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How Does The Brain Store Memories

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What Is Information Processing And How Does It Work

How do we store memories in the brain?

Now that you know a little bit more about what memories are and what two of the most important types of memories are, you now need to understand a little bit about information processing. Information processing, to put it simply, is the way the brain processes and works with information. This includes retrieving memories from the hippocampus or the prefrontal lobe. There are two things to remember about information processing. First, there are three stages of memorizing something. Secondly, there are four steps of the actual information processing stage.

The three stages of memory are the motions your brain goes through to bring a memory to the surface of your mind. Now that you know about the different types of memories, you can begin to put this together. First things first, theres a good chance that a sensory memory will be your trigger. Whether it is a sight, sound, feeling, or smell that you experience, this will likely be the first part, or the trigger, to remembering something. Once this happens, the short-term memory plays a role. While it only holds information for a certain amount of time, it is useful when there is already a pre-established connection in the long-term memory department. When something is memorized enough, it will become a physical part of the hippocampus, becoming a long-term memory. There is no limit to how many long-term memories that you can have.

How Traumatic Memories Hide In The Brain And How To Retrieve Them

Special brain mechanism discovered to store stress-related, unconscious memories

Some stressful experiences such as chronic childhood abuse are so overwhelming and traumatic, the memories hide like a shadow in the brain.

At first, hidden memories that cant be consciously accessed may protect the individual from the emotional pain of recalling the event. But eventually those suppressed memories can cause debilitating psychological problems, such as anxiety, depression, post-traumatic stress disorder or dissociative disorders.

A process known as state-dependent learning is believed to contribute to the formation of memories that are inaccessible to normal consciousness. Thus, memories formed in a particular mood, arousal or drug-induced state can best be retrieved when the brain is back in that state.

In a new study with mice, Northwestern Medicine scientists have discovered for the first time the mechanism by which state-dependent learning renders stressful fear-related memories consciously inaccessible.

Its difficult for therapists to help these patients, Radulovic said, because the patients themselves cant remember their traumatic experiences that are the root cause of their symptoms.

The best way to access the memories in this system is to return the brain to the same state of consciousness as when the memory was encoded, the study showed.

What Exactly Are Memories And How Does Storing Them Work

To understand how the brain stores a memory, you first have to understand how memories work. For example, no memory can exist solely on its own. Memories are broken down and sorted into windows of time. This is one of the reasons why it is harder to remember things that happened long ago, but when you start thinking about it, you begin to remember a lot of things that happened from that time period.

There are also several different types of memories. There are sensory memories, short-term memories, and long-term memories. Most people are familiar with the concept of short-term and long-term memories. Short-term memory typically involves remembering things such as your hotel room number when you are travelling and memorizing a shopping list. Long-term memories, on the other hand, are technically short-term memories that have been moved to a deeper part of the brain. Here, in the hippocampus, memories are condensed into more of an episodic-like format where you experience the whole event, rather than the specific sights, smells, and sounds. These are the two types of memories that you will need to know about if you want to understand how the brain stores memories.

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Encoding A Terrifyingly Complex Tapestry In Real Time

When we actually want to learn something, it is long-term memories we are interested in. So how are they formed? The first step is to encode a piece of information otherwise it quickly disappears, like breath on a mirror.

Information is channelled to the hippocampus, the brain region crucial for the formation of new memories and one of the only places in the brain where brand new neurons are regularly generated. The hippocampus links all of the relevant information together and encodes it into a new memory by forming new synapses. Its basically like someone knitting a terrifyingly complex tapestry in real time.

But not all information is equal in the eyes of the hippocampus. Important things are encoded more readily and effectively than routine or incomprehensible things, like an uneventful daily commute, or the lyrics of a dance song in a language you dont recognise. The hippocampus will prioritise those that have been rehearsed repeatedly in the short-term memory, or those with a strong emotional component. The hippocampus is selective because it is very busy.

What Is A Hidden Memory

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The brain will sometimes hide particularly stressful, traumatic or fear-related memories. This can be protective in the short term, when the emotional pain of recalling the event is still profound. However, in the long term, suppressed memories can create serious emotional health concerns such as anxiety, depression, post-traumatic stress disorder and dissociative disorders.

Because these memories are often formed through state-dependent learning, resolving the ensuing conditions, even with the help of a therapist, can be difficult. When patients are unable to remember their experiences, therapists can struggle to help them identify and treat the root cause of their symptoms.

