Bio

Bio


Dr. Weber is currently working to develop techniques to measure pain-related functional and structural changes in the brain and spinal cord with advanced magnetic resonance imaging techniques. His second area of focus it to better understand the neurophysiology of clinical pain and its treatment. The ultimate goal of Dr. Weber’s research is to discover more effective treatments and preventative strategies for clinical pain syndromes.

Honors & Awards


  • NIH Clinical Research Extramural Loan Repayment Program Award, National Institute of Neurological Disorders and Stroke (2018 - 2020)
  • Mentored Patient-Oriented Research Career Development Award (K23NS104211), National Institute of Neurological Disorders and Stroke (2018 - 2023)
  • Young Investigator Award, American Pain Society (2018)
  • Ruth L. Kirschstein National Research Service Award Individual Fellowship (F32AT007800), National Center for Complementary and Integrative Health (2012 - 2015)

Professional Education


  • Doctor of Philosophy, Northwestern University (2016)
  • Doctor of Chiropractic, Palmer College of Chiropractic (2009)
  • Bachelor of Science, Saginaw Valley State College (2006)

Stanford Advisors


Research & Scholarship

Projects


  • Neuroimaging-Based Brain and Spinal Cord Biomarkers for Cervical Radiculopathy

    Location

    Palo Alto, CA

Lab Affiliations


Publications

All Publications


  • Thermal Stimulation Alters Cervical Spinal Cord Functional Connectivity in Humans. Neuroscience Weber, K. A., Sentis, A. I., Bernadel-Huey, O. N., Chen, Y., Wang, X., Parrish, T. B., Mackey, S. 2017

    Abstract

    The spinal cord has an active role in the modulation and transmission of the neural signals traveling between the body and the brain. Recent advancements in functional magnetic resonance imaging (fMRI) have made the in vivo examination of spinal cord function in humans now possible. This technology has been recently extended to the investigation of resting state functional networks in the spinal cord, leading to the identification of distinct patterns of spinal cord functional connectivity. In this study, we expand on the previous work and further investigate resting state cervical spinal cord functional connectivity in healthy participants (n = 15) using high resolution imaging coupled with both seed-based functional connectivity analyses and graph theory-based metrics. Within spinal cord segment functional connectivity was present between the left and right ventral horns (bilateral motor network), left and right dorsal horns (bilateral sensory network), and the ipsilateral ventral and dorsal horns (unilateral sensory-motor network). Functional connectivity between the spinal cord segments was less apparent with the connectivity centered at the region of interest and spanning < 20 mm along the superior-inferior axis. In a subset of participants (n = 10), the cervical spinal cord functional network was demonstrated to be state-dependent as thermal stimulation of the right ventrolateral forearm resulted in significant disruption of the bilateral sensory network, increased network global efficiency, and decreased network modularity.

    View details for DOI 10.1016/j.neuroscience.2017.10.035

    View details for PubMedID 29101078

  • Lateralization of cervical spinal cord activity during an isometric upper extremity motor task with functional magnetic resonance imaging. NeuroImage Weber, K. A., Chen, Y., Wang, X., Kahnt, T., Parrish, T. B. 2016; 125: 233-243

    Abstract

    The purpose of this study was to use an isometric upper extremity motor task to detect activity induced blood oxygen level dependent signal changes in the cervical spinal cord with functional magnetic resonance imaging. Eleven healthy volunteers performed six 5minute runs of an alternating left- and right-sided isometric wrist flexion task, during which images of the cervical spinal cord were acquired with a reduced field-of-view T2*-weighted gradient-echo echo-planar-imaging sequence. Spatial normalization to a standard spinal cord template was performed, and group average activation maps were generated in a mixed-effects analysis. The task activity significantly exceeded that of the control analyses. The activity was lateralized to the hemicord ipsilateral to the task and reliable across the runs at the group and subject level. Finally, a multi-voxel pattern analysis was able to successfully decode the left and right tasks at the C6 and C7 vertebral levels.

