Impulse control disorders (ICDs) are increasingly reported as a considerable side-effect
of treatment with dopaminergic medication (both levodopa and dopamine agonists (DA)).
ICDs together with punding are described within the entity of dopamine dysregulation
syndrome along with immediate reward seeking and addictive behaviors. The brain functions
involved in reward processing in general and their modulation by medication can be
characterized by neuropsychological assessments and underlying neurobiology can be
investigated by functional neuroimaging techniques such as functional magnetic resonance
imaging (fMRI) or positron emission tomography (PET). By this approach, functional
changes of brain areas involved in reward processing under short-term or chronic DA
therapy were studied. Functional changes in a network involving striatal-thalamic
loops, key structures of the reward system, together with limbic areas (such as the
amygdala) and the ventral tegmental area could be related to pharmacological alterations
of reward processing by dopaminergic medication. In particular, altered ventral striatal
functioning seems to relate to ICDs such as pathological gambling. A general medication
effect in patients under DA in terms of a sensitization toward ICD could be demonstrated.
A synopsis is given on the applications of functional neuroimaging to investigate
reward processing and the influence of dopaminergic medication.