Browsing by Author "Chou, Ying-Hui"

Now showing 1 - 6 of 6

Open Access
Association between increased magnetic susceptibility of deep gray matter nuclei and decreased motor function in healthy adults.
(Neuroimage, 2015-01-15) Li, Wei; Langkammer, Christian; Chou, Ying-Hui; Petrovic, Katja; Schmidt, Reinhold; Song, Allen W; Madden, David J; Ropele, Stefan; Liu, Chunlei
In the human brain, iron is more prevalent in gray matter than in white matter, and deep gray matter structures, particularly the globus pallidus, putamen, caudate nucleus, substantia nigra, red nucleus, and dentate nucleus, exhibit especially high iron content. Abnormally elevated iron levels have been found in various neurodegenerative diseases. Additionally, iron overload and related neurodegeneration may also occur during aging, but the functional consequences are not clear. In this study, we explored the correlation between magnetic susceptibility--a surrogate marker of brain iron--of these gray matter structures with behavioral measures of motor and cognitive abilities, in 132 healthy adults aged 40-83 years. Latent variables corresponding to manual dexterity and executive functions were obtained using factor analysis. The factor scores for manual dexterity declined significantly with increasing age. Independent of gender, age, and global cognitive function, increasing magnetic susceptibility in the globus pallidus and red nuclei was associated with decreasing manual dexterity. This finding suggests the potential value of magnetic susceptibility, a non-invasive quantitative imaging marker of iron, for the study of iron-related brain function changes.
Open Access
Frontoparietal activation during visual conjunction search: Effects of bottom-up guidance and adult age.
(Hum Brain Mapp, 2017-04) Madden, David J; Parks, Emily L; Tallman, Catherine W; Boylan, Maria A; Hoagey, David A; Cocjin, Sally B; Johnson, Micah A; Chou, Ying-Hui; Potter, Guy G; Chen, Nan-Kuei; Packard, Lauren E; Siciliano, Rachel E; Monge, Zachary A; Diaz, Michele T
We conducted functional magnetic resonance imaging (fMRI) with a visual search paradigm to test the hypothesis that aging is associated with increased frontoparietal involvement in both target detection and bottom-up attentional guidance (featural salience). Participants were 68 healthy adults, distributed continuously across 19 to 78 years of age. Frontoparietal regions of interest (ROIs) were defined from resting-state scans obtained prior to task-related fMRI. The search target was defined by a conjunction of color and orientation. Each display contained one item that was larger than the others (i.e., a size singleton) but was not informative regarding target identity. Analyses of search reaction time (RT) indicated that bottom-up attentional guidance from the size singleton (when coincident with the target) was relatively constant as a function of age. Frontoparietal fMRI activation related to target detection was constant as a function of age, as was the reduction in activation associated with salient targets. However, for individuals 35 years of age and older, engagement of the left frontal eye field (FEF) in bottom-up guidance was more prominent than for younger individuals. Further, the age-related differences in left FEF activation were a consequence of decreasing resting-state functional connectivity in visual sensory regions. These findings indicate that age-related compensatory effects may be expressed in the relation between activation and behavior, rather than in the magnitude of activation, and that relevant changes in the activation-RT relation may begin at a relatively early point in adulthood. Hum Brain Mapp 38:2128-2149, 2017. © 2017 Wiley Periodicals, Inc.
Open Access
Functional brain connectivity and cognition: effects of adult age and task demands.
(Neurobiology of aging, 2013-08) Chou, Ying-Hui; Chen, Nan-Kuei; Madden, David J
Previous neuroimaging research has documented that patterns of intrinsic (resting state) functional connectivity (FC) among brain regions covary with individual measures of cognitive performance. Here, we examined the relation between intrinsic FC and a reaction time (RT) measure of performance, as a function of age group and task demands. We obtained filtered, event-related functional magnetic resonance imaging data, and RT measures of visual search performance, from 21 younger adults (19-29 years old) and 21 healthy, older adults (60-87 years old). Age-related decline occurred in the connectivity strength in multiple brain regions, consistent with previous findings. Among 8 pairs of regions, across somatomotor, orbitofrontal, and subcortical networks, increasing FC was associated with faster responding (lower RT). Relative to younger adults, older adults exhibited a lower strength of this RT-connectivity relation and greater disruption of this relation by a salient but irrelevant display item (color singleton distractor). Age-related differences in the covariation of intrinsic FC and cognitive performance vary as a function of task demands.
Open Access
Maintenance and Representation of Mind Wandering during Resting-State fMRI.
