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Wernicke's area (; ), also called Wernicke's speech area, is one of the two parts of the
cerebral cortex The cerebral cortex, also known as the cerebral mantle, is the outer layer of of the of the in and other s. The cerebral cortex mostly consists of the six-layered , with just 10% consisting of . It is separated into two , by the that divide ...
that are linked to speech, the other being
Broca's area Broca's area, or the Broca area (, also , ), is a region in the frontal lobe of the dominant hemisphere Hemisphere may refer to: * A half of a sphere As half of the Earth * A hemispheres of Earth, hemisphere of Earth ** Northern Hemisphere ** So ...
. It is involved in the comprehension of written and spoken language, in contrast to Broca's area, which is involved in the production of language. It is traditionally thought to reside in Brodmann area 22, which is located in the
superior temporal gyrus The superior temporal gyrus (STG) is one of three (sometimes two) gyri In neuroanatomy, a gyrus (pl. ''gyri'') is a ridge on the cerebral cortex. It is generally surrounded by one or more sulcus (neuroanatomy), sulci (depressions or furrows; s ...

superior temporal gyrus
in the dominant cerebral hemisphere, which is the left hemisphere in about 95% of
right-handed In human biology, handedness is the better, faster, or more precise performance or individual preference for use of a hand, known as the dominant hand. The incapable, less capable or less preferred hand is called the non-dominant hand. Right-ha ...
individuals and 70% of left-handed individuals. Damage caused to Wernicke's area results in receptive,
fluent aphasia Wernicke's aphasia, also known as receptive aphasia, sensory aphasia or posterior aphasia, is a type of aphasia Aphasia is an inability to comprehend or formulate language because of damage to specific brain A brain is an organ (biology), ...
. This means that the person with aphasia will be able to fluently connect words, but the phrases will lack meaning. This is unlike
non-fluent aphasia Expressive aphasia, also known as Broca's aphasia, is a type of aphasia Aphasia is an inability to comprehend or formulate language because of damage to specific brain A brain is an organ (biology), organ that serves as the center of the ne ...

non-fluent aphasia
, in which the person will use meaningful words, but in a non-fluent, telegraphic manner.


Structure

Wernicke's area is traditionally viewed as being located in the posterior section of the
superior temporal gyrus The superior temporal gyrus (STG) is one of three (sometimes two) gyri In neuroanatomy, a gyrus (pl. ''gyri'') is a ridge on the cerebral cortex. It is generally surrounded by one or more sulcus (neuroanatomy), sulci (depressions or furrows; s ...

superior temporal gyrus
(STG), usually in the left cerebral hemisphere. This area encircles the
auditory cortex The auditory cortex is the part of the temporal lobe The temporal lobe is one of the four major lobes of the cerebral cortex in the brain of mammal Mammals (from Latin language, Latin , 'breast') are a group of vertebrate animals co ...

auditory cortex
on the
lateral sulcus The lateral sulcus (also called Sylvian fissure or lateral fissure) is one of the most prominent features of the human brain The human brain is the central organ (anatomy), organ of the human nervous system, and with the spinal cord makes up th ...

lateral sulcus
, the part of the
brain A brain is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's tis ...

brain
where the
temporal lobe The temporal lobe is one of the four major lobes of the cerebral cortex The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. The cerebral cortex m ...

temporal lobe
and
parietal lobe The parietal lobe is one of the four major lobes of the cerebral cortex The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. The cerebral cortex m ...

parietal lobe
meet. This area is neuroanatomically described as the posterior part of Brodmann area 22. However, there is an absence of consistent definitions as to the location. Some identify it with the unimodal auditory association in the superior temporal gyrus anterior to the primary auditory cortex (the anterior part of BA 22). This is the site most consistently implicated in auditory
word recognition Word recognition, according to Literacy Information and Communication System (LINCS) is "the ability of a reader to recognize written words correctly and virtually effortlessly". It is sometimes referred to as "isolated word recognition" because it ...
by functional brain imaging experiments. Others include also adjacent parts of the heteromodal cortex in
BA 39
BA 39
and
BA40
BA40
in the
parietal lobe The parietal lobe is one of the four major lobes of the cerebral cortex The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. The cerebral cortex m ...

parietal lobe
. Despite the overwhelming notion of a specifically defined "Wernicke's Area," the most careful current research suggests that it is not a unified concept. While previously thought to connect Wernicke's area and
Broca's area Broca's area, or the Broca area (, also , ), is a region in the frontal lobe of the dominant hemisphere Hemisphere may refer to: * A half of a sphere As half of the Earth * A hemispheres of Earth, hemisphere of Earth ** Northern Hemisphere ** So ...
, new research demonstrates that the
arcuate fasciculus The arcuate fasciculus (AF) is a bundle of Axon, axons that generally connects the Broca's area and the Wernicke's area in the Human brain, brain. It is an association fiber nerve tract, tract connecting Caudal (anatomical term), caudal Temporal ...
instead connects to posterior receptive areas with premotor/motor areas, and not to Broca's area. Consistent with the word recognition site identified in brain imaging, the
uncinate fasciculus The uncinate fasciculus is a white matter White matter refers to areas of the central nervous system (CNS) that are mainly made up of myelin Myelin is a lipid-rich (fatty) substance that surrounds nerve cell axons (the nervous system's "wi ...
connects anterior superior temporal regions with
Broca's area Broca's area, or the Broca area (, also , ), is a region in the frontal lobe of the dominant hemisphere Hemisphere may refer to: * A half of a sphere As half of the Earth * A hemispheres of Earth, hemisphere of Earth ** Northern Hemisphere ** So ...
.


