Terry Sejnowski, professor and head of the Computational Neurobiology Laboratory at the Salk Institute for Biological Studies, has also studied sleep’s role in memory. Sejnowski sees Born’s findings as an important advance in the study of memory consolidation.
“Previous studies only showed that memory improvements were correlated with brain oscillations, and only for nonfactual forms of memory, such as motor learning,” says Sejnowski. “This study provides evidence that the link between sleep and memory is causal and may lead to a practical way to improve memory.”
Born agrees with this last point, and he believes that someday electrical stimulation during sleep may be a possible therapy for those with memory-loss problems.
However, others like Jerome Siegel are wary of linking sleep with memory. Siegel, a psychiatrist at the University of California at Los Angeles and head of its Center for Sleep Research, says that while sleep may have some role in forming memories, it is not an essential role. He warns that there is a danger in misinterpreting data when trying to establish a causal role.
“You have to wonder to what extent you are getting chance results just because you measure a lot of variables,” says Siegel. “Also, there’s the performance issue, where if sleep is deeper, performance is better, and it’s different from memory.”
In future studies, Born plans to tease out the many variables from this initial experiment by looking at the effects of specific currents and whether applying them for varying amounts of time will have significant effects.
“We also have a plan to see if you can use stimulation not only to intensify an ongoing sleep stage like non-REM sleep,” says Born, “but if you can, for example, change the brain state from the waking state into the sleeping state, which is so far what we see as a dream–the researcher’s dream.”