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Abstract:
Abstract: Neural responses to intensely threatening pictures
were studied using functional Magnetic Resonance Imaging (fMRI).
N=6 normal women viewed blocks of 4 highly arousing, negatively
valenced pictures, alternating with blocks of 8 neutral pictures,
for a total of 6 cycles. Each picture was shown for 4 seconds.
Pictures were chosen primarily from the International Affective
Picture System (IAPS), and supplemented with additional negative
images. Twenty coronal images were acquired every 2 seconds (64 x
64, single shot echo planar flash, TE=40), capturing approximately
the entire supratentorial brain. Subjects were instructed to attend
to their subjective emotional experience during the entire picture
presentation. We will present an analysis identifying brain regions
with increased signal intensity during threat compared to neutral
picture blocks. For each brain region identified, the duration of
the response to emotional stimuli will be examined. Regional
differences in the rate of decline of the hemodynamic signal
following the threatening picture blocks may permit localization of
regions with relatively phasic or relatively tonic responses to
emotional stimuli. Finally, the time-course of regional hemodynamic
responses will be compared with the time-course of behavioral
reports of the subjective experience of emotion during the picture
presentation.
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