According to Geschwind, how does the linguistic information flow?
Geschwind proposal is that Wernicke’s area is specialized in language comprehension, whereas Broca’s area is specialized in language production. Auditory and visual areas need to pass information to Wernicke’s area in order for it to be understood. This explains why damage to Broca’s area disrupts language production, and comprehension remains relatively unimpaired. In contrast, a lesion in Wernicke’s area affects all aspects of language.
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- Why do we call the model disconnectionist?
It’s called disconnectionist because it describes two main areas that can function independently, despite the fact that language processing in the unimpaired brain requires the two areas to be connected through the arcuate fasciculus.
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- Why do we call the model connectionist?
Because the model is based on the connections between Wernicke’s and Broca’s areas to explains language processing.
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- We were able to falsify the model by noticing that it predicted behaviors in Broca’s and Wernicke’s patients that were not observed. What were those behaviors?
The problem is that not all areas of production or comprehension are impaired when there is a lesion in these areas. Instead, there is selectivity and some problems with production arise. However, the model does not predict these specific patterns. In other words, the predictions of the model are too strong.
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- What other ways are there to falsify this model?
The model would be falsified if damage to other areas of the brain lead to impairment of language production and comprehension. This would show that all language functions are not dependent on the connection between Broca’s and Wernicke’s areas.