    View details for DOI 10.1016/j.neuroimage.2015.10.014

    View details for PubMedID 26488256

  • Functional Magnetic Resonance Imaging of the Cervical Spinal Cord During Thermal Stimulation Across Consecutive Runs. NeuroImage Weber, K. A., Chen, Y., Wang, X., Kahnt, T., Parrish, T. B. 2016

    Abstract

    The spinal cord is the first site of nociceptive processing in the central nervous system and has a role in the development and perpetuation of clinical pain states. Advancements in functional magnetic resonance imaging are providing a means to non-invasively measure spinal cord function, and functional magnetic resonance imaging may provide an objective method to study spinal cord nociceptive processing in humans. In this study, we tested the validity and reliability of functional magnetic resonance imaging using a selective field-of-view gradient-echo echo-planar-imaging sequence to detect activity induced blood oxygenation level-dependent signal changes in the cervical spinal cord of healthy volunteers during warm and painful thermal stimulation across consecutive runs. At the group and subject level, the activity was localized more to the dorsal hemicord, the spatial extent and magnitude of the activity was greater for the painful stimulus than the warm stimulus, and the spatial extent and magnitude of the activity exceeded that of a control analysis. Furthermore, the spatial extent of the activity for the painful stimuli increased across the runs likely reflecting sensitization. Overall, the spatial localization of the activity varied considerably across the runs, but despite this variability, a machine-learning algorithm was able to successfully decode the stimuli in the spinal cord based on the distributed pattern of the activity. In conclusion, we were able to successfully detect and characterize cervical spinal cord activity during thermal stimulation at the group and subject level.

    View details for DOI 10.1016/j.neuroimage.2016.09.015

    View details for PubMedID 27616641

  • Midsagittal tissue bridges are associated with walking ability in incomplete spinal cord injury: A magnetic resonance imaging case series. The journal of spinal cord medicine O'Dell, D. R., Weber, K. A., Berliner, J. C., Elliott, J. M., Connor, J. R., Cummins, D. P., Heller, K. A., Hubert, J. S., Kates, M. J., Mendoza, K. R., Smith, A. C. 2018: 1–4

    Abstract

    CONTEXT: Following spinal cord injury (SCI), early prediction of future walking ability is difficult, due to factors such as spinal shock, sedation, impending surgery, and secondary long bone fracture. Accurate, objective biomarkers used in the acute stage of SCI would inform individualized patient management and enhance both patient/family expectations and treatment outcomes. Using magnetic resonance imaging (MRI) and specifically a midsagittal T2-weighted image, the amount of tissue bridging (measured as spared spinal cord tissue) shows potential to serve as such a biomarker. Ten participants with incomplete SCI received MRI of the spinal cord. Using the midsagittal T2-weighted image, anterior and posterior tissue bridges were calculated as the distance from cerebrospinal fluid to the damage. Then, the midsagittal tissue bridge ratio was calculated as the sum of anterior and posterior tissue bridges divided by the spinal cord diameter. Each participant also performed a 6-minute walk test, where the total distance walked was measured within six minutes.FINDINGS: The midsagittal tissue bridge ratio measure demonstrated a high level of inter-rater reliability (ICC=0.90). Midsagittal tissue bridge ratios were significantly related to distance walked in six minutes (R=0.68, P=0.03).CONCLUSION/CLINICAL RELEVANCE: We uniquely demonstrated that midsagittal tissue bridge ratios were correlated walking ability. These preliminary findings suggest potential for this measure to be considered a prognostic biomarker of residual walking ability following SCI.

    View details for DOI 10.1080/10790268.2018.1527079

    View details for PubMedID 30346248

  • Dynamic per slice Shimming for Simultaneous Brain and Spinal Cord fMRI. Magnetic resonance in medicine Islam, H., Law, C. S., Weber, K. A., Mackey, S. C., Glover, G. H. 2018

