Human memory

Main article: Human brain

​​Kak does memory work?

The physiological basis of memory is the "traces" of previously former nervous processes that persist in the brain. Any nerve process caused by external irritation (for example, the transfer of an image of a pattern to the brain) does not pass for the nervous tissue without a trace, but leaves a "trace" in it in the form of certain functional changes. Thus, when certain information is perceived, a connection is formed between some groups of neurons, which encodes this information. And the more often this information enters the brain, the more often the nerve impulse passes through the connection and the more the connection is "fixed."

When we see, for example, the drawing again, the nerve impulse will pass along a familiar path and the connection between certain neurons will become even stronger, and so on.

According to the latest research for 2020, the material carrier of information about different events is not the excitation of different neurons, but various complexes of neural networks, which are formed at the time of perception of information.

Below is a recording of an experiment on this topic: here neurons form new connections between themselves right in the test tube.

Memory capacity

Can a person's brain run out of memory space?

Maybe. But not a single person has survived to this point.

In your memory brain, about 2 quadrillion bytes - if you imagine that your brain is a video camera, which was turned on for round-the-clock recording in good quality, then there will be enough space for 300 years. The limit is in life, not in memory.

How information is stored

There is no central store of information in the brain - the data is distributed in a complex and confusing synaptic network, which for 2020 we still know very little about.

Each fragment of memory (word, view, feeling) is encoded in the area that created it (temporal or occipital lobe, limbic system) and is activated every time it comes to mind.

Metamemory

In addition to memory, we also have meta-memory, where everything that we remember (or should remember) is stored, and what not.

The similarity of the brain device, or rather the memory block, with the computer for 2020 is becoming more and more obvious.

In the brain there is an analogue of the list of lists. This meta-memory is responsible for the deja vu effect and "what is the name of this actor who was filming there?." The researchers found that such a file cabinet is located in our prefrontal cortex.

Consciousness

Main article: Consciousness

Chronicle

2024

Surprise discovery: Human brain creates multiple 'backups' of memories

In mid-August 2024, Swiss specialists from the Biocenter of the University of Basel released the results of a study saying that the human brain forms several copies of the same memories. Scientists compare this model with computer systems for reserving information.

With the help of imaging tools, the project participants studied the hippocampus: this is part of the limbic system of the brain and the hippocampus formation, which plays an important role in learning, memory and emotions. The researchers found that memories of certain events are stored in the brain as multiple parallel copies distributed across at least three different clusters of neurons. These clusters form at different stages of embryonic development. Copies differ in their characteristics, in particular, in the duration of data storage and the possibility of modification.

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Фото: Freepik

One of the clusters uses "early birth" neurons to store memories, which develop earlier than others as the fetus grows. Such a structure stores weak copies of memories, which are strengthened over time. In turn, neurons of "late birth" (appear at the late stages of embryonic development) initially store strong memories, but subsequently they are lost. The third cluster is intermediate: neurons appearing between the early and late groups provide the highest stability of information storage.

Understanding the mechanism of storage of memories in perspective can find application in various fields of medicine. In particular, the results of the work can help mitigate painful memories in people who have suffered trauma or any event that has had a negative impact on the mental state.^[1]

How the brain preserves memories for life. Scientific explanation

At the end of June 2024, American researchers from the University of New York reported the discovery of a mechanism that plays a key role in the formation of long-term memory. It has been established that this process is associated with the KIBRA molecule, which performs the functions of a kind of "glue" for other molecules, which allows the brain to save memories for life.

It is noted that previous attempts to understand how long-term memory works were focused on the study of individual molecules. Neurons are known to store information in memory as a structure of strong and weak synapses. However, the molecules in the synapses are unstable: they constantly move around neurons, wear out and are replaced within hours or days. In the new work, scientists have revealed the principle of joint work of molecules in the formation of long-term memory.

