The Wernicke center is the sensory language center in humans and ensures language comprehension. Because thought is inextricably linked to language, the Wernicke center plays a role not only in language production and processing, but in every human thought process. Damage to the area often results in personality change.
What is Wernicke’s center?
Medical professionals and biologists refer to the areas of the brain that have an essential function in language processing and production as the language center. In principle, the brain represents a network whose individual areas are interconnected. Therefore, language processing and production cannot be limited to individual areas. What is known as the language center is therefore not the only essential brain structure for language. However, the language center is characterized by a much higher involvement in language production and processing than other parts of the brain. Together with Broca’s area, the Wernicke’s area is primarily referred to as the language center in today’s state of medicine. This brain area was first described in the 19th century by the German neurologist Carl Wernicke. The Wernicke center is the sensory language center, which plays a role primarily for semantic connections. The brain area corresponds to a cortical cerebral area and is located within the parietal and temporal lobes.
Anatomy and structure
The Wernicke area is located on the dorsal part of the superior temporal gyrus and extends from there to over the angular and supramarginal gyri in the parietal lobe, which correspond to Brodmann areas 22, 39, and 40. The sensory language center is located in each of the dominant hemispheres and consequently is located left hemispherically for right-handers, whereas it may be located right hemispherically for left-handers. The Wernicke center receives its projections from different parts of the brain. Afferent inputs reach the area essentially from the auditory cortex. For this reason, the Wernicke center is considered a part of the secondary auditory cortex. In addition to afferents from the primary auditory cortex (gyri temporalis transversi or Heschl’s transverse turn), the brain area has a close relationship with the secondary visual cortex. The projections travel via the angular gyrus. In addition, Wernicke’s center is reciprocally connected to motor language areas such as Broca’s area. This connection corresponds predominantly to the fasciculus arcuatus. The Wernicke center makes projections to numerous association fields in which what is heard undergoes integrative processing. In particular, the connections between Wernicke’s speech center and motor speech center are noteworthy in this context. The fibrae arcuatae cerebri play a major role in this process. Because language formation is inextricably interconnected with language comprehension, Broca’s center cannot perform its task without the inflows from Wernicke’s area.
Function and tasks
Together with Broca’s area, Wernicke’s center is significantly involved in language comprehension and production. Whereas the Broca’s center is primarily involved in speech production, including all movements required for this purpose, the Wernicke’s center is primarily involved in semantic language processing and thus language comprehension. Inputs from the auditory cortex provide the Wernicke center with auditory sensory stimuli, which are processed and thus understood within the area. The Broca’s center in turn draws on the semantic understanding of the Wernicke’s center during speech production. The efferences between Wernicke’s and Broca’s centers enable speech movements to be made meaningful and thus to be understood. Thus, in addition to semantic processing, the Wernicke center also takes over the integration of speech as well as textual content, which corresponds to language comprehension. Since the Wernicke center interacts continuously with the Broca center and thus with the speech motor cortex areas, the brain part in speech production has a responsibility for the semantic level of speech as it is relevant for arbitrary linguistic messages and speech reactions to external sensory stimuli. Both language centers are irreplaceable for human communication. During evolution, humans have moved away from non-verbal communication and focused more and more on the verbal act of communication.The Wernicke and Broca centers play an important role in this evolutionary biological feature. It is now also known that large parts of human thinking are tied to language. For example, as long as someone does not know a word for a particular object, he has a harder time remembering it.
Diseases
Like all other parts of the brain, the Wernicke center can experience damage from exposure to violence, inflammation, tumors, degenerative diseases, reduced oxygen supply, and hemorrhage. Complete or partial loss of the Wernicke region results in sensory aphasia. This type of language disorder manifests itself through symptoms such as disturbances in speech comprehension. The extent of these disorders depends on the severity of the damage. Unlike patients with motor aphasia, those with sensory aphasia can mimic spoken sounds to a limited extent, but do not understand what is said. Since speech comprehension also plays a role in speech production, speech production disorders are present in addition to comprehension disorders. In many cases, patients with damage to Wernicke’s area produce only arbitrary series of sounds that cause little comprehension by outsiders as well as themselves. Since the Wernicke center is connected to the auditory cortex, damage to the Wernicke area can also lead to an inability to associate auditory impressions. For example, when standing next to a car that starts, they hear the engine but do not associate the sound with its actual source. Patients with damage to Broca’s center may have limited verbal communication, but written communication is still possible. With damage to the Wernicke center, both types of communication are impossible. Because all human thinking is tied to language, patients with impaired language comprehension show general weaknesses in thinking that often result in serious personality changes.
