DECLARATIVE MEMORY: CHARACTERISTICS, TYPES AND EXAMPLES - NEUROPSYCHOLOGY - 2025

The declarative memory is that stores concepts and life events that can be expressed explicitly. They are data that we consciously retrieve and are part of long-term memory.

This type of memory is the one that may sound the most familiar to us; it has a conscious component that allows us to store facts and events. There is a clear intention of the person to remember. For example, when you remember a trip to Rome or a learned fact like “Madrid is the capital of Spain”.

Declarative memory is often associative. That is, it links some memories with others. Thus, when a person thinks of a place where she has been, a large number of associated memories are likely to come to mind. For example, the emotions you felt on that site, the people you were with, or other experiences.

Psychologists have divided long-term memory into two broad categories: declarative (also called explicit or relational) and non-declarative (or implicit) memory.

Declarative memory is "know what", while non-declarative memory is "know how." The declarative allows us to remember names, addresses, phone numbers, etc. That is, it is what we have learned in school, in university, or the situations in our life that we can express verbally.

In contrast, nondeclarative memory is unconscious and includes memories of skills or habits such as riding a bicycle, driving a car, or playing the piano.

Declarative memory types

Declarative memory is divided into two large groups: episodic and semantic memory. The first author to make a distinction between episodic and semantic memory was Endel Tulving in 1972. Each of them are described below:

- Episodic memory

This type of memory reminds us of past events that we have been part of. They are remembered as an "episode", that is, as a scene in which we act.

A memory can be etched more strongly in our memory if it has an emotional component. For example, the wedding of a friend, the death of a loved one, etc.

Another important factor is the force with which the brain registers the memory the first time it experiences it. If that first time we focus carefully and precisely (we pay more attention), the memory will register with more power and it will be easier to remember later.

Episodic memory appears to be associated with a brain structure called the hippocampus, which maintains connections with the cerebral cortex to evoke memories.

Hippocampus

Examples

Some examples of episodic memory are: the name of your first pet, remembering what your mother's previous birthday was like, your brother's wedding, where you were when you learned about the September 11 attack, etc.

- Semantic memory

This type of declarative memory is our general knowledge of the world. It also refers to the information necessary for the language, which would be a kind of dictionary.

Unlike episodic memory, semantic memory is better maintained over time. From the age of 60, it goes into a slight decline.

This type of memory is very resistant to forgetting, being these very durable knowledge. Proof of the existence of these two types of memory is the multiple investigations that have shown that there are patients with damage to episodic memory but not to semantics and vice versa.

Examples

Some examples of semantic memory are: understanding the concept of time, knowing what an object is for, knowing how to name mammalian animals, knowing the date of Valentine's Day.

Brain support of declarative memory

In order for explicit memory to be stored properly, the subject must reorganize the data first. There appear to be different neural circuits for declarative and non-declarative memory.

Declarative memory is linked to the medial temporal lobe of the brain when this type of knowledge is being learned. In this part is the hippocampus, a fundamental structure in the formation of autobiographical and factual memories.

Temporal lobe

Other areas closely related to the hippocampus are the amygdala, the prefrontal cortex, and the thalamic nuclei, which also participate in declarative memory. Depending on whether they are episodic or semantic knowledge, some areas of the brain or others will be activated.

It appears that in episodic memory the hippocampus is activated, in collaboration with the cerebral cortex. The prefrontal cortex appears to have a specific function in episodic memory; it's about monitoring and choosing memories appropriately.

Prefrontal cortex

On the other hand, semantic memory seems to be associated with the perirhinal cortex. Once permanently stored in memory, the information is stored throughout the cerebral cortex depending on what type of information it is.

For example, data that has visual components is stored in the occipital cortex of the brain, where vision is supported. On the other hand, if they are auditory elements, they are stored in the temporal cortex.

It has been suggested that the left dorsolateral prefrontal cortex is associated in encoding declarative memory, while the right and posterior parietal cortex appear to influence data retrieval.

On the other hand, the amygdala plays an important role in declarative memories that have emotional significance.

Amygdala

Factors influencing the recall of declarative memories

Important events

We better remember events that are important to us and vivid, such as the death of a loved one.

Context

Recovery depends on the context in which we find ourselves. That is, we remember certain information better if we are in the context where we learned it than if we are in a different context.

