“We all have good days and bad days, times when we’re foggy, or when we’re sharp,” said Michael Kahana, who with Youssef Ezzyat led the research team. “We found that jostling the system when it’s in a low-functioning state can jump it to a high-functioning one.”
Researchers cautioned that implantation is a delicate procedure and that the reported improvements may not apply broadly. The study was of epilepsy patients; scientists still have much work to do to determine whether this approach has the same potential in people with other conditions, and if so how best to apply it. But in establishing the importance of timing, the field seems to have turned a corner, experts said.
Experts said the new report gives scientists a needed blueprint for so-called closed-loop cognitive stimulation: implanted electrodes that both monitor the functional state of memory areas, moment to moment, and deliver pulses only in the very microseconds when they’re helpful. The hope is that such sensitive, timed implants could bolster thinking and memory in a range of conditions, including Alzheimer’s and other dementias, as well as deficits from brain injury.
“The cool thing about this paper is that they showed why stimulation works in some conditions, and why it doesn’t in others,” said Bradley Voytek, an assistant professor of cognitive science and neuroscience at the University of California, San Diego, who was not involved in the work. “It gives us a blueprint for moving forward.”
Justin Sanchez, director of the biotechnologies office at the Pentagon’s Defense Advanced Research Projects Agency, which has doled out some $77 million to advance cognitive stimulation, said: “To me, this paper is one of the breakthrough moments on this problem, to find locations in the brain to stimulate in this particular way to boost performance.”
The new study is the latest chapter in an extraordinary, decades-long collaboration among cognitive scientists, brain surgeons and people with severe epilepsy being evaluated for an operation. The preoperative “evaluation” is a fishing expedition of sorts, in which doctors sink an array of electrodes through the top of the skull and wait for a seizure to occur, to see whether it’s operable. Many of the electrodes sit in or near memory areas, and the wait can take weeks in the hospital. Cognitive scientists use this opportunity, with patients’ consent, to present memory tests and take recordings.
This approach — called direct neural recording, and piggybacking entirely on the clinical placement of the electrodes — has become the leading edge of research…