Cerebral Cortex Advance Access published online on December 5, 2007
Cerebral Cortex, doi:10.1093/cercor/bhm207
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Reduced resting-state brain activity in the "default network" in normal aging
1 Department of Neurology, VU University Medical Center, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands, 2 Oxford Centre for Functional Magnetic Resonance Imaging of the Brain, University Oxford, John Radcliffe Hospital, UK, 3 Department of Radiology, VU University Medical Center, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands, 4 Department of Clinical Neurophysiology, VU University Medical Center, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands, 5 Department of Physics and Medical Technology, VU University Medical Center, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands, 6 Leiden Institute for Brain and Cognition, Department of Radiology, Leiden University Medical Center, Institute for Psychological Research, Leiden University, Leiden, The Netherlands
Address correspondence to Jesssica S. Damoiseaux. Email: J.Damoiseaux{at}vumc.nl.
Normal aging is associated with cognitive decline even in the absence of disease. Functions such as attention, information processing, and working memory are compromised. Based on the observation of age-related white matter degeneration, O'Sullivan et al. (2001) proposed the "disconnection" hypothesis, stating that decline in normal aging emerges from changes in connections between brain areas, in addition to dysfunction of specific areas. Here, we examined the functional properties of brain networks based on spontaneous fluctuations within brain systems using functional magnetic resonance imaging. We hypothesized that functional connectivity of intrinsic brain activity in the "default-mode" network (DMN) is affected by normal aging and that this relates to cognitive function. Ten younger and 22 older subjects were scanned at "rest," that is, lying awake with eyes closed. Our results show decreased activity in older versus younger subjects in 2 resting-state networks (RSNs) resembling the previously described DMN, containing the superior and middle frontal gyrus, posterior cingulate, middle temporal gyrus, and the superior parietal region. These results remain significant after correction for RSN-specific gray matter volume. The relevance of these findings is illustrated by the correlation between reduced activity of one of these RSNs and less effective executive functioning/processing speed in the older group.
Key Words: connectivity default-mode network fMRI ICA intrinsic brain activity neuropsychology