"Welltimed pulses from electrodes implanted in the brain can enhance memory in some people scientists reported http on Thursday in the most rigorous demonstration to date of how a pacemakerlike approach might help reduce symptoms of dementia head injuries and other conditions. The report is the result of decades of work decoding brain signals helped along in recent years by large Department of Defense grants https intended to develop novel treatments for people with traumatic brain injuries a signature wound of the Iraq and Afghanistan wars. The research led by a team at the University of Pennsylvania is published in the journal Current Biology. Previous attempts to stimulate human memory with implanted electrodes had produced mixed results Some experiments seemed to sharpen memory but others muddled it. The new paper resolves this confusion by demonstrating that the timing of the stimulation is crucial. Zapping memory areas when they are functioning poorly improves the brains encoding of new information. But doing so when those areas are operating well  as they do for stretches of the day in most everyone including those with deficits  impairs the process.  We all have good days and bad days times when were foggy or when were sharp said Michael Kahana who with Youssef Ezzyat led the research team. We found that jostling the system when its in a lowfunctioning state can jump it to a highfunctioning 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 socalled closedloop 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 theyre helpful. The hope is that such sensitive timed implants could bolster thinking and memory in a range of conditions including Alzheimers 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 doesnt 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 Pentagons Defense Advanced Research Projects Agency which has doled out some  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 right hemisphere of a study participants brain. The electrodes are overlaid in blue and the one researchers targeted for stimulation is toward the right highlighted in yellow.CreditJoel Stein and Youssef Ezzyat The new study is the latest chapter in an extraordinary decadeslong 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 its 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 into the biology of human memory. This study used data from  patients and had  collaborators from institutions around the country including Emory University the University of Washington the Mayo Clinic and the University of California San Francisco. In a series of experiments the researchers had patients memorize lists of words and later after a distraction asked them to freely recall as many of the words as they could. All the while the scientists monitored a handful of hot spots in the brain which previous work had shown were strongly related to memory encoding. Before the stimulation tests the team determined the precise settings for each patients high and lowfunctioning states. Each participant carried out the wordmemorization tests repeatedly with different words every time some lists were memorized with brain stimulation and other lists with no stimulation which served as a control. The authors then examined memory performance based on whether stimulation arrived during low compared with highfunctioning brain states. The team then statistically analyzed the results and found that people scored slightly higher than usual on words when stimulation arrived during a low or foggy state  and worse when the pulse arrived in a high state. The average enhancement effect was about  to  percent Dr. Kahana said. And when stimulation arrived in a good state the average was about  to  percent worse than usual. Dr. Doris Greenblatt a psychiatrist who participated in the trial at Emory said she sought the surgery because her epilepsy had long caused memory problems. Each seizure I had tore at the fabric of memory and it was as if my memories werent attached to anything Dr. Greenblatt said. She agreed to the memory testing for the study. It was a little humiliating to be honest she said of the testing. I would remember one or two items from a list of objects in a kitchen for instance then think Oh no what else was there  She said she had no idea whether the electrodes in her brain were stimulating or not. All I can say is that it was exhausting and I worried about how I was doing. She had the surgery for her epilepsy a year ago with Dr. Robert Gross and has not had a seizure since her memory is also improved she said. The timed component in this study represented a clear break from previous approaches. In  the Defense Department had funded another group testing stimulation in epilepsy patients  directly to a brain area near the hippocampus which is crucial to memory formation. That approach did not take into account brain states the high and low function and it was not successful. To me said Dr. Voytek the new approach is a clear demarcation that the era of dumb stimulators is over."