Function


Right homologous area

Research using
Transcranial magnetic stimulation Transcranial magnetic stimulation (TMS) is a noninvasive form of brain stimulation in which a changing magnetic field A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and m ...

Transcranial magnetic stimulation
suggests that the area corresponding to the Wernicke's area in the non-dominant cerebral hemisphere has a role in processing and resolution of subordinate meanings of ambiguous words—such as ‘‘river’’ when given the ambiguous word "bank." In contrast, the Wernicke's area in the dominant hemisphere processes dominant word meanings (‘‘teller’’ given ‘‘bank’’).


Modern views

Neuroimaging Neuroimaging or brain imaging is the use of various techniques to either directly or indirectly Medical imaging, image the neuroanatomy, structure, function, or pharmacology of the nervous system. It is a relatively new discipline within medicine ...
suggests the functions earlier attributed to Wernicke's area occur more broadly in the
temporal lobe The temporal lobe is one of the four major lobes of the cerebral cortex The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. The cerebral cortex m ...

temporal lobe
and indeed happen also in Broca's area. Support for a broad range of speech processing areas was furthered by a recent study carried out at the
University of Rochester The University of Rochester (U of R, UR, or U of Rochester) is a private Private or privates may refer to: Music * "In Private "In Private" was the third single in a row to be a charting success for United Kingdom, British singer Dusty Sp ...
in which
American Sign Language American Sign Language (ASL) is a natural language In neuropsychology Neuropsychology is a branch of psychology. It is concerned with how a person's cognition and behavior are related to the brain and the rest of the nervous system. Pr ...

American Sign Language
native speakers were subject to
MRI Magnetic resonance imaging (MRI) is a medical imaging Medical imaging is the technique and process of imaging Imaging is the representation or reproduction of an object's form; especially a visual representation (i.e., the formation of ...
while interpreting sentences that identified a relationship using either syntax (relationship is determined by the word order) or inflection (relationship is determined by physical motion of "moving hands through space or signing on one side of the body"). Distinct areas of the brain were activated with the frontal cortex (associated with ability to put information into sequences) being more active in the syntax condition and the temporal lobes (associated with dividing information into its constituent parts) being more active in the inflection condition. However, these areas are not mutually exclusive and show a large amount of overlap. These findings imply that while speech processing is a very complex process, the brain may be using fairly basic, preexisting computational methods.


Clinical significance


Aphasia

Wernicke's area is named after
Carl Wernicke Carl (or Karl) Wernicke (; ; 15 May 1848 – 15 June 1905) was a German physician A physician (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set o ...

Carl Wernicke
, a
German German(s) may refer to: Common uses * of or related to Germany * Germans, Germanic ethnic group, citizens of Germany or people of German ancestry * For citizens of Germany, see also German nationality law * German language The German la ...

German
neurologist Neurology (from el, νεῦρον (neûron), "string, nerve" and the suffix -logia ''-logy'' is a suffix in the English language, used with words originally adapted from Ancient Greek ending in (''-logia''). The earliest English example ...
and
psychiatrist A psychiatrist is a physician A physician (American English), medical practitioner (English in the Commonwealth of Nations, Commonwealth English), medical doctor, or simply doctor, is a professional who practices medicine, which is c ...
who, in 1874, hypothesized a link between the left posterior section of the superior temporal gyrus and the reflexive mimicking of words and their syllables that associated the sensory and motor images of spoken words. He did this on the basis of the location of brain injuries that caused
aphasia Aphasia is an inability to comprehend or formulate language because of damage to specific brain regions. The major causes are a cerebral vascular accident (stroke) or head trauma. Aphasia can also be the result of brain tumors, brain infections ...

aphasia
.
Receptive aphasia Wernicke's aphasia, also known as receptive aphasia, sensory aphasia or posterior aphasia, is a type of aphasia in which individuals have difficulty understanding written and spoken language A spoken language is a language A language is a ...
in which such abilities are preserved is also known as Wernicke's aphasia. In this condition there is a major impairment of language comprehension, while speech retains a natural-sounding rhythm and a relatively normal
syntax In linguistics Linguistics is the scientific study of language, meaning that it is a comprehensive, systematic, objective, and precise study of language. Linguistics encompasses the analysis of every aspect of language, as well as the ...

