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The network of regions shown by functional imaging studies to be deactivated by experimental tasks relative to nominally more passive baselines (task < baseline) may reflect processes engaged during the resting state or "default mode." Deactivation may result when attention and resources are diverted from default-mode processes toward task processes. Aging(More)
To explore neural correlates of cognitive decline in aging, we used longitudinal behavioral data to identify two groups of older adults (n = 40) that differed with regard to whether their performance on tests of episodic memory remained stable or declined over a decade. Analysis of structural and diffusion tensor imaging (DTI) revealed a heterogeneous set(More)
Age-related differences in cognitive performance are well documented. These differences are most pronounced during tasks with high demands on cognitive control, and it has been proposed that selective alteration of prefrontal activity is associated with cognitive changes in old age. Here, differences in the neural systems underlying selection requirements(More)
Regions that show task-induced deactivations may be part of a default-mode network related to processes that are more engaged during passive than active task conditions. Alteration of task-induced deactivations with age and dementia is indicated by atypical engagement of default-mode network regions. Genetic studies show a relation between the(More)
Functional brain-imaging data document overlapping sites of activation in prefrontal cortex across memory tasks, suggesting that these tasks may share common executive components. We leveraged this evidence to develop a training regimen and a set of transfer tasks to examine the trainability of a putative executive-control process: interference resolution.(More)
BACKGROUND Previous research has shown that polymorphisms of apolipoprotein E (APOE) represent genetic risk factors for dementia and for cognitive impairment in the elderly. The neural mechanisms by which these genetic variations influence behavioral performance or clinical severity are not well understood. METHODS The authors used diffusion tensor(More)
Cross-sectional estimates of age-related changes in brain structure and function were compared with 6-y longitudinal estimates. The results indicated increased sensitivity of the longitudinal approach as well as qualitative differences. Critically, the cross-sectional analyses were suggestive of age-related frontal overrecruitment, whereas the longitudinal(More)
The time course of the microglial cell reaction in central nervous system primary sensory projection territories has been examined following peripheral nerve injury in the adult rat using qualitative and quantitative analysis of immunoreactivity with the monoclonal antibody OX-42, which recognises the complement receptor CR3. The regions examined included(More)
A resource depletion framework motivated a novel strategy for investigating whether the central executive is unitary or separable into relatively independent subprocesses. The idea that tasks with overlapping neural representations may involve similar executive components was also critical to our approach. Of particular interest were tasks requiring(More)
Episodic memory for simple commands is better following enacted than verbal encoding. This has been proposed to be due to the possibility to base retrieval on motor information. Here we used PET to test the hypothesis that motor brain areas show increased retrieval-related activity following enacted compared to verbal encoding. Brain activity was also(More)