AUTHOR=Moustafa Ahmed A. TITLE=Levodopa Enhances Reward Learning but Impairs Reversal Learning in Parkinson's Disease Patients JOURNAL=Frontiers in Human Neuroscience VOLUME=4 YEAR=2011 URL=https://www.frontiersin.org/journals/human-neuroscience/articles/10.3389/fnhum.2010.00240 DOI=10.3389/fnhum.2010.00240 ISSN=1662-5161