1. ¹Department of Experimental Psychology, Behavioural and Clinical Neurosciences Institute, University of Cambridge, Cambridge, UK
2. ²Cambridge Centre for Brain Repair, Cambridge, UK

Correspondence: Dr R Cools, Department of Experimental Psychology, Behavioural and Clinical Neuroscience Institute, University of Cambridge, Downing street, Cambridge, Cambridgeshire CB2 3EB, UK. Tel: +44 1223 333587; Fax: +44 1223 333564; E-mail: roshan.cools@gmail.com

Received 24 February 2006; Revised 16 May 2006; Accepted 30 May 2006; Published online 12 July 2006.

Abstract

Evidence indicates that dopaminergic medication in Parkinson's disease may impair certain aspects of cognitive function, such as reversal learning. We used functional magnetic resonance imaging in patients with mild Parkinson's disease to investigate the neural site at which L-DOPA acts during reversal learning. Patients were scanned both ON and OFF their normal dopamine-enhancing L-DOPA medication during the performance of a probabilistic reversal learning task. We demonstrate that L-DOPA modulated reversal-related activity in the nucleus accumbens, but not in the dorsal striatum or the prefrontal cortex. These data concur with evidence from studies with experimental animals and indicate an important role for the human nucleus accumbens in the dopaminergic modulation of reversal learning.