Aphasias: the main language disorders

One of the reasons why the neuropsychology is that it allows us to see to what extent mental processes that seem to be a single thing are, in reality, the result of many different mechanisms that act simultaneously in the human brain. The prosopagnosia, for example, it is proof that a person with the ability to see perfectly may become unable to recognize human faces.

Although the sight of something that should be familiar and its recognition seem to have to go hand in hand, an injury in certain brain areas it can make that illusion vanish, by overriding one of those mechanisms and making the other have to continue to function without it.

But this does not only happen with the basic mental processes related to perception, but it is also extensible to those more related to the most abstract thought. Aphasias, for example, are an example of how certain facets of language use and mastery, and not others, can be altered from certain lesions in the brain.

What are aphasias?

Aphasias are a group of language disorders caused by brain damage. Unlike what happens with other kinds of language disorders, such as the

alexia, an aphasia affects both spoken and written language.

A person with aphasia has an impaired ability to use language itself, both in understanding and in producing it. even if you do not have any perceptual or motor problems that could prevent you from hearing or seeing well or moving the muscles in your mouth to speak.

What causes aphasia?

The variety of brain lesions that can trigger the appearance of an aphasia (or several types of aphasia at the same time) are very varied, because the network of neurons that play a role in language production or understanding is widely distributed.

Aphasias are generally considered to occur when an injury disrupts the flow of information through which it is passed from images and thoughts to linguistic symbols organized following the structure of language (in a similar way to when we notice that we have a word "on the tip of the tongue") or when this brain damage prevents the words heard or read from being transformed into images and thoughts.

However, this is still the subject of discussion, since it is not clear to what extent our brain distinguishes between thoughts formulated as part of language and thoughts that exist independently of the languages ​​that are mastered. On the other hand, the concept "aphasia" is quite abstract. Rather, what many patients with language disorders present are types of aphasia.

Types of aphasias

From a practical point of view, it is not as useful to talk about the causes of aphasia in general as it is to talk about the different types of aphasia, since this allows to know what happens to each patient in particular. Furthermore, the existence of these different kinds of aphasia allows us to see that in language it is actually a puzzle of different mental processes that would not normally occur to us to consider separately.

Then you can read what these types of aphasias are.

Broca's aphasia

People with Broca's aphasia have more difficulties producing language than understanding it. They have a hard time writing and speaking, they take a long time to choose the words they want to say, and they also have trouble pronouncing and modulate the tone of voice. The symptoms of this type of aphasia can be detected even by someone who does not understand the patient's language.

Although they have less difficulty understanding texts or oral language compared to their ability to speak and write, people with Broca's aphasia they will be unable to literally repeat the phrases or words they hearregardless of whether they understand them or not.

An example of a fictional character with symptoms similar to Broca's classic aphasia is Hodor, from the series Game of Thrones and the books Song of ice and fire: Even though he seems to understand what is being said to him, his ability to speak is almost completely nullified.

Wernicke's aphasia

Unlike what happens in the previous type of aphasia, in Wernicke's speech is fluent and it is not difficult to speak at a normal rhythm or even very quickly, while maintaining correct pronunciation and intonation.

However, in general the phrases or words produced by a person with Wernicke's aphasia are not well constructed, since words are often substituted for other belonging to the same semantic field (for example, replace "oven" with "washing machine"), change some phonemes for others (change "cat" for "gado") or sentences are constructed with great syntactic errors in which nothing can be understood because there is no adequate structure and verbs have been replaced by adverbs, nouns by articles, etc.

What's more, in this type of aphasia the understanding of oral and written language is quite alteredas well as the ability to repeat words.

Conduction aphasia

If in Broca's and Wernicke's aphasias the lesion affects the areas related, respectively, to the production of language and the organization of language To form meaningful units, in conduction aphasia, brain damage affects the networks of neurons that connect these two nuclei of the brain. brain.

That is why a patient with this type of aphasia will have fluent speech and his ability to understand language will remain in a relatively good state, but he will not be able to literally repeat the words or phrases that he hears and sees written, since to be able to do that, the circuits that lead from the part of the brain where the word or phrase as a meaningful whole up to that in which this information is "translated" into speech instructions or writing.

In addition, in this type of aphasia, the phrases that are produced also tend to present improper substitutions for phonemes and words.

Global aphasia

Another type of aphasia is global aphasia. Consists in a generalized language impairment that severely affects both language production and understanding. Generally, people with this syndrome also cannot repeat words or phrases, and in some cases They will only be able to say one or a few syllables or words that they will repeat regardless of the context.

Transcortical aphasias

The transcortical aphasias They are characterized by maintaining the ability to repeat phrases and words, something that did not occur in the four previous types of aphasia.

Transcortical motor aphasia

In this syndrome there are symptoms similar to those of Broca's aphasia, with non-fluent speech and the ability to understand language more preserved, but adding the possibility of repeating the sentences they hear or read, no matter how long. That is, someone with transcortical motor aphasia is not able to speak spontaneously, but can repeat anything.

Transcortical sensory aphasia

It resembles a version of Wernicke's aphasia in which you can repeat what you hear, but not what you read. What's more, sometimes all kinds of syllables or words that have been heard are repeated involuntarily, a phenomenon known as echolalia.

Mixed transcortical aphasia

This type of aphasia is similar to a mild version of global aphasia in which the ability to repeat is preserved, even if what is being said is not understood. Echolalia is also common among the typical symptoms of this class of language impairment.

Anomic aphasia

Unlike what happens with the rest of types of aphasia, in the anomic aphasia both language production and comprehension can be almost normal, and its main symptom is anomie, that is, the difficulty in finding the right words to say something. People with anomic aphasia tend to use a lot of generic terms like "thing", "that", and so on.

From time to time these difficulties lead them to use circumlocutions, to try to explain themselves again using alternative phrases or lengthening what is being said a lot to try to accumulate the details and clues about what is wanted say.

The language is more complicated than it seems

It is not always easy to know how to identify the types of aphasias that some patients present, since symptoms can vary greatly and be more or less severe, but in all of them (except the global one) it is clear that behind the use of language there are many parts of the brain more or less specialized in a task and coordinating with each other so that everything works as should.

Therefore, certain abilities may be lost while others, closely related to the former, are preserved.