups of participants learned the location of words on a computer screen. During the testing phase, participants were presented with each of the words in the center of the screen. Their task was to identify where they thought they belonged.
One group then slept for 90 minutes. The second group stayed awake. Each group then repeated the test.
In both groups, the location recalled at the second test was closer to that recalled at the first test than to the originally-learned location. This indicated that memory updating had taken place and new memory traces had been formed.
That said, when comparing the wake and sleep groups directly, the locations recalled by the sleep group were closer in distance to both the updated location (i.e. previously retrieved) and the original location. This suggests that sleep had enhanced both the new and old versions of the memory.
Research author and Professor Gareth Gaskell thinks the study demonstrates that sleep offers a protective effect on memory and acts as a pathway to the adaptive updating of memories.
“For the sleep group, we found that sleep strengthened both their memory of the original location as well as the new location. In this way, we were able to demonstrate that sleep benefits all the multiple representations of the same experience in our brain.”
The researchers state that although this process helps us by allowing our memories to adapt to changes in the world around us, it can also act as a barrier by incorporating incorrect material into our memory stores.
Over time, our memory can draw upon both accurate and inaccurate tapes of the same experience, causing potential distortions in how we recall previous events.
Source: University of York/EurekAlert
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