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Abstract:
We used 3-Tesla fMRI to study the cerebral representation of
two categories of words, numerals and names of body parts, which
are known to be dissociable in brain-lesioned patients. Our
factorial experimental design aimed at isolating the brain areas
associated with abstract knowledge of these two categories,
independently of input modality and language. In distinct blocks,
five subjects were presented with numerals or with names of body
parts, in the visual or the auditory modality, and in the subjects'
first or second language. Several occipital and temporal areas were
significantly affected by either modality, language, or both. Yet,
using SPM96's conjunction and masking analyses, we identified two
distinct cerebral regions which were significantly more active for
a given category of words regardless of modality and language: a
right intraparietal area for numerals, and a left ventral temporal
area for body parts. These areas were observed in a group analysis
as well as in most individual analyses. Our results confirm that
some brain areas code for specific categories of knowledge, and
reveal that they totally abstract from the specific characteristics
of the input.
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