"Working memory" is a critical cognitive process. The "secret code" the brain uses to create a key type of memory has finally been cracked. This type of memory, called working memory, is what allows people to temporarily hold on to and manipulate information for short periods of time. You use working memory, for example, when you look up a phone number and then briefly remember the sequence of digits in order to dial, or when you ask a friend for directions to a restaurant and then keep track of the turns as you drive there. The new work represents a "fundamental step forward" in the study of working memory, Derek Nee, an assistant professor of psychology and neuroscience at Florida State University, told Live Science in an email. A critical process For decades, scientists have wondered how and where the brain encodes transient memories. One theory suggests that working memory relies on special "storehouses" in the brain, separate from where the brain handles incoming sensory information from the eyes or nose, for instance, or where long-term memories — like memories of who you attended prom with, or foundational knowledge you learned in school — are stored, said Nee, who was not involved in the new study. Another, opposing theory suggests that "there are no such special storehouses," Nee told Live Science. In this alternate theory, working memory is essentially an emergent phenomenon — one that shows up "when sensory and motor representations are kept around as we link the past to the future," Nee said. According to this theory, the same brain cells light up when you first read through a phone number as do when you run through that number again and again in working memory. The new study, published April 7 in the journal Neuron, challenges both of these theories. Rather than reflecting what happens during perception or relying on special memory storehouses, working memory seems to operate one step up from sensory information gathering; it extracts only the most relevant sensory information from the environment and then sums up that information in a relatively simple code. "There have been clues for decades that what we store in [working memory] might be different from what we perceive," study senior author Clayton Curtis, a professor of psychology and neural science at New York University (NYU), told Live Science in an email. To solve the mysteries of working memory, Curtis and co-author Yuna Kwak, a doctoral student at NYU, used a brain scanning technique called functional magnetic resonance imaging (fMRI), which measures changes in blood flow to different parts of the brain. Active brain cells require more energy and oxygen, so fMRI provides an indirect measure of brain cell activity. The team used this technique to scan the brains of nine volunteers while they performed a task that engaged their working memory; the two study authors also completed the task and contributed brain scans to the study. In one of the trials, the participants viewed a circle composed of gratings, or slashes, on a screen for roughly four seconds; the graphic then disappeared, and 12 seconds later, the participants were asked to recall the angle of the slashes. In other trials, the participants viewed a cloud of moving dots that all shifted in the same direction, and they were asked to recall the exact angle of the dot cloud's motion. "We predicted that participants would recode the complex stimulus" — the angled grating or moving dots — "into something more simple and relevant to the task at hand," Curtis told Live Science. Participants were only asked to pay attention to the orientation of the slashes or angle of the dot cloud's motion, so the researchers theorized that their brain activity would reflect only those specific attributes of the graphics. And when the team analyzed the brain scan data, that's just what they found. Source
