Michael Kraut

Michael Kraut
Johns Hopkins Medicine | JHUSOM · Department of Radiology and Radiological Science

About

207
Publications
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Publications

Publications (207)
Article
Objective High Definition transcranial Direct Current Stimulation (HD-tDCS) has been shown to improve cognitive performance in individuals with chronic traumatic brain injury (TBI), although electrophysiological mechanisms remain unclear. Methods Veterans with TBI underwent active anodal (N = 15) vs sham (N = 10) HD-tDCS targeting the pre-suppleme...
Conference Paper
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Objective: We examined the therapeutic effects on word finding difficulty in persons with multiple sclerosis (PwMS) using high-definition transcranial direct current stimulation (HD-tDCS) targeting the pre-Supplementary Motor Area (pre-SMA). Background: Word finding difficulty is prevalent in PwMS and can impact communication, job performance, and...
Article
Transcranial magnetic stimulation (TMS) is a type of noninvasive neurostimulation used increasingly often in clinical medicine. While most studies to date have focused on TMS's ability to treat major depressive disorder, it has shown promise in several other conditions including post-traumatic stress disorder (PTSD) and traumatic brain injury (TBI)...
Article
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Beta-amyloid deposition (Aβ) is one of the earliest pathological markers associated with Alzheimer’s disease. Mild cognitive impairment in the setting of Aβ pathology is widely considered to represent a preclinical manifestation of Alzheimer’s disease. In-vivo imaging studies are unique in their potential to advance our understanding of the role of...
Conference Paper
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Anodal high definition transcranial direct current stimulation (HD-tDCS) targeting the pre-supplementary motor area/dorsal anterior cingulate cortex (pre-SMA/dACC) has recently been shown to improve verbal and executive functions in veterans with chronic traumatic brain injury (cTBI), but the underlying mechanisms remain unknown. We examined electr...
Article
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Depression in late-life is associated with increased risk of cognitive decline and development of all-cause dementia. The neurobiology of late-life depression (LLD) may involve both neurochemical and neurodegenerative mechanisms that are common to depression and dementia. Transgenic amyloid mouse models show evidence of early degeneration of monoam...
Article
Anodal high definition transcranial direct current stimulation (HD-tDCS) targeting the pre-supplementary motor area/dorsal anterior cingulate cortex (pre-SMA/dACC) has recently been shown to improve verbal retrieval deficits in veterans with chronic traumatic brain injury (TBI)[42], but predictors of treatment response are unclear. We hypothesized...
Article
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We report a patient who has cognitive sequalae including verbal retrieval deficits after severe traumatic brain injury (TBI). The cortico-caudate-thalamic circuit involving the pre-Supplementary Motor Area (pre-SMA) has been proposed to underlie verbal retrieval functions. We hypothesized that High Definition-transcranial Direct Current Stimulation...
Article
Emotional processing and cognitive control are implicated as being dysfunctional in posttraumatic stress disorder (PTSD) and targeted in cognitive processing therapy (CPT), a trauma-focused treatment for PTSD. The N2 event-related potential has been interpreted in the context of emotional processing and cognitive control. In this analysis of second...
Article
Background Magnetic resonance spectroscopy (MRS) methods have quantified changes in levels of neurotransmitters and neurometabolites in patients with major depression across the lifespan. The application of 7T field strengths and greater have not been a major focus of study in patients with late-life depression (LLD). Methods Nine LLD patients who...
Article
Late-life Depression (LLD) is associated with increased risk of all-cause dementia and may involve Alzheimer’s disease pathology. Twenty-one LLD patients who met DSM-V criteria for a current major depressive episode and 21 healthy controls underwent clinical and neuropsychological assessments, magnetic resonance imaging to measure gray matter volum...
Article
Patients with late-life depression (LLD) have a more variable response to pharmacotherapy relative to patients with mid-life depression. Degeneration of the serotonergic system and lower occupancy of the initial target for antidepressant medications, the serotonin transporter (5-HTT) may contribute to variability in treatment response. The focus of...
Article
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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...
Preprint
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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...
Article
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...