The new study suggests the best way to access hidden memories is to return the brain to the same state of consciousness it was in when the memory was formed. Jelena Radulovic, MD, PhD, Dunbar Professor in Bipolar Disease in Psychiatry and Behavioral Sciences and Pharmacology at Northwestern University Feinberg School of Medicine, finds the radio to be a useful analogy.

The brain functions in different states, much like a radio operates at AM and FM frequency bands, Dr. Radulovic said. Its as if the brain is normally tuned to FM stations to access memories, but needs to be tuned to AM stations to access subconscious memories.

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What Is Declarative Memory

Declarative memory, which is required to learn calculus, appears to be stored primarily in the cerebral cortex. Calculus involves a lot of abstract knowledge. The process of solving an equation is a skill, but it is primarily a cognitive skill involving abstract manipulations in short-term memory using explicitly memorized steps. The only visuo-motor aspects of calculus involve moving the pencil on the paper and recognizing the shape of mathematical symbols. Abstract declarative memories fade faster if there is not regular repetition to keep them refreshed. Declarative memory is intertwined with language.

Changing The Brains Radio Frequencies

Two amino acids, glutamate and GABA, are the yin and yang of the brain, directing its emotional tides and controlling whether nerve cells are excited or inhibited . Under normal conditions the system is balanced. But when we are hyper-aroused and vigilant, glutamate surges. Glutamate is also the primary chemical that helps store memories in our neuronal networks in a way that they are easy to remember.

GABA, on the other hand, calms us and helps us sleep, blocking the action of the excitable glutamate. The most commonly used tranquilizing drug, benzodiazepine, activates GABA receptors in our brains.

There are two kinds of GABA receptors. One kind, synaptic GABA receptors, works in tandem with glutamate receptors to balance the excitation of the brain in response to external events such as stress.

The other population, extra-synaptic GABA receptors, are independent agents. They ignore the peppy glutamate. Instead, their job is internally focused, adjusting brain waves and mental states according to the levels of internal chemicals, such as GABA, sex hormones and micro RNAs. Extra-synaptic GABA receptors change the brains state to make us aroused, sleepy, alert, sedated, inebriated or even psychotic. However, Northwestern scientists discovered another critical role these receptors also help encode memories of a fear-inducing event and then store them away, hidden from consciousness.

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How The Brain Decides Which Memories To Hold On To

This post originally appeared on Quora, in response to the question, How does the human brain decide which memories to store? Below is computational neuroscientist Paul Kings answer, which weve republished here with permission.

The brain uses a number of automatic mechanisms to determine what information to retain. Everything else naturally fades away.

The brains overriding principle, given to it from millions of years of evolution, is to retain whatever is likely to be useful later for long-term survival.

Since the future utility of information is impossible to predict, the brain uses a number of heuristics that have been honed over the millenia.

Here are some of the most well studied:

1. Repetition

Things that happen repeatedly are either highly significant or irrelevant. However even if they are irrelevant like the background noise that you tune out they must be identified so that they can be removed from perception. When studying for a test, students often use repetition to activate the brains importance circuits.

2. Primacy and recency

Things that happened first are often more important because they predict what comes later. And things that happened most recently are often the most relevant because they are closest to the present. Things in the middle tend to get forgotten. This is why so many presentations start and end with an overview of the key points.

3. Surprise

4. Emotional impact

4. Leads to positive or negative outcome

How Are False Memories Created

How Does Our Brain Store Memories?

False memories can be as simple as concluding that you were shown a word that you actually werent, but it may also include believing you experienced a dramatic event that you didnt. People may produce such false recollections by unwittingly drawing on the details of actual, related experiences, or in some cases, as a response to another persons detailed suggestions about an imaginary event that is purported to be real.

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What Happens In Your Brain When You Make A Memory

You might imagine memory is a Santas sack of life events and the first half of jokes. You would be wrong. Neuroscientist Dean Burnett explains all in our new series, Use your head

We all have memories, as far as I can remember. But where do these memories come from and how do they get made?

People often compare the brain to a computer, but the brain doesnt have USB slots that allow you to pick up new information by jamming a flash drive in your ear. That would be convenient, if a little painful.

So where do we get all this information sloshing around in our skulls? You might imagine human memory is a bit like a Santas sack filled with life events, song lyrics and the first half of jokes. But in truth, memory is not one single solid thing. It is a term covering lots of types of recollections that are surprisingly distinct, and used constantly in different combinations by a typical human.

