Milan, Italy, 25 March 2010 - One of the most common complaints among healthy older adults relates to a decline in memory performance. This decline has been linked to an inability to ignore irrelevant information when forming memories. In order to ignore distracting information, the brain should act to suppress its responses to distractions, but it has been shown that in older adults there is in fact an increase in brain activity at those times. In a new study published in the April 2010 issue of Elsevier's Cortex (http://www.elsevier.com/locate/cortex) researchers at the University of California San Francisco have shown that even prior knowledge of an impending distraction does not help to improve the working memory performance of older adults.
Drs. Theodore Zanto and Adam Gazzaley studied 21 adults aged between 60 and 80 years while they performed a working memory task in which they were shown random sequences of pictures containing faces and scenes. From a given sequence, participants were asked to remember either only the faces (ignoring scenes) or only the scenes (ignoring faces). In a second round of testing, the participants were given prior information about which specific pictures in the sequence would be relevant and which to ignore. The participants' brain activity during the tasks was recorded using electroencephalograms (EEGs).
Previous research from this laboratory has indicated that the increase in brain activity in response to distractions occurs very soon (within 200 milliseconds) after the distraction appears. Since there is only a very short amount of time allotted for the brain to identify an item as irrelevant and suppress any further neural processing, it was suggested that older adults might benefit from prior knowledge of the impending distraction. However, results from the new study have proved that this is not the case.
Interestingly, the researchers found that later stages of neural processing (500-650 milliseconds after item presentation) do show signs of suppression, confirming that the "suppression deficit" is related to early stages of neural processing. The findings suggest that a working memory decline in older adults is indeed due to an inability to ignore distracting information, which furthermore cannot be improved with preparedness.
Notes to Editors:
The article is "Predictive knowledge of stimulus relevance does not influence top-down suppression of irrelevant information in older adults" by Theodore P. Zanto, Kelly Hennigan, Mattias Östberg, Wesley C. Clapp and Adam Gazzaley and appears in Cortex, Volume 46, Issue 4 (April 2010), published by Elsevier in Italy. Full text of the article featured above is available to members of the media upon request. Please contact the Elsevier press office, firstname.lastname@example.org. To schedule an interview, contact Dr Adam Gazzaley, email@example.com.
Cortex is an international journal devoted to the study of cognition and of the relationship between the nervous system and mental processes, particularly as these are reflected in the behaviour of patients with acquired brain lesions, normal volunteers, children with typical and atypical development, and in the activation of brain regions and systems as recorded by functional neuroimaging techniques. It was founded in 1964 by Ennio De Renzi. The Editor in-chief of Cortex is Sergio Della Sala, Professor of Human Cognitive Neuroscience at the University of Edinburgh. Fax: 0131 6513230, e-mail: firstname.lastname@example.org. Cortex is available online at http://www.sciencedirect.com/science/journal/00109452
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