Article
Background Central nervous system (CNS) complications are among the most common, devastating sequelae of sickle cell disease (SCD) occurring throughout the lifespan. Objective These evidence-based guidelines of the American Society of Hematology are intended to support the SCD community in decisions about prevention, diagnosis, and treatment of th...
Article
Full-text available
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...
Article
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...
Preprint
Full-text available
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...
Article
Importance Delirium occurs in up to 52% of patients after cardiac surgery and may result from changes in cerebral perfusion. Using intraoperative cerebral autoregulation monitoring to individualize and optimize cerebral perfusion may be a useful strategy to reduce the incidence of delirium after cardiac surgery. Objective To determine whether targ...
Article
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...
Article
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...
Article
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...
Article
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Background Patients who have pacemakers or defibrillators are often denied the opportunity to undergo magnetic resonance imaging (MRI) because of safety concerns, unless the devices meet certain criteria specified by the Food and Drug Administration (termed “MRI-conditional” devices). Methods We performed a prospective, nonrandomized study to asse...
Article
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Computer-based assessment of many cognitive processes (eg, anticipatory and response readiness processes) requires the use of invariant stimulus display times (SDT) and intertrial intervals (ITI). Although designs with invariant SDTs and ITIs have been used in functional magnetic resonance imaging (fMRI) research, such designs are problematic for f...
Article
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...
Article
We recently reported that alpha-2 macroglobulin (A2M) is a biomarker of neuronal injury in Alzheimer's disease (AD) and identified a network of nine genes co-expressed with A2M in the brain. This network includes the gene encoding SPARCL1, a protein implicated in synaptic maintenance. Here, we examine whether SPARCL1 is associated with longitudinal...
Article
Full-text available
Traumatic brain injury (TBI) is often considered to be a risk factor for the later development of neurodegenerative conditions, but some findings do not support a link. Differences in research methods, clinical samples, and limitations encountered when assessing and documenting TBI details likely contribute to the mixed reports in the literature. D...
Article
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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 respo...
Article
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Neuropathological and neuroimaging studies have consistently demonstrated degeneration of monoamine systems, especially the serotonin system, in normal aging and Alzheimer's disease. The evidence for degeneration of the serotonin system in mild cognitive impairment is limited. Thus, the goal of the present study was to measure the serotonin transpo...
Article
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Resting-state functional connectivity alterations have been demonstrated in Alzheimer's disease (AD) and mild cognitive impairment (MCI) before the observation of AD neuropathology, but mechanisms driving these changes are not well understood. Serotonin neurodegeneration has been observed in MCI and AD and is associated with cognitive deficits and...
Article
Gulf War veterans meeting criteria for Haley Syndrome 2 of Gulf War illness endorse a particular constellation of symptoms that include difficulty with processing information, word-finding, and confusion. To explore the neural basis of their word-finding difficulty, we assessed event-related potentials (ERPs) associated with semantic memory retriev...
Article
Full-text available
Individuals who have suffered a traumatic brain injury (TBI) often have word retrieval deficits; however, the underlying neural mechanisms of such deficits are yet to be clarified. Previous studies in normal subjects have shown that during a word retrieval task, there is a 750 ms event-related potential (ERP) divergence detected at the left fronto-...
Article
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...
Article
(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...
Article
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...
Article
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We recently showed that Alzheimer disease (AD) patients have lower plasma concentrations of the phosphatidylcholines [PC16:0/20:5 (PC1620); PC16:0/22:6 (PC1622); and PC18:0/22:6 (PC1822)] relative to healthy controls. We now extend these findings by examining associations between plasma concentrations of these PCs with cognitive performance and bra...
Article
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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...
Article
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Quantification of β-amyloid (Aβ) in vivo is often accomplished using the distribution volume ratio (DVR), based on a simplified ratio tissue model. We investigated the local relationships between DVR and cerebral blood flow (CBF), as well as relative blood flow (R1), in nondemented older adults. Fifty-five nondemented participants (mean age 78.5 ye...
Article
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...
Article
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...
