Memory has never been an easy subject to study in the brain, and it may have just gotten a bit more complicated, because researchers from Radboud University’s Donders Institute have just discovered that memories of the same events co-exist as different “resolutions” across the hippocampus.
“Memories, similar to the internal representation of space, can be recalled at different resolutions ranging from detailed events to more comprehensive, multi-event narratives,” wrote the authors in Nature Communications.
Or in more concrete terms, you could remember a general event like going out to dinner on a Friday, or a specific one like reading an article on a science website during dessert—because for any memory, there are “coarse” and “fine” details.
As it turns out, such memories of the same event aren’t stored in one location, but are dispersed across the hippocampus. The finest scale memories are distributed near the rear of the hippocampus, while the coarser ones exist near the front.
“We think that memories of these events are stored in different locations of the hippocampus to avoid interference when retrieving either coarse or detailed memories,” explained first author Silvy Collin in a statement.
The Sims help out
“We showed participants life-like events created with the videogame The Sims 3. These were integrated into multi-event narratives,” Collins said.
The participants—29 college students from the university—watched four approximately five-second clips, some of which were related together by two later clips. As the events in the Sims unfolded before them, and later when they were asked to recall what had happened, the participants rested in an MRI scanner in order to see where in the hippocampus activity was happening.
What’s next?
The researchers have expressed an interest in how memories are stored within brains other than those of young, healthy adults. The brains of dementia patients, for example, may have different memory storage if certain levels of detail don’t get placed in the hippocampus.
“We see that the various memory resolutions are formed automatically, but we believe that they can exist independent from each other,” explained Principal investigator Christian Doeller.
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Feature Image: Silvy Collin and colleagues
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