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Abstract:
Abstract: Lesion/deficit correlations have traditionally been
studied in patients with chronic lesions, after the occurrence of
substantial reorganization of structure/function relationships. To
examine lesion/deficit relationships before reorganization we
identified correlations between hypoperfused, dysfunctional brain
regions on MR Perfusion Imaging (MRPI) and concurrent lexical
deficits in hyperacute stroke. Twenty-two acutely aphasic patients
underwent MRPI and a battery of naming, reading, and comprehension
tests to identify the level of impairment in lexical and sublexical
processing. For each patient, 10 Brodmann's areas thought to be
involved in language processing were evaluated for hypoperfusion. A
correlation matrix showed that hypoperfusion of area 22 (Wernicke's
area) was associated with impairment of lexical-semantics (r=.78;
p<.0001), but not deficits at the level of the phonological
output lexicon, orthography-to-phonology conversion (OPC), or motor
speech. Hypoperfusion of areas 37 (posterior middle temporal
gyrus), 39 (supramarginal gyrus) and area 40 (angular gyrus) were
associated with phonological output lexicon (r.72; p<.0003), and
semantic (r.54; p<.01), deficits. Hypoperfusion of areas 39 and
40 were associated with OPC (r.83; p<.001) deficits. A
Bonferroni analysis indicated that the number and strength of
associations identified was far above chance (p<<.0001).
These results converge with results from other lesion studies and
from PET and fMRI, validating MRPI as a promising tool for
identifying more controversial brain/language relationships in
previously normal subjects, prior to reorganization after
stroke.
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