    Abstract

    PURPOSE: Simultaneous brain and spinal cord functional MRI is emerging as a new tool to study the central nervous system but is challenging. Poor B0 homogeneity and small size of the spinal cord are principal obstacles to this nascent technology. Here we extend a dynamic shimming approach, first posed by Finsterbusch, by shimming per slice for both the brain and spinal cord.METHODS: We shim dynamically by a simple and fast optimization of linear field gradients and frequency offset separately for each slice in order to minimize off-resonance for both the brain and spinal cord. Simultaneous acquisition of brain and spinal cord fMRI is achieved with high spatial resolution in the spinal cord by means of an echo-planar RF pulse for reduced FOV. Brain slice acquisition is full FOV.RESULTS: T2*-weighted images of brain and spinal cord are acquired with high clarity and minimal observable image artifacts. Fist-clenching fMRI experiments reveal task-consistent activation in motor cortices, cerebellum, and C6-T1 spinal segments.CONCLUSIONS: High quality functional results are obtained for a sensory-motor task. Consistent activation in both the brain and spinal cord is observed at individual levels, not only at group level. Because reduced FOV excitation is applicable to any spinal cord section, future continuation of these methods holds great potential.

    View details for DOI 10.1002/mrm.27388

    View details for PubMedID 30284730

  • Altered Cervical Spinal Cord Resting State Activity in Fibromyalgia. Arthritis & rheumatology (Hoboken, N.J.) Martucci, K. T., Weber, K. A., Mackey, S. C. 2018

    Abstract

    OBJECTIVE: Altered afferent input and central neural modulation are thought to contribute to fibromyalgia symptoms, and these processes converge within the spinal cord. We hypothesized that, using resting state functional magnetic resonance imaging (rs-fMRI) of the cervical spinal cord, we would observe altered frequency dependent activity in fibromyalgia.METHODS: Cervical spinal cord rs-fMRI was performed in fibromyalgia patients and healthy controls. We analyzed a measure of low frequency oscillatory power, the amplitude of low frequency fluctuations (ALFF), for frequencies 0.01 - 0.198 Hz and frequency sub-bands, to determine regional and frequency-specific alterations in fibromyalgia. Functional connectivity and graph metrics were also analyzed.RESULTS: As compared to controls, greater ventral and lesser dorsal Mean ALFF of the cervical spinal cord was observed in fibromyalgia (p < 0.05, uncorrected) for frequencies 0.01 - 0.198 Hz and all sub-bands. Additionally, lesser Mean ALFF within the right dorsal quadrant (p < 0.05, corrected) for frequencies 0.01 - 0.198 Hz and sub-band frequencies 0.073 - 0.198 Hz was observed in fibromyalgia. Regional Mean ALFF was not correlated with pain, however, regional lesser Mean ALFF was correlated with fatigue in patients (r = 0.763, p = 0.001). Functional connectivity and graph metrics were similar between groups.CONCLUSION: Our results indicate unbalanced activity between the ventral and dorsal cervical spinal cord in fibromyalgia. Increased ventral neural processes and decreased dorsal neural processes may reflect the presence of central sensitization and contribute to fatigue and other bodily symptoms in fibromyalgia. This article is protected by copyright. All rights reserved.

    View details for DOI 10.1002/art.40746

    View details for PubMedID 30281205

  • Tract-Specific Volume Loss on 3T MRI in Patients with Cervical Spondylotic Myelopathy. Spine Hopkins, B. S., Weber, K. A., Cloney, M. B., Paliwal, M., Parrish, T. B., Smith, Z. A. 2018

    Abstract

    Case-control.The aim of this study was to understand the role of high-resolution magnetic resonance (MR) in identifying regional cord volume loss in cervical spondylotic myelopathy (CSM).Preliminary studies suggest that compression of the ventral region of the cord may contribute disproportionately to CSM symptomology; however, tract-specific data are lacking in the CSM population. The current study is the first to use 3T MR imaging (MRI) images of CSM patients to determine specific volume loss at the level of detail of individual descending white matter tracts.Twelve patients with CSM and 14 age-matched were enrolled prospectively and underwent 3-Tesla MRI of the cervical spine. Using the high-resolution images of the spinal cord, straightening and alignment with a template was performed and specific spinal cord tract volumes were measured using Spinal Cord Tool-box version 3.0.7. Modified Japanese orthopedic association (mJOA) and Nurick disability scores were collected in a prospective manner and were analyzed in relation to descending spinal tract volumes.Having CSM was predicted by anterior/posterior diameter, eccentricity of the cord [odds ratio (OR) 0.000000621, P = 0.004], ventral reticulospinal tract volume (OR 1.167, P = 0.063), lateral corticospinal tract volume (OR 1.034, P = 0.046), rubrospinal tract volume (OR 1.072, P = 0.011), and ventrolateral reticulospinal tract volume (OR 1.474, P = 0.005) on single variable logistic regression. Single variable linear regression showed decreases in anterior/posterior spinal cord diameter (P = 0.022), ventral reticulospinal tract volumes (P = 0.007), and ventrolateral reticulospinal tract volumes (P = 0.017) to significantly predict worsening mJOA scores. Similarly, decreases in ventral reticulospinal tract volumes significantly predicted increasing Nurick scores (P = 0.039).High-resolution 3T MRI can detect tract-specific volume loss in descending spinal cord tracts in CSM patients. Anterior/posterior spinal cord diameter, ventral reticulospinal tract, ventrolateral reticulospinal tract, lateral corticospinal tract, and rubrospinal tract volume loss are associated with CSM symptoms.2.

