Technion Prof. Simone Engelender and Harvard Medical School Prof. Ole Isacson say the toxic protein behind Parkinson’s disease may not spread like an infection from nerve cell to nerve but rather that the protein, called alpha-synuclein, may simultaneously affect all parts of the nervous system inside and outside of the brain. They describe this game-changing insight as “threshold theory” of Parkinson’s for the first time in a report recently published in Trends in Neuroscience.