From treating depression to curtailing the effects of Parkinson's disease to awakening patients in a vegetative state, stimulating the brain with electrical currents holds all kind of potential. One very promising branch of this research centers on arresting cognitive decline by boosting memory and learning, and a string of recent studies have uncovered its exciting potential in this regard. The latest, conducted by scientists at Boston University, has outlined a non-invasive technique that was able to restore working memory in 70-year-old subjects, so much so they functioned like a healthy 20-year-old.

A good deal of the research on brain stimulation makes use of electrodes implanted into specific parts of the organ to deliver electrical pulses with great precision. This, known as Deep Brain Stimulation, has its advantages in that it allows greater targeting of certain brain regions, but implanting electrodes into a patient's brain simply isn't practical all of the time.

Alternatively, the stimulation can be delivered non-invasively through electrodes placed on the scalp, which is easier to apply and study. This was the method adopted by Rob Reinhart, a neuroscientists at Boston University, in seeking to enhance the minds of older folks whose memory may be slipping.

More specifically, his experiments focused on working memory, the active part of our brains that kicks into gear when we remember which items to grab at the grocery store, make decisions, or find our car keys. According to Reinhart, this can start to deteriorate as early as our late 20s as different sections of the brain grow apart and become uncoordinated. When we reach 60 or 70, this disconnect can result in observable cognitive decline.

Now he has discovered a way to rebuild the broken pathways, and it centers on two elements of brain function. The first is "coupling," which refers to when the various rhythms bouncing around in different parts of the brain work together in just the right way, just like a well-managed orchestra. The other is "synchronization," when slower rhythms known as theta rhythms, are properly in synch. Both of these functions deteriorate as we age, and take our memory skills along with them.

For his study, Reinhart enlisted a healthy group of subjects in their 20s, along with a group in their 60s and 70s, and had them all perform memory tasks. This meant viewing an image, taking a pause, viewing a second image, and then determining whether the second was slightly different to the original.

Unsurprisingly, the younger group performed much more accurately than the older group. But then Reinhart had 25 minutes of mild stimulation applied to the older subjects' scalps, with the pulses tuned to each patient's neural circuits. Thereafter, the performance gap between the groups disappeared and lasted at least 50 minutes after the stimulation. What's more, Reinhart found that he was able to boost memory function in even the young subjects who had performed poorly in the tasks.

"We showed that the poor performers who were much younger, in their 20s, could also benefit from the same exact kind of stimulation," Reinhart says. "We could boost their working memory even though they weren't in their 60s or 70s."

From here, Reinhart hopes to continue exploring how brain stimulation can improve the brain circuitry of humans in other ways, with Alzheimer's sufferers a particular point of focus.

"It's opening up a whole new avenue of potential research and treatment options," he says. "And we're super excited about it."

The research was published in the journal Nature Neuroscience.

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