    View details for DOI 10.1097/BRS.0000000000002667

    View details for PubMedID 29649085

  • High-resolution magnetization transfer MRI in patients with cervical spondylotic myelopathy. Journal of clinical neuroscience : official journal of the Neurosurgical Society of Australasia Suleiman, L. I., Weber, K. A., Rosenthal, B. D., Bhatt, S. A., Savage, J. W., Hsu, W. K., Patel, A. A., Parrish, T. B. 2018

    Abstract

    Magnetization transfer (MT) contrast has been established as a marker of myelin integrity, and cervical spondylotic myelopathy is known to cause demyelination. Ten patients with clinical and magnetic resonance imaging (MRI) manifestations of cervical spondylotic myelopathy (CSM) were compared to the MRIs of seven historic healthy controls, using the magnetization transfer ratio (MTR) and Nurick scores as the primary metrics. Transverse slices through the intervertebral discs of the cervical spine were acquired using a gradient echo sequence (MEDIC) with and without an MT saturation pulse on a 3 Tesla Siemens Prisma scanner (TR = 300 ms, TEeff = 17 ms, flip angle = 30°, in-plane resolution = 0.47 × 0.47 mm2). The CSM patients tended to have a lower mean MTR (30.4 ± 6.5) than the controls (34.8 ± 3.8), but the difference was not significant (independent samples t-test, p = 0.110, Cohen's d = 0.80). The mean MTR across all intervertebral disc levels was not significantly correlated to the Nurick score (Spearman's ρ = -0.489, p = 0.151). The intervertebral level with the lowest MTR in each cohort was not significantly different between groups (equal variances not assumed, t = 1.965, dof = 14.8, p = 0.068, Cohen's d = 0.88), but the CSM patients tended to have a lower MTR. The mean MTR at this level was negatively correlated to the Nurick score among CSM patients (Spearman's ρ = -0.725, p = 0.018). CSM patients tended to have decreased MTR indicating myelin degradation compared to our healthy subjects, and MTR was negatively correlated with the severity of CSM.

    View details for DOI 10.1016/j.jocn.2018.02.023

    View details for PubMedID 29530383

  • Ambulatory function in motor incomplete spinal cord injury: a magnetic resonance imaging study of spinal cord edema and lower extremity muscle morphometry. Spinal cord Smith, A. C., Weber, K. A., Parrish, T. B., Hornby, T. G., Tysseling, V. M., McPherson, J. G., Wasielewski, M., Elliott, J. M. 2017

