A recent study highlights the importance of inactive periods for long-term memory formation.
Can you recall what you did last Tuesday before breakfast? Probably not. Memory is a valuable asset. And long-term memory is even more precious. We retain a good amount of details of our experiences for a few minutes or perhaps hours. However, the vast majority of these details are gone within a week or so.
A crucial question, then, arises: what determines if an experience is committed to long-term memory? We actually know quite a bit about long-term memory consolidation. We know, for instance, that soft memories are transferred to long-term storage during rest. That's one reason why sleeping is so important — a lack of sleep severely limits memory consolidation. Yet, a fundamental piece of the puzzle about which experiences earn the privilege to become long-term memories has just been unveiled in a recent study.
One of the primary brain regions involved in memory management is the hippocampus. A telltale activity in the hippocampus is the so-called "sharp wave-ripple," which means that a significant proportion, around 15%, of all the neurons in the hippocampus fire simultaneously. This sharp wave-ripple activity occurs during rest when memories are transferred to long-term memory. This has been known.
The new finding suggests that the same firing pattern also occurs during the day immediately after memories are formed. Moreover, there is a very straightforward correlation between the frequency of these sharp wave-ripple events during memory formation and the likelihood that the memory is transferred to long-term memory at night. The more sharp wave-ripples we experience after an experience, the more likely it is that we'll remember this experience.
The prevalence of this relatively large-scale brain event, which is reasonably easy to capture with brain imaging, makes it simpler to pinpoint which of our experiences make it into our long-term memory. It seems that the key factor that influences which experiences make it and which ones will be forgotten forever is whether the experience is followed by an inactive period when the individual does very little.
The sharp wave-ripples during the day do not occur while the remembered experience is still ongoing. No, they occur in an inactive period just after the experience. If there is no inactive period following the experience, there is no time window for the sharp wave-ripples and, therefore, less chance that the experience will be remembered long-term.
These findings have far-reaching implications. Inactive periods, in our era of smartphones and online entertainment, are precious commodities. We are seldom inactive for the same duration as we have our phones for scrolling through our online entertainment feed, which is the exact opposite of an inactive period.
Consequently, regardless of primary areas of focus for how significant an experience might have been, fewer sharp wave-ripples will occur in its immediate aftermath and then these sharp wave-ripples cannot be replayed during rest. This means they will likely not be committed to long-term memory.
What follows from this is that to forget something pleasant that has happened to you, you probably shouldn't post about it on social media immediately afterward. Nor should you WhatsApp your friends about it. You should probably sit down on a bench in a park and do nothing.
Inaction may not be a virtue, but it is a necessary step towards having lasting memories of things worth remembering.
I think you meant that second to last paragraph to begin "What follows from this is that to *remember* something pleasant..."
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