24/03/2009

Lexical semantics (2/4)

Let us work our way up to the next question.

Is it located at any given place in the brain?

Well, at first the answer seemed to be yes. Wernicke's area has been recognized as early as in 1874 to be associated with word meaning. Patients with lesions in this area are afflicted with a kind of condition which leaves them unable to grasp the sense of words or to produce meaningfull speech, though importantly they are essentially unimpaired in other cognitive functions. Wernicke's area is close to the auditory cortex, but the associated deficit is not limited to the oral modality and extends to written language comprehension.


But of course and as often in cognitive science, things are a great deal more complicated. Researchers now agree that semantic retrieval involves at least a network of distant regions lying in the left frontal and temporal lobes, as suggested by the picture on the right (see this 2004 brain imagery study from Noppeney et al and this Nature neuroscience review from Patterson et al -both feature authoritative collaborators).

Characterizing the neural correlates of semantics remains work in progress, and as a matter of fact entire research labs are commited to this pursuit. Let me point to one important lab at the university of Wisconsin, which should also get the credit for the artwork.

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