J. Spence's research while affiliated with University of Texas at Dallas and other places

Publications (142)

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Neural-vascular coupling (NVC) is the process by which oxygen and nutrients are delivered to metabolically active neurons by blood vessels. Murine models of NVC disruption have revealed its critical role in healthy neural function. We hypothesized that, in humans, aging exerts detrimental effects upon the integrity of the neural-glial-vascular syst...
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Amnestic mild cognitive impairment (aMCI) is marked by episodic memory deficits, which can be used to classify individuals into early MCI (EMCI) and late MCI (LMCI). Although mounting evidence suggests that individuals with aMCI have additional cognitive alterations including deficits in cognitive control, few have examined if EMCI and LMCI differ...
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Introduction Mitochondrial dysfunction is a neurometabolic hallmark signaling abnormal brain energy metabolism (BEM) targeted as a potential early marker of Alzheimer’s disease (AD). Advanced imaging technologies, such as ³¹ phosphorus magnetic resonance spectroscopy ( ³¹ P MRS) at ultra-high-field (UHF) magnetic strength 7T, provide sensitive phos...
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Introduction: Brain health is neglected in public health, receiving attention after something goes wrong. Neuroplasticity research illustrates that preventive steps strengthen the brain's component systems; however, this information is not widely known. Actionable steps are needed to scale proven population-level interventions. Objectives: This pil...
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Introduction Research shows that cognitive performance and emotional well-being can be significantly strengthened. A high-performance brain training protocol, Strategic Memory Advanced Reasoning Training (SMART), was developed by cognitive neuroscientists at The University of Texas at Dallas Center for BrainHealth based on 25-plus years of scientif...
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Introduction Prior Go/NoGo studies have localized specific regions and EEG spectra for which traditional approaches have distinguished between Go and NoGo conditions. A more detailed characterization of the spatial distribution and timing of the synchronization of frequency bands would contribute substantially to the clarification of neural mechani...
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A bstract The neural underpinnings of inhibitory control, an executive cognitive control function, has been a topic of interest for several decades due to both its clinical significance and the maturation of cognitive science disciplines. Behavioral, imaging, and electrophysiological studies suggest that the pre-supplementary motor area (preSMA) se...
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Background The human brain has high energy requirements that continuously support healthy neuronal activity and cognition. A disruption in brain energy metabolism (BEM) may contribute to early neuropathological changes such as accumulation of β-amyloid and tau in vulnerable populations. One such population is amnestic mild cognitive impairment (aMC...
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To test the hypothesis that semantic processes are represented in multiple subsystems, we recorded electroencephalogram (EEG) as we elicited object memories using the modified Semantic Object Retrieval Test, during which an object feature, presented as a visual word [VW], an auditory word [AW], or a picture [Pic], was followed by a second feature a...
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Behavioral studies investigating fundamental cognitive abilities provide evidence that processing speed accounts for large proportions of performance variability between individuals. Processing speed decline is a hallmark feature of the cognitive disruption observed in healthy aging and in demyelinating diseases such as multiple sclerosis (MS), neu...
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The neural mechanisms underlying motor impairment in multiple sclerosis (MS) remain unknown. Motor cortex dysfunction is implicated in blood-oxygen-level-dependent (BOLD) functional magnetic resonance imaging (fMRI) studies, but the role of neural–vascular coupling underlying BOLD changes remains unknown. We sought to independently measure the phys...
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Post‐traumatic stress disorder (PTSD) is a debilitating condition that may develop after experiencing a traumatic event. Combat exposure increases an individual's chance of developing PTSD, making veterans especially susceptible to the disorder. PTSD is characterized by dysregulated emotional networks, memory deficits, and a hyperattentive response...
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Background Cognitive slowing occurs in ~70% of multiple sclerosis (MS) patients. The pathophysiology of this slowing is unknown. Neurovascular coupling, acute localized blood flow increases following neural activity, is essential for efficient cognition. Loss of vascular compliance along the cerebrovascular tree would result in suboptimal vasodilat...
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Chronic verbal retrieval deficits have been noted in traumatic brain injury (TBI), but no U.S. Food and Drug Administration-approved interventions are available. The present study investigated whether 10 sessions of 20 min of 1 mA anodal high-definition transcranial direct current stimulation (HD-tDCS) targeting pre-supplementary motor area/dorsal...
