When mice are dosed with the toxic compound MPTP, the dopaminergic neurons in the midbrain are killedn resulting in a phenotype that resembles that of Parkinson's disease in humans. Using lightsheet imaging it is possible to quantify the absolute number of TH positive neurons in the adult mouse brain. The combination of MPTP treatment and lightsheet imaging can therefore be used to qualify therapeutic approaches aimed at treating Parkinson's disease in humans.