The ability to hold for a short period of time new information in the brain is a very common and necessary action to cope with the needs of everyday life. This ability, known as working memory, allows us, for example, to briefly hold a phone number, names of new people or the way to get to a place where we have never been before.

Scientists have long suspected that the working memory operates just reactivating or repeating the information to retain it in mind. Still, this theory has not been able to be demonstrated because a lack of accurate enough measuring instruments. Now, an international group of neuroscientists has confirm the hypothesis. The results have been advanced in the online edition of the American journal Current Biology. The study is coordinated by Lluís Fuentemilla, researcher of the Cognition and Brain Plasticity research group of the Bellvitge Biomedical Research Institute (IDIBELL) and the University of Barcelona (UB).

Researchers have conducted an experiment with eight healthy adults, who were made to see different pictures and remember some details. Using a technique of recording neuronal activity called magnetoencephalography along with the development of new analytical study methods, the researchers were able to decode, millisecond to millisecond, the brain activity of participants associated with the maintenance of images in the memory.

Theta oscillations

The researchers found evidence that the information is repeated continuously in mind. They also identified that the neural mechanism responsible for coordination of rhythmic repetition were brain oscillations called theta oscillations, which occur at a frequency of between 4 and 8 hertz.

These results demonstrate for the first time that working memory is related to the periodic repetition of information in the brain and the mechanisms that coordinate this repetition on a regular basis improve the accuracy of working memory.

Article reference

Fuentemilla L*, Penny W, Cashdollar N, Bunzeck N, Düzel E. Theta-Coupled Periodic Replay in Working Memory. Current Biology. 20, 1–7, April 13. [Epub ahead of print].

*IDIBELL-UB researcher