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Abstract:
Abstract: We used fMRI to investigate brain activation
associated with processing of auditory stimuli across the
sleep-wake cycle. Sleep and waking electrophysiological correlates
were assessed by polygraphic recording obtained during burst-mode
fMRI. This technique allowed us to acquire high quality EEG, EMG,
and EOG in predetermined intervals between functional acquisitions.
Subjects were presented with auditory stimuli of two types: short
beeps and replay of the subject name. Polygraphic monitoring showed
prevalence of alpha rhythm during wake and theta-delta rhythm
during sleep. For fMRI data analysis, all volumes were realigned,
motion corrected, normalized to a standard template and smoothed
using a 6 mm FWHM Gaussian kernel. Statistical inference was
obtained using Statistical Parametric Mapping 1999 (http://
www.fil.ion.ucl.ac.uk /spm/ spm99.html). Results show that during
wake processing of auditory stimuli produced bilateral activation
in primary auditory and prefrontal/parietal cortices associated
with both auditory stimuli. During sleep the activation in primary
auditory cortices is reduced and there is no activation in the
prefrontal/parietal cortex . These results suggest that auditory
inputs are processed in the primary sensory areas during sleep.
However, decreased activity in the prefrontal parietal regions may
impair manipulation and recollection of these informations.
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