Decoding the "secret code" that the brain uses to encode fleeting memories

Working memory is a cognitive system of limited use and capacity, which is responsible for temporarily storing information available for processing, which allows information to be retained and processed temporarily for short periods of time

For decades, scientists have wondered how and where the brain encodes fleeting memories. One theory proposes that working memory depends on special 'stores' in the brain, separate from where the brain deals with sensory information from the eyes or nose, and another opposing theory suggests that there are no such private stores at all.

Here, these two theories are challenged by a new study , published April 7 in the journal Neuron. Instead of reversing what happens during cognition or relying on special memory stores, working memory appears to collect and extract the most relevant sensory information from the environment and then summarize it Its relatively simple code.

Working memory is a cognitive system of limited use and capacity, responsible for temporarily storing information available for processing, that allows people to hold and temporarily process information for short periods of time, used, for example, when you look up a phone number and then briefly remember the sequence of numbers in order to call, or When you ask a friend for directions to a place and then follow the turns to get to it.

Modern tablet displaying MRI brain scan

Working memory essentially acts as a bridge between perception (when we read a phone number) and action (when we dial that number). The term working memory is often used similarly or synonymously with short-term memory, but many theorists assert a significant difference between them. Working memory allows processing and altering stored information, while short-term memory refers to only temporarily storing information.

Working memory puzzles

“There has been evidence for decades that what we store (in working memory) may be compromised ,” senior study author Clayton Curtis, a professor of psychology and neurosciences at New York University, said in a report to Live Science in an email. It will be different from what we imagine."

To solve the puzzles of working memory, Curtis and Yona Kwak, a doctoral student at New York University, used a brain-scanning technology called functional magnetic resonance imaging (fMRI) that measures brain activity by monitoring changes associated with blood flow to different parts of the brain.

This technology is based on the fact that brain blood flow and neuronal activation are linked, and when an area of ​​the brain is in use, blood flow to that area also increases, so this technology provides an indirect measure of brain cell activity.

The team used this technique to scan the brains of 9 volunteers as they performed a task that occupied their working memory. In one experiment, participants watched a circle of gratings on a screen for about 4 seconds; Then the graphic disappeared, and after 12 seconds, the participants were asked to remember the angle of the slash.

In other experiments, participants watched a cloud of moving points that all turned in the same direction, and were asked to remember the exact angle of movement of the point cloud.

Participants were asked to pay attention only to the direction of diagonal lines or the angle of movement of a point cloud, so the researchers hypothesized that their brain activity would only reflect those specific features of the graphics, and that's what they actually found when the team analyzed later brain-scan data.

A major step forward

The researchers used computer modeling to visualize complex brain activity, creating a type of topographic map that represented activity in different groups of brain cells, which helped them understand how participants' brain activity correlated with what they observed on a screen during a memory task.

Experts in imaging and radiology study images of patients by computer monitors

This analysis reveals that instead of encoding all the minute details of each graphic, the brain stored only relevant information needed for the task. Line-like patterns of brain activity appeared in the visual cortex, where the brain receives and processes visual information, and the parietal cortex is a key area for processing and storing memory.

Derek Ni, assistant professor of psychology and neuroscience at Florida State University, tells Live Science in an email that the new work represents a "key step forward" in the study of working memory. "This study provides unprecedented insight into this mysterious intermediate region between cognition and action," he added.

One limitation of the study is that the team used highly simplified graphics, which do not necessarily reflect the visual complexity of the real world. This limitation extends to many studies of working memory. "The field will need to move toward richer stimuli that better match our natural visual experiences to move us from the laboratory to the practical utility," the academic concluded.

Source : Live Science