Discovering the relationship between Alzheimer’s and the “replay mode” of the brain!

According to IsnaTo consolidate memories, our brain replays them during rest periods as a kind of “replay mode”. A new study on mice shows that disruption of this process can play a role in the memory loss that is one of the complications of Alzheimer’s disease.

According to the University College London research team, the findings could pave the way for opportunities to diagnose Alzheimer’s at an early stage and treat the associated brain damage.

Neuroscientist Sarah Shipley says Alzheimer’s disease is caused by the accumulation of harmful proteins and plaques in the brain, leading to symptoms such as memory loss and disorientation, but it is not clear exactly how these plaques disrupt normal brain processes.

He added: “We wanted to understand how the function of brain cells changes as the disease progresses to determine what causes these symptoms.”

The studied mice were put in conditions similar to Alzheimer’s with the toxic accumulation of “amyloid beta” protein in their brains. These experimental animals showed signs of being unable to register a spatial map in their memory while navigating the spirals.

Both during the spiral challenges and while the rats were resting between sessions, Shipley and his colleagues monitored the activity of their hippocampus, an area of ​​the brain that contains spatial memory neurons known as place cells.

In order for the mice to remember where they have been, these cells must be activated in a specific order. As memories are “stored” for long-term storage, that activation sequence repeats itself like a replay.

The frequency of these repeats did not change in mice with amyloid-beta plaques in their brains, but the order of the sequences did. It was as if the memories were scenes from a short film that had been cut into pieces and stored in different places.

This was also observed in spiral navigation behavior, with lesioned rats often forgetting which parts of the spiral they had previously visited (even within a single session). Place cells also became more unstable over time, and cell-to-place mapping was disrupted.

Although this study used a model of Alzheimer’s in the brain of mice, there are good reasons to believe that the same type of impairment occurs in humans with the disease, something that could be confirmed through future studies.

Neuroscientist Caswell Barry says: We have discovered a disorder in the way the brain consolidates memories, which is visible at the level of individual neurons. Notably, replay events still occur, but have lost their natural structure. It’s not that the brain stops trying to consolidate memories, but that the process itself is impaired.

Alzheimer’s disease is a complex disease with multiple risk factors. There are many different potential causes and countless influences on the brain that may work together or separately.

Part of the difficulty for researchers is trying to figure out what causes Alzheimer’s to develop and what happens as a result, and that uncertainty is also present in the build-up of amyloid beta.

Studies like this add pieces to the overall puzzle, allowing us to see more of the “big picture of Alzheimer’s” and how all these causes and effects fit together as brain function declines over time.

Each new discovery means we may be able to detect symptoms earlier, allowing more time for treatments and supports, and developing treatments to target specific parts of Alzheimer’s.

In this case, the result may be the development of drugs that help intensify the feedforward activity in hippocampal place cells. However, this will not be possible until further research can identify the processes involved and how to specifically regulate them safely.

“We hope our findings can help develop tests to diagnose Alzheimer’s early, before extensive damage has occurred, or lead to new treatments that target this relapsing process,” says Berry.

This research was published in Current Biology magazine.

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