Wernicke's area
Encyclopedia
Wernicke's area is one of the two parts of the cerebral cortex
linked since the late nineteenth century to speech (the other is Broca's area
). It is involved in the understanding of written and spoken language. It is traditionally considered to consist of the posterior section of the superior temporal gyrus
in the dominant cerebral hemisphere (which is the left hemisphere in about 97% of people).
(STG) in the left (or dominant) cerebral hemisphere. This area encircles the auditory cortex on the Sylvian fissure (part of the brain where the temporal lobe
and 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. Others include also adjacent parts of the heteromodal cortex in BA 39
and BA40
in the parietal lobe
.
While previously thought to connect Wernicke's area and Broca's area
, new research demonstrates that the arcuate fasciculus
instead connects to posterior receptive areas with premotor/motor areas, and not to Broca's area.
neurologist
and psychiatrist
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
. Receptive aphasia
in which such abilities are preserved is now sometimes called 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
. Language as a result is largely meaningless (a condition sometimes called fluent or jargon aphasia
).
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 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.
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’’).
suggests the functions earlier attributed to the Wernicke's area occur more broadly in the temporal lobe
and indeed happen also in the Broca's area.
Support for a broad range of speech processing areas was furthered by a recent study done at University of Rochester in which American Sign Language native speakers were subject to MRIs 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.
Cerebral cortex
The cerebral cortex is a sheet of neural tissue that is outermost to the cerebrum of the mammalian brain. It plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness. It is constituted of up to six horizontal layers, each of which has a different...
linked since the late nineteenth century to speech (the other is Broca's area
Broca's area
Broca's area is a region of the hominid brain with functions linked to speech production.The production of language has been linked to the Broca’s area since Pierre Paul Broca reported impairments in two patients. They had lost the ability to speak after injury to the posterior inferior frontal...
). It is involved in the understanding of written and spoken language. It is traditionally considered to consist of the posterior section of the superior temporal gyrus
Superior temporal gyrus
The superior temporal gyrus is one of three gyri in the temporal lobe of the human brain, which is located laterally to the head, situated somewhat above the external ear.The superior temporal gyrus is bounded by:* the lateral sulcus above;...
in the dominant cerebral hemisphere (which is the left hemisphere in about 97% of people).
Location
The Wernicke's area is classically located as the posterior section of the superior temporal gyrusSuperior temporal gyrus
The superior temporal gyrus is one of three gyri in the temporal lobe of the human brain, which is located laterally to the head, situated somewhat above the external ear.The superior temporal gyrus is bounded by:* the lateral sulcus above;...
(STG) in the left (or dominant) cerebral hemisphere. This area encircles the auditory cortex on the Sylvian fissure (part of the brain where the temporal lobe
Temporal lobe
The temporal lobe is a region of the cerebral cortex that is located beneath the Sylvian fissure on both cerebral hemispheres of the mammalian brain....
and parietal lobe
Parietal lobe
The parietal lobe is a part of the Brain positioned above the occipital lobe and behind the frontal lobe.The parietal lobe integrates sensory information from different modalities, particularly determining spatial sense and navigation. For example, it comprises somatosensory cortex and the...
meet). This area is neuroanatomically described as the posterior part of Brodmann area
Brodmann area
A Brodmann area is a region of the cerebral cortex defined based on its cytoarchitectonics, or structure and organization of cells.-History:...
22
Brodmann area 22
Brodmann area 22 is one of Brodmann's cytologically defined regions of the brain. It is involved in auditory processing.-Human:Brodmann area 22 is a region of the human brain . On the left side of the brain this area helps with generation and understanding of individual words...
.
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. Others include also adjacent parts of the heteromodal cortex in BA 39
Brodmann area 39
Brodmann area 39, or BA39, is part of the parietal cortex in the human brain. BA39 encompasses the angular gyrus, lying near to the junction of temporal, occipital and parietal lobes....
and BA40
Brodmann area 40
Brodmann area 40, or BA40, is part of the parietal cortex in the human brain. The inferior part of BA40 is in the area of the supramarginal gyrus, which lies at the posterior end of the lateral fissure, in the inferior lateral part of the parietal lobe....
in the parietal lobe
Parietal lobe
The parietal lobe is a part of the Brain positioned above the occipital lobe and behind the frontal lobe.The parietal lobe integrates sensory information from different modalities, particularly determining spatial sense and navigation. For example, it comprises somatosensory cortex and the...