    Abstract

    This research utilized a cross-sectional design.Spinal cord edema length has been measured with T2-weighted sagittal MRI to predict motor recovery following spinal cord injury. The purpose of our study was to establish the correlational value of axial spinal cord edema using T2-weighted MRI. We hypothesized a direct relationship between the size of damage on axial MRI and walking ability, motor function and distal muscle changes seen in motor incomplete spinal cord injury (iSCI).University-based laboratory in Chicago, IL, USA.Fourteen participants with iSCI took part in the study. Spinal cord axial damage ratios were assessed using axial T2-weighted MRI. Walking ability was investigated using the 6-min walk test and daily stride counts. Maximum plantarflexion torque was quantified using isometric dynomometry. Muscle fat infiltration (MFI) and relative muscle cross-sectional area (rmCSA) were quantified using fat/water separation magnetic resonance imaging.Damage ratios were negatively correlated with distance walked in 6 min, average daily strides and maximum plantarflexion torque, and a negative linear trend was found between damage ratios and lower leg rmCSA. While damage ratios were not significantly correlated with MFI, we found significantly higher MFI in the wheelchair user participant group compared to community walkers.Damage ratios may be useful in prognosis of motor recovery in spinal cord injury. The results warrant a large multi-site research study to investigate the value of high-resolution axial T2-weighted imaging to predict walking recovery following motor incomplete spinal cord injury.Spinal Cord advance online publication, 28 February 2017; doi:10.1038/sc.2017.18.

    View details for DOI 10.1038/sc.2017.18

    View details for PubMedID 28244504

  • Quantitative Magnetization Transfer MRI Measurements of the Anterior Spinal cord Region are Associated with Clinical Outcomes in Cervical Spondylotic Myelopathy. Spine Cloney, M. B., Smith, Z. A., Weber, K. A., Parrish, T. B. 2017

    Abstract

    case-control.To understand the role of magnetization transfer ratio in identifying patients with clinically significant myelopathy and disability.Magnetization transfer ratio (MTR) is a quantitative measure that correlates with myelin loss and neural tissue destruction in a variety of neurological diseases. However, the usefulness of MTR in patients with cervical spondylotic myelopathy (CSM) has not been examined.We prospectively enrolled seven CSM patients and seven age-matched controls to undergo MRI imaging of the cervical spine. Nurick, Neck Disability Index (NDI), and modified Japanese Orthopedic Association (mJOA) scores were collected for all patients. Clinical hyperreflexia was tested at the MCP joint, using a 6-axis load cell. Reflex was simulated by quickly moving the joint from maximum flexion to maximum extension (300 °/sec). Anterior, lateral, and posterior cord MTR measurements were compared to clinical outcomes.Compared to controls, CSM patients had lower anterior cord MTR (38.29 v. 29.97, Δ = -8.314, p = 0.0022), and equivalent posterior cord (p = 0.2896) and lateral cord (p = 0.3062) MTR. Higher Nurick scores were associated with lower anterior cord MTR (p = 0.0205), but not lateral cord (p = 0.5446) or posterior cord MTR (p = 0.1222). Lower mJOA was associated with lower anterior cord MTR (p = 0.0090), but not lateral cord (p = 0.4864) or posterior cord MTR (p = 0.4819). There was no association between NDI and MTR of the anterior (p = 0.4351), lateral (p = 0.7557), or posterior cord (p = 0.9171). There was a linear relationship between hyperreflexia and anterior cord MTR (slope = -117.3, R = 0.6598, p = 0.0379), but not lateral cord (p = 0.1906, R = 0.4511) or posterior cord (p = 0.2577, R = 0.3957) MTR.Anterior cord MTR correlates with clinical outcomes as measured by mJOA index, Nurick score, and quantitative hyperreflexia, and could play a role in the preoperative assessment of CSM.2.

    View details for DOI 10.1097/BRS.0000000000002470

    View details for PubMedID 29068880

  • Lateral corticospinal tract damage correlates with motor output in incomplete spinal cord injury. Archives of physical medicine and rehabilitation Smith, A. C., Weber, K. A., O'Dell, D. R., Parrish, T. B., Wasielewski, M., Elliott, J. M. 2017

    Abstract

    To investigate the relationship between spinal cord damage and specific motor function in participants with incomplete spinal cord injury (iSCI).single-blinded cross-sectional study design SETTING: University setting research laboratory.Fourteen individuals with chronic cervical iSCI (1 female and 13 males, average age = 43 ± 12 years old).Not applicable.Axial T2 MRI of spinal cord damage was performed in 14 participants with iSCI. Each participants' damage was processed for total damage quantification, lateral corticospinal tract (LCST) and gracilis fasciculus (GF) analysis. Plantarflexion and knee extension were quantified using an isokinetic dynamometer. Walking ability was assessed using a 6-minute walk test.Total damage was correlated with plantarflexion, knee extension, and distance walked in 6 minutes. Right LCST damage was correlated with right plantarflexion and right knee extension, while left LCST damage was correlated with left sided measures. Right and left GF damage were not correlated with the motor output measures.MRI measures of spinal cord damage were correlated to motor function, and this measure appears to have spatial specificity to descending tracts, which may offer prognostic value following spinal cord injury.

