HOW BRAIN FORM MEMORIES

In brief

A research team mapped the electrical connections generated when surgical patients with electrodes implanted directly on their brains created memories. Using this information, they were able to generate the first whole-brain map of electrical connections in the brain during memory creation.

Which way to the amygdala?

What’s a computation device that we all carry with us, that holds all of the most important information about our lives, and that does so without us knowing exactly how? No, not our smartphones — our brains. Now, neuroscientists at the University of Pennsylvania (Penn) have moved one step closer to cracking how the dense masses of fat in our skulls create memory, and they did so by constructing the first whole-brain map of electrical connections in the brain.

To generate their whole-brain map, the Penn researchers gathered data from nearly 300 neurosurgical patients who had electrodes implanted directly on their brains as part of their seizure monitoring. Each patient was shown a series of words on a screen and then asked to repeat back as many of the words as they could recall.

The researchers found that when a person was effectively creating a new memory — in this case, remembering a word they saw on the screen — their brain showed heightened low-frequency activity. This type of activity primarily drives communication between the frontal, temporal, and medial lobes, parts of the brain that are key to processing events into memories. At the same time, the patient’s brain also showed weaker high-frequency activity.

“This suggests that, for someone to form new memories, two functions must happen simultaneously,” Ethan Solomon, an M.D./Ph.D. student in Penn’s Department of Bioengineering and the paper’s lead author, said in a press release. “Brain regions must individually process a stimulus, and then those regions must communicate with each other at low frequencies.”