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Abstract:
Abstract: Situational stressors and anxiety have been shown
to impede performance on "creativity" tests requiring cognitive
flexibility. Previous research revealed better performance on a
task requiring cognitive flexibility, the anagram task, after
taking propranolol (a beta-adrenergic antagonist) than after taking
ephedrine (a beta-adrenergic agonist). However, propranolol and
ephedrine have both peripheral and central beta-blocking
properties. In order to determine whether noradrenergic modulation
of cognitive flexibility is a centrally or peripherally mediated
phenomenon, we compared the effects of propranolol (peripheral and
central b-blocker), nadolol (peripheral beta-blocker), and placebo
on performance of the anagram task. Eighteen normal subjects
participated (9 male and 9 female) in the study. Each subject
attended three test sessions, one week apart. Prior to each test
session, the subjects were given one of the three drugs. Time taken
to complete each test item was recorded. The natural log of each of
the test item solution times was summed for each test session.
These test session scores were compared across the drug conditions
using analysis of variance (ANOVA). Anagram solution times after
propranolol were significantly lower than after nadolol (p=0.028).
This suggests that the modulatory influence of the noradrenergic
system on cognitive flexibility is centrally mediated.
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