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A bstract Prior Go/NoGo studies have localized specific regions and EEG spectra for which traditional approaches have distinguished between Go and NoGo conditions. A more detailed characterization of the spatial distribution and timing of the synchronization of frequency bands would contribute substantially to the clarification of neural mechanisms...
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Background Transcranial direct current stimulation (tDCS), a non-invasive stimulation, represents a potential intervention to enhance cognition across clinical populations including Alzheimer’s disease and mild cognitive impairment (MCI). This randomized clinical trial in MCI investigated the effects of anodal tDCS (a-tDCS) delivered to left inferi...
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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...
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To investigate differences in inhibitory control and processing speed over the life span, participants in 7- to 8-, 10- to 11-, 12- to 15-, 18- to 25-, and 54- to 80-year-old age cohorts completed a Go/No-Go task requiring varying levels of semantic categorization. Discriminant function analysis of correct rejection rates (CRRs), hit rates (HRs), a...
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Factors that contribute to overcoming decision-making biases in later life pose an important investigational question given the increasing older adult population. Limited empirical evidence exists and the literature remains equivocal of whether increasing age is associated with elevated susceptibility to decision-making biases such as framing effec...
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The hemodynamic response function (HRF), a model of brain blood-flow changes in response to neural activity, reflects communication between neurons and the vasculature that supplies these neurons in part by means of glial cell intermediaries (e.g., astrocytes). Intact neural-vascular communication might play a central role in optimal cognitive perf...
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Both age and amnestic Mild Cognitive Impairment (aMCI), two major risk factors associated with Alzheimer's disease, have been associated with increased latency of event-related potentials, but how these factors interact has been less extensively evaluated. We examined the effects of age as a factor in 25 individuals with aMCI and in 25 age-matched...
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Background: The objective was to test whether repetitive Transcranial Magnetic Stimulation (rTMS) just prior to Cognitive Processing Therapy (CPT) would significantly improve the clinical outcome compared to sham rTMS prior to CPT in veterans with PTSD. Methods: Veterans 18-60 years of age with current combat-related PTSD symptoms were randomize...
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Higher-order cognitive training has shown to enhance performance in older adults, but the neural mechanisms underlying performance enhancement have yet to be fully disambiguated. This randomized trial examined changes in processing speed and processing speed-related neural activity in older participants (57-71 years of age) who underwent cognitive...
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Non-invasive interventions, such as cognitive training (CT) and physical exercise, are gaining momentum as ways to augment both cognitive and brain function throughout life. One of the most fundamental yet little studied aspects of human cognition is innovative thinking, especially in older adults. In this study, we utilize a measure of innovative...
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Multiple sclerosis (MS) involves damage to white matter microstructures. This damage has been related to grey matter function as measured by standard, physiologically-nonspecific neuroimaging indices (i.e., blood-oxygen-level dependent signal [BOLD]). Here, we used calibrated functional magnetic resonance imaging and diffusion tensor imaging to exa...
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As with other medical events, concussion history is typically dependent upon self-report, although little is known about the accuracy or reliability of such information. We assessed the reliability of lifetime self-reported concussion histories from 27 retired players from the National Football League (NFL) at baseline and one to two years later. T...
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Abstraction, a unique aspect of human reasoning, is affected by TBI. Lack of sensitive metrics to characterize abstraction in TBI recovery may impede detection of cognitive deficits and impact daily function. Recent findings found lower performance in abstracting meaning from complex information, referred to as gist reasoning, in adults with TBI. T...
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Cognitive deficits in executive function and memory among individuals with bipolar disorder (BD) are well-documented; however, only recently have efforts begun to address whether such cognitive deficits can be ameliorated through cognitive training. This pilot study examined the effects of a top–down, cognitive reasoning training program in adults...
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Background Neuroimaging studies have yielded significant advances in the understanding of neural processes relevant to the development and persistence of addiction. However, these advances have not explored extensively for diagnostic accuracy in human subjects. The aim of this study was to develop a statistical approach, using a machine learning fr...
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Insidious declines in normal aging are well established. Emerging evidence suggests that non-pharmacological interventions, specifically cognitive and physical training, may counter diminishing age-related cognitive and brain functions. This randomized trial compared effects of two training protocols: cognitive training (CT) versus physical trainin...
