Zusammenfassung
The relationship between the semantic processing of words and of pictures
is a matter of debate among cognitive scientists. We studied the
functional anatomy of such processing by using positron-emission
tomography (PET). We contrasted activity during two semantic tasks
(probing knowledge of associations between concepts, and knowledge
of the visual attributes of these concepts) and a baseline task (discrimination
of physical stimulus size), performed either with words or with pictures.
Modality-specific activations unrelated to semantic processing occurred
in the left inferior parietal lobule for words, and the right middle
occipital gyrus for pictures. A semantic network common to both words
and pictures extended from the left superior occipital gyrus through
the middle and inferior temporal cortex to the inferior frontal gyrus.
A picture-specific activation related to semantic tasks occurred
in the left posterior inferior temporal sulcus, and word-specific
activations related to semantic tasks were localized to the left
superior temporal sulcus, left anterior middle temporal gyrus, and
left inferior frontal sulcus. Thus semantic tasks activate a distributed
semantic processing system shared by both words and pictures, with
a few specific areas differentially active for either words or pictures.
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