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Anatomy of language processing. Mark Harju. Most components for language processing are located in the left hemisphere Left= dominant language hemisphere Nearly all right-handed people Two-thirds of lefties
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Anatomy of language processing Mark Harju
Most components for language processing are located in the left hemisphere • Left= dominant language hemisphere • Nearly all right-handed people • Two-thirds of lefties • The cortical area most involved in the left hemisphere is central around the sylvan fissure
The two most traditionally distinct areas are • Wernicke’s area
The two most traditionally distinct areas are • Wernicke’s area • Broca’s area
Wernicke’s area comprises a region that includes: • the posterior part of the superior temporal gyrus • parietooccipitotemporal junction, including the angular gyrus
Wernicke’s area is concerned with the comprehension of spoken language. • The angular gyrus has to do with comprehension of written language
Broca’s area comprises a region covering the posterior part of triangular gyrus • Opercular gyrus in the inferior frontal gyrus
Broca’s area is concerned with speech production • Within Broca a vocalization program is formulated
This program transmits to the face, tongue, vocal chords, and pharynx areas of the motor cortex for execution of speech.
It is also connected with the supplementary motor area, which is concerned with the initiation of speech.
Broca and Wernicke are connected by the arcuate fasciculus • A fiber bundle pathway, necessary for repetition of spoken language
The cortical areas are used in sequence when processing language.
For example, if you were reading aloud you would need to involve your visual cortex, located in your occipital lobe
You would also need your primary motor cortex to use your face, tongue, vocal chords, and pharynx to speak
….And your supplementary motor cortex in order to initiate speech.
The output from the visual cortex goes to the angular gyrus, where it links the image of the written words to language.
Then to Wernicke’s area where the words are processed and given meaning
Then through the arcuate fasciculus to Broca’s area, where the vocalization of the words is formulated
Then the vocalized program is delivered to the primary motor cortex, and initiated into speech by a signal to the supplementary motor cortex.
In the case of speaking words you hear, you would need to involve
In the case of speaking words you hear, you would need to involve • The auditory cortex to hear the words
And the supplementary motor cortex to tell your face to start talking.
A quick word on language in the right hemisphere • Corresponding areas have been measured as metabolically active in right hemisphere during speech • This is believed to be linked with melodic function of speech (prosody)
This may explain some cases of autism or brain damage where the subjects are unable to speak yet are able to sing