One of the reasons neuropsychology is interesting is that it allows us to see the extent to which mental processes that appear to be one thing are, in fact, the result of many different mechanisms acting simultaneously in the human brain. Prosopagnosia, for example, is evidence that a person who can see perfectly can become unable to recognize human faces.
While seeing something that should be familiar and recognizing it seems like it should go hand in hand, injury to certain areas of the brain can make this illusion go away, overriding one of these mechanisms and forcing the other to continue. function. without counting on him.
But this not only happens with the basic mental processes related to perception, but is also extendable to those which are more related to more abstract thinking. Aphasias, for example, are an example of how certain facets of language use and mastery, And not others, can be altered by certain brain damage.
What are aphasias?
Aphasias are a group of language disorders caused by brain damage. Unlike other types of language disorders, such as alexia, 1 aphasia affects both spoken and written language.
A person with aphasia has a reduced ability to use language itself, both in comprehension and in its production, even though they do not have any perception or motor problems that might prevent them from feeling or to see well or to move the muscles of the mouth to speak.
What causes aphasia?
The variety of brain lesions that can trigger the onset of aphasia (or several types of aphasia at the same time) is very varied, because the network of neurons that play a role in the production or understanding of language is widely disseminated.
Aphasias are generally considered to occur when an injury causes the flow of information through which images and thoughts are interrupted to the linguistic symbol organized according to the structure of the language (in a manner similar to that where we notice that we have a word “at the tip of the tongue”) or when this brain damage prevents the words heard or read from turning into pictures and thoughts.
However, this is still the subject of discussion, as it is not clear to what extent our brain distinguishes between thoughts formulated within the framework of language and thoughts that exist regardless of the languages they speak. In contrast, the concept of “aphasia” is quite abstract. What many patients with speech impairments present are rather types of aphasia.
Types of aphasia
From a practical standpoint, 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, because this lets you know what is happening to each particular patient. Moreover, the existence of these different classes of aphasias allows us to see that in language it is in fact a puzzle of different mental processes that we would not normally think of considering separately.
Then you can read what these types of aphasia are.
People with Broca’s aphasia have more difficulty producing language than understanding it. They have difficulty writing and speaking, take a long time to choose the words they want to say, and also have difficulty pronouncing and modulate the tone of voice. Symptoms of this type of aphasia can be detected even by a person who does not understand the patient’s language.
Although they have less difficulty understanding texts or oral language than their ability to speak and write, people with Broca’s aphasia they will be unable to literally repeat the sentences or words they hearWhether they understand them or not.
An example of a fictional character who exhibits symptoms similar to the classic image of Broca’s aphasia is Hodor, from the Game of Thrones series and the Song of Ice and Fire books: although he seems to understand what he is being told. said, his ability to speak is canceled almost completely.
Unlike what happens in the previous type of aphasia, in Wernicke speech is fluent and it is not difficult to work while speaking at a normal pace or even very quickly, maintaining correct pronunciation and intonation.
However, in general, the sentences or words produced by a person with Wernicke’s aphasia are not well constructed, as the words are often replaced by others belonging to the same semantic field (for example, replacing “four” by “washing machine”).) Change some phonemes for others (replace “cat” by “cat”) or construct sentences with big syntactic errors in which nothing can be understood because there is no structure appropriate and the verbs were replaced by adverbs, nouns for articles, etc.
Outraged, in this type of aphasia, the comprehension of oral and written language is quite impaired, As well as the ability to repeat words.
If in Broca’s and Wernicke’s aphasia, the lesion affects areas related respectively to language production and language organization to form significant units, in conduction aphasia, brain damage affects neural networks that connect these two brain nuclei.
This is why a patient with this type of aphasia will be fluent and their ability to understand the language will be maintained in a relatively good condition, but you will not be able to literally repeat the words or phrases you hear and see writtenBecause it does this by circuits leading from the part of the brain in which the word or phrase is recognized as a meaningful whole to that in which this information is “translated” into oral or written instructions.
In addition, in this type of aphasia, the sentences that occur will also tend to have incorrect phoneme and word substitutions.
Another type of aphasia is global aphasia. consists of generalized language impairment that seriously affects both language production and understanding. In general, people with this syndrome also cannot repeat words or phrases and in some cases will only be able to say one or a few syllables or words that they will repeat regardless of the context.
the transcortical aphasia they are characterized by the preserved maintenance of the ability to repeat sentences and words, which was not the case in the four types of aphasia above.
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 the language more preserved, but by adding the possibility of repeating the sentences they hear or read, regardless of their length. In other words, a person with transcortical motor aphasia is not able to speak spontaneously, but they can repeat everything.
Transcortical sensory aphasia
It sounds like a version of Wernicke’s aphasia where you can repeat what you hear, but not what you read. Outraged, sometimes all kinds of syllables or words heard are involuntarily repeated, 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 retained, even if you do not understand what is being said. The typical symptoms of this type of language disorder are also common in echolalia.
Unlike other types of aphasia, in the anemic aphasia language production and comprehension can be almost normal, and its main symptom is anomyIn other words, the difficulty of finding the right words to say something. People with anomic aphasia tend to use many generic terms such as “thing”, “that”, etc.
Every now and then these difficulties cause them to use circumlocutions, to try to explain themselves again using alternate sentences, or to considerably lengthen what is said to try to accumulate details and clues as to what it means.
The language is more complicated than it looks
It is not always easy to know how to identify the types of aphasia in some patients symptoms can vary widely and be more or less severeBut in all of them (less globally) 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 to make everything work properly.
As a result, some abilities may be lost while others, closely related to the former, are retained.