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Memory and the brain
How Memory Works
Forgetting and Amnesia

Sleep accelerates improvement in working memoryLien :  Ukrainian translation of topic 1



A patient who was followed for thirty years by the great Soviet neurologist Alexander Luria had the amazing ability to remember everything. After looking for a few minutes at pages with 30, 50, or 70 words or numbers, he could repeat them flawlessly one week, six months, or even 15 years later, without forgetting a thing!

Though he was not insane or autistic, this patient was not entirely normal either. Among other things, he experienced synesthesia, which means that he had no boundaries between his various senses. As a result, he experienced some strange associations.For example, he had the unusual ability to associate a colour, sound, or texture with a word or number. This gave him a ready means of creating sensory “hooks” that let him secure words and numbers in his memory permanently.

But this special ability also had some drawbacks. For example, this man had tremendous difficulty in retaining the meaning of a text that he was learning. To answer a simple question about the text, he would have to “re-read” the entire thing in his head! This contrast shows the great power of an ordinary person’s memory, which encodes the meaning first and foremost. In other words, we may forget the exact wording of a story, but we remember its essential elements, which is far more useful in everyday life.

Lien :  MEET MR.PILien :  Outstanding Performers: Created, Not Born?Lien :  SynesthesiaLien :  On Remembering Everything
Lien : For Some, the Words Just Roll Off the TongueTactile-emotion synaesthesiaHell is a Perfect MemorySynesthesia and Cross-Modality in Contemporary Audiovisuals


Psychologically, forgetting is the temporary or permanent inability to retrieve a piece of information or a memory that had previously been recorded in the brain.

Forgetting differs from amnesia in that forgetting is usually regarded as a normal phenomenon. Also, forgetting involves specific pieces of content, whereas amnesia affects a relatively broad category of memories or wipes out an entire segment of memory.

The chances of your retrieving a memory depend on many factors, including how well you have been sleeping and how precisely you labelled this memory in the first place.

Sleep is a mysterious phenomenon, but one of its roles appears to be to consolidate the memory traces stored in the brain over the course of the day.

Thus, in both animals and humans, an increase in the amount of rapid-eye-movement (REM) sleep is observed during the night following a learning experience. Conversely, sleep deprivation adversely affects learning.

Low-frequency sleep, which occurs mainly at the start of the night, also seems to play a role in consolidating memories. Some data also suggest that both major phases of sleep are involved, and that it is the alternation of low-frequency sleep with REM sleep that produces the beneficial effect.

Expérience :  La mémoire se consolide durant le sommeilOutil: Les fonctions possibles du sommeilLien : Brain Gain: Brain Wave Boost during Sleep Sharpens MemoryLink : Why Sleep Is Needed To Form Memories
Link : For memory enhancement, the kind of sleep you get is importantLink : Memories can be strengthened while we sleep by providing the right triggers

In commiting something to memory, just as in any other work, organization is essential. Two main strategies are available for this purpose: repetition and elaboration.

In repetition, you take the piece of information that you are trying to memorize, and you repeat it continuously, to try to keep it in your short-term memory, as long as possible.

In elaboration you associate the new piece of information with other information that you have already recorded in your long-term memory. In other words, you incorporate the new fact into a broader, coherent narrative with which you are already familiar.

This strategy of elaboration is the basis for many mnemonic devices methods, some of them very old, for organizing new information so that you do not forget it.

Tool Module: Two Classic Mnemonic DevicesHistory : THE ART OF MEMORYLink : Les arts de la mémoireLink : Mnemonic techniques
History :  History of memoryLink : Graphic OrganizersLink : Mind Maps - A Powerful Approach to Note TakingLink : Champions du monde de mémoire

Lien : Brain Rules: Long-Term MemoryLink : Championnat de mémorisation: un sport extrêmeLink : Lien: The Memory Toolbox: 75 Tips and Resources to Go from Amnesic to Elephantic

Lien : How to Optimize Your Brain: Why Refining Emotional Recall is the Secret to Better Memory

Le sommeil, Salvador Dali (1937)


Linked Module: Types of AmnesiaLinked Module: TAXONOMIE DES TROUBLES DE LA MEMOIRE

As we grow up, we all experience various physiological forms of amnesia.

For example, infantile amnesia is what keeps us from remembering the first three or four years of our lives. Until children are three or four, they do not form any genuine episodic memories. But paradoxically, this is the age when they are acquiring a great deal of knowledge.

