Cells behave differently when removed from their environments, just as cells that develop in cultures do not behave like cells in living creatures. To study the effects of Alzheimer’s disease in a more natural environment, scientists have successfully circumscribed this challenge by transplanting human neural cells into mouse brains containing amyloid plaques, one of the hallmarks of Alzheimer’s disease. The results of their research showed that, unlike mouse neurons, human neurons that developed in this environment were extremely susceptible to Alzheimer’s disease.