Explicit Memory Definition
Among the most important subgroups of human long-term memory is explicit memory, often known as declarative memory. Other kinds of long-term memory are implicit or non-declarative memory.
Explicit memory is a method of storing and retrieving conscious memories. It is frequently referred to as’ declarative’ since it may be remembered and expressed deliberately or inadvertently.
Recalling events that occurred during an incident, recalling and understanding concepts, and recalling events and information are all examples. If you’re reading this post as part of your schoolwork, you’re probably trying to improve your explicit memory even now!
Explicit Memory vs. Implicit Memory
There are two forms of long-term memory: explicit and implicit. Explicit memory belongs to memories that are intentionally recalled, whereas implicit memory belongs to memories that are recalled unconsciously or procedurally. Implicit memory includes the ability to perform tasks, respond to inputs, and establish links between stimuli. You may not be able to recollect this sort of knowledge consciously. It’s tough to describe how to ride a bike, for example; you simply do it. It’s a lot easier.
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Types and Examples of Explicit Memory
Based on the kind of information kept, explicit memory is divided into two types: episodic memory and semantic memory. The distinction between these groups is unclear, and the two systems are likely to interact quite a bit.
Other explicit memory kinds, including autobiographical and spatial memory, have their own classification systems.
Episodic memory is the retention and recall of first-hand personal experiences. Examples include the ability to recall a series of events that occurred at a certain moment, as well as the location and time of that occasion, and also details such as clothes you wore and what you ate for lunch.
When the moment associated with the memory was noteworthy, episodic memories are usually more vivid. Many individuals, for example, will remember where they were when they learnt of Michael Jackson’s untimely death.
Semantic memory refers to the method of retaining factual information. This knowledge may be deliberately expressed, similar to episodic memory, and contains facts and numbers, definitions, and ideas. “The capital of Italy is Rome,” “the mitochondrion is the cell’s powerhouse,” as well as “explicit memory” relate, for instance, to conscious memories.
The combination of whole episodic and semantic memories composes autobiographical memory. It is sometimes mistaken for episodic memory, although research indicates that they are two separate processes. The duration of autobiographical memory is longer than that of episodic memory. It is meant to be the accumulation of our life experiences, giving us insight into who we are as people. It has a “human” quality to it.
An individual’s awareness of their environment or their mobility in a given environment is referred to as spatial memory. For example, spatial memory allows you to navigate around your hometown and remember where various areas are in relation to one another.
Explicit Memory and the Brain
The hippocampus, prefrontal cortex, and amygdala represent the three key brain regions responsible for the preservation of explicit memories.
The hippocampus is an S-shaped neural region in the temporal lobe of the brain. The hippocampus participates in the consolidation of memories, spatial navigation, and learning. It’s assumed to have a role in the creation of new explicit memories in particular. Injury or atrophy of the hippocampus often limits the formation of fresh memories, but it may also impair the recall of existing memories.
The prefrontal cortex is an area of the frontal lobe of the brain that is involved in personality, decision-making, and group communication. It is also believed to have a role in recalling explicit memories, particularly verbal and semantic ones. Together, the prefrontal cortex and hippocampus create long-term memory retention.
Deep inside the brain are two almond-shaped structures called amygdalae (singular: amygdala). They are located near the hippocampus and collaborate with it. The amygdalae’s main function is to regulate emotions like anger and fear, as well as decision-making.
However, because of their function in emotional learning, the amygdalae play a significant part in memory. It is more probable that an event will be stored in long-term memory if it has a major emotional component. For instance, it is doubtful that you would recollect anything you were working on May 4, 2003, yet you would undoubtedly remember what you have been performing on September 11, 2001.
Alzheimer’s disease is responsible for more than half of all dementia cases globally. Chronic neurodegeneration characterises the condition, which manifests itself in a steady deterioration of explicit memory. This kind of memory loss is often the primary sign of Alzheimer’s disease and other dementias.
The buildup of protein clumps, termed amyloid plaques, in the brain causes Alzheimer’s disease. These plaques destroy neurons and harm the brain regions in which they are located. In Alzheimer’s disease, the hippocampus is one of the earliest and most seriously affected structures.
Anterograde amnesia is the failure to develop and remember fresh memories after a traumatic occurrence, such as brain damage. Long-term memories are maintained, but event-specific memories and future recollections are not. Certain medications and alcohol intoxication have the potential to induce abrupt anterograde amnesia.
Patients suffering from anterograde amnesia often retain implicit memory, allowing them to remember how to do activities and acquire new ones. For instance, patients suffering from anterograde amnesia may frequently practise playing a musical instrument. However, patients have lost the ability to recall facts and events.
The Case of Henry Molaison
Henry Molaison has had epileptic seizures since infancy. By the time he reached his mid-twenties, the condition had gotten so serious that he was unable to function properly. Doctors conducted a lobotomy on him in 1953 to alleviate his epilepsy. They did it by removing the hippocampus, para hippocampus, and amygdalae, which are all important brain regions.
He was made completely unable to develop new memories as a result of this operation, leading to extreme anterograde amnesia He was able to acquire new skills since his implicit memory stayed undamaged. His explicit memory, on the other hand, was severely impaired, and he was unable to recall any new knowledge.
Throughout the remainder of his lifetime, and even after he passed away, Henry Molaison remained the focus of extensive inquiry. In the neuroscience research community, he is known as “H.M.” and his complete identity was not revealed until after his death. His tragic experience altered our knowledge of how memory is controlled by different areas of the brain.
- Camina, E., & Güell, F. (2017, June 30). The neuroanatomical, neurophysiological and psychological basis of memory: Current models and their origins. Frontiers in Pharmacology, Vol. 8. https://doi.org/10.3389/fphar.2017.00438
- Jawabri, K. H., & Cascella, M. (2020). Physiology, Explicit Memory. In StatPearls. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/32119438
- Squire, L. R. (2009, January 15). The Legacy of Patient H.M. for Neuroscience. Neuron, Vol. 61, pp. 6–9. https://doi.org/10.1016/j.neuron.2008.12.023