Summary: Sleep helps us to strengthen both old and new versions of experiences, allowing us to use our memories adaptively, researchers report.
Source: University of York.
Researchers at the University of York have shed new light on sleep’s vital role in helping us make the most of our memory.
Sleep, they show, helps us to use our memory in the most flexible and adaptable manner possible by strengthening new and old versions of the same memory to similar extents.
The researchers also demonstrate that when a memory is retrieved – when we remember something – it is updated with new information present at the time of remembering. The brain appears not to ‘overwrite’ the old version of the memory, but instead generates and stores multiple (new and old) versions of the same experience.
The results of the research, carried out at York’s Sleep, Language and Memory (SLAM) Laboratory, are presented in the journal Cortex today.
Lead researcher 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 the study, two groups of subjects learned the location of words on a computer screen. In a test phase, participants were presented with each of the words in the centre of the screen and had to indicate where they thought they belonged.
One group then slept for 90 minutes while a second group remained awake before each group 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, indicating that memory updating had taken place and new memory traces had been formed.
However, when comparing the sleep and wake 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, suggesting that sleep had strengthened both the new and old version of the memory.
Corresponding author Professor Gareth Gaskell of York’s Department of Psychology said: “Our study reveals that sleep has a protective effect on memory and facilitates 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 point out that although this process helps us by allowing our memories to adapt to changes in the world around us, it can also hinder us by incorporating incorrect information into our memory stores. Over time, our memory will draw on both accurate and inaccurate versions of the same experience, causing distortions in how we remember previous events.
The study builds on a research model created by Ken Paller, Professor of Psychology at Northwestern University, USA, an eminent researcher in the field of memory and a co-author on this study.
Funding: The research was funded by the Economic and Social Research Council (ESRC).
Source: Caron Lett – University of York
Publisher: Organized by NeuroscienceNews.com.
Image Source: NeuroscienceNews.com image is in the public domain.
Original Research: Full open access research for “Sleep preserves original and distorted memory traces” by Scott A. Cairney, Shane Lindsay, Ken A.Paller, and M. Gareth Gaskell in Cortex. Published online October 16 2017 doi:10.1016/j.cortex.2017.10.005
[cbtabs][cbtab title=”MLA”]University of York “New Insights Into Why Sleep is Good For Memory.” NeuroscienceNews. NeuroscienceNews, 15 November 2017.
<https://neurosciencenews.com/sleep-memory-7953/>.[/cbtab][cbtab title=”APA”]University of York (2017, November 15). New Insights Into Why Sleep is Good For Memory. NeuroscienceNews. Retrieved November 15, 2017 from https://neurosciencenews.com/sleep-memory-7953/[/cbtab][cbtab title=”Chicago”]University of York “New Insights Into Why Sleep is Good For Memory.” https://neurosciencenews.com/sleep-memory-7953/ (accessed November 15, 2017).[/cbtab][/cbtabs]
Sleep preserves original and distorted memory traces
Retrieval facilitates the long-term retention of memories, but may also enable stored representations to be updated with new information that is available at the time of retrieval. However, if information integrated during retrieval is erroneous, future recall can be impaired: a phenomenon known as retrieval-induced distortion (RID). Whether RID causes an “overwriting” of existing memory traces or leads to the co-existence of original and distorted memory traces is unknown. Because sleep enhances memory consolidation, the effects of sleep after RID can provide novel insights into the structure of updated memories. As such, we investigated the effects of sleep on memory consolidation following RID. Participants encoded word locations and were then tested before (T1) and after (T2) an interval of sleep or wakefulness. At T2, the majority of words were placed closer to the locations retrieved at T1 than to the studied locations, consistent with RID. After sleep compared with after wake, the T2-retrieved locations were closer to both the studied locations and the T1-retrieved locations. These findings suggest that RID leads to the formation of an additional memory trace that corresponds to a distorted variant of the same encoding event, which is strengthened alongside the original trace during sleep. More broadly, these data provide evidence for the importance of sleep in the preservation and adaptive updating of memories.
“Sleep preserves original and distorted memory traces” by Scott A. Cairney, Shane Lindsay, Ken A.Paller, and M. Gareth Gaskell in Cortex. Published online October 16 2017 doi:10.1016/j.cortex.2017.10.005