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Abstract:
The purpose of this study was to examine semantic processing
in elderly individuals (mean age = 74.8) during word and object
naming. Positron emission tomography was used to examine the
relative cerebral blood (relCBF) flow during the naming of words
and objects. Eight elderly control subjects were scanned twice in
each of five conditions: Visual Noise, Word Reading, Nonword
Reading, Object Naming, and Nonobject Viewing (with speech). After
movement correction and spatial normalization, the data were
analyzed in SPM99 to determine differences in relCBF as a function
of the differing processing demands of the task. All encoding
conditions vs. Visual Noise revealed activation of Broca's area and
left anterior temporal lobe and strong bilateral activation of the
ventral occipital region which extended into the posterior temporal
region in the left hemisphere. Object Naming vs. Nonobject Viewing
(with speech) comparison showed strong left inferior and superior
temporal lobe, right occipital lobe, and Broca's area activation.
Word Reading vs. Nonword Reading displayed left inferior temporal
lobe, left frontal pole and retrospleneal cortex activation.
Word/Nonword conditions vs. Object/Nonobject conditions showed left
superior temporal and Broca's area activation while
Object/Nonobject vs. Word/Nonword showed right posterior and right
inferior temporal lobe. Meaningful items vs. nonsense items
revealed fusiform gyrus activation and strong left anterior
inferior temporal lobe activation, which was greater for objects
than for words.
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