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Abstract:
Abstract: The present investigation uses MR Spectroscopy
(MRS) to monitor changes in lactate during language processing in
dyslexics and age/IQ matched controls. Proton spectra were acquired
using Proton Echo-Planar Spectroscopic Imaging (PEPSI), which
allows fast spectroscopic imaging. A 20mm axial slice along the
Sylvian fissure was selected for spectroscopic imaging (TR/TE
4000/272, 256x32x32 matrix). Eight dyslexic and eight matched
control males (ages 8-13) participated in PEPSI sessions that
required rhyme, semantic, and tone judgments to aurally presented
stimuli. We have previously demonstrated increases in lactate
levels in the left anterior quadrant of this brain volume during
PEPSI in dyslexic children when compared to control children during
rhyme judgments (Richards et al., 1999). A new cohort of subjects
was used in the present study. In preliminary analyses, patterns of
activation (increased lactate levels e" 2SDs above the global mean)
indicate that controls showed ! expected patterns of left temporal
activity during linguistic (rhyme and semantic) tasks and right
temporal activity during the nonlinguistic (tone) task. Dyslexic
children showed patterns of regional activity different from
controls for linguistic and nonlinguistic tasks. These unexpected
activation patterns could reflect either abnormal or compensatory
pathways in the linguistic strategies of dyslexics.
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