Browsing by Author "Neal, Joshua"

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    Age-Related Intrinsic Functional Connectivity Changes of Locus Coeruleus from Childhood to Older Adults
    Song, Inuk; Neal, Joshua; Lee, Tae-Ho (MDPI, 2021-11-10)
    The locus coeruleus is critical for selective information processing by modulating the brain’s connectivity configuration. Increasingly, studies have suggested that LC controls sensory inputs at the sensory gating stage. Furthermore, accumulating evidence has shown that young children and older adults are more prone to distraction and filter out irrelevant information less efficiently, possibly due to the unoptimized LC connectivity. However, the LC connectivity pattern across the life span is not fully examined yet, hampering our ability to understand the relationship between LC development and the distractibility. In this study, we examined the intrinsic network connectivity of the LC using a public fMRI dataset with wide-range age samples. Based on LC-seed functional connectivity maps, we examined the age-related variation in the LC connectivity with a quadratic model. The analyses revealed two connectivity patterns explicitly. The sensory-related brain regions showed a positive quadratic age effect (u-shape), and the frontal regions for the cognitive control showed a negative quadratic age effect (inverted u-shape). Our results imply that such age-related distractibility is possibly due to the impaired sensory gating by the LC and the insufficient top-down controls by the frontal regions. We discuss the underlying neural mechanisms and limitations of our study.
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    A collection of 157 individual neuromelanin-sensitive images accompanied by non-linear neuromelanin-sensitive atlas and a probabilistic locus coeruleus atlas
    Lee, Tae-Ho; Kim, Sun Hyung; Neal, Joshua; Katz, Benjamin; Kim, Il Hwan (2024-02)
    The current dataset aims to support and enhance the research reliability of neuromelanin regions in the brain- stem, such as locus coeruleus (LC), by offering raw neuromelanin-sensitive images. The dataset includes raw neuromelanin-sensitive images from 157 healthy individuals (8–64 years old). In addition, leveraging individual neuromelanin-sensitive images, a non-linear neuromelanin- sensitive atlas, generated through an iterative warping pro- cess, is included to tackle the common challenge of a limited field of view in neuromelanin-sensitive images. Finally, the dataset encompasses a probabilistic LC atlas generated through a majority voting approach with pre-existing multiple atlas-based segmentations. This process entails warping pre-existing atlases onto individual spaces and identifying voxels with a majority consensus of over 50 % across the atlases. This LC probabilistic atlas can minimize uncertainty variance associated with choosing a specific single atlas.
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    The connection between the triple network model and locus coeruleus integrity in those exhibiting inattentive symptoms
    Neal, Joshua (Virginia Tech, 2024-01)
    The locus coeruleus (LC) is a nucleus within the brainstem associated with physiological arousal and attention performance, with altered structure and function previously identified in neurodegenerative disorders. Pathologies related to difficulties with attention have previously been understood within a cortical triple network model, abnormalities in which may be relate to dysfunction in either LC structure or function. To examine the possibility of LC alteration being associated with inattentive symptom report, a set of analyses have been performed. In the first analysis, LC neuromelanin contrast was regressed onto ADHD symptom report for 141 individuals across the lifespan, finding a significant negative relationship between neuromelanin in the right hemisphere of the LC and inattentive symptom report. A second analysis tested for possible mediation of the neuromelanin contrasts with structural volumes of regions associated with the salience network, which has also been previously associated with attention deficits and ADHD symptoms. These findings support the relationship between LC and attention-related behavior through both neuromelanin-sensitive and structural imaging, and observes multiple significant structural associations for cortical regions previously associated to inattention functionally.