WERNICKE AREA: FUNCTIONS AND ANATOMY (WITH IMAGES) - ANATOMY AND PHYSIOLOGY - 2024

The Wernicke 's area is one of the main areas of the cerebral cortex responsible for understanding spoken and written language. It is considered the center of receptive language and is usually located in the left hemisphere. This is true for 90% of right-handed people and approximately 70% of left-handed people.

Specifically, Wernicke's area encompasses the posterior part of the left temporal lobe. However, the exact location and extent of this area has been a controversial issue among scientists.

Wernicke area location

Recent studies have shown that Wernicke's area is activated in deaf people who communicate with sign language. This this area of ​​Wernicke is not only used for spoken language, but for any language modality.

Its name comes from the fact that it was discovered by the German neurologist Karl Wernicke in 1874. This scientist discovered this area while observing people who had damage to the back of the temporal lobe of the brain.

People who have damage to Wernicke's area can develop a condition called Wernicke's aphasia. It is characterized by the impossibility of understanding language, repeating words or phrases, despite having preserved the articulation of speech sounds.

Discovery of the Wernicke area

Karl Wernicke observed that his patients were unable to speak properly. Although they pronounced well and preserved a certain grammatical structure, the speech was meaningless and difficult to understand.

Apparently, what happened to these patients is that they could not understand language, and therefore could not maintain a fluent conversation. Wernicke found lesions in the brain in the left hemisphere, but in the posterior part of the temporal lobe.

In 1874, Wernicke published a work on aphasia that some authors consider to be the first neurolinguistic theory. This scientist proposed that there is a "center for auditory images of words", which is located in the first temporal gyrus. This center allows us to understand the language we hear.

Wernicke described the first connectionist model of the neural bases of language. According to this perspective, language arises from the joint work of several language centers that are connected to each other.

Wernicke's thesis maintains that there are two anatomical locations for language. The first is the anterior area, which is located at the back of the frontal lobe (Broca's area). This area contains "memories" of speech movements, thus controlling the production of language.

The second would be known as Wernicke's area, located in the posterior temporal lobe. In this area there are "images of sounds" and their function is to process the words we hear and make sense of them.

Location

Wernicke area (red)

Wernicke's area is normally located in the left hemisphere, specifically in the temporal lobe.

Temporal lobe

It corresponds to the Brodmann areas 21 and 22, covering the posterior zone of the superior temporal gyrus. This area of ​​our brain includes the auditory cortex and the lateral sulcus, the part where the temporal and parietal lobe converge.

However, its exact length is unclear and there appears to be disagreement between authors. Sometimes the primary auditory cortex and other nearby areas are included. For example, Brodmann areas 39 and 40, located in the parietal lobe. These areas have been associated with reading and with semantic aspects of language.

Connections

Wernicke and Broca area

Wernicke's area is connected to another region of the brain called Broca's area. This area is located in the lower part of the left hemisphere of the frontal lobe and controls the motor functions involved with the production of speech.

The difference between Broca's area and Wernicke's area is that the former is mainly responsible for planning the production of speech, while the latter receives the language and interprets it.

Broca's area and Wernicke's area are joined by a structure called the arcuate fasciculus, which is a large bundle of nerve fibers.

Likewise, recent studies have shown that these two areas are also connected by another structure called “Geschwind territory”, a kind of parallel pathway that circulates through the lower parietal lobe.

These two areas, Broca's and Wernicke's, allow us to speak, interpret, process, and understand spoken and written language.

Features

The main functions of Wernicke's area are related to the reception and comprehension of language. Through various brain imaging experiments, three areas have been found in Wernicke's area that are activated depending on the function performed:

- One is activated when words that we emit ourselves are pronounced.

- The second responds to the words spoken by another person, although it is also activated by remembering a list of different words.

- The third is related to planning the production of the speech.

This shows that the general objective of Wernicke's area is to represent phonetic sequences (sounds), whether they are those we hear from other people, those that we generate ourselves, or those remembered by our memory.

When we read a book, we do not store images of the words in our memory, but rather, we remember the words in the form of language. This occurs because what we perceive through our senses tends to become language once processed. Later, it is stored in memory in that "format."

Wernicke's area is the main area of ​​the brain that interprets heard language. The first way we learn language is through the sounds of speech. This explains its closeness and connection with the primary and secondary auditory areas of the temporal lobe.

Ultimately, Wernicke's area deals with the recognition, interpretation, compression and semantic processing of spoken or written language. In fact, this area also participates in both reading and writing.

Wernicke area injuries

Wernicke area (red)

When there is a lesion in Wernicke's area, it is expected that certain alterations in the understanding of language are found.

Wernicke's aphasia

The most typical consequence of damage in this area is Wernicke's aphasia. It consists of difficulties in understanding what he hears, while the pronunciation of the phonemes is preserved.

By not understanding language, they find it difficult to construct a speech that has a coherent meaning, although they can easily articulate the sounds of words.

An injury to Wernicke's area would cause:

- Problems differentiating the phonemes of language (that is, the sounds of language). This directly causes speech not to be understood.

- Due to difficulties in identifying the sounds of language, it is common for these patients to join words incoherently.

- Due to the above, they will not be able to evoke the graphic representations of the phonemes, having altered the writing.

Pure deafness for words

There are authors who emphasize that for Wernicke's aphasia to appear, more brain areas must be damaged, specifically adjacent areas. They indicate that a lesion located exclusively in Wernicke's area would produce a disorder called “pure deafness for words”.

It seems that this disorder affects only the reception of heard language, so that these patients understand written language better. In addition, they have preserved the identification of non-verbal sounds (such as a siren, a sneeze…) and writing.

It is important to note that there are other areas in the brain that have interpretive capabilities; the patient can use these to regain his function. They consist of some areas of the temporal lobe and the angular gyrus of the opposite hemisphere.

References

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