Deficit in switching between functional brain networks underlies the impact of multitasking on working memory in older adults
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Edited by Marcus E. Raichle, Washington University, St. Louis, MO, and approved March 8, 2011 (received for review October 12, 2010)

Abstract
Multitasking negatively influences the retention of information over brief periods of time. This impact of interference on working memory is exacerbated with normal aging. We used functional MRI to investigate the neural basis by which an interruption is more disruptive to working memory performance in older individuals. Younger and older adults engaged in delayed recognition tasks both with and without interruption by a secondary task. Behavioral analysis revealed that working memory performance was more impaired by interruptions in older compared with younger adults. Functional connectivity analyses showed that when interrupted, older adults disengaged from a memory maintenance network and reallocated attentional resources toward the interrupting stimulus in a manner consistent with younger adults. However, unlike younger individuals, older adults failed to both disengage from the interruption and reestablish functional connections associated with the disrupted memory network. These results suggest that multitasking leads to more significant working memory disruption in older adults because of an interruption recovery failure, manifest as a deficient ability to dynamically switch between functional brain networks.
Footnotes
- ↵1To whom correspondence should be addressed. E-mail: adam.gazzaley{at}ucsf.edu.
Author contributions: W.C.C. and A.G. designed research; W.C.C. and J.S. performed research; W.C.C. and M.T.R. analyzed data; and W.C.C. and A.G. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1015297108/-/DCSupplemental.