Article
Introduction: Impaired autoregulation during cardiac surgery with cardiopulmonary bypass (CPB) is associated with perioperative mortality and morbidity. Identifying risk factors for impaired autoregulation during CPB surgery may facilitate risk stratification, and guide intra- and postoperative monitoring of high-risk patients. Hypothesis: We hypot...
Article
Full-text available
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...
Article
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Background: Silent cerebral infarcts are the most common neurologic injury in children with sickle cell anemia and are associated with the recurrence of an infarct (stroke or silent cerebral infarct). We tested the hypothesis that the incidence of the recurrence of an infarct would be lower among children who underwent regular blood-transfusion th...
Article
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...
Article
Although overweight and obesity are associated with poor health outcomes in the elderly, the biological bases of obesity-related behaviors during aging are poorly understood. Common variants in the FTO gene are associated with adiposity in children and younger adults as well as with adverse mental health in older individuals. However, it is unclear...
Article
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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...
Article
The present study examined the transfer of higher-order cognitive strategy training to inhibitory control. Middle school students enrolled in a comprehension- and reasoning-focused cognitive strategy training program and passive controls participated. The training program taught students a set of steps for inferring essential gist or themes from ma...
Article
Hearing impairment in older adults is independently associated in longitudinal studies with accelerated cognitive decline and incident dementia, and in cross-sectional studies, with reduced volumes in the auditory cortex. Whether peripheral hearing impairment is associated with accelerated rates of brain atrophy is unclear. We analyzed brain volume...
Article
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Detecting silent cerebral infarcts on magnetic resonance images (MRIs) in children with sickle cell anemia is challenging, yet reproducibility of readings has not been examined in this population. We evaluated consensus rating, inter-, and intra-grader agreement associated with detecting silent cerebral infarct on screening MRI in the Silent Infarc...
Article
Patients undergoing aortic operations with hypothermic circulatory arrest (HCA) may require prolonged rewarming, a maneuver associated with impaired cerebral blood flow (CBF) autoregulation. The purpose of this study was to determine the effects of HCA on CBF autoregulation with a validated method based on near-infrared spectroscopy. Regional cereb...
Article
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To develop targeted intervention strategies for the treatment of Alzheimer's disease, we first need to identify early markers of brain changes that occur before the onset of cognitive impairment. Here, we examine changes in resting-state brain function in humans from the Baltimore Longitudinal Study of Aging. We compared longitudinal changes in reg...
Article
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White matter lesions (WMLs) are associated with depressive symptoms in older adults. However, it is not clear whether different symptom dimensions of depression have distinct associations with WMLs. The authors assessed the longitudinal relationships of the Center for Epidemiologic Studies Depression Scale (CES-D) total score and subscale scores wi...
Article
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Recent positron emission tomography studies of cerebral glucose metabolism have identified the functional neural circuitry associated with mood and cognitive responses to antidepressant treatment in late life depression (LLD). The structural alterations in these networks are not well understood. The present study used magnetic resonance (MR) imagin...
Article
Optimizing blood pressure using near-infrared spectroscopy monitoring has been suggested to ensure organ perfusion during cardiac surgery. Near-infrared spectroscopy is a reliable surrogate for cerebral blood flow in clinical cerebral autoregulation monitoring and might provide an earlier warning of malperfusion than indicators of cerebral ischemia...
Article
The present study examined functional MRI (fMRI) BOLD signal changes in response to object categorization during response selection and inhibition. Young adults (N=16) completed a Go/NoGo task with varying object categorization requirements while fMRI data were recorded. Response inhibition elicited increased signal change in various brain regions,...
Article
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...
Article
Objective: To determine whether correlates of white matter integrity can provide general as well as specific insight into the chronic effects of head injury coupled with depression symptom expression in professional football players. Method: We studied 26 retired National Football League (NFL) athletes who underwent diffusion tensor imaging (DTI...
Article
We investigated whether individuals with impaired glucose tolerance (IGT) in midlife subsequently show regionally specific longitudinal changes in regional cerebral blood flow (rCBF) relative to those with normal glucose tolerance (NGT). Sixty-four cognitively normal participants in the neuroimaging substudy of the Baltimore Longitudinal Study of A...