 altered Ca2 plus signalling is involved in the pathogenesis of Alzheimer's disease. Here, the authors show Ca2 plus hypoactivity in astrocytes a plaque deposition onset related to reduced expression of the Ca2 plus sensor STIM1 and impaired synaptic plasticity that was rescued by STIM1 over expression in astrocytes. This article was authored by Anna Maria Lea, Gabrielle Sanseveiro, Angela Ciavigato, and others.