As the most common form of age-related dementia, Alzheimer's disease (AD) is an enormous and growing problem for an aging society. AD is a neurodegenerative disorder like Parkinson's disease (PD), but the former presents as a cognitive disorder, and the latter as a motor disorder (at least in early stages). The reason for this is not so much what happens (ultimately cell death in both cases), but *where* it happens (respectively, the entorhinal cortex, or EC, or the substantia nigra). This project attempts to explore what is it about the EC that makes it particularly susceptible to the pathological processes underlying AD, with particular emphasis on the role of activity. To do this, we combine transgenic lines we have created which allow us to manipulate the activity of neurons in this region with transgenic models of AD, and record the effects on both activity and AD-like phenotypes.