    View details for DOI 10.1016/j.apmr.2017.10.002

    View details for PubMedID 29107041

  • Advancements in Imaging Technology: Do They (or Will They) Equate to Advancements in Our Knowledge of Recovery in Whiplash? JOURNAL OF ORTHOPAEDIC & SPORTS PHYSICAL THERAPY Elliott, J. M., Dayanidhi, S., Hazle, C., Hoggarth, M. A., Mcpherson, J., Sparks, C. L., Weber, K. A. 2016; 46 (10): 862-873

    Abstract

    Synopsis It is generally accepted that up to 50% of those with a whiplash injury following a motor vehicle collision will fail to fully recover. Twenty-five percent of these patients will demonstrate a markedly complex clinical picture that includes severe pain-related disability, sensory and motor disturbances, and psychological distress. A number of psychosocial factors have shown prognostic value for recovery following whiplash from a motor vehicle collision. To date, no management approach (eg, physical therapies, education, psychological interventions, or interdisciplinary strategies) for acute whiplash has positively influenced recovery rates. For many of the probable pathoanatomical lesions (eg, fracture, ligamentous rupture, disc injury), there remains a lack of available clinical tests for identifying their presence. Fractures, particularly at the craniovertebral and cervicothoracic junctions, may be radiographically occult. While high-resolution computed tomography scans can detect fractures, there remains a lack of prevalence data for fractures in this population. Conventional magnetic resonance imaging has not consistently revealed lesions in patients with acute or chronic whiplash, a "failure" that may be due to limitations in the resolution of available devices and the use of standard sequences. The technological evolution of imaging techniques and sequences eventually might provide greater resolution to reveal currently elusive anatomical lesions (or, perhaps more importantly, temporal changes in physiological responses to assumed lesions) in those patients at risk of poor recovery. Preliminary findings from 2 prospective cohort studies in 2 different countries suggest that this is so, as evidenced by changes to the structure of skeletal muscles in those who do not fully recover. In this clinical commentary, we will briefly introduce the available imaging decision rules and the current knowledge underlying the pathomechanics and pathophysiology of whiplash. We will then acknowledge known prognostic factors underlying functional recovery. Last, we will highlight emerging evidence regarding the pathobiology of muscle degeneration/regeneration, as well as advancements in neuroimaging and musculoskeletal imaging techniques (eg, functional magnetic resonance imaging, magnetization transfer imaging, spectroscopy, diffusion-weighted imaging) that may be used as noninvasive and objective complements to known prognostic factors associated with whiplash recovery, in particular, poor functional recovery. J Orthop Sports Phys Ther 2016;46(10):861-872. doi:10.2519/jospt.2016.6735.

    View details for DOI 10.2519/jospt.2016.6735

    View details for Web of Science ID 000384398400008

    View details for PubMedID 27690836

  • Measuring Pain for Patients Seeking Physical Therapy: Can Functional Magnetic Resonance Imaging (fMRI) Help? Physical therapy Elliott, J. M., Owen, M., Bishop, M. D., Sparks, C., Tsao, H., Walton, D. M., Weber, K. A., Wideman, T. H. 2016

    Abstract

    In the multidisciplinary fields of pain medicine and rehabilitation, advancing techniques such as functional magnetic resonance imaging (fMRI) are used to enhance our understanding of the pain experience. Given that such measures, in some circles, are expected to help us understand the brain in pain, future research in pain measurement is undeniably rich with possibility. However, pain remains intensely personal and represents a multifaceted experience, unique to each individual; no single measure in isolation, fMRI included, can prove or quantify its magnitude beyond the patient self-report. Physical therapists should be aware of cutting-edge advances in measuring the patient's pain experience, and they should work closely with professionals in other disciplines (eg, magnetic resonance physicists, biomedical engineers, radiologists, psychologists) to guide the exploration and development of multimodal pain measurement and management on a patient-by-patient basis. The primary purpose of this perspective article is to provide a brief overview of fMRI and inform physical therapist clinicians of the pros and cons when utilized as a measure of the patient's perception of pain. A secondary purpose is to describe current known factors that influence the quality of fMRI data and its analyses, as well as the potential for future clinical applications relevant to physical therapist practice. Lastly, the interested reader is introduced and referred to existing guidelines and recommendations for reporting fMRI research.