.
While previously thought to connect Wernicke's area and Broca's area
Broca's area
Broca's area is a region of the hominid brain with functions linked to speech production.The production of language has been linked to the Broca’s area since Pierre Paul Broca reported impairments in two patients. They had lost the ability to speak after injury to the posterior inferior frontal...
, new research demonstrates that the arcuate fasciculus
Arcuate fasciculus
The arcuate fasciculus is the neural pathway connecting the posterior part of the temporoparietal junction with the frontal cortex in the brain and is now considered as part of the superior longitudinal fasciculus..-Neuroanatomy:...
instead connects to posterior receptive areas with premotor/motor areas, and not to Broca's area.
Wernicke and aphasia
Wernicke's area is named after Carl Wernicke, a GermanGermany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
neurologist
Neurologist
A neurologist is a physician who specializes in neurology, and is trained to investigate, or diagnose and treat neurological disorders.Neurology is the medical specialty related to the human nervous system. The nervous system encompasses the brain, spinal cord, and peripheral nerves. A specialist...
and psychiatrist
Psychiatrist
A psychiatrist is a physician who specializes in the diagnosis and treatment of mental disorders. All psychiatrists are trained in diagnostic evaluation and in psychotherapy...
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
Acquired brain injury
An acquired brain injury is brain damage caused by events after birth, rather than as part of a genetic or congenital disorder such as fetal alcohol syndrome, perinatal illness or perinatal hypoxia. ABI can result in cognitive, physical, emotional, or behavioural impairments that lead to permanent...
that caused aphasia
Aphasia
Aphasia is an impairment of language ability. This class of language disorder ranges from having difficulty remembering words to being completely unable to speak, read, or write....
. Receptive aphasia
Receptive aphasia
Receptive aphasia, also known as Wernicke’s aphasia, fluent aphasia, or sensory aphasia, is a type of aphasia traditionally associated with neurological damage to Wernicke’s area in the brain,...
in which such abilities are preserved is now sometimes called 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
Syntax
In linguistics, syntax is the study of the principles and rules for constructing phrases and sentences in natural languages....
. Language as a result is largely meaningless (a condition sometimes called fluent or jargon aphasia
Aphasia
Aphasia is an impairment of language ability. This class of language disorder ranges from having difficulty remembering words to being completely unable to speak, read, or write....
).
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 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.
Right homologous area
Research using Transcranial magnetic stimulationTranscranial magnetic stimulation
Transcranial magnetic stimulation is a noninvasive method to cause depolarization or hyperpolarization in the neurons of the brain...
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
NeuroimagingNeuroimaging
Neuroimaging includes the use of various techniques to either directly or indirectly image the structure, function/pharmacology of the brain...
suggests the functions earlier attributed to the Wernicke's area occur more broadly in the temporal lobe
Temporal lobe
The temporal lobe is a region of the cerebral cortex that is located beneath the Sylvian fissure on both cerebral hemispheres of the mammalian brain....
and indeed happen also in the Broca's area.
Support for a broad range of speech processing areas was furthered by a recent study done at University of Rochester in which American Sign Language native speakers were subject to MRIs 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.
See also
- Arcuate fasciculusArcuate fasciculusThe arcuate fasciculus is the neural pathway connecting the posterior part of the temporoparietal junction with the frontal cortex in the brain and is now considered as part of the superior longitudinal fasciculus..-Neuroanatomy:...
- Broca's areaBroca's areaBroca's area is a region of the hominid brain with functions linked to speech production.The production of language has been linked to the Broca’s area since Pierre Paul Broca reported impairments in two patients. They had lost the ability to speak after injury to the posterior inferior frontal...
- CortexCerebral cortexThe cerebral cortex is a sheet of neural tissue that is outermost to the cerebrum of the mammalian brain. It plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness. It is constituted of up to six horizontal layers, each of which has a different...
- Human brainHuman brainThe human brain has the same general structure as the brains of other mammals, but is over three times larger than the brain of a typical mammal with an equivalent body size. Estimates for the number of neurons in the human brain range from 80 to 120 billion...
- Uncinate fasciculusUncinate fasciculusThe uncinate fasciculus is a white matter tract in the human brain that connects parts of the limbic system such as the hippocampus and amygdala in the temporal lobe with frontal ones such as the orbitofrontal cortex. Its function is unknown though it is affected in several psychiatric conditions...