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Abstract:
Previous imaging studies of novelty detection have focused on
identifying neural responses to objectively novel and objectively
familiar (previously exposed) stimuli. Using event-related fMRI
methods (BOLD fMRI, 3.0T GE scanner with ANMR EPI, 16 axial slices,
TR=2 sec), we examined the subjective experience of novelty in a
change detection paradigm (Simons & Levin, 1997). Participants
viewed pairs of Miyashita abstract shapes (Miyashita, 1991), one
image presented immediately after the other, and determined whether
the second image was the "same" as or "different" from the first.
On half the trials, stimulus pairs were identical (Identical), and
on the other half the second image was different from the first
(Changed). Stimulus changes were based on an algorithm that altered
shape. Accuracy of "same"-"different" judgments was significantly
above chance. When correct Identical trials were subtracted from
correct Changed trials, greater activation was observed in frontal
opercular and fusiform cortices. Importantly, when incorrect
Changed trials (subjective response of "same") were subtracted from
incorrect Identical trials (subjective response of "different"), a
similar pattern of activation was observed. Results thus far
indicate no differences when comparing objectively Identical and
objectively Changed trials irrespective of participants' subjective
responses. Thus, brain activation was closely related to the
subjective perception of novelty.
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