Additional Study Information: A clinical trial that uses focused ultrasound to non-invasively open the blood-brain barrier in Alzheimer's disease patients, in order to help get medication into their brain. In this study, we will focus on the safety and efficacy of this technique, without the use of an anti-Alzheimer's drug. We will also test whether treatment with focused ultrasound alone alters the amyloid protein levels in the treated brain areas and its potential effects on the cognitive function of Alzheimer's patients.