What Is An Engram

A memory engram, or memory trace, is a term for the set of changes in the brain on which a memory is based. These are thought to include changes at the level of the synapses that connect brain cells. Research suggests an engram is not located in one specific location in the brain, but in multiple, interconnected locations. Engram cells are groups of cells that support a memory: They are activated and altered during learning and reactivated during remembering.

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Long Term Vs Short Term Memories

If we try to look into the depth of what memories are there can be two types. Based on the time limit, memories can be broadly classified into long and short-termed memories.

Short Term Memory

A short-term memory has the time span ranging from seconds to a few minutes. They are stored temporarily and then either get to the long-term memory storage, or they are discarded. Let us say someone gives us the mobile number. As the number is new so our memory will retain it for the short term. There are the possible chances that we are going to forget about this number after few moments.

Long Term Memory

These are the memories stored in the brain over a more extended period. They are several short-term memories organized to form a long memory that is stored permanently. Depending upon the importance and number of recalls, it can fade or be remembered forever. For example, you can recall your 18th birthday but not what you ate on Monday three weeks ago.

Finding A Home For Your Memories

How Does The Brain Store And Process Memories? [Infographic]

Coding a memory is all well and good, but it is useless if it has nowhere to go. Finding a storage place is the next step.

Newer memories, onceconsolidated, appear to reside in the hippocampus for a while. But as more memories are formed, the neurons that represent a specific memory migrate further into the cortex. As a result, memories are stored throughout the brain. Its a bit like the internet, which is made of information spread all across the planet and accessed via countless connections.

Similar memories tend to clump together spoken memories near the language centres, visual memories near the visual cortex and theres a lot of redundancy too you can have several memories for the same thing. Every time they are activated they are strengthened. Human memories arent stored like books in a library theyre constantly being updated and tweaked.

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Um Whats Memory Again

First, a quick recap of the basics.

The fascinating case of Henry Molaison, known as HM, gave scientists a number of insights into the nature of memory and how its stored in the brain.

In the 1950s, as a treatment for incapacitating epilepsy, HM had a drastic operation in which his hippocampus, and some of the surrounding area, was removed. The procedure reduced his seizures, but drastically affected his memory. For the rest of his life, HM was unable to form any long-term memories and couldnt remember specific autobiographical events from his life. However, he could still learn new motor skills and was able to repeat these later on, even though he couldnt remember learning them.

Before HM, it was commonly thought that when you remembered something, all the neurons in your brain worked together to evoke a memory. But the case of HM showed that different areas of the brain are responsible for different kinds of memory. And the hippocampus, it seems, is particularly important for memory, especially of specific autobiographical events .

Interestingly, one exception to HMs inability to remember autobiographical events was his memory of a birthday plane ride around Hartford, perhaps because it had great emotional significance.

What Are The Stages Of Information Processing

Now that you know even more about the stages of memory and understanding how your brain categorizes things, you can begin to understand the actual process of bringing that information from the hippocampus to the surface of your brain, where you are actively remembering an event.

The first stage of information processing is known as the attending stage, and this is where you are actively participating in the event that you will remember. You are physically experiencing the senses, the events, and everything that is happening. By focusing on the event at hand, you are preparing your brain to create a memory for it, and this begins the first stage of information processing.

While you are participating in the event that is going to be remembered, you move on to the encoding stage. This stage happens while you are experiencing the event, and it can be equated to just taking notes on the event. When you place enough importance on something to pay attention to it, your brain will start encoding it into your memory. If you dont pay attention to an event, your brain will not bother encoding it, even if you are attending the event, which is why teachers put such an emphasis on paying attention in class.

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The Hippocampus And Long

A short-term memory can be consolidated into an enduring long-term memory. This involves a system of brain structures within the medial temporal lobe that are essential for forming declarative memories. The hippocampus is a key region in the medial temporal lobe, and processing information through the hippocampus is necessary for the short-term memory to be encoded into a long-term memory.

The long-term memory does not remain stored permanently in the hippocampus. These long-term memories are important and having them stored in only one brain location is risky damage to that area would result in the loss of all of our memories.

Instead, it is proposed that long-term memories become integrated into the cerebral cortex . This process is referred to as cortical integration it protects the information stored in the brain.

However, damage to areas of the brain, particularly the hippocampus, results in loss of declarative memories, which is known as amnesia.

The famous case study of H.M. – Henry Molaison – demonstrated the hippocampus is vital to the formation of long-term memories. H.M. had his hippocampus removed as a 23-year-old in an attempt to treat epileptic seizures that originated in his medial temporal lobe.

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