Image of Human Neurons (image) Humane Society International Share Print E-Mail Caption Stylised photograph of human neuronal cells in connection with each other. Parkinson's disease is a progressive neurodegenerative that affects nerve cells in the basal ganglia and the substantia nigra. Credit CIPhotos Usage Restrictions Image is purchased and downloaded from istock and must only be used in accordance with their restrictions. Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.