Infantile amnesia is not due solely to the fact that the first years of our lives are the furthest back in time. It is also due, at least in part, to the lack of language and the immaturity of the neocortex and other structures in the brain.

Linked Module: The Mystery Behind Infant Memories

There are several different types of amnesia, but all can be grouped into two broad categories, according to the type of trauma that causes them. These two categories are neurological (or organic) amnesias and psychogenic (or functional) amnesias.

Neurological amnesias are caused by specific kinds of damage to the brain, generally in the region where the hippocampus is located.

The famous case of patient H.M. is a highly revealing example of the importance of this region.

The damage may result from a cranial trauma (a blow to the head), a cerebro-vascular accident (a burst artery in the brain), a tumour (if it presses against part of the brain), hypoxia (lack of oxygen), certain kinds of encephalitis, chronic alcoholism, and so on.


Psychogenic amnesias are memory disorders that result from psychological traumas.

Though these traumas do affect the brain in a certain sense, patients who suffer from psychogenic amnesia show no detectable brain injury or brain malfunction.

Instead, the memory loss is caused by some disagreeable event such as chronic stress, intense fear, rape, incest, etc.

Thus, there are many causes of amnesia. The symptoms associated with each type are well known. In most cases, it is episodic memory–the memory of personal experiences–that is affected most severely.

For older people, even if they are perfectly healthy, it is normal to have a bit more trouble remembering events from the last few days or weeks. This phenomenon chiefly affects long-term episodic memory and has little effect on working memory.

Thus, older people do not lose their semantic memory (though they may be slower at word-identification tasks) or their procedural memory (their memory of how to do things), provided they have the opportunity to maintain the acquired knowledge through practice.

For though we now know that our stock of neurons is so large that we can maintain our memory’s performance to the end of our lives, we also know that memory needs to be exercised frequently to work properly. People should therefore keep giving their memory a regular workout as long as possible.


Is There an Evolutionary Continuity between Spatial Navigation and Declarative Memory?

The most famous patient in the history of memory studies was known by his initials, H.M. He was followed for 40 years in Montreal by Dr. Brenda Milner. To relieve his attacks of epilepsy, doctors had removed a part of H.M.’s cerebral cortex, including the hippocampus. The unexpected secondary effect of this experiment was spectacular: H.M.’s memories of the episodes of his youth were intact, but he could not acquire the slightest new long-term memory. People’s faces, his own actions and gestures–everything disappeared from his mind in just a few minutes, thus confirming the major role that the missing part of his cortex had played in acquiring new memories. Interestingly, his procedural memory (the kind of “know-how” that lets someone get better at solving the Hanoi Towers puzzle, for example) was not affected at all, and this supports the hypothesis that various memory systems associated with different physical structures coexist in the human brain.

Histoire :  The H. M. patientHistoire :  The Day His World Stood Still: The Strange Story of "H.M."Lien :  Voyage au centre de la mémoireExpérience :  Tower of Hanoi
Thanks for the memories HMR.I.P. H.M.Lien :  The Man With Half A Brain

Another distinction between two major types of amnesia is based on whether the patient is forgetting past facts or forgetting things as they happen.

In retrograde amnesia, patients forget events that occurred in their lives before they experienced the trauma, and the oldest facts are the ones least likely to be forgotten.

Recovery is possible, but the events that occurred closest to the time of the accident are harder to retrieve and may be lost forever.

Here too, episodic memory is more severely affected than semantic memory. Typically, the patient remembers words and general knowledge, such as who their country’s leader is.

Retrograde amnesia is often associated with neurodegenerative pathologies such as senile dementia and Alzheimer’s disease. In such cases, the further the disease progresses, the more the memories of the past dissolve.


Anterograde amnesia is the inability to memorize new facts, and hence the inability to learn. Following an injury that affects Papez’s circuit, a person becomes incapable of retaining new facts (explicit memory). This is sometimes referred to as “forgetting as you go”.

In this type of amnesia, short-term memory and procedural memory are preserved, because they are independent of Papez’s circuit. Affected individuals retain their skills but not the memory of having acquired them (since that would involve episodic explicit memory).

Anterograde amnesia often occurs following an acute event such as a concussion, a heart attack, oxygen deprivation, or an epileptic attack.

Many amnesias have both anterograde and retrograde components, and the recovery process may affect each of these components differently. But these two types of deficits still have well defined characteristics that help us understand severe cases of amnesia, such as patient H.M.’s (see sidebar).

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