Researchers at the University of York have shown that sleep strengthens new and old versions of the same memory to similar extents. Instead of overwriting the old version of the memory, the brain generates and stores multiple (new and old) versions of the same experience, helping you use your memory in the most flexible and adaptable way.
“Previous studies have shown sleep’s importance for memory,” explains Dr Scott Cairney of York’s Department of Psychology, in a news release. “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 the study, two groups of participants learned the location of words on a computer screen over two sessions. Between the sessions, one group slept for 90 minutes while the second group did not. The catch was that researchers jumbled up some of the words and the participants had to indicate where they thought the words originally belonged. Researchers found that those that slept in between the sessions had better memory for both the locations – the original and the updated, indicating that sleep had strengthened both the new and old version of the memory.
“Our study reveals that sleep has a protective effect on memory and facilitates the adaptive updating of memories,” says professor Gareth Gaskell of York’s Department of Psychology. “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.”
Although the process allows our memories to adapt to changes in the world around us, it can hinder us by dragging in wrong information into our memory stores, researchers say. Over time, our memory tends to show both accurate and inaccurate versions of the same experience, causing distortions in how we recall events happened before.
The study titled “Sleep preserves original and distorted memory traces” has been published in the journal Cortex.
Source: University of York