Cortical language areas
Cortical language areas
Many cortical (and non-cortical!) regions are involved in language processing. The primary language pathway begins in Wernicke’s area (posterior temporal lobe), which receives information from the auditory and visual cortices and assigns meaning (= language comprehension). The arcuate fasciculus connects Wernicke’s area to Broca’s area (posterior inferior frontal lobe). Broca’s area is responsible for the production of meaningful language. Output from Broca’s area goes to motor cortex for initiation of the complex muscle movements necessary for speech. |
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PET scan of the brain during different components of language processing. Areas in red/yellow are the most active; areas in purple/blue are the least active. 
language processing involves many regions of the the brain (evidenced by the blue regions in the frontal cortex and the cerebellum in these images, for example), not just the classic areas localized by Broca and Wernicke to the perisylvian cortex of the dominant (left) hemisphere - the exact regions can vary from person to person, and within the same person, in unpredictable ways
- for example, bilingual patients do not necessarily use the same cortical regions to produce the names of the same object in two different languages
- despite these qualifications, a general language pathway can be described:
- language input from visual or auditory cortex (1) goes first to Wernicke's area (posterior temporal lobe) (2), which performs the final stages of language comprehension
- Wernicke's area connects to Broca's area (posterior inferior frontal lobe) via the arcuate fasciculus
- Broca's area (3) is responsible for production of meaningful language
- output from Broca's area goes to motor cortex (4) for control of the voluntary muscles required to speak or write words
- this process of articulating specific words (i.e., issues of syntax and grammar) must be merged with emotional context (i.e., prosody), which is processed by the corresponding anatomical regions in the non-dominant (right) hemisphere
recent imaging studies have shown that the inferior parietal lobule (angular gyrus and supramarginal gyrus = Geschwind's territory) is connected by large bundles of nerve fibres to both Broca’s area and Wernicke’s area, providing by a second, parallel route for language production in addition to the general language pathway
- the inferior parietal lobule is located at the junction of, and is connected to the auditory, visual, and somatosensory cortexes
- cells in this region are multimodal (i.e., they respond to many different kinds of stimuli)
- this lobule may help classify and label things, which is a prerequisite for forming concepts and thinking abstractly
- the inferior parietal lobule is one of the last structures to mature, which may explain why children typically do not begin to read and write until they are 5 or 6 years old.