Hart, John
Permanent URI for this collectionhttps://hdl.handle.net/10735.1/4006
John Hart is Medical Science Director at the Center for BrainHealth, where he also holds the Jane and Bud Smith Distinguished Chair and the Cecil Green Distinguished Chair at The University of Texas at Dallas. He is also a Professor of Behavioral and Brain Sciences with a joint appointment in the departments of Neurology and Psychiatry at The University of Texas Southwestern Medical Center at Dallas. Dr. Hart's research interests focus on the neural basis of semantic memory. Learn more about Professor Hart here.
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Item Gulf War Illness Associated with Abnormal Auditory P1 Event-Related Potential: Evidence of Impaired Cholinergic Processing Replicated in a National Sample(Elsevier Ireland Ltd, 2018-11-10) Tillman, Gail D.; Spence, Jeffrey S.; Briggs, Richard W.; Haley, Robert W.; Hart, John; Kraut, Michael A.; Tillman, Gail D.; Hart, John, Jr.Our team previously reported event-related potential (ERP) and hyperarousal patterns from a study of one construction battalion of the U.S. Naval Reserve who served during the 1991 Persian Gulf War. We sought to replicate these findings in a sample that was more representative of the entire Gulf War-era veteran population, including male and female participants from four branches of the military. We collected ERP data from 40 veterans meeting Haley criteria for Gulf War syndromes 1-3 and from 22 matched Gulf War veteran controls while they performed an auditory oddball task. Reports of hyperarousal from the ill veterans were significantly greater than those from the control veterans, and P1 amplitudes in Syndromes 2 and 3 were significantly higher than P1 amplitudes in Syndrome 1, replicating our previous findings. Many of the contributors to the generation of the P1 potential are also involved in the regulation of arousal and are modulated by cholinergic and dopaminergic systems-two systems whose dysfunction has been implicated in Gulf War illness. These differences among the three syndrome groups where their means were on either side of controls is a replication of our previous ERP study and is consistent with previous imaging studies of this population.Item Changing Brain Networks Through Non-Invasive NeuromodulationTo, Wing Ting; De Ridder, Dirk; Hart, John, Jr.; Vanneste, Sven; Wang, Zijie; Perananthan, Sahila; Panangala, Samitha D.; Ferraris, John P.; Balkus, Kenneth J.; To, Wing Ting; Hart, John, Jr.; Vanneste, SvenBackground/Objective: Non-invasive neuromodulation techniques, such as repetitive Transcranial Magnetic Stimulation (rTMS) and transcranial Direct Current Stimulation (tDCS), have increasingly been investigated for their potential as treatments for neurological and psychiatric disorders. Despite widespread dissemination of these techniques, the underlying therapeutic mechanisms and the ideal stimulation site for a given disorder remain unknown. Increasing evidence support the possibility of non-invasive neuromodulation affecting a brain network rather than just the local stimulation target. In this article, we present evidence in a clinical setting to support the idea that non-invasive neuromodulation changes brain networks. Method: This article addresses the idea that non-invasive neuromodulation modulates brain networks, rather than just the local stimulation target, using neuromodulation studies in tinnitus and major depression as examples. We present studies that suppo rt this hypothesis from different perspectives. Main Results/Conclusion: Studies stimulating the same brain region, such as the dorsolateral prefrontal cortex (DLPFC), have shown to be effective for several disorders and studies using different stimulation sites for the same disorder have shown similar results. These findings, as well as results from studies investigating brain network connectivity on both macro and micro levels, suggest that non-invasive neuromodulation affects a brain network rather than just the local stimulation site targeted. We propose that non-invasive neuromodulation should be approached from a network perspective and emphasize the therapeutic potential of this approach through the modulation of targeted brain networks.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.;