Attention-Related Brain Activation Is Altered in Older Adults With White Matter Hyperintensities Using Multi-Echo fMRI

Cognitive decline is often undetectable in the early stages of accelerated vascular aging. Attentional processes are particularly affected in older adults with white matter hyperintensities (WMH), although specific neurovascular mechanisms have not been elucidated. We aimed to identify differences in attention-related neurofunctional activation and behavior between adults with and without WMH. Older adults with moderate to severe WMH (n = 18, mean age = 70 years), age-matched adults (n = 28, mean age = 72), and healthy younger adults (n = 19, mean age = 25) performed a modified flanker task during multi-echo blood oxygenation level dependent functional magnetic resonance imaging. Task-related activation was assessed using a weighted-echo approach. Healthy older adults had more widespread response and higher amplitude of activation compared to WMH adults in fronto-temporal and parietal cortices. Activation associated with processing speed was absent in the WMH group, suggesting attention-related activation deficits that may be a consequence of cerebral small vessel disease. WMH adults had greater executive contrast activation in the precuneous and posterior cingulate gyrus compared to HYA, despite no performance benefits, reinforcing the network dysfunction theory in WMH

The Hyades Kinematical Structure with Gaia Era

268-273In this work, we have improved the Hyades members with crossmatch between Hipparcos and the recent Gaia EDR3 source, the obtained members with highly probable are about 186 candidates. Considering the classical convergent point and depending on proper motions and radial velocities, we have computed the apex position A, D 93. 36 0. 046, 7. 43 0. 713 which is in line with others. The internal structural parameters of the Hyades open cluster are demonstrated here with space spatial velocities; i.e., , V, V; km s (-5.97±0.41, 45.54±6.75, 5.52±0.43) and , V, W ; km s (-42.11±6.50, -19.09±4.37, -1.32±0.44) and on basis of matrix elements μ, the Velocity Ellipsoid Parameters were achieved, e.g., λ, λ, λ; km s 2137.36 23.12, 6.06 0.41, 2.53 0.63 and σ, σ, σ; km s 46.23 6.80, 2.47 0.64, 1.59 0.80. For the observational quantities, we have deduced a correlation coefficient of about 0.83 for the kinematical property of proper motions on both sides μ cos δ , μ; mas yr and the physical property with the angular distances λ from the vertex, and those prove that the attributes are completely related linearly

Advanced application of BOLD fMRI to study cerebrovascular and neurovascular physiology in people with Cerebral Small Vessel Disease

Cerebral Small Vessel Disease (CSVD) is one of the most common neurological disorders among older adults. Advances in neuroimaging have helped to identify the many structural changes seen in CSVD, of which lesions in the white matter, white matter hyperintensities (WMH), have been studied extensively. The CSVD literature scarcely addresses the relationship between structural changes and functional neurovascular and vascular outcomes. This thesis investigates blood oxygenation level dependent functional magnetic resonance imaging (BOLD fMRI) applications to better understand CSVD effects on cerebrovascular reactivity, functional activation, and brain tissue pulsatility. The first study of this thesis explores vasoactive capacity of people with a range of CSVD. I use a vascular transfer function to describe the extent to which and time taken for blood vessels to vasodilate in response to an external stimulus (i.e. CO2). The results demonstrated lower cerebrovascular reactivity in normal appearing white matter in those with more severe amounts of WMH, and further declined after one year in the CSVD population. The second study uses advanced BOLD fMRI image acquisition to observe neurovascular response through an attention-network probing task in CSVD. Widespread network activation in healthy older adults was altered in CSVD and healthy younger adults, and yet CSVD participants performed the poorest on the attention task. The third study investigates tissue-level cardiac-related pulsatility in the brain through repurposing of BOLD fMRI. These data revealed an association between insular pulsatility and middle cerebral artery pulsatility, the latter of which is an index of peripheral arterial stiffness and informs on possible mechanisms of CSVD cerebrovascular dysfunction. This thesis develops robust neuroimaging to show 1) functional deficits of CSVD, and 2) potential contributing factors to disease development. Establishment of functional outcomes is essential to understanding CSVD pathophysiology, the mechanisms behind its contribution to other neurodegenerative disorders, and the development of potential therapeutic targets.Ph.D

