Aging in brain is accompanied by changes in brain vasculature such as increased stiffness of vascular wall and reduced blood supply, potentially important factors in affecting cognition. Furthermore, although functional neuroimaging techniques have provided tremendous insight into the adaptability of the aging brain, the fMRI signal relies upon an indirect signal--changes in oxygenation and blood flow--to detect intensity of neural activation across different sites. It is likely that age differences in vascular health affect blood flow and thereby change fMRI signals independent of the neural changes, which complicates the interpretation of fMRI results. Until recently, it has been difficult to assess vascular health in the brain in a detailed manner. Recently, new imaging techniques have become available (some developed by the Principal Investigator) that allow a quantitative assessment of vascular health in the same session that functional imaging data is collected. The present proposal seeks to utilize these new techniques to collect detailed measures of vascular health from a large lifespan study of neurocognitive function currently being conducted by Denise Park at the University of Texas at Dallas and as UT Southwestern Medical Center. These measures of vascular health will be related to both functional activation patterns and cognitive measures of behavior, allowing us to determine in a definitive way the role that vascular healthy plays in mediating BOLD signal and cognitive function across the lifespan.
The specific aims of the proposal are: 1. Measure cerebral blood flow, cerebral vessel reactivity, and basal venous oxygenation across the lifespan. 2. Determine the role of vascular health in cognitive function. 3. Examine how the BOLD signal in functional imaging of cognitive tasks is modified by the vascular measures. These data will be fundamentally important in advancing our theoretical interpretation of the meaning of functional activation changes observed in neuroimaging studies across the lifespan.
An important aspect of brain aging is the microscopic changes of the blood vessels. These changes will affect the brain health by limiting blood supply which is key to the functioning of neuron. In this project, different aspects of brain vascular health will be assessed using advanced MRI technologies and the results will be compared to cognitive changes across the adult lifespan.
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