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Spielberg J.M.,Neuroimaging Research for Veterans Center | Spielberg J.M.,Boston University | Miller G.A.,University of California at Los Angeles | Miller G.A.,University of Illinois at Urbana - Champaign | And 3 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2015

The ability to inhibit distracting stimuli from interfering with goaldirected behavior is crucial for success in most spheres of life. Despite an abundance of studies examining regional brain activation, knowledge of the brain networks involved in inhibitory control remains quite limited. To address this critical gap, we applied graph theory tools to functionalmagnetic resonance imaging data collected while a large sample of adults (n = 101) performed a color-word Stroop task. Higher demand for inhibitory control was associated with restructuring of the global network into a configuration that was more optimized for specialized processing (functional segregation), more efficient at communicating the output of such processing across the network (functional integration), and more resilient to potential interruption (resilience). In addition, there were regional changes with right inferior frontal sulcus and right anterior insula occupying more central positions as network hubs, and dorsal anterior cingulate cortex becoming more tightly coupled with its regional subnetwork. Given the crucial role of inhibitory control in goal-directed behavior, present findings identifying functional network organization supporting inhibitory control have the potential to provide additional insights into how inhibitory control may break down in a wide variety of individuals with neurological or psychiatric difficulties.

Salat D.H.,Massachusetts General Hospital | Salat D.H.,Neuroimaging Research for Veterans Center
Neuroscience | Year: 2014

Alterations in cerebrovascular structure and function may underlie the most common age-associated cognitive, psychiatric, and neurological conditions presented by older adults. Although much remains to understand, existing research suggests several age-associated detrimental conditions may be mediated through sometimes subtle small vessel-induced damage to the cerebral white matter. Here we review a selected portion of the vast work that demonstrates links between changes in vascular and neural health as a function of advancing age, and how even changes in low-to-moderate risk individuals, potentially beginning early in the adult age-span, may have an important impact on functional status in late life. © 2013 .

Hayes S.M.,Boston University | Hayes S.M.,Neuroimaging Research for Veterans Center | Alosco M.L.,Boston University | Alosco M.L.,Kent State University | And 2 more authors.
Current Geriatrics Reports | Year: 2014

Aging is characterized by a decline in cognitive functions, particularly in the domains of executive function, processing speed and episodic memory. These age-related declines are exacerbated by cardiovascular disease (CVD) and cardiovascular risk factors (hypertension, diabetes, obesity, elevated total cholesterol). Structural and functional alterations in brain regions, including the fronto-parietal and medial temporal lobes, have been linked to age- and CVD-related cognitive decline. Multiple recent studies indicate that aerobic exercise programs may slow the progression of age-related neural changes and reduce the risk for mild cognitive impairment as well as dementia. We review age- and CVD-related decline in cognition and the underlying changes in brain morphology and function, and then clarify the impact of aerobic exercise on moderating these patterns. © 2014 Springer Science+Business Media New York (outside the USA).

Coutu J.-P.,Harvard University | Coutu J.-P.,Harvard Massachusetts Institute of Technology Division of Health Sciences and Technology | Chen J.J.,Harvard University | Chen J.J.,Rotman Research Institute | And 3 more authors.
Neurobiology of Aging | Year: 2014

Age-associated white matter degeneration has been well documented and is likely an important mechanism contributing to cognitive decline in older adults. Recent work has explored a range of noninvasive neuroimaging procedures to differentially highlight alterations in the tissue microenvironment. Diffusional kurtosis imaging (DKI) is an extension of diffusion tensor imaging (DTI) that accounts for non-Gaussian water diffusion and can reflect alterations in the distribution and diffusion properties of tissue compartments. We used DKI to produce whole-brain voxel-based maps of mean, axial, and radial diffusional kurtoses, quantitative indices of the tissue microstructure's diffusional heterogeneity, in 111 participants ranging from the age of 33 to 91years. As suggested from prior DTI studies, greater age was associated with alterations in white-matter tissue microstructure, which was reflected by a reduction in all 3 DKI metrics. Prominent effects were found in prefrontal and association white matter compared with relatively preserved primary motor and visual areas. Although DKI metrics co-varied with DTI metrics on a global level, DKI provided unique regional sensitivity to the effects of age not available with DTI. DKI metrics were additionally useful in combination with DTI metrics for the classification of regions according to their multivariate "diffusion footprint", or pattern of relative age effect sizes. It is possible that the specific multivariate patterns of age-associated changes measured are representative of different types of microstructural pathology. These results suggest that DKI provides important complementary indices of brain microstructure for the study of brain aging and neurologic disease. © 2014 Elsevier Inc.

Sorond F.A.,Harvard University | Hurwitz S.,Brigham and Womens Hospital | Hurwitz S.,Harvard University | Salat D.H.,Neuroimaging Research for Veterans Center | And 7 more authors.
Neurology | Year: 2013

Objective: To investigate the relationship between neurovascular coupling and cognitive function in elderly individuals with vascular risk factors and to determine whether neurovascular coupling could be modified by cocoa consumption. Methods: Sixty older people (aged 72.9 6 5.4 years) were studied in a parallel-arm, double-blind clinical trial of neurovascular coupling and cognition in response to 24 hours and 30 days of cocoa consumption. Cognitive measures included Mini-Mental State Examination and Trail Making Test A and B. Neurovascular coupling was measured from the beat-to-beat blood flow velocity responses in the middle cerebral arteries to the N-Back Task. In a subset of MRI-eligible participants, cerebral white matter structural integrity was also measured. Results: Neurovascular coupling was associated with Trails B scores (p 50.002) and performance on the 2-Back Task. Higher neurovascular coupling was also associated with significantly higher fractional anisotropy in cerebral white matter hyperintensities (p 5 0.02). Finally, 30 days of cocoa consumption was associated with increased neurovascular coupling (5.6% 6 7.2% vs 22.4% 6 4.8%; p 5 0.001) and improved Trails B times (116 6 78 seconds vs 167 6 110 seconds; p 5 0.007) in those with impaired neurovascular coupling at baseline. Conclusion: There is a strong correlation between neurovascular coupling and cognitive function, and both can be improved by regular cocoa consumption in individuals with baseline impairments. Better neurovascular coupling is also associated with greater white matter structural integrity. © 2013 American Academy of Neurology.

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