Article from WeChat public account:Neural reality (ID: neureality), author: CEPELEWICZ, translation: amoxicillin Eastern, revision: Monday sunny, editor: small sunflower, title figure from: Scott Balmer
A sharp wave that exists in the hippocampus’ electrical activity can bring the dawn of memory research?
“In biology, it’s easy to break something,” says neuroscientist Loren Frank of the University of California, San Francisco (Loren Frank) pointed out, “It is very difficult to make one thing work better.”
Nevertheless, researchers at New York University School of Medicine reported in the early summer of 2019 that they successfully improved their memory by adjusting the length of a dynamic signal in the brain of experimental animals[1]; and neuroscientists (eg Frank) started this brain signal decades ago Fascinated. The result itself is exciting enough to bring about the possibility of enhancing human memory. But it reveals a more comprehensive understanding of memory and discovers an important clue that is rooted in the duration of neurological events; this understanding may lead us to better understand the principles of memory.
Discovering memory 涟漪
Since the 1980s, scientists have been paying attention to a short-lived cluster-like discharge of neurons in a region of the brain called the hippocampus (short bursTs of synchronised neural activity). This activity consists of a complex and cascaded (Shantanu Jadhav) said that these discharge types “sound like an explosion.”
When a large number of neurons suddenly repeat their previous discharge pattern at high speed, it is as if these “spikes” appear when playing back fragments that have been experienced in the past; therefore, they have been closely related to memory since they were discovered. The land is connected. This phenomenon can occur when animals are asleep, perhaps to help them consolidate newly acquired knowledge for long-term storage.
Finally, people are beginning to realize that sharp waves are not just a sign of passive memory consolidation; they also appear in more active memory processes Such as memory retrieval, and use memory to guide new inferences) . These “hippocampus fireworks show”, which takes up a lot of sleep time, are also often awake, but idle and inconsistent, before the decision is made, or in the animal brain that is exploring the new environment. “The content of the information contained in it may be a real replay of past experience,” said Dr. Defis, a neuroscientist at the University of Texas
The “spike wave” observed in hippocampus electrical activity has two forms: DOI:10.1126/science.aax0758
In other words, “what do you think of memory, or the expectation of future possibilities based on the past, what it looks like in your mind,” said the sharp wave, “What it looks like,” Frank said. In any case, these flaws are “completely structured and are likely to play an important role in the learning-driven mechanism in the brain; and this driving mechanism is a key to the brain’s learning of new knowledge” – the sharp wave is a variety of memories “Cognitive Biomarkers” [2].
—Lucy Reading-Ikkanda/Quanta Magazine
Frank, Yard Haver and others consolidate this understanding in 2012: they let mice learn to find their way in a trident-shaped three-way maze and use electrical impulses to disturb their sharp waves. When the mice are in the left and right arms of the maze, they need to go back to the middle to get rewards; when they are in the middle, if they choose to go left last time, this time they need to go to the right arm to get rewards, and vice versa. In the first part of the task, the mice only had to go back to the starting point, and disturbing sputum had no effect on the performance of the mice. However, when they need to alternate between the left and right arms, (that is, they need to remember their last choice), disturbing 涟漪 Then their performance is significantly worse [3].
long, short
At present, the research team led by neuroscientist Gilgi Buzasaki
György Buzsáki Image Source: buzsakilab.com
“I think they can find a way to speed up learning by enhancing the laws of existing activities – which is inherently innovative and effective,” Frank said. “And, this strengthens the rules and learning and memory. Relevance.”
But at the same time, this achievement also underscores the importance of timeliness – a researcher who has never explored this before. Scientists have previously discovered that although a small portion of the natural sputum in the hippocampus will last more than 0.1 second, most of it will last only about 0.1 second.
However, scientists have not studied whether the duration of the cockroach has an effect and what influences this factor. “People have long known that the duration of spikes varies, but I think they have always defaulted to these lengths,” A. David Ridish (A. David Redish), a neuroscientist at the University of Minnesota. Radisch was not involved in the study.
In fact, this uneven distribution occurs on many levels of the brain, such as the frequency of neuronal firing, the strength of connections between synapses, and the conduction velocity of axons[4]. Buzasaki pointed out that experts generally believe that “(this distribution) can maintain the confrontational needs of dynamic systemsThe balance,” and this balance may protect the stability or robustness of the system. However, he and his team decided to continue to delve into the specific meaning of this phenomenon.
Lucy Reading-Ikkanda/Quanta Magazine
When rats enter a new environment (for example, when they start exploring the three-way maze), the researchers found that The number will generally be more than usual. As these animals become more exposed to the environment, the duration of the sputum will gradually become shorter. Contrasts in other experiments have led to the same conclusion: longer sputum may be associated with tasks that require more memory and cognitive ability. “It’s like there’s an internal process that says, ‘I need a longer sharp wave,’” said Reddy.
Buzasaki and others used light to stimulate the brain, making the duration of sputum longer; they found that other related neurons also joined this activity. The hippocampus appears to be in more part of the playback sequence – in this experiment, the hippocampus appears to be playing more information about the way the mouse walked through the maze before, “shows (it walked through) the entire path,” Buzasaki pointed out.
“Extensions will actually extend the path information that is reactivated,” said Yard Haver. “This is probably a mechanism to imagine all feasible paths,” and the rat can then choose a realistic path.
All in all, this study shows that “the length of the sharp wave has practical significance,” said Ridsch, “the length is related to the information processed by the cockroach, and the sharp wave of handling more information is more necessary for memory.
A cluster of light in the dark
At present, researchers can review their previous research to find out if the length of sputum will provide a new perspective for the study of memory mechanisms. Riddisch is an example: before this, he found that the sharp wave sputum marked the nerve state of the rat to establish a new mental connection; by reviewing this finding, he pointed out that those sputum are also longer than the average. “So these longer spikes may also help establish better contact capabilities.”
But at the same time, this possibility has brought about a variety of other questions – what is the function of the short? What role does 涟漪 在 play in long-term memory or future plans? Does the long scorpion and short scorpion have different ways of interacting with brain regions other than the hippocampus? – Buzasaki is currently preparing to explore the last question.
Evgenia Chuvardina
The concern about sharp waves, and the experiments Frank and Buzasaki used to study sharp waves, is also very interesting in itself, because it contains many different ways of thinking about memory. “We are very clear: memory is the past, planning and imagination are the future,” one brain area is responsible for active short-term memory, and the other is responsible for long-term memory of “offline,” Buzasaki pointed out, “but the brain may It doesn’t work like this. The boundaries between these mechanisms are not so easy to divide.”
He added, therefore, perhaps studying the memory “on a more general level” may be justified.
When discussing the best way to define memory and study memory, Frank said: “I think that as a field, we still don’t understand what we are doing, we are still groping in the dark.” But in these clusters In the event of shackles, we may find a little light.
References
[2] https://onlinelibrary.wiley.com/doi/full/10.1002/hipo.22488
[3] https://science.sciencemag.org/content/336/6087/1454.long
[4] https://www.nature.com/articles/nrn3687
Article from WeChat public account:Neural reality (ID: neureality) author: CEPELEWICZ, translation: amoxicillin Eastern, revision: sunny Monday, editor: small sunflower