Public Release: 

Scientists bring 'forgotten' memories back to mind

American Association for the Advancement of Science

New evidence overturns a theory that in order for a short-term memory to be maintained, the neurons that represent that memory must be continuously active. Instead, the neural activity supporting that memory need only arise when the person trying to recall it consciously focuses his or her attention on the memory, the study's results show. The results suggest that there are different ways in which the "working," or short-term, memory stores information, depending on whether the related information is actively called upon, or not. Scientists continue to probe the processes involved in memory recovery, aspects of which remain unclear, particularly when it comes to how "dormant" memories that are part of our working memory are recalled when needed. In this study, Nathan Rose et al. analyzed the brain activity of participants as they were exposed to stimuli such as a face or a word. One stimulus in particular would be marked as important for the participant to remember; the researchers then used software to pinpoint the brain activity that represented that particular stimulus in the person's working memory over time. Notably, as the participants were distracted with other cues, the brain activity representing the marked stimulus faded, as if it were forgotten, suggesting that information that's stored in working memory is maintained through mechanisms other than sustained, elevated neural activity. Intriguingly, a targeted pulse of transcranial magnetic stimulation was sufficient to revive the memory, but only when recalling the related information was potentially going to be needed by the participant later in the experiment. These findings suggest that short-term memory is dynamic and modifiable via cognitive control, the authors say.

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