Around 150 people aged 65 and over took a test to try and improve their memory. In this Boston experiment, they received a form of noninvasive electrical brain stimulation for four consecutive days. Each session lasted 20 minutes. The results are revealed this Monday in the scientific journal Natural neuroscience: Two types of memory of study participants improved for at least one month. The team now wants to know if the effects of this stimulation can last longer and explore how the transition to clinical practice can be made.