State

Mood seems to be important in memory. That is, when we learn something linked to a certain state of mind, it is easier for this to be remembered when we have the same emotion again.

This is called a state-dependent recall. Explain why when we are sad we usually remember negative experiences.

Gap filling

On the other hand, it may happen that we claim to remember things that have not really happened, since we tend to fill gaps or gaps in memory without realizing it. This can happen to people who are called to testify in court proceedings.

Declarative memory pathologies

There are a number of pathological conditions in which declarative memory can be affected. This is usually known as amnesia.

However, hypomnesias can occur, which are a memory disorder in which there is a weakening of existing memories. While amnesia is the total loss of memories.

The causes of memory disturbances are wide and varied. For example, for vascular problems that affect the hippocampus, infectious diseases of the brain, tumors, or brain injuries from head injuries or dementias.

Some of the pathologies of declarative memory are:

Anterograde amnesia

These are deficits to remember events that happen after a brain injury. They are usually accompanied by some degree of retrograde amnesia. This occurs because there is an inability to transmit information from short-term memory to long-term memory, with declarative or explicit memories being specifically affected.

Antegrade amnesia is also often associated with confabulation, in which the patient fills in memory gaps with fabricated data. He is not aware that the story is false or unreal. At an extreme level the patient may be unable to remember what he has just done.

This type of amnesia is also seen in Korsakoff syndrome. It is a vitamin B1 (thiamine) deficiency that is due to malnutrition or chronic alcoholism.

Thiamine, being essential for the brain, when it is absent causes damage to this organ. Specifically in the diencephalon, and / or in the frontal lobe.

Antegrade amnesia can also appear from head injuries, strokes, or tumors.

Retrograde amnesia

It is the difficulty to remember events that occurred before the brain injury. This type of amnesia can cause gaps that range from months to years.

Retrograde amnesia follows Ribot's Law, that is, the most recent memories are lost first, while the last memories to be forgotten are the most stable and used memories in your life. For example, your daily routine habits, your name or that of your relatives, etc.

Lacunar amnesia

In this, there is a loss of memories for a limited period of time, in which an alteration in the level of consciousness was suffered. For example, as it happens after certain epileptic seizures, after the consumption of toxins or drugs, or by sequelae of head injuries.

Dissociative or psychogenic amnesia

In this case, the patient cannot recall events or experiences that have been very unpleasant or traumatic, as occurs in post-traumatic stress disorder.

Declarative memory impairment in healthy people

We can all have memory problems at certain times without any pathology.

Stress has been found to influence the formation of declarative memories. That is, if you try to store some declarative knowledge while under great stress, this knowledge will be remembered much worse. Even if the stress is extreme, many details may not be remembered.

Something similar happens with lack of sleep and rest. It appears that proper sleep after a learning episode is essential for declarative memories to become fixed in memory.

Declarative memory also declines with aging. Mainly the autobiographical data or the own experience, although anomia is also frequent. This is the inability to evoke the names of objects.

One of the most affected functions in old age is the ability to store new information, such as associating names with faces.

References

1. Ardila, A., & Ostrosky, F. (2012). Guide for neuropsychological diagnosis. Florida: American Board of Professional Neuropsychology.
2. Chapter 7: Learning and Memory. (sf). Retrieved on February 11, 2017, from the University of Texas: neuroscience.uth.tmc.edu.
3. Declarative Memory: Definition & Examples. (sf). Retrieved on February 11, 2017, from Study: study.com.
4. Declarative Memory: Definitions & Examples. (February 5, 2014). Obtained from Livescience: livescience.com.
5. Explicit memory. (sf). Retrieved on February 11, 2017, from Wikipedia: en.wikipedia.org.
6. Explicit Memory. (sf). Retrieved on February 11, 2017, from Brain HQ: brainhq.com.
7. Mañeru, C., Junqué, C., Botet, F., Tallada, M., Segarra, D., & Narberhaus, A. (2002). Declarative and procedural memory in adolescents with a history of perinatal asphyxia. Psicothema, 14 (2), 463-468.
8. Memory. (February 21, 2013). Obtained from the University of Oviedo: unioviedo.es.
9. Memory and amnesias. (sf). Retrieved on February 11, 2017, from the University of Murcia: ocw.um.es.
10. Portellano Pérez, JA & García Alba, J. (2014). Neuropsychology of attention, executive functions and memory. Madrid: Synthesis.