Study identifies brain process vital to short-term memory

Feb. 20 (UPI) -- Researchers at Cedars-Sinai Medical Center in Los Angeles have discovered the process the brain uses to create and maintain short-term memories.

The study showed how the persistently active neuron, a type of brain cell, remains active for several seconds when a person is required to memorize an object or image and recall it later.

"This study is the first clear demonstration of precisely how human brain cells work to create and recall short-term memories," Ueli Rutishauser, Ph.D., associate professor of neurosurgery in the Cedars-Sinai Department of Neurosurgery and senior author of the study, said in a press release. "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."

Neurosurgeons at Cedars-Sinai implanted electrodes to locate the source of seizures in 13 epilepsy patients and studied the electrical activity of individual neurons while patients performed certain memory tests. Patients viewed a sequence of three images followed by a 2- to 3-second delay. Patients were then shown another image and were asked to decide whether they had seen the image before.

Researchers found persistently active neurons in the medial frontal lobe and in the medial temporal lobe that remained active even after the patient stopped looking at an object or image. The medial temporal lobe was believed to only be involved in the formation of new long-term memories, but the new findings show that both areas of the brain maintain short-term memory and use the activity of the neurons for memorization.

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

The study was published in Nature Neuroscience.