The most fascinating and unique feature of prion diseases is that they are caused almost exclusively by a proteinaceous and infectious particle termed prions by the Nobel Prize laureate S B Prusiner, who discovered this class of pathogens. In the latter part of the 1990s, mad-cow disease, a disease caused by prions acquired through foodborne transmission, raised unprecedented public concern due to the concrete possibility that prions in animals could be transmitted to humans through the food chain. For roughly two decades, prions were under intense scrutiny and many studies were undertaken worldwide. These investigations have led our community to a better risk assessment and management of prion diseases in humans and in animals, substantially limiting the possibility of new prion epidemics. Nowadays, prions have been brought once again to the foreground after the discovery that a variety of neurodegenerative diseases, in particular Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis, share fundamental features with prions, including protein misfolding and aggregation in the brain, cell-to-cell transmission and in vivo infectivity. Therefore, studying prions might help to understand the pathological mechanism of these disorders. The Prion Phenomena In Neurodegenerative Diseases: New Frontiers in Neuroscience is a book that benefits from the contribution of leading scientists in different fields of neuroscience, including Gianluigi Zanusso, Holger Wille, Fabrizio Tagliavini, Andrew F Hill, Jerson L Silva, Vladimir N Uversky, Henrike Heise, David W Colby, Neil R Cashman and the Nobel Prize laureate Eric R Kandel. This chapter collection discusses the development of prions and their various diseases, and provides a detailed overview about the state of the art of the novel prion phenomena observed in other fatally damaging protein misfolding disorders. This book represents an up-to-date review of different protein-misfolding diseases, serving as an invaluable tool for both specialized researchers working in the field of neurodegeneration and for a broad spectrum of academic readers that wish to learn more about the prion phenomena.