Cedars-Sinai Blog

Making Memory: New Study Explains the Brain's RAM

An MRI of a brain

"This study is the first clear demonstration of precisely how human brain cells work to create and recall short-term memories"

Scientists are still trying to nail down exactly how and where our brains store memories. Last week, Cedars-Sinai scientists linked a specific set of brain cells with short-term memory. This discovery may help develop treatments for Alzheimer's diseaseepilepsy, and other diseases that impair memory.

"This study is the first clear demonstration of precisely how human brain cells work to create and recall short-term memories," said Ueli Rutishauser, PhD, associate professor of Neurosurgery and the study's senior author. "Confirmation of this process and the specific brain regions involved is a critical step in developing meaningful treatments for memory disorders that affect millions of Americans."

The findings reveal new information on how our brains store and maintain short-term memories. Short-term memory—the ability to remember ideas, thoughts, images, and objects for seconds or minutes—is critical for making decisions and mental calculations.

"Because impaired short-term memory severely weakens someone's ability to complete everyday tasks, it is essential to develop a better understanding of this process so new treatments for memory disorders can be developed," said Jan Kamiński, PhD, a neuroscientist at Cedars-Sinai and lead author of the study.

Researchers found persistently active neurons in the medial frontal lobe and medial temporal lobes of the brain that stayed active even after the person stopped looking at an image. Previously, scientists believed the medial temporal lobe was only involved in forming new long-term memories, but this study shows both these areas in the brain are important for short-term memory function.

"A surprising finding of this new study is that some of the persistently active neurons were only active if the patient memorized a specific image," Kamiński said. "For example, the researchers discovered a neuron that reacted every time the patient memorized an image of Han Solo, a character in the movie Star Wars, but not any other memory."

In Discoveries: Eyes on the Brain

The study was conducted with patients who were being treated at Cedars-Sinai for severe epilepsy, and who had electrodes implanted in their brains to locate the source of their seizures. These patients were shown a sequence of three images, followed by a 2-3 second delay. Then they were shown another image and asked to decide whether they’d already seen the image.

"We noticed that the larger the increase in activity, the more likely the patient was to remember the image," said Dr. Adam M. Mamelak, director of Functional Neurosurgery at Cedars-Sinai and the study’s co-author. "In contrast, if the neuron’s activity was weak, the patient forgot the image and thus lost the memory."

Read the full study findings at Nature Neuroscience.