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9. Brain reserve affects the expression of cognitive reserve networks.

Author

Coors, Annabell, Lee, Seonjoo, Gazes, Yunglin, Gacheru, Margaret, Habeck, Christian, and Stern, Yaakov

Subjects
LARGE-scale brain networks, OLDER people, GRAY matter (Nerve tissue), INTELLIGENCE levels, TASK performance
Abstract

Cognitive reserve (CR) explains differential susceptibility of cognitive performance to neuropathology. However, as brain pathologies progress, cognitive decline occurs even in individuals with initially high CR. The interplay between the structural brain health (= level of brain reserve) and CR‐related brain networks therefore requires further research. Our sample included 142 individuals aged 60–70 years. National Adult Reading Test intelligence quotient (NART‐IQ) was our CR proxy. On an in‐scanner Letter Sternberg task, we used ordinal trend (OrT) analysis to extract a task‐related brain activation pattern (OrT slope) for each participant that captures increased expression with task load (one, three, and six letters). We assessed whether OrT slope represents a neural mechanism underlying CR by associating it with task performance and NART‐IQ. Additionally, we investigated how the following brain reserve measures affect the association between NART‐IQ and OrT slope: mean cortical thickness, total gray matter volume, and brain volumes proximal to the areas contained in the OrT patterns. We found that higher OrT slope was associated with better task performance and higher NART‐IQ. Further, the brain reserve measures were not directly associated with OrT slope, but they affected the relationship between NART‐IQ and OrT slope: NART‐IQ was associated with OrT slope only in individuals with high brain reserve. The degree of brain reserve has an impact on how (and perhaps whether) CR can be implemented in brain networks in older individuals. [ABSTRACT FROM AUTHOR]

Published
2024
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28. Dual-Tasking Alleviated Sleep Deprivation Disruption in Visuomotor Tracking: An fMRI Study

Author

Gazes, Yunglin, Rakitin, Brian C., and Steffener, Jason

Abstract

Effects of dual-responding on tracking performance after 49-h of sleep deprivation (SD) were evaluated behaviorally and with functional magnetic resonance imaging (fMRI). Continuous visuomotor tracking was performed simultaneously with an intermittent color-matching visual detection task in which a pair of color-matched stimuli constituted a target and non-matches were non-targets. Tracking error means were binned time-locked to stimulus onset of the detection task in order to observe changes associated with dual-responding by comparing the error during targets and non-targets. Similar comparison was made with fMRI data. Our result showed that despite a significant increase in the overall tracking error post SD, from 20 pixels pre SD to 45 pixels post SD, error decreased to a minimum of about 25 pixels 0-6 s after dual-response. Despite an overall reduced activation post SD, greater activation difference between targets and non-targets was found post SD in task-related regions, such as the left cerebellum, the left somatosensory cortex, the left extrastriate cortex, bilateral precuneus, the left middle frontal gyrus, and the left motor cortex. Our results suggest that dual-response helps to alleviate performance impairment usually associated with SD. The duration of the alleviation effect was on the order of seconds after dual-responding. (Contains 3 figures and 2 tables.)

Published
2012
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30. Tracing brain amyloid-β in asymptomatic older adults relying on a memory marker for Alzheimer's disease

Author

Parra, Mario A., Gazes, Yunglin, Habeck, Christian, and Stern, Yaakov

Subjects
RC0321
Abstract

Recent approaches to the early diagnosis of Alzheimer’s disease (AD) are aimed at detecting neuropathological signatures of this type of dementia in still healthy older adults. Should these efforts prove fruitful, strategies then focus on identifying the cognitive and functional decline that ensue. These approaches have proved both little effective and costly. In the present study, we investigated the hypothesis that effective cognitive markers for AD could help detect among still healthy older adults who would have likely started to accumulate the neuropathological changes pursued by costly neuroimaging procedures. A sample of 39 healthy older adults was recruited and assessed with an extensive neuropsychological and neuroimaging protocol. As the memory marker, we used the Visual Short-Term Memory Binding Task. Using existing data, participants were divided in two groups depending on whether or not they displayed the typical binding profile seen in AD subjects (i.e., strong binders – SB and weak binders - WB). The results show that in addition to the increased binding cost seen in WB, SB and WB could only be differentiated by the amount of Amyloid- accumulated in brain regions known to be involved in this cognitive function. No other neuropsychological tests proved informative, and neither volumetric nor cortical thickness metrics provided meaningful neuropathological signals. Our findings have significant implications for our understanding of the transition from normal ageing to preclinical AD and methodological approaches currently used to ascertain it. These are discussed at length.

Published
2022

44. White matter regions with low microstructure in young adults spatially coincide with white matter hyperintensities in older adults

Author

Lao, Patrick J., Vorburger, Robert S., Narkhede, Atul, Gazes, Yunglin, Igwe, Kay C., Colón, Juliet, Amarante, Erica, Guzman, Vanessa A., Last, Briana S., Habeck, Christian, Stern, Yaakov, Brickman, Adam M., Lao, Patrick J., Vorburger, Robert S., Narkhede, Atul, Gazes, Yunglin, Igwe, Kay C., Colón, Juliet, Amarante, Erica, Guzman, Vanessa A., Last, Briana S., Habeck, Christian, Stern, Yaakov, and Brickman, Adam M.

Abstract

Microstructural and macrostructural white matter damage occurs frequently with aging, is associated with negative health outcomes, and can be imaged non-invasively as fractional anisotropy (FA) and white matter hyperintensities (WMH), respectively. The extent to which diminished microstructure precedes or results from macrostructural white matter damage is poorly understood. This study evaluated the hypothesis that white matter areas with normatively lower microstructure in young adults are most susceptible to develop WMH in older adults. Forty-nine younger participants (age = 25.8 ± 2.8 years) underwent diffusion-weighted imaging (DWI), and 557 older participants (age = 73.9 ± 5.7 years) underwent DWI and T2-weighted magnetic resonance imaging (MRI). In older adults, WMH had a mostly periventricular distribution with higher frequency in frontal regions. We found lower FA in areas of frank WMH compared to normal-appearing white matter (NAWM) in older adults. Then, to determine if areas of normatively lower white matter microstructure spatially overlap with areas that frequently develop macrostructural damage in older age, we created a WMH frequency map in which each voxel represented the percentage of older adults with a WMH in that voxel. We found lower normative FA in young adults with regions frequently segmented as WMH in older adults. We conclude that low white matter microstructure is observed in areas of white matter macrostructural damage, but white matter microstructure is also normatively low (i.e., at ages 20–30) in regions with high WMH frequency, prior to white matter macrostructural damage.

Published
2020

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