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Abstract:
Abstract: In negative priming, the subject identifies a
target in the presence of a distractor. When the target also
appears as the distracter in the preceding trial, response time is
increased, potentially due to the need to overcome inhibition of
the stimulus. We used fMRI to explore whether brain activity
differs in negative priming, and whether patterns of activation
would support theories that inhibition is involved. Participants
viewed pairs of trials, both of which showed a red shape (triangle,
circle, square, or rhombus) and a green shape. In the prime trial,
subjects were told to attend to the red shape and ignore the green
shape. The probe trial required the subjects to decide if the red
shape in the probe matched the red shape in the prime trial. In the
Attended condition the target probe was the same as the preceding
target; in the Control condition, the target probe was different
from the preceding target and distractor; and in the Ignored
condition the target probe was the same as the preceding
distractor. Significantly greater activation was seen in the
Attended than in the Ignored condition in the supplementary motor,
premotor, and primary motor cortex contralateral to the response
hand, indicating less activity in these response preparation and
execution areas related to inhibition.
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