Introducing the brain: forming memories (Introduction)

by David Turell , Wednesday, July 03, 2024, 17:40 (141 days ago) @ David Turell

Studies in the hippocampus:

https://www.the-scientist.com/how-the-brain-selects-what-experiences-to-keep-71978?utm_...

"In a study published in Science, Buzsáki’s team described how a pattern of brain activity known as sharp wave ripples (SWR) labeled mice’s experiences in a maze, which were later replayed in their brain when the animals slept. Their findings point to the waking SWR as a mechanism for selecting experiences that might later be consolidated into long-term memories.

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"Hippocampal SWR have captured Buzsáki’s interest for over 30 years. These are bursts of electrical activity that primarily occur during sleep, but they are also seen in the awake state when the brain is resting.3 Previous work from Buzsáki’s team and others revealed a key role of sleep SWR in memory consolidation, as well as awake SWR in supporting memory in rodents.4-7 Yet, researchers did not know whether these hippocampal oscillations also helped the brain decide which experiences to store and which to eliminate.

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"Despite being considered the most synchronous events that occur in the mammalian brain, neurons that participate in SWR fire in sequence.8 The researchers exploited this feature to examine the role of awake SWR on the selection of events. Since awake SWR emerge when the brain is idling, the team allowed the mice to take a break from the task by providing a water reward every time they concluded a trial in the maze. When the researchers looked at the SWR that emerged during the reward, they found that the neuronal firing sequence contained in those SWR was most similar to the firing sequence seen in the last five runs of the maze.

"The team next investigated the relationship between these awake SWR and the ones that occur during sleep. They discovered that the neuronal firing patterns seen during the sleep SWR resembled those observed during the awake SWR. “[Sleep SWR] are replaying mostly those events that were marked by the waking sharp waves,” said Buzsáki.

"Since sleep plays an important role in memory consolidation and sleep SWR have been also implicated in that process, the researchers proposed that awake SWR function as a tagging mechanism that selects information for later replay during sleep and long-term storage.

“'These sharp ripples that occur in the hippocampus have been linked to this physiological process of selective reactivation of experiences, and only those experiences which are reactivated in sleep are the ones that are consolidated in the long term,” explained Shantanu Jadhav, a neuroscientist at Brandeis University who was not involved in the research. “But what selects them for reactivation has been unknown. This study tries to get at that.”

" Despite the compelling evidence suggesting that the awake SWR tag experiences for replay during sleep, Jadhav and Frank remain curious about whether these labeled events are consolidated and turn into memories in the animal’s brain. “If they're promoting memory storage, what does that mean? What does it mean in the rest of the brain that these memories are stored and then how are they brought back up again to be used to do something?” Frank said."

Comment: identifying EEG waves that show memory formation is at a superficial level of understanding memory formation. How does electric activity form images in memory? Totally unknown. This is simply part of mapping where specific activities occur in the brain.