Understanding the pathophysiology and treatment of Alzheimer's disease is vitally important. Alzheimer's disease threatens to affect currently at least 30% of all individuals currently alive in the 12 most financially developed countries, unless interventions are discovered to prevent or treat the disease. Although memory loss is the cardinal symptom of Alzheimer's disease, the pathophysiological mechanisms leading to cognitive deficits are poorly understood. It is difficult to address this problem in human studies, and impossible in cultured cells. Therefore, animal models are needed to elucidate the molecular mechanisms leading to dementia. A large number of animal models have focussed upon the role of amyloid plaques in the pathogenesis of Alzheimer's disease, because amyloid plaques are an essential diagnostic feature of the disease. However, the mechanism by which amyloid plaques or their principal molecular constituent, the amyloid-β protein (Aβ), disrupt cognitive function is not well understood. Herein, I describe my perspectiveon what we have learned about how Aβ impairs memory from research on Alzheimer's disease in mice and rats.