February 12, 2010

Resting May Boost Memory

Photo of a woman resting on the grass

Memories grow stronger when people take a break to rest, according to a new study. The finding may have important implications for how students study and how people can best learn new things.

The brain’s hippocampus region is critical for creating a memory, but long-term storage of a memory—called memory consolidation—is thought to involve interactions between the hippocampus and parts of the brain’s cortex. Scientists believe that memories are "replayed," with the brain reactivating the same patterns of activity as during the experience itself. Several studies have suggested that this happens during sleep.

Sleep is unlikely to be the only time memories can be consolidated. A team at New York University led by Arielle Tambini and Dr. Lila Davachi set out to investigate whether memories could be consolidated while we’re awake but resting. Previous studies had found links in activity between hippocampus and cortical activity during rest, but the significance of the correlations was unclear. Their work was supported by NIH’s National Institute of Mental Health (NIMH) and Dart Neuroscience.

The researchers scanned the brains of 16 people using functional magnetic resonance imaging during 2 different tasks as well as during rest periods before and after the tasks. The scientists focused on the hippocampus and on regions known to be involved in visual processing. The people were shown either a human face and an object, such as a beach ball, or a human face and a scene, such as a beach. They weren’t told that their memory for the images would later be tested. Rather, they were simply instructed to rest and think about anything they wanted to as long as they remained awake.

The results appeared in the January 28, 2010, issue of Neuron. As expected, correlations between the brain regions were low during the initial period of rest and high when the people were shown any of the object pairs.

The memory for object-face pairs proved to be significantly better than for scene-face pairs. Activity between the hippocampus and one region of the cortex—a portion of the lateral occipital complex—correlated significantly during the rest period after the people saw the object-face pairs. In contrast, the researchers detected no connection between the regions after people saw the scene-face pairs. The higher the correlation between the brain regions during the later rest period, the researchers found, the better the person remembered the object-face pair.

These results strongly suggest that the hippocampus and a portion of the lateral occipital complex coordinate to replay recent experiences during periods of rest in order to consolidate memories. "Taking a coffee break after class can actually help you retain that information you just learned," Davachi says.

"Your brain is working for you when you're resting, so rest is important for memory and cognitive function," Davachi explains. "This is something we don't appreciate much, especially when today's information technologies keep us working round-the-clock."

—by Harrison Wein, Ph.D.

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