Emotional processing in Parkinson's disease: a systematic review.

Parkinson's disease provides a useful model for studying the neural substrates of emotional processing. The striato-thalamo-cortical circuits, like the mesolimbic dopamine system that modulates their function, are thought to be involved in emotional processing. As Parkinson's disease is histopathologically characterized by the selective, progressive, and chronic degeneration of the nigrostriatal and mesocorticolimbic dopamine systems, it can therefore serve as a model for assessing the functional role of these circuits in humans. In the present review, we begin by providing a synopsis of the emotional disturbances observed in Parkinson's disease. We then discuss the functional roles of the striato-thalamo-cortical and mesolimbic circuits, ending with the conclusion that both these pathways are indeed involved in emotional processing.