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Abstract:
Abstract: Previous studies indicate that dissociable neural
subsystems underlie recognition of abstract categories of shapes
(e.g., cups vs. pens) and recognition of specific exemplars of
shapes (e.g., individual pens). Because these subsystems may rely
on different parts-based versus whole-based processing strategies
to accomplish their respective goals, they may differ in
sensitivity to the neuromodulatory effects of serotonin (which
constrains information processing in a manner that may enhance
parts-based processing but impair whole-based processing).
Alternatively, these subsystems may differ in less malleable, more
structural ways that are not sensitive to the neuromodulatory
effects of serotonin. In the present study, we measured abstract
and specific visual-form repetition priming in participants with
varying central-nervous-system serotonin levels. We manipulated
levels of tryptophan, a precursor for the synthesis of serotonin,
through dietary means and ingestion of different beverages. On one
day, participants consumed a tryptophan-enhanced beverage assumed
to raise the levels of serotonin in the brain. On another day,
participants consumed a tryptophan-depleted beverage assumed to
lower serotonin levels. On both days, participants performed
repetition priming tasks as well as control tasks.
Abstract-category priming was measured as visual repetition priming
that was equivalent for same- and different-exemplar-primed
stimuli, whereas specific-exemplar priming was measured as visual
repetition priming that was greater for same- than for
different-exemplar-primed stimuli. Results illuminated the role
serotonin may play in abstract and specific visual-form
processing.
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