Wernicke's area

Brain: Wernicke's area
Approximate location of Wernicke's area highlighted in grey
NeuroNames	ancil-252

Wernicke's area ("Wernicke" English pronunciation: /ˈvɛrnɪkə/ or /ˈvɛrnɪkiː/; German: [ˈvɛʁniːkə]) is one of the two parts of the cerebral cortex linked since the late nineteenth century to speech (the other is the 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 90% of people).

Location

The Wernicke's area is classically located as the posterior section of the superior temporal gyrus (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 its location.^[1] Some identify it with the unimodal auditory association in the superior temporal gyrus anterior to the primary auditory cortex.^[2] Others include also adjacent parts of the heteromodal cortex in BA 39 and BA40 in the parietal lobe.^[3]

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.^[4]

Wernicke and aphasia

Wernicke's area is named after Carl Wernicke, a German 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.^[5]

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 PET 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.^[1][6]

Right homologous area

Research using 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’’).^[7]

Modern views

Neuroimaging 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.

Footnotes

See also

• Arcuate fasciculus
• Broca's area
• Cortex
• Human brain
• Uncinate fasciculus