(Scientific reports, 2017-01-12) Chou, Ying-Hui; Sundman, Mark; Whitson, Heather E; Gaur, Pooja; Chu, Mei-Lan; Weingarten, Carol P; Madden, David J; Wang, Lihong; Kirste, Imke; Joliot, Marc; Diaz, Michele T; Li, Yi-Ju; Song, Allen W; Chen, Nan-Kuei
Major advances in resting-state functional magnetic resonance imaging (fMRI) techniques in the last two decades have provided a tool to better understand the functional organization of the brain both in health and illness. Despite such developments, characterizing regulation and cerebral representation of mind wandering, which occurs unavoidably during resting-state fMRI scans and may induce variability of the acquired data, remains a work in progress. Here, we demonstrate that a decrease or decoupling in functional connectivity involving the caudate nucleus, insula, medial prefrontal cortex and other domain-specific regions was associated with more sustained mind wandering in particular thought domains during resting-state fMRI. Importantly, our findings suggest that temporal and between-subject variations in functional connectivity of above-mentioned regions might be linked with the continuity of mind wandering. Our study not only provides a preliminary framework for characterizing the maintenance and cerebral representation of different types of mind wandering, but also highlights the importance of taking mind wandering into consideration when studying brain organization with resting-state fMRI in the future.
Open Access
Phonemic fluency and brain connectivity in age-related macular degeneration: a pilot study.
(Brain connectivity, 2015-03) Whitson, Heather E; Chou, Ying-Hui; Potter, Guy G; Diaz, Michele T; Chen, Nan-Kuei; Lad, Eleonora M; Johnson, Micah A; Cousins, Scott W; Zhuang, Jie; Madden, David J
Age-related macular degeneration (AMD), the leading cause of blindness in developed nations, has been associated with poor performance on tests of phonemic fluency. This pilot study sought to (1) characterize the relationship between phonemic fluency and resting-state functional brain connectivity in AMD patients and (2) determine whether regional connections associated with phonemic fluency in AMD patients were similarly linked to phonemic fluency in healthy participants. Behavior-based connectivity analysis was applied to resting-state, functional magnetic resonance imaging data from seven patients (mean age=79.9±7.5 years) with bilateral AMD who completed fluency tasks prior to imaging. Phonemic fluency was inversely related to the strength of functional connectivity (FC) among six pairs of brain regions, representing eight nodes: left opercular portion of inferior frontal gyrus (which includes Broca's area), left superior temporal gyrus (which includes part of Wernicke's area), inferior parietal lobe (bilaterally), right superior parietal lobe, right supramarginal gyrus, right supplementary motor area, and right precentral gyrus. The FC of these reference links was not related to phonemic fluency among 32 healthy individuals (16 younger adults, mean age=23.5±4.6 years and 16 older adults, mean age=68.3±3.4 years). Compared with healthy individuals, AMD patients exhibited higher mean connectivity within the reference links and within the default mode network, possibly reflecting compensatory changes to support performance in the setting of reduced vision. These findings are consistent with the hypothesis that phonemic fluency deficits in AMD reflect underlying brain changes that develop in the context of AMD.
Open Access
Sources of disconnection in neurocognitive aging: cerebral white-matter integrity, resting-state functional connectivity, and white-matter hyperintensity volume.
(Neurobiol Aging, 2017-06) Madden, David J; Parks, Emily L; Tallman, Catherine W; Boylan, Maria A; Hoagey, David A; Cocjin, Sally B; Packard, Lauren E; Johnson, Micah A; Chou, Ying-Hui; Potter, Guy G; Chen, Nan-Kuei; Siciliano, Rachel E; Monge, Zachary A; Honig, Jesse A; Diaz, Michele T
Age-related decline in fluid cognition can be characterized as a disconnection among specific brain structures, leading to a decline in functional efficiency. The potential sources of disconnection, however, are unclear. We investigated imaging measures of cerebral white-matter integrity, resting-state functional connectivity, and white-matter hyperintensity volume as mediators of the relation between age and fluid cognition, in 145 healthy, community-dwelling adults 19-79 years of age. At a general level of analysis, with a single composite measure of fluid cognition and single measures of each of the 3 imaging modalities, age exhibited an independent influence on the cognitive and imaging measures, and the imaging variables did not mediate the age-cognition relation. At a more specific level of analysis, resting-state functional connectivity of sensorimotor networks was a significant mediator of the age-related decline in executive function. These findings suggest that different levels of analysis lead to different models of neurocognitive disconnection, and that resting-state functional connectivity, in particular, may contribute to age-related decline in executive function.