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Abstract:
The cerebral systems involved in attentional interference at
high presentation rates were examined using fMRI recordings during
a rapid serial visual presentation (RSVP) task. Strings of letters
were presented (25 ms duration, 10 /sec) centrally on a screen, and
the subjects had to identify a pair of white letters (targets T1
and T2) embedded in a series of black distractor-letters. T1 was
preceded by 7 letters and followed by 8. T2 followed T1 in one of
three fixed positions (T1+3, T1+5, or T1+7). In each condition, 12
experimental trials alternated with 12 control trials (passively
viewing a series black Xs at 10/sec). T2* weighted volume images of
19 contiguous slices were obtained every 2.5 seconds using a
Siemens Magnetom Vision1.5T. Two sets of 96 images were acquired
for each condition. Significant activations were observed
bilaterally in the occipital cortex and adjacent parietal and
posterior inferotemporal cortex, as well as in inferior premotor
and anterior cingulate cortex. Few differences were found between
the three inter-target delays.
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