syntax
. Language as a result is largely meaningless (a condition sometimes called ''fluent'' or '' jargon aphasia''). Wernicke's area receives information from the auditory cortex, and functions to assign word meanings. This is why damage to this area results in meaningless speech, often with paraphasic errors and newly created words or expressions. Paraphasia can involve substituting one word for another, known as semantic paraphasia, or substituting one sound or syllable for another, defined as phonemic paraphasia. This speech is often referred to as “word salad,” as speech sounds fluent but does not have sensible meaning. Normal sentence structure and prosody are preserved, with normal intonation, inflection, rate, and rhythm. This differs from Broca's aphasia, which is characterized by nonfluency. Patients are typically not aware that their speech is impaired in this way, as they have altered comprehension of their speech. Written language, reading, and repetition are affected as well. Damage to the posterior temporal lobe of the dominant hemisphere is the cause of Wernicke's aphasia. The etiology of this damage can vary greatly, with the most common cause being a cerebrovascular event such as an ischemic stroke. Ischemic stroke is the result of a thrombus occluding a blood vessel, restricting blood supply to a particular area of the brain. Other causes of focal damage potentially leading to Wernicke's aphasia include head trauma, infections affecting the central nervous system, neurodegenerative disease, and neoplasms. A cerebrovascular event is more likely the cause in an acute-onset presentation of aphasia, whereas a degenerative disease should be suspected in aphasia with gradual progression over time. Imaging is often useful in identifying a lesion, with most common initial imaging consisting of computed tomography (CT) scan or magnetic resonance imaging (MRI). Electroencephalography (EEG) can also be useful in patients with transient aphasia, where findings may be due to seizures, although this is a less common cause. Diagnosis of aphasia, as well as characterization of type of aphasia, is done with language testing by the provider. Testing should evaluate fluency of speech, comprehension, repetition, ability to name objects, and writing skills. Fluency is assessed by observing the patient's spontaneous speech. Abnormalities in fluency would include shortened phrases, decreased number of words per minute, increased effort with speech, and agrammatism. Patients with Wernicke's aphasia should have fluent speech, so abnormalities in fluency may indicate a different type of aphasia. Comprehension is assessed by giving the patient commands to follow, beginning with simple commands and progressing to more complex commands. Repetition is evaluated by having the patient repeat phrases, progressing from simple to more complex phrases. Both comprehension and repetition would be abnormal in Wernicke's aphasia. Content should also be assessed, by listening to a patient's spontaneous or instructed speech. Content abnormalities include paraphasic errors and neologisms, both indicative of a diagnosis of Wernicke's aphasia. Neologisms are novel words that may resemble existing words. Patients with severe Wernicke's aphasia may also produce strings of such neologisms with a few connecting words, known as jargon. Errors in the selection of phonemes of patients with Wernicke's aphasia include addition, omission, or change in position. Another symptom of Wernicke's aphasia is use of semantic
paraphasiaParaphasia is a type of language output error commonly associated with aphasia, and characterized by the production of unintended syllables, words, or phrases during the effort to speak. Paraphasic errors are most common in patients with fluent form ...
s or "empty speech" which is the use of generic terms like "stuff" or "things" to stand in for the specific words that the patient cannot think of. Some Wernicke's aphasia patients also talk around missing words, which is called "
circumlocution Circumlocution (also called circumduction, circumvolution, periphrasis In linguistics Linguistics is the science, scientific study of language. It encompasses the analysis of every aspect of language, as well as the methods for studying an ...
." Patients with Wernicke's aphasia can tend to run on when they talk, due to circumlocution combined with deficient self-monitoring. This overabundance of words or press of speech can be described as logorrhea. If symptoms are present, a full neurologic exam should also be done, which will help differentiate aphasia from other neurologic diagnoses potentially causing altered mental status with abnormal speech and comprehension. As an example, a patient with Wernicke's aphasia was asked what brought him to the hospital. His response was, "Is this some of the work that we work as we did before? ... All right ... From when wine hyI'm here. What’s wrong with me because I ... was myself until the taenz took something about the time between me and my regular time in that time and they took the time in that time here and that’s when the time took around here and saw me around in it’s started with me no time and I bekan work of nothing else that's the way the doctor find me that way..." Treatment of Wernicke's aphasia first involves addressing the underlying cause. Speech and language therapy is the first line treatment for the aphasia itself, and has a goal of improving language deficits as well as preserving the patient's remaining language skills. A subsequent critical goal of therapy is to teach the patient how to communicate in alternative ways, so they can successfully communicate in daily life. This may include gestures, pictures, or use of electronic devices. While neuroimaging and lesion evidence generally support the idea that malfunction of or damage to Wernicke's area is common in people with receptive aphasia, this is not always so. Some people may use the right hemisphere for language, and isolated damage of Wernicke's area cortex (sparing white matter and other areas) may not cause severe receptive aphasia. Even when patients with Wernicke's area lesions have comprehension deficits, these are usually not restricted to
language processing Language processing refers to the way humans use words to communicate ideas and feelings, and how such communications are processed and understood. Language processing is considered to be a uniquely human ability that is not produced with the same ...

language processing
alone. For example, one study found that patients with posterior lesions also had trouble understanding nonverbal sounds like animal and machine noises. In fact, for Wernicke's area, the impairments in nonverbal sounds were statistically stronger than for verbal sounds.


References


External links

* {{DEFAULTSORT:Wernicke's Area Cerebral cortex Neurolinguistics Temporal lobe