Volume 5 of the series "Advances in Research on Neurodegeneration" is concerned with themes which are currently the focus of intensive research, and in which advances in our understanding of the pathological mechanisms un­ derlying neurodegenerative diseases are expected in the near future. The first section contains five reviews devoted to the various neuroimaging technolo­ gies. The discussion is concerned with the question of whether neuroimaging techniques make it possible to follow the process of degeneration as it occurs, and which methods offer the required sensitivity and quantifiability for this purpose. However, the question needs to be examined of whether, given the physical and chemical limitations of these techniques, even under optimal conditions, anatomical resolution can be improved to the extent that neuro­ degenerative diseases can be diagnosed earlier than currently possible and a confident diagnosis made. The possibilities of using neuroimaging techniques to provide information regarding the effects of neuroprotective or neuroregen­ erative therapeutic strategies, and for correlating the results of neuropsycho­ logical research with imaging data are also discussed. The second section is concerned with the significance of endogenous or exogenous neurotoxins as triggers for neurodegenerative processes that may lead to Parkinsonism. Vulnerability factors, which include such factors as nerve ending sensitivity, the synergistic effects of drugs and the various mechanisms underlying different toxins are discussed.