Better Memory through Electrical Brain Ripples?

Better Memory through Electrical Brain Ripples

Simon Makin

However, nobody had manipulated ripples to enhance memory—until now, that is.

Researchers at NYU School of Medicine led by neuroscientist György Buzsáki have now done exactly that. In a June 14 study in Science, the team showed that prolonging sharp wave ripples in the hippocampus of rats significantly improved their performance in a maze task that taxes working memory—the brain’s “scratch pad” for combining and manipulating information on the fly. “This is a very novel and impactful study,” says Jadhav, who was not involved in the research. “It’s very hard to do ‘gain-of-function’ studies with physiological processes in such a precise way.” As well as revealing new details about how ripples contribute to specific memory processes, the work could ultimately have implications for efforts to develop interventions for disorders of memory and learning.

The researchers first examined the properties of ripples recorded in rats performing tasks from a database acquired over years of experiments. They found more long-duration ripples occurred when rats had to make their way through mazes than when they were simply exploring or running along tracks. Negotiating mazes required rats to exercise their memories.

In one task, the M-maze, rats were trained to first navigate through the right-hand arm of a maze shaped as an “M” to receive a sugary reward, then through the left-hand arm on the next trial. The researchers saw significantly longer ripples in trials the rats performed correctly, compared to those they got wrong. “You can record a very simple electrical pattern in the brain and tell whether the animal's performance will be good or not, or whether the animal is learning or not,” Buzsáki says. These findings suggest that the hippocampus generates longer ripples during memory-intensive activities, and that these longer-duration signals improve performance.