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Abstract:
Abstract: Ten healthy young adults were scanned while
performing a 3-condition lexical decision experiment. In the
new-item condition a random sequence of words (75%) and nonsense
words (25%) was presented for lexical decisions, which were
indicated by pressing a "yes" or "no" button with the fingers of
the right hand. In the repeated-item condition, words and nonsense
words from the preceding new-item sequence were presented in a
different random order for lexical decisions. In each
control-condition trial, a row of X's appeared on the screen, and
participants were to press the "no" button. A 9-minute, 6-cycle
block sequence was used, in which each cycle consisted of 30 sec of
new-item trials, 15 sec of control trials, 30 sec of repeated-item
trials, and 15 sec of control trials. Imaging was performed using a
1.5 T whole-body MRI scanner with a full head coil. The entire
brain was imaged in 29 coronal planes. Lexical decisions on both
new and repeated items elicited increased activation, primarily in
pre-frontal cortical regions, relative to the control condition.
However, the activation intensities were attenuated for repeated
items relative to new items. This result is consistent with
previous imaging results showing repetition-related reductions in
cortical activity in the regions activated by the task itself. This
research was supported by NIH/NIA grant 2R01AG12995 awarded to
Gabrieli.Results illuminated the role serotonin may play in
abstract and specific visual-form processing.
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