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Abstract:
The current study attempts to merge cognitive and
neuropsychological approaches to the study of lexical-semantic
processing in order to investigate associated substrates. To this
end, we used an explicitly semantic auditory priming task in which
both response time and regional cerebral blood flow (rCBF) data
were collected during positron emission tomography (PET) scanning.
Twelve subjects were presented with 4 priming conditions, crossing
prime-target association type (word versus semantic association)
with prime-target distance (0 versus 2 intervening words). An
artifactual judgement (man-made/ not man-made) was made for every
word (prime and target). An identical, but non-priming, control
condition was also presented. Subtraction of control condition rCBF
from that of the priming conditions found: (I) rCBF increases in
the medial precuneus and left parietal regions, and (II) bilateral
rCBF decreases in posterior basal temporal areas (PBTA), and medial
frontal areas. Covariation analyses found the left parietal focus
to correlate negatively with both the PBTA and frontal sites.
Correlation of the individual priming effect sizes with rCBF
revealed significant positive correlations with the PBTA and
frontal sites. The above results demonstrate that: (1) the PBTA
plays a role in access/storage of lexical-semantic information, (2)
the PBTA and the frontal and left parietal areas appear to be part
of a functional network, and (3) the reduced rCBF noted in the PBTA
during lexical-semantic priming reflects a more efficient access to
the semantic network.
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