While we’re asleep at night, our brain is doing something incredible. The hippocampus and the neocortex, two of its key regions, talk back and forth, processing information for long-term storage—what’s known as memory consolidation. Catching Z’s, as it turns out, is critical for building our mental library. “During sleep, a magical process happens,” says Itzhak Fried, a neurosurgeon at the University of California at Los Angeles.

In a study recently published in Nature Neuroscience, Fried and his team have discovered that this process can be hacked. By gently stimulating the brain’s frontal lobe (part of the neocortex) in sync with the electrical waves of the hippocampus during sleep, the team improved the accuracy of recognition memory—the ability to recognize things previously encountered—in patients with epilepsy. They hope that this sort of stimulation might one day help improve memory for people with other brain disorders—like Parkinson’s or Alzheimer’s.

The idea that sleep is important for memory is not new, and was of interest to the likes of Sigmund Freud. In recent years, scientists have used animals to determine how exactly that process might occur. By looking at the mouse brain, they found that the hippocampus, the brain’s memory hub, generates little bouts of high-frequency “ripples” thought to be useful in long-term memory. Likewise, the neocortex (which governs things like movement and language) and the thalamus (close to the brain’s center) emit more prolonged waves—known as slow waves. According to Gyorgy Buzsaki, a neuroscientist at New York University, a synchronized dance between these ripples and slow waves is what generates successful memories during sleep.

The neocortex’s slow wave, Buzsaki says, is an interplay of “up” and “down” states. “Sometimes, the neocortex is active and is ready to take in [information],” he says. “Other times, it’s just dead—in the down state.” If those hippocampal ripples travel to the neocortex during its down state, the messages are not well-received—which is why coordination between the two parts of the brain is so important.

Fried and his team wondered if enhancing this synchronized dance between the hippocampus and neocortex might improve memory consolidation during sleep. To test this hypothesis, they turned to a select group of patients. These people, who had a form of epilepsy unresponsive to drug treatment, already had electrodes implanted in various areas of their brain for clinical reasons. “It’s a very rare opportunity to look at brain activity from the inside with very high precision, since these electrodes are implanted in brain regions that are important for memory and sleep,” says Yuval Nir, a neuroscientist at Tel Aviv University in Israel and a coleader of the study.

The scientists focused on two electrodes inside the brain: one to measure wave activity near the hippocampus and another in the brain’s frontal lobe to deliver the stimulation. During the active (“up”) state of the slow wave, the electrode inside the frontal lobe would deliver a series of brief and gentle pulses. Nir describes this as “listening” to the hippocampus—using its wave patterns to determine when it was trying to communicate information to other parts of the brain. “Then we gave very precise and minor stimuli in the cortex—sort of like a pinch—to wake it up and make it be attentive so that it could receive the message from the hippocampus,” he adds.