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Every day, you are faced with a number of different situations and your brain is filled with a phenomenal amount of information. In order to avoid overload, the latter operates daily a form of major nighttime cleaning, which takes place while you sleep. Hence the importance of sleeping properly and maintaining a healthy sleep schedule. This is when the brain sorts through the memories of the day to decide which ones to keep for the longer term. However, the exact mechanisms of this sorting remained, until today, still a little vague.
A recent study published on March 28 of this year in the journal Science has just provided completely new clarifications< /strong> on this sorting and selection process.
The role of sawtooth waves
This sorting process takes place in the hippocampus, a region of the brain essential for memory, and is based on a mechanism called “sharp wave ripples” (sawtooth waves). The latter therefore occur mainly during sleep and play an elementary role in the selection and consolidation of memories.
György Buzsáki is a professor of neuroscience at the University of New York Medicine and lead author of the study. It was he himself who highlighted this wave phenomenon. « Sawtooth waves are a pattern that occurs in the hippocampus, and in the waking state, it is this pattern that selects what will be stored permanently and what will be sorted ” he explains. Indeed, they also take place during the diurnal period.
Even if less frequent during the day, they are just as essential. By synchronizing neurons, they indicate which memories are important enough to keep, as if to mark them for later consolidation during sleep. When night comes, these multiply (between 2,000 and 4,000 times), allowing the selected memories to be firmly anchored. Among the entire mammalian kingdom, these waves are the most synchronized sequences of neuronal activity ever observed.
Resting and consolidation
In addition to having highlighted the importance of these waves, the study also highlighted their role during rest phases which can occur during the day. By observing rodents evolving in a maze, the researchers found that these waves frequently occurred when they took a break to drink sugar water. The longer the rodents took their break, the more intense the waves were. This phenomenon also proves to be central to consolidating memories. The brain thus seems to function in two distinct modes: an active acquisition mode and a passive storage mode.
A discovery which clearly shows the importance of the breaks that you can give yourself during your day, which are also very important in the memorization process. These moments of relaxation are essential and allow your brain to process and effectively reinforce the complex information acquired throughout the day.
Reorganizing memories
In addition to sorting, the brain arranges memories in a logical way. Buzsáki explains: “ A large part of our daily experiences is cut up and assembled with other experiences through this particular pattern [Editor's note: sawtooth waves] in the hippocampus». In other words, the brain selects and combines fragments of experiences during the day to form coherent memories from them. Sequencing also occurs mainly when the brain is in a resting phase.
Here too, these waves are fundamental in this reorganization process. Once again, thanks to the observation of rodents, the researchers found that the memories reinforced and preserved were those of events experienced just before a period of rest. Imagine that a rat wants to go through a maze and takes a break during its journey. The sawtooth waves that occur during this moment of tranquility will help ensure better memorization of the labyrinth route.
For neuroscience, this discovery is fundamental. It will help to better understand the functioning of memory by providing more precise insight into one of its many mechanisms. A better understanding of the brain processes involved in memory is proving to be a potential weapon to help develop new treatments against certain disorders such as Alzheimer's or other forms of dementia. The cognitive decline associated with these diseases could one day be slowed by targeting these famous sawtooth waves. However, further research would of course be necessary for this to become a clinical reality. In the meantime, keep this in mind during your next coffee break: your brain continues to work, and it's for your own good !
- A study has just highlighted the importance of sawtooth waves in the process of memorizing and sorting memories.
- These waves have takes place mainly at night, but also during the day, when the brain is at rest.
- These also play an important role in the process of reorganizing memories.
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