The language center consists primarily of the Wernicke and Broca areas in the cortical region of the cerebrum and frontal lobe. While the Wernicke area is responsible for semantic language processing, Broca’s area is primarily responsible for syntactic and grammatical language production. Inflammation– or hemorrhage-related damage in one of the areas manifests in speech comprehension or speech production disorders.
What is the speech center?
The sensory language center is a cortical area of the cerebrum and is located within the parietal and temporal lobes. These brain areas are also referred to as Wernicke’s and Broca’s areas. They serve semantic processing of language as well as morphological and syntactic language production. Broca’s area is primarily where the production of syntax and other grammatical aspects of language takes place. The Wernicke center, on the other hand, is primarily responsible for the recognition of sentence and word meaning. Only the cooperation of the two areas enables speech and comprehension. Until the 20th century, medicine assumed the language centers of Wernicke’s and Broca’s areas to be the only language-processing and language-producing brain regions. This assumption is now considered to be disproved. Thus, many other brain regions perform supporting tasks in the structural and content processing and production of language.
Anatomy and structure
As a sensory language center, the Wernicke center is at the heart of the human ability to communicate. It is located on each of the dominant hemispheres of the cerebrum. It extends from the dorsal part of the superior temporal gyrus beyond the angular and supramarginal gyri, thus extending above the parietal lobe. In right-handers, Wernicke’s area is located in the left hemisphere. In left-handers, it may be located in either the left or right hemisphere. The sensory language center encompasses three Brodmann areas. These are areas 22, 39, and 40. Areas 39 and 40 correspond to projection centers and association areas involved in speech production as well as speech processing. In addition, areas under the cerebral cortex, such as the putamen and caudate nucleus, are involved in language processing. The putamen is part of the gray matter of the brain. The caudate nucleus is primarily responsible for controlled voluntary movements. In addition, auditory processing areas are interconnected with the speech center and are relevant for speech production and processing. Wernicke’s area has afferent inputs to the primary auditory cortex. The angular gyrus also connects the speech center to the secondary visual cortex. With the goal of semantic speech articulation, the sensory speech center is also reciprocally connected to the motor speech areas, i.e., Broca’s areas. This connection corresponds largely to the fasciculus arcuatus. Broca’s area, unlike Wernicke’s center, is located in the frontal lobe and is also closely related to Wernicke’s center.
Function and Tasks
The function of the sensory language center is primarily language comprehension. Semantic processing of speech and text content takes place in these areas of the brain. However, the speech center also performs a role in the voluntary articulation of specific, semantic content. The speech motor centers of the cortex are mainly responsible for the articulation of semantic speech content. However, they are interconnected with the Wernicke center. Thus, a speech response to external stimulus can take place. In particular, the auditory and visual centers are connected to the language centers. Therefore, auditory and visual stimuli can trigger specific, language responses. It is in Broca’s area that language is built. That is, once Werenicke’s area has detected the utterance sense of an interlocutor, it responds with a semantic reaction. This semantic reaction is implemented syntactically and morphologically in Broca’s area. The communication of the individual areas takes place via projection. Thus, neural connections perform an important task in language production in response to perceived stimuli. Without the sensory language center, humans would not be able to comprehend utterances. On the other hand, he would also no longer be able to make meaningful statements about certain facts or situations. A disturbed connection between Broca’s and Wernicke’s areas, for example, no longer allows correct sentence utterances.
Diseases
Damage to Wernicke’s area manifests predominantly in impaired speech comprehension. A so-called Wernicke’s aphasia develops. This is a language impairment that is primarily due to a lack of language comprehension. This form of aphasia thus corresponds predominantly to a receptive aphasia. Despite fluent spontaneous utterance, the speech is empty in content. Often, patients of Wernicke’s aphasia break off in the middle of a sentence, double words or reinvent words. Depending on the exact localization, Wernicke’s area damage is also accompanied by paraphasia. In this case, the content-empty flow of speech hardly breaks off. Damage to Broca’s area, in turn, results predominantly in speech production disorders such as incorrect grammar. In most cases, a stroke is responsible for damage to the speech centers. In particular, strokes in the stromal area of the middle cerebral artery can cause impaired speech comprehension. Under certain circumstances, however, the phenomenon is also related to a degenerative disease. The tissue-destroying diseases Parkinson’s and Alzheimer’s, for example, can also affect Wernicke’s center. The same applies to the autoimmune disease multiple sclerosis. On an MRI, aphasia usually manifests as lesions of Wernicke’s center or Broca’s area. Nerve conduction velocity tests may be able to further determine whether a stroke, inflammatory disease, or degenerative disease is the cause. In rarer cases, a tumor may also cause speech center deficits.
