The results of the study appear as an advance online publication in the journal Nature Neuroscience.
In two separate experiments with adults, UCI neuroscientist Michael Rugg, in collaboration with colleagues from University College London, looked at neural activity that preceded the presentation of single words. They found that measures of the activity could predict whether the words would be remembered in a later memory test.
In the experiments, Rugg and his colleagues presented a group of young adults with a different word every four or five seconds, requiring them to make a judgment about a specific characteristic of the word, such as whether it referred to a living or a non-living thing. A moment before each word was presented, participants were "cued" with a visual signal that alerted them of the upcoming word. Neural activity caused by the cue was monitored through electroencephalograpy, or EEG, a method by which electrodes attached to the scalp measure underlying brain activity. Later, participants were shown the words again, along with words they had not previously been shown, and were asked to identify which ones had been presented in the first part of the experiment.
Rugg and his colleagues found that the distinct neural activity that occurred at the time of the cue indicated whether the word would be remembered in this test phase of the experiment.
"These experiments show that there is more to why we remember an event than just the neural activity evoked by the event itself," said Rugg, a professor of neurobiology and behavior and director of the Center for the Neurobiology of Learning and Memory. "Whether we remember something can depend on how the brain prepares beforehand."
Rugg believes the study could significantly influence the way scientists study how and why memories are stored. While researchers have long investigated brain activity that follows an event to study how memories are formed, they will now need to also take into consideration the role of activity preceding the event.
A leading cognitive neuroscientist, Rugg is an expert in the field of human memory and how it changes with age and disease. He has helped pioneer the development of methods for investigating human brain function with electroencephalography and functional neuro-imaging. The experiments were funded by the U.K.'s Wellcome Trust and the National Institute of Mental Health.
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