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Using diffusion tensor imaging (DTI), we assessed the relationship of white matter integrity and performance on the Boston Naming Test (BNT) in a group of retired professional football players and a control group. We examined correlations between fractional anisotropy (FA) and mean diffusivity (MD) with BNT T-scores in an unbiased voxel-wise analys...
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(free download: http://authors.elsevier.com/a/1THEecAwkKMHN) Abstract How the brain combines the neural representations of features that comprise an object in order to activate a coherent object memory is poorly understood, especially when the features are presented in different modalities (visual vs. auditory) and domains (verbal vs. nonverbal). W...
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Objective: Cognitive training offers a promising way to mitigate cognitive deterioration in individuals with mild cognitive impairment (MCI). This randomized control pilot trial examined the effects of Gist Reasoning Training on cognition as compared with a training involving New Learning in a well-characterized MCI group. Methods: Fifty partici...
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We examined the effects of amnestic mild cognitive impairment (aMCI) on behavioral (response times and error rates) and scalp-recorded event-related potential (ERP) measures of response execution and inhibition, using Go/NoGo tasks involving basic and superordinate semantic categorization. Twenty-five aMCI (16 F; 68.5±8 years) and 25 age- and gende...
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Veterans with posttraumatic stress disorder (PTSD) underwent a systematic evaluation to determine which factors were associated with the degree of functional status. Demographic information, self-report scales, and symptom ratings performed by trained evaluators were investigated in multiple regression models to determine their contribution to func...
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Traumatic brain injury (TBI) is a chronic health condition. The prevalence of TBI, combined with limited advances in protocols to mitigate persistent TBI-related impairments in higher order cognition, present a significant challenge. In this randomised study (n = 60), we compared the benefits of Strategic Memory Advanced Reasoning Training (SMART,...
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To our knowledge, this is the first study to show an association between concussion, cognition, and anatomical structural brain changes across the age spectrum in former National Football League athletes. To assess the relationship of hippocampal volume, memory performance, and the influence of concussion history in retired National Football League...
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Deficits in semantic memory in individuals with amnestic mild cognitive impairment (aMCI) have been previously reported, but the underlying neurobiological mechanisms remain to be clarified. We examined event-related potentials (ERPs) associated with semantic memory retrieval in 16 individuals with aMCI as compared to 17 normal controls using the S...
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We used event-related potentials (ERPs) to study age effects of perceptual (basic-level) vs. perceptual-semantic (superordinate-level) categorization on cognitive control using the go/nogo paradigm. Twenty-two younger (11M; 21±2.2yrs) and 22 older adults (9M; 63±5.8yrs) completed two visual go/nogo tasks. In the single car task (SiC) (basic), go/no...
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Gist reasoning (abstracting meaning from complex information) was compared between adults with moderate-to-severe traumatic brain injury (TBI, n = 30) at least one year post injury and healthy adults (n = 40). The study also examined the contribution of executive functions (working memory, inhibition, and switching) and memory (immediate recall and...
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The ability to extrapolate essential gist through the analysis and synthesis of information, prediction of potential outcomes, abstraction of ideas, and integration of relationships with world knowledge is critical for higher-order learning. The present study investigated the efficacy of cognitive training to elicit improvements in gist reasoning a...
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Significance The existing literature on the long-term effects of marijuana on the brain provides an inconsistent picture (i.e., presence or absence of structural changes) due to methodological differences across studies. We overcame these methodological issues by collecting multimodal measures in a large group of chronic marijuana using adults with...
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Glioblastoma (GBM), the most common primary brain tumor, is resistant to currently available treatments. The development of mouse models of human GBM has provided a tool for studying mechanisms involved in tumor initiation and growth as well as a platform for preclinical investigation of new drugs. In this study we used (1) H MR spectroscopy to stu...
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Numerous studies have found evidence for corticolimbic theta band electroencephalographic (EEG) oscillations in the neural processing of visual stimuli perceived as threatening. However, varying temporal and topographical patterns have emerged, possibly due to varying arousal levels of the stimuli. In addition, recent studies suggest neural oscilla...
