The brain holds in mind what has just been seen by synchronizing brain waves in a working memory circuit, an animal study supported by the National Institutes of Health suggests. The more in-sync such electrical signals of neurons were in two key hubs of the circuit, the more those cells held the short-term memory of a just-seen object.
Charles Gray, Ph.D., of Montana State University, Bozeman, a grantee of NIH's National Institute of Mental Health (NIMH), and colleagues, report their findings Nov. 1, 2012, online, in the journal Science Express.
"This work demonstrates, for the first time, that there is information about short term memories reflected in in-sync brainwaves," explained Gray.
"The Holy Grail of neuroscience has been to understand how and where information is encoded in the brain. This study provides more evidence that large scale electrical oscillations across distant brain regions may carry information for visual memories," said NIMH director Thomas R. Insel, M.D.
Prior to the study, scientists had observed synchronous patterns of electrical activity between the two circuit hubs after a monkey saw an object, but weren't sure if the signals actually represent such short-term visual memories in the brain. Rather, it was thought that such neural oscillations might play the role of a traffic cop, directing information along brain highways.
To find out more, Gray, Rodrigo Salazar Ph.D., and Nick Dotson of Montana State and Steven Bressler, Ph.D., at Florida Atlantic University, Boca Raton, recorded electrical signals from groups of neurons in both hubs of two monkeys performing a visual working memory task. To earn a reward, the monkeys had to remember an object or its location that they saw momentarily on a computer screen and correctly match it. The researchers expected to see the telltale boost in synchrony during a delay period immediately after an object disappeared from the screen, when
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NIH/National Institute of Mental Health