Under the Long-term memory one understands a neural, multimodal function that processes information and stores it in the long term.
What is long-term memory?
Long-term memory can be divided into declarative and non-declarative memory. The declarative memory contains concrete knowledge, whereas the non-declarative memory contains information that can be traced back to experience.
Declarative content is stored in the cortex regions that were also involved in processing. The non-declarative long-term memory is assigned quite heterogeneous memory performance. These include, for example, associative or non-associative learning, priming or habits and skills.
The non-declarative memory is related to the cerebellum, the amygdala and the striatum and is not dependent on conscious memory, whereas declarative knowledge can be consciously remembered and can therefore be used flexibly. Endel Tulving (* 1972) also calls these two forms semantic or episodic long-term memory.
The episodic memory comprises concrete events of a person, whereby space-time characteristics are also stored. This memory is also known as the so-called source memory. The semantic long-term memory contains word meanings, facts and systems of rules. With episodic remembering, a single event can be called up, which is not possible with semantic remembering.
Another form is procedural memory, also known as behavioral memory. It stores automated skills like driving a car or running. These actions are learned through constant practice and can then be called up without thinking.
Function & task
The information is not stored in a specific place in the brain, but is found in the overall structure of the nerve cells and in their connections. The limbic system, the frontal and temporal lobes as well as the hippocampus, which transfers content from short-term to long-term memory, are involved.
If content gets into the long-term memory, it is stored here permanently. For this purpose, so-called engrams are formed (memory traces as structural changes in the brain caused by stimuli), which make it possible to remember. Examples of long-term memory skills are remembering a poem, an unpleasant situation or the face of an acquaintance. Information is actively encoded, processed, saved and then reproduced or remembered.
An essential function of long-term memory is therefore the provision of information in order to subsequently be able to make optimal decisions. Altogether there are four processes of long-term memory: learning, retention, remembering and forgetting.
Long-term memory has an almost unlimited capacity. Learning takes place between the motor and sensory neuron (nerve cell). When the sensory neuron is stimulated, more neurotransmitters are released and strong muscle activation occurs. The learning process takes place initially as short-term storage and later as long-term storage, with the synapse enlarging and changing its function.
By relating the learning material to what is already known, information can be stored in long-term memory. However, it is only very rarely that certain facts or events are faithfully reproduced. Previous knowledge apparently plays an important role in remembering, but thinking or certain retrieval processes can also modify or distort content.
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➔ Medicines against memory disorders and forgetfulnessIllnesses & ailments
One possible condition related to long-term memory is memory problems. Disturbances in memory, poor concentration and forgetfulness, if they do not occur more intensely, are often due to exhaustion or stress. However, if the problems increase and normal daily routines become problematic, a doctor should be consulted, as forgetfulness can also hide a more serious illness.
One possible illness is dementia, which affects the ability to think or mental performance. Those affected have problems absorbing new content and then playing it back. In addition, speaking, arithmetic and orientation skills are also affected.
The most common form is Alzheimer's disease, in which brain cells perish due to protein clumps that appear outside or inside the nerve cells. Another common form is vascular dementia, which is due to circulatory disorders in the brain. So-called Lewy body dementia is less common.
Lewy bodies are spherical structures that can be found in the cerebral cortex or in the brain stem. Those affected develop a progressive memory disorder and the patients suffer from movement disorders and psychotic symptoms.
Dementia can also occur in the context of Pick's disease. Above all, the ability to think abstractly is impaired and certain brain regions slowly die off. In contrast, dementia in Creutzfeldt-Jakob disease develops very quickly. There are mainly disturbances in concentration, attention and memory, the cause of which are poisonous proteins that cause the brain tissue to die. Accompanying dementia is also possible with Parkinson's or HIV. Other conditions that can lead to forgetfulness include:
- Meningitis: Viruses or bacteria can lead to confusion, drowsiness or poor concentration.
- Meningitis: Symptoms such as confusion or impaired consciousness occur here.
- Sleep apnea: As night sleep gets out of rhythm with this disease, poor concentration, forgetfulness or fatigue occur during the day.
- Chronic exhaustion syndrome: Typical for this is physical and mental exhaustion, which is accompanied by irritability and poor concentration.
- Depression and anxiety disorders can also affect the brain and lead to forgetfulness.
Other causes can be medication, lack of fluids and food, sleep disorders, stress, alcohol abuse and cancer therapies.
