According to Stern and Greicius, this approach to the brain could reveal how diseases like Alzheimer's -- which may begin as a memory problem -- jump tracks and spread along these networks to other regions of the brain, disrupting areas dealing with personality and sleep.
Stern is also interested in what brain networks may reveal about why "superagers" stay sharp well into their golden years.
But Greicius cautions that memory training has not been proved to prevent or slow the effects of old age or dementia, despite the claims of the brain game industry.
In a 2014 open letter signed by study authors Greicius and Dresler, 75 scientists slammed the brain game industry's "exaggerated and misleading claims (that) exploit the anxiety of older adults."
"There's no real-world clinical connection at this stage whatsoever," Greicius said.
There is no indication a memory palace has any impact on everyday memory either, said Stern -- which may be why top memory athletes still lose their keys. The memory gains seem to appear only when using the memory palace.
When memory athletes are fooled -- by being told they won't be tested on a list of words and then getting quizzed by researchers anyway -- they don't perform much better than average, said Konrad, who is continuing to study his fellow memory athletes.
Konrad, who also trained the newcomers to build their first memory palace, said that one finding in particular stood out to him as motivating: Everyone improved, regardless of where they started.
Even for the reigning world champion, Mullen has managed to surprise himself when he thought he had hit a wall or reached a personal limit. He has come a long way since his college years, when he was frustrated with forgetting things from one class to the next, he said.
"Before I learned about the techniques, I was an average Joe Schmoe," Mullen said.
"Not to say that I'm not an average Joe Schmoe anymore," he added.
According to CNN.com