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Фото: Unsplash

The most important molecule for strengthening synapses in mammals is the protein kinase M-zeta (PKMzeta): but this enzyme is destroyed after a few days. The researchers found that KIBRA is the "missing link" in long-term memory: the molecule serves as a "permanent synaptic label" or "glue" that attaches to strong synapses and to PKMzeta, while avoiding weak synapses.

During memory formation, synapses involved in this process are activated. KIBRA is selectively placed at these synapses, and PKMzeta then attaches to the KIBRA synaptic label, making synapses more resistant to change. This allows synapses to connect to the newly created KIBRA, attracting even more new PKMzeta molecules.

Breaking the KIBRA-PKMzeta bond erases old memories. Previous studies have shown that an accidental increase in PKMzeta levels in the brain enhances weak or faded memories. This was a mystery, since in theory there would have to be a reverse effect. However, the presence of KIBRA explains this process: the molecule binds only to strong synapses, which strengthens memories.^[2]

Brain can store 10 times more data than thought

In early June 2024, a new University of Chicago study emerged that confirms that the brain can store nearly 10 times more information than previously thought.

As with computers, the brain's memory capacity is measured in "bits," and the number of bits it can store depends on connections between neurons, known as synapses. Previously, scientists believed that the range of values ​ ​ for the size and strength of synapses is not so large, which, in turn, limits the amount of memory in the brain. However, this theory has come under question in recent years.

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Фото: Unsplash

In the new study, researchers developed a highly accurate method to assess the strength of synaptic connections between neurons using the rat brain as an example. These connections provide a framework for learning and memory as brain cells communicate at these points, allowing them to store data and share information.

Human brain neurons are connected through more than 100 trillion synapses. As we learn, the amount of information transmitted through certain synapses gradually grows. This "strengthening" of synapses allows us to store new information.

The researchers looked at strengthening and weakening synaptic connections and showed that they could store 10 times more information than previously thought. Analysis of rat synapses from the hippocampal region showed that they could store 4.1 to 4.6 bits of information. Scientists believe that the new analysis method will allow, on the new side, to study the mechanisms of not only learning, but also aging and diseases that affect the synaptic connections of the brain.

These mechanisms underlie the ability of neural circuits to process information, says Jai Yu, assistant professor of neurophysiology at the University of Chicago. - Now we have the opportunity to evaluate the amount of information transmitted by synapses, and this is an important step in the study of thinking[3]

2023: Proven for the first time - memory of the past and memory of the future are in different parts of the brain

On October 23, 2023, American researchers from Cornell University proved for the first time in the world that the memory of the past and the memory of the future are in different parts of the brain. This discovery in perspective could lead to the emergence of new methods of treating neurodegenerative ailments, in particular Alzheimer's disease.

Scientists focused on the hippocampus - this is part of the limbic system of the brain, involved in the mechanisms of the formation of emotions, memory consolidation, etc. In Alzheimer's disease and other forms of dementia, it is the hippocampus that becomes one of the first brain structures to lose their functions. In particular, there is a loss of short-term memory and disorientation.

American researchers prove for the first time in the world that the memory of the past and the memory of the future are in different parts of the brain

As part of the study, experts revealed the difference between the role of the hippocampus in two memory functions: one remembers the associations between time, place and what a person did, and the other allows you to predict or plan future actions based on previous experience. The results of scientific work suggest that these two problems, encoded in the hippocampus, can be separated. In particular, experts have found that these aspects of memory and cognition are supported by two different neural codes.

One type of code controls the ability to create associations, such as remembering that apples are sold at a nearby grocery store. Another kind of neural code is predictive and assumes the ability to flexibly use memory to plan actions, for example, to select an alternative route to the store if the main road is blocked. However, it was not clear exactly how the hippocampus supports these functions or whether there was any connection between them.

In experiments on rats, scientists deployed a system with multiple electrodes to track neuronal activity while rodents performed certain actions. The team then used optogenetics to control neuronal activity very precisely. Scientists used a special virus and, as a result, were able to act on certain neurons without changing the general properties of the brain. The researchers, in particular, showed that in this way it is possible to preserve the associative aspects of memory, but suppress the predictive component.^[4]

Notes