At a retirement community in San Francisco, a 71-year-old woman is having her brain trained. She sits at a computer, poised to react to a sequence of sounds, like “baa, tack, tab, cat.” As she hears them, she clicks on the written equiva­lents on the computer screen. As her speed and accuracy improve, the sounds come faster, the sequences grow longer. The process, researchers say, could give her more years of auditory acuity.

Procedures like this one are a step toward realizing a radical vision: stopping, or at least forestalling, cognitive decline using interactive technologies. It’s the vision that animates the work of Michael Merzenich, a neuroscientist and cofounder of Posit Science in San Francisco, which is developing what he calls a “brain fitness program” -- a set of interactive training exercises for the mind. “If you haven’t played violin seriously for 10 years, you could recover your mastery with intensive practice,” says Merzenich, a professor at the University of California, San Francisco. “That’s what we’re trying to achieve with training.”