Semantic memory: functioning and associated disorders

Memory is a psychological concept in which we usually think of as if it were a single thing: the act of remembering what we had for dinner yesterday seems to have the same nature than to remember which is the capital of Egypt or how are the steps of a choreography that we have been practicing. However, from the perspective of Psychology this is not the case, since there are different types of memory.

For example, part of the memory is not made up of concepts, but of emotions and patterns and movements. However, within the type of memory composed of verbalizable aspects of knowledge, which is called declarative memory, there is also a subdivision. On the one hand, there is episodic memory, which is the one that contains memories about narrative information of our past experiences (such as what happened to us yesterday when we went to buy bread), and on the other we find the semantic memory, which we will focus on in this article.

• Related article: "Types of memory: how does the human brain store memories?"

What is semantic memory?

In short, semantic memory is one that contains all the information related to the concepts thanks to which we understand the world and ourselves. That is to say, it is something like the store of concepts about everything we know: the names of the countries, the characteristics of the mammals, the history of the region in which we live, etc.

In other words, semantic memory makes it possible for us to understand the environment in which we find ourselves and, also, to ourselves, since it allows us to reflect on our characteristics personal.

Yes ok Being a type of declarative memory, it is composed of conceptsUnlike episodic memory, it does not follow a narrative progression. The fact that Africa is a continent has nothing to do with an experience with a beginning, middle and end, it is enough to know the term "Africa" ​​and link it to a territory that we have been able to see on a map and that exists beyond that map, not just as part of an anecdote of our lives private.

The information contained in semantic memory can be understood as a pyramid of concepts; some of them are very general and are composed of other concepts, which in turn are formed by others, until arriving at units of information that are very basic and insignificant because they are too specific.

Thus, it is a mental capacity that expresses itself consciously and often voluntarily, for example, when we need to access relevant information to correctly answer an exam question (something that does not happen with the emotional memory, or not to the same extent).

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semantic memory functions

All types of memory are of crucial importance and complement each other, but the case of semantic memory is special since thanks to it we are able to create concepts needed to develop language and to become able to think abstractly.

If non-declarative memory is useful in directing our behavior based on our learning and episodic allows us to understand the specific context in which we live and what specific situations we have been through, semantics is which generates all those ideas we need to build beliefs, expectations, goals, etc.

Thus, this type of memory is closely linked to the ability to use language, which is no other thing that a system of symbols with an abstract meaning not tied to a place and time determined.

Parts of the brain involved

The differentiation between semantic memory and other types of memory is not simply theoretical: it is materially embodied in the brain.

For example, emotional memory is closely related to the activity carried out by a part of the brain called amygdala, while episodic memory is related to another structure called hippocampus and the cerebral cortex.

As for semantic memory, it also depends in part on the hippocampus, but to a lesser extent than episodic memory. It is believed that, compared to the episodic, the importance of the general activity of the cerebral cortex is greater.

Related disorders

As each type of memory has several brain structures more oriented to it than the others, this means that certain neurological pathologies also affect some more than the rest.

In the case of semantic memory, it seems to be especially vulnerable to lesions in the prefrontal cortex, yes ok alterations in the hippocampus also affect it much, as it happens with the episodic.

However, in practice, many pathologies that wear down our ability to remember concepts damage several areas of the brain at the same time. This is what happens, for example, with the dementias; practically all of them play against this type of mental capacity, since they kill many neurons distributed throughout almost the entire brain (although more in some areas than in others).