In Parkinson's disease, neurons of the striatum become dysregulated. Therefore signals are not processed correctly and as a consequence the symptoms of PD arise. Lentiviral vectors transduce both dividing and non-dividing cells in the brain and we have shown that they can be targeted to certain cell types. We will combine the recent development of short interference RNA technology (siRNA) to knock-down specific genes in mammalian cells with our lentiviral vectors to specifically tragett the dysregulated neurons and will evaluate the functional outcome of this in a pre-clinical model of PD. The effect will be evaluated using behavioral testing as well as molecular techniques. If successful, these experiments may provide a new therapeutical tool for PD.