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Cerebral Cortex Advance Access published online on October 5, 2009
Cerebral Cortex, doi:10.1093/cercor/bhp206
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© The Author 2009. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oxfordjournals.org

Age-Related Shifts in Brain Activity Dynamics during Task Switching

Koji Jimura1 and Todd S. Braver1,2

1 Department of Psychology, 2 Department of Radiology, Washington University in St Louis, St Louis, MO 63139, USA

Address correspondence to Koji Jimura, PhD, Department of Psychology, Washington University in St Louis, CB1125, One Brookings Drive, St Louis, MO 63139, USA. Email: kjimura{at}wustl.edu.

Cognitive aging studies have suggested that older adults show declines in both sustained and transient cognitive control processes. However, previous neuroimaging studies have primarily focused on age-related change in the magnitude, but not temporal dynamics, of brain activity. The present study compared brain activity dynamics in healthy old and young adults during task switching. A mixed blocked/event-related functional magnetic resonance imaging design enabled separation of transient and sustained neural activity associated with cognitive control. Relative to young adults, older adults exhibited not only decreased sustained activity in the anterior prefrontal cortex (aPFC) during task-switching blocks but also increased transient activity on task-switch trials. Another pattern of age-related shift in dynamics was present in the lateral PFC (lPFC) and posterior parietal cortex (PPC), with younger adults showing a cue-related response during task-switch trials in lPFC and PPC, whereas older adults exhibited switch-related activation during the cue period in PPC only. In all 3 regions, these qualitatively distinct patterns of brain activity predicted qualitatively distinct patterns of behavioral performance across the 2 age groups. Together, these results suggest that older adults may shift from a proactive to reactive cognitive control strategy as a means of retaining relatively preserved behavioral performance in the face of age-related neurocognitive changes.

Key Words: cognitive control • mixed blocked/event-related fMRI • parietal cortex • prefrontal cortex • task set


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