Language is one of the most prominent intellectual tasks depending on memory. Even though the neural basis of language is not yet fully understood, scientists have learned a great deal about this function of the brain from studies of patients who have lost this ability due to stroke, and from behavioral and functional neuroimaging studies of people who do posses speech and language abilities.

The Left Side

Based upon these studies, a prominent and influential model has been developed. This model proposes that the underlying structure of speech comprehension arises in a part of the left side of the brain, called Wernicke’s area. This temporal lobe region is connected with another region, called Broca’s area, in the frontal lobe, where a program for vocal expression is created. This program is then transmitted to a nearby area in the motor cortex that activates the mouth, tongue and larynx.

A Reading Model

This model also proposes that, when we read a word, the information is transmitted from the primary visual cortex to the angular cyrus, where the message is somehow matched with the words when they are spoken. The auditory form of the word is subsequently processed in Wernicke’s area as if the word has been heard. Writing in response to an oral instruction requires the information to be passed along the same pathways, but in the opposite direction (from the auditory cortex to Wernicke’s area to the angular cyrus).

This model accounts for much of the data obtained from patients and is the most widely used for clinical diagnosis. Some refinements of this model might be necessary, however, because of results from recent studies.

Necessary Refinements

Using PET imaging, for example, it has been shown that some reading tasks performed by regular people do not activate Wernicke’s area or the angular cyrus. These results suggest that, under certain conditions, there is a direct reading route that does not involve speech-sound recording of the visual stimulus before processing of either meaning or speaking. Other studies also have indicated that it is likely that familiar words do not have to be recorded into sound before they can be understood.

New Insights

So, the understanding of the complex mechanism of how language is implemented in the brain, is far from complete. But with the aid of several new techniques that may be used to gain new insights into this critical function of the brain, progress will be made.