Browsing by Author "Chiang, Hsueh-Sheng"
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Item Event-Related Neural Oscillation Changes Following Reasoning Training in Individuals with Mild Cognitive Impairment(Elsevier Science B.V., 2018-10-17) Mudar, Raksha A.; Nguyen, Lydia T.; Eroh, Justin; Chiang, Hsueh-Sheng; Rackley, Audette; Chapman, Sandra B.; Eroh, Justin; Rackley, Audette; Chapman, Sandra B.Emerging evidence suggests cognitive training programs targeting higher-order reasoning may strengthen not only cognitive, but also neural functions in individuals with Mild Cognitive Impairment (MCI). However, research on direct measures of training-induced neural changes, derivable from electroencephalography (EEG), is limited. The current pilot study examined effects of Gist Reasoning training (n = 16) compared to New Learning training (n = 16) in older adults with amnestic MCI on measures of event-related neural oscillations (theta and alpha band power) corresponding to Go/NoGo tasks during basic and superordinate semantic categorization. EEG data were recorded while participants performed the Go/NoGo task pre- and post-training, and power in theta and alpha frequency bands was examined. Both groups were comparable at pre-training on all measures and both groups showed greater event-related theta synchronization post-training. Furthermore, the Gist Reasoning group had enhanced event-related desynchronization in low-frequency alpha band (8-10 Hz)on response inhibition (NoGo) trials and high-frequency alpha band (11-13 Hz) on response execution (Go) trials during superordinate categorization, relative to the New Learning group. These findings suggest that Gist Reasoning training in MCI impacted neural processing linked to strategic processing of Go and NoGo trials during the more complex superordinate categorization task. Targeting higher-order top-down cognitive processing seems to better harness residual neuroplastic potential in MCI.Item Theta and Alpha Alterations in Amnestic Mild Cognitive Impairment in Semantic Go/NoGo Tasks(Frontiers) Nguyen, Lydia T.; Mudar, Raksha A.; Chiang, Hsueh-Sheng; Schneider, Julie M.; Maguire, Mandy J.; Kraut, Michael A.; Hart, John, Jr.; 0000 0003 5139 1227 (Maguire, MJ); 0000 0000 5491 4773 (Hart, J); Chiang, Hsueh-Sheng; Schneider, Julie M.; Maguire, Mandy J.; Hart, John, Jr.Growing evidence suggests that cognitive control processes are impaired in amnestic mild cognitive impairment (aMCI); however the nature of these alterations needs further examination. The current study examined differences in electroencephalographic theta and alpha power related to cognitive control processes involving response execution and response inhibition in 22 individuals with aMCI and 22 age-, sex-, and education-matched cognitively normal controls. Two Go/NoGo tasks involving semantic categorization were used. In the basic categorization task, Go/NoGo responses were made based on exemplars of a single car (Go) and a single dog (NoGo). In the superordinate categorization task, responses were made based on multiple exemplars of objects (Go) and animals (NoGo). Behavioral data showed that the aMCI group had more false alarms during the NoGo trials compared to controls. The EEG data revealed between group differences related to response type in theta (4-7 Hz) and low-frequency alpha (8-10 Hz) power. In particular, the aMCI group differed from controls in theta power during the NoGo trials at frontal and parietal electrodes, and in low-frequency alpha power during Go trials at parietal electrodes. These results suggest that alterations in theta power converge with behavioral deterioration in response inhibition, whereas alterations in low-frequency alpha power appear to precede behavioral changes in response execution. Both behavioral and electrophysiological correlates combined provide a more comprehensive characterization of cognitive control deficits in aMCI.Item West Nile Virus Neuroinvasive Disease: Neurological Manifestations and Prospective Longitudinal Outcomes(Biomed Central) Hart, John, Jr.; Tillman, Gail; Kraut, Michael A.; Chiang, Hsueh-Sheng; Strain, Jeremy F.; Li, Yufeng; Agrawal, Amy G.; Jester, Penny; Gnann, John W., Jr.; Whitley, Richard J.; 0000 0000 5491 4773 (Hart, J); 2006185065 (Hart, J)Background: West Nile Virus (WNV) is a mosquito-borne flavivirus that has caused ongoing seasonal epidemics in the United States since 1999. It is estimated that =1% of WNV-infected patients will develop neuroinvasive disease (West Nile encephalitis and/or myelitis) that can result in debilitating morbidities and long-term sequelae. It is essential to collect longitudinal information about the recovery process and to characterize predicative factors that may assist in therapeutic decision-making in the future.; Methods: We report a longitudinal study of the neurological outcomes (as measured by neurological examination, Glascow Coma Scale, and Modified Mini-Mental State Examination) for 55 subjects with WNV neuroinvasive disease (confirmed by positive CSF IgM) assessed on day 7, at discharge, and on days 14, 30, and 90. The neurological outcome measures were coma (presence and degree), global cognitive status, presence of cranial neuropathy, tremors and/or weakness.; Results: At initial clinical presentation 93% presented with a significant neurological deficit (49% with weakness, 35% with tremor, and 16% with cranial neuropathy). The number of patients with a cognitive deficit fell from 25 at initial evaluation to 9 at their last evaluation. Cranial neuropathy was present in 9 at onset and in only 4 patients at study conclusion. Of the 19 patients who had a tremor at enrollment, 11 continued to exhibit a tremor at follow-up. Seven patients died after initial enrollment in the study, with 5 of those having presented in a coma. The factors that predict either severity or long-term recovery of neurological function include age (older individuals were weaker at follow-up examination), gender (males recovered better from coma), and presentation in a coma with cranial nerve deficits (had a poorer recovery particularly with regard to cognition).; Conclusions: This study represents one of the largest clinical investigations providing prospectively-acquired neurological outcomes data among American patients with WNV central nervous system disease. The findings show that the factors that influence prognosis from the initial presentation include age, gender, and specific neurological deficits at onset.; Trial Registration: ClinicalTrials.gov identifier: NCT00138463 and NCT00069316.;