Do you remember what you had for breakfast yesterday? How did you order an essay from the professional essay writing service? Who have you been talking to since you woke up? If the answer is yes, it means that your declarative memory is working correctly.
This type of memory without which we could not function, stores all the explicit memories, that is, all the memories about episodes, facts, and data of our life. From our eighth birthday to the taste of an orange.
Declarative memory, also called explicit memory, is the ability to voluntarily bring up episodes or events in our lives. It is thanks to her that we can relive experiences that happened long ago, recognize the faces of famous people and name them, or even what we have eaten throughout the week.
The history of declarative memory is relatively young. Its history dates back to the studies of the HM patient in 1957, which shed light on two questions: what components constitute memory, and wherein the brain can we find declarative memory.
Patient HM, who suffered from severe temporal epilepsy lobe, had these lobes sectioned in both hemispheres. The epilepsy was successfully controlled, but something unexpected happened: he had lost many memories from eleven years ago and did not remember anything from the last two years, and was unable to create new memories. Thus, his declarative memory had been affected.
Surprisingly, he did retain the memory that stores motor skills. Riding a bicycle, using language, etc., are skills that are stored differently because they are not data or episodes, but "ways of doing". This memory is called procedural or implicit memory. Thus, the existence of two large memory blocks with different and anatomically independent functions was evidenced.
The first difference between declarative and procedural memory is that they are located in distinct regions. From this, it follows that, at a functional level, they use different neural circuits and have a different way of processing information.
In procedural memory, most of the information is stored as it is received from the senses. Psychologists say that it is bottom-up processing, that is, from the physical directly to the psychic. Instead, in declarative memory, the physical data is reorganized before being stored. Since information depends on cognitive elaboration, we speak of a top-down process. Declarative memory, on the other hand, depends on conceptually controlled or "top-down" processes, in which the subject reorganizes data to store it.
In this way, the way we remember information is highly influenced by the way we process it. This is why the internal stimuli that we use when storing information can help us to recall them spontaneously. In the same way, the contextual stimuli that are processed with the data can be a source of recovery. Some mnemonic methods exploit this feature of memory, such as the loci method.
Through the study of animals and humans, Petri and Mishkin propose that implicit and explicit memory follow different neural circuits. The structures that are part of declarative memory are located in the temporal lobe. Those most important are the amygdala, which plays a crucial role in the emotional process of memories, the hippocampus, which is responsible for storing or retrieving memories, and the prefrontal cortex, which deals with the memory that stores more short-term data.
Other structures are also included such as the nuclei of the thalamus, which connect the temporal lobe with the prefrontal lobe, and the brain stem that sends stimuli to the rest of the brain to be processed. The neurotransmitter systems most involved in these processes are acetylcholine, serotonin, and norepinephrine.
Endel Tulving, through his studies on memory, distinguished in 1972 two subtypes of declarative memory: episodic memory and semantic memory. Let's look at each of them below.
According to Tulving, episodic or autobiographical memory consists of that which allows a person to recall past personal experiences or events. It enables human beings to recall past personal experiences. It requires three elements:
To understand how memory works, Tulving explains it using the metaphor of time travel. According to this metaphor, autobiographical memory is a kind of time machine that allows consciousness to travel backwards and voluntarily revisit past episodes. This is a capacity that requires awareness and is therefore theorized to be unique to our species.
Knowledge of the world - everything that is not autobiographical - Tulving called semantic memory. This type of declarative memory includes all the knowledge that we can evoke explicitly that has nothing to do with our own memories. It is our personal encyclopedia, containing millions of entries about what we know about the world.
It contains information learned in school such as vocabulary, mathematics, some aspects of reading and writing, historical figures or dates, knowledge about art and culture, and so on.