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Abstract To investigate neural mechanisms that support semantic functions in aging, we recorded scalp EEG during an object retrieval task in 22 younger and 22 older adults. The task required determining if a particular object could be retrieved when two visual words representing object features were presented. Both age groups had comparable accurac...
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Stress response biologic systems are altered in alcohol-dependent individuals. Early life stress (ELS) is associated with a heightened risk of alcohol dependence, presumably because of stress-induced neuroplastic changes. This study was designed to assess the contribution of ELS to a stress-induced neural response in alcohol-dependent participants....
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Physical exercise, particularly aerobic exercise, is documented as providing a low cost regimen to counter well-documented cognitive declines including memory, executive function, visuospatial skills, and processing speed in normally aging adults. Prior aging studies focused largely on the effects of medium to long term (>6 months) exercise trainin...
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Complex mental activity induces improvements in cognition, brain function, and structure in animals and young adults. It is not clear to what extent the aging brain is capable of such plasticity. This study expands previous evidence of generalized cognitive gains after mental training in healthy seniors. Using 3 MRI-based measurements, that is, art...
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Threatening stimuli have been found to modulate visual processes related to perception and attention. The present functional magnetic resonance imaging (fMRI) study investigated whether threat modulates visual object recognition of man-made and naturally occurring categories of stimuli. Compared with nonthreatening pictures, threatening pictures of...
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Stress-response biological systems are altered in alcohol-dependent individuals and are reported to predict future relapse. This study was designed to assess neural disruptions in alcohol-dependent participants when exposed to a conditioned stimulus (CS) warning of the impending onset of a universal, nonpersonalized stressor. Fifteen alcohol-depend...
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Measurements of blood flow in the human hippocampus are complicated by its relatively small size, unusual anatomy and patterns of blood supply. Only a handful of arterial spin labeling (ASL) MRI articles have reported regional cerebral blood flow (rCBF) values for the human hippocampus. Numerous reports have found heterogeneity in a number of other...
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Object Coagulopathy and thrombocytopenia are common after traumatic brain injury (TBI), yet transfusion thresholds for mildly to moderately abnormal ranges of international normalized ratio and platelet count remain controversial. This study evaluates associations between fresh frozen plasma (FFP) and platelet transfusions with long-term functional...
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To properly formulate functional magnetic resonance imaging (fMRI) experiments with complex mental activity, it is advantageous to permit great flexibility in the statistical components of the design of these studies. The length of an experiment, the placement of various stimuli and the modeling approach used all affect the ability to detect mental...
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An exaggerated response to emotional stimuli is among the many symptoms widely reported by veterans of the 1991 Persian Gulf War. These symptomologies have been attributed to damage and dysfunction associated with deployment-related exposures. We collected event-related potential data from 22 veterans meeting Haley criteria for Gulf War (GW) Syndro...
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Anxiety experienced in anticipation of impending aversive events induces striatal-limbic activation. However, previous functional magnetic imaging (fMRI) studies of anticipatory anxiety have utilized post-test measures of anxiety, making a direct association between neural activation and distress problematic. This paradigm was designed to assess th...
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The default mode network (DMN) is a reliably elicited functional neural network with potential clinical implications. Its discriminant and prognostic utility following traumatic axonal injury (TAI) have not been previously investigated. The present study used three approaches to analyze DMN functional connectedness, including a whole-brain analysis...
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An exaggerated response to emotional stimuli is one of the several symptoms widely reported by veterans of the 1991 Persian Gulf War. Many have attributed these symptoms to post-war stress; others have attributed the symptoms to deployment-related exposures and associated damage to cholinergic, dopaminergic, and white matter systems. We collected e...
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Several authors have proposed nonparametric semivariogram estimators. Shapiro and Botha (1991) did so by application of Bochner’s theorem and Cherry et al. (1996) further investigated this technique where it performed favorably against parametric estimators even when data were generated under the parametric model. While the former makes allowanc...
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Since its introduction by [Stone, M. (1974), ‘Cross-validatory Choice and the Assessment of Statistical Predictions (with discussion)’, Journal of the Royal Statistical Society, B36, 111–133] and [Geisser, S. (1975), ‘The Predictive Sample Reuse Method with Applications’, Journal of the American Statistical Association, 70, 320–328], cross-validati...