Inferior Vena Caval Measures Do Not Correlate with Carotid Artery Corrected Flow Time Change Measured Using a Wireless Doppler Patch in Healthy Volunteers

(1) Background: The inspiratory collapse of the inferior vena cava (IVC), a non-invasive surrogate for right atrial pressure, is often used to predict whether a patient will augment stroke volume (SV) in response to a preload challenge. There is a correlation between changing stroke volume (SV∆) and corrected flow time of the common carotid artery (ccFT∆). (2) Objective: We studied the relationship between IVC collapsibility and ccFT∆ in healthy volunteers during preload challenges. (3) Methods: A prospective, observational, pilot study in euvolemic, healthy volunteers with no cardiovascular history was undertaken in a local physiology lab. Using a tilt-table, we studied two degrees of preload augmentation from (a) supine to 30-degrees head-down and (b) fully-upright to 30-degrees head down. In the supine position, % of IVC collapse with respiration, sphericity index and portal vein pulsatility was calculated. The common carotid artery Doppler pulse was continuously captured using a wireless, wearable ultrasound system. (4) Results: Fourteen subjects were included. IVC % collapse with respiration ranged between 10% and 84% across all subjects. Preload responsiveness was defined as an increase in ccFT∆ of at least 7 milliseconds. A total of 79% (supine baseline) and 100% (head-up baseline) of subjects were preload-responsive. No supine venous measures (including IVC % collapse) were significantly related to ccFT∆. (5) Conclusions: From head-up baseline, 100% of healthy subjects were ‘preload-responsive’ as per the ccFT∆. Based on the 42% and 25% IVC collapse thresholds in the supine position, only 50% and 71% would have been labeled ‘preload-responsive’

Cerebrovascular assessments to help understand brain-related changes associated with aerobic exercise after stroke

Evidence suggests exercise is ‘good medicine’ post-stroke, yet consensus is lacking on the time to initiate, type, exertion level, and duration per session. It remains a challenge to identify outcome measures for stroke-exercise trials that are sufficiently sensitive to intervention parameters. Cerebrovascular assessments, namely cerebral blood flow and intracranial pulsatility, are herein discussed as examples of quantitative brain-specific measures that may be useful to monitor exercise-related brain changes and help to guide stroke rehabilitation interventions. Bullets:Cerebral blood flow and arterial stiffness are potential vascular targets for stroke exercise trials.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

The Hyades Kinematical Structure with Gaia Era

In this work, we have improved the Hyades members with crossmatch between Hipparcos and the recent Gaia EDR3 source, the obtained members with highly probable are about 186 candidates. Considering the classical convergent point and depending on proper motions and radial velocities, we have computed the apex position (A_cp,D_cp )=(〖93〗^o.36±0^o.046,7^o.43±0^o.713) which is in line with others. The internal structural parameters of the Hyades open cluster are demonstrated here with space spatial velocities; i.e., (V ̅_X,V ̅_Y,V ̅_Z; km s^(-1) )=(-5.97±0.41, 45.54±6.75, 5.52±0.43) and (U ̅,V ̅,W ̅; km s^(-1) )= (-42.11±6.50, -19.09±4.37, -1.32±0.44) and on basis of matrix elements (μ_ij ), the Velocity Ellipsoid Parameters were achieved, e.g., (λ_1,λ_1,λ_1; km s^(-1) )=(2137.36 ± 23.12,6.06 ± 0.41,2.53 ± 0.63) and (σ_1,σ_1,σ_1; km s^(-1) )=(46.23 ± 6.80,2.47 ± 0.64,1.59 ± 0.80). For the observational quantities, we have deduced a correlation coefficient of about ≈0.83 for the kinematical property of proper motions on both sides (μ_α cos⁡δ,μ_δ; mas yr^(-1) ) and the physical property with the angular distances (λ) from the vertex, and those prove that the attributes are completely related linearly