Short-term memory: New research reveals clues to its functioning

Researchers Cedars-Sinai University Hospital, USA, have discovered how brain cells responsible for working memory (the type needed to remember, for example, a telephone number long enough to dial it) coordinate intentional concentration and storage of information short term.

The study, published in the journal Nature, sheds light on the complex processes involved in this critical aspect of life. Memory.

working memoryallowing the brain to store information for only a few seconds. fragile and requires constant attention to maintain. According to the doctor Uli RutishauserDirector Cedars-Sinai Center for Neuroscience and Medicine and lead author of the study, working memory can be affected by various diseases and conditions, such as Alzheimer’s disease or disorder Attention deficit and hyperactivity disorder.

“We believe that understanding the management aspect of working memory will be fundamental to the development of new treatments for these and other neurological conditions,” Rutishauser said.

To study how working memory works, the researchers recorded the brain activity of 36 hospitalized patients who had electrodes surgically implanted in their brains as part of a diagnostic procedure. epilepsy.

On a computer screen, patients were shown one photograph or a series of three photographs of different people, animals, objects or landscapes. The screen then goes dark for just under three seconds, causing patients to remember the photos they just saw. They were then shown another photo and asked to decide whether it was the same photo (or one of three) they had seen before.

When patients perform a task working memory were able to respond quickly and accurately, the researchers observed the activation of two groups of neurons: “category” neurons that are activated in response to one of the categories shown in the photographs, such as animals, and “phase-amplitude-coupled” neurons or PAC neurons.

The newly identified PAC neurons in this study do not contain any content but use a process called phase-amplitude coupling to ensure that Category neurons focus and store content they have purchased.

PAC neurons are activated simultaneously with theta waves brain, which are associated with concentration and control, as well as gamma waves, which are associated with information processing. This allows them to coordinate their activity with categorical neurons, improving patients’ ability to recall information stored in working memory.

“Imagine that when a patient sees a photo of a dog, his categorical neurons start activating the command “dog, dog, dog,” and his PAC neurons fire the command “focus/remember,” Rutishauser said.

“Thanks to phase-amplitude coupling, two groups of neurons create harmony their messages overlap, resulting in “remember the dog.” It is a situation in which the whole is greater than the sum of its parts, as if we were listening to the musicians of an orchestra playing together. The director, like the PAC neurons, coordinates the actions of the various actors so that they act harmoniously.”

PAC neurons They do their job in hippocampus, a part of the brain that has long been known to be important for long-term memory. This study offers the first evidence that the hippocampus also plays a role in the control of working memory.

This research was conducted as part of a multi-institutional consortium funded by the National Institutes of Health’s Brain Research Initiative through Advancing Innovative Neurotechnologies or BRAIN Initiativeand is led by Cedars-Sinai in collaboration with the University of Toronto and Johns Hopkins School of Medicine.

“One of the goals BRAIN Initiative is to discover, through innovative technologies, properties of the human brain that have until now been difficult, if not impossible, to study,” said John Ngai, Ph.D., director of the NIH BRAIN Initiative.

“Here, taking advantage of the unusual opportunities presented by an initiative to illuminate complex processes in the human body, the Rutishauser laboratory sheds light on how certain neurons support the way memories are stored in the brain, a process that is far from being “understood in destructive processes.” brain disorders such as Alzheimer’s disease and other types of dementia.”

Other Cedars-Sinai authors involved in this study include Jan Kaminski, Umais Khan, Michael Kizar, Crystal Reed and Adam Mamelak. The study also included Andrea Shetnan and Tawfik Valiante of the University of Toronto, and Youssef Salimpour and William Anderson of the Johns Hopkins School of Medicine.