    View details for DOI 10.2522/ptj.20160089

    View details for PubMedID 27470977

  • White matter microstructure changes induced by motor skill learning utilizing a body machine interface. NeuroImage Wang, X., Casadio, M., Weber, K. A., Mussa-Ivaldi, F. A., Parrish, T. B. 2013; 88C: 32–40

    Abstract

    The purpose of this study is to identify white matter microstructure changes following bilateral upper extremity motor skill training to increase our understanding of learning-induced structural plasticity and enhance clinical strategies in physical rehabilitation. Eleven healthy subjects performed two visuo-spatial motor training tasks over 9 sessions (2-3 sessions per week). Subjects controlled a cursor with bilateral simultaneous movements of the shoulders and upper arms using a body machine interface. Before the start and within 2days of the completion of training, whole brain diffusion tensor MR imaging data were acquired. Motor training increased fractional anisotropy (FA) values in the posterior and anterior limbs of the internal capsule, the corona radiata, and the body of the corpus callosum by 4.19% on average indicating white matter microstructure changes induced by activity-dependent modulation of axon number, axon diameter, or myelin thickness. These changes may underlie the functional reorganization associated with motor skill learning.

    View details for DOI 10.1016/j.neuroimage.2013.10.066

    View details for PubMedID 24220038

    View details for PubMedCentralID PMC4016193

  • Understanding inhibitory mechanisms of lumbar spinal manipulation using H-reflex and F-wave responses: A methodological approach JOURNAL OF NEUROSCIENCE METHODS Dishman, J. D., Weber, K. A., Corbin, R. L., Burke, J. R. 2012; 210 (2): 169-177

    Abstract

    The purpose of this research was to characterize unique neurophysiologic events following a high velocity, low amplitude (HVLA) spinal manipulation (SM) procedure. Descriptive time series analysis techniques of time plots, outlier detection and autocorrelation functions were applied to time series of tibial nerve H-reflexes that were evoked at 10-s intervals from 100 s before the event until 100 s after three distinct events L5-S1 HVLA SM, or a L5-S1 joint pre-loading procedure, or the control condition. Sixty-six subjects were randomly assigned to three procedures, i.e., 22 time series per group. If the detection of outliers and correlograms revealed a pattern of non-randomness that was only time-locked to a single, specific event in the normalized time series, then an experimental effect would be inferred beyond the inherent variability of H-reflex responses. Tibial nerve F-wave responses were included to determine if any new information about central nervous function following a HVLA SM procedure could be ascertained. Time series analyses of H(max)/M(max) ratios, pre-post L5-S1 HVLA SM, substantiated the hypothesis that the specific aspects of the manipulative thrust lead to a greater attenuation of the H(max)/M(max) ratio as compared to the non-specific aspects related to the postural perturbation and joint pre-loading. The attenuation of the H(max)/M(max) ratio following the HVLA SM procedure was reliable and may hold promise as a translational tool to measure the consistency and accuracy of protocol implementation involving SM in clinical trials research. F-wave responses were not sensitive to mechanical perturbations of the lumbar spine.

    View details for DOI 10.1016/j.jneumeth.2012.07.014

    View details for Web of Science ID 000309376900006

    View details for PubMedID 22878176

  • Non-invasive brain stimulation enhances fine motor control of the hemiparetic ankle: implications for rehabilitation EXPERIMENTAL BRAIN RESEARCH Madhavan, S., Weber, K. A., Stinear, J. W. 2011; 209 (1): 9-17

    Abstract

    We set out to answer two questions with this study: 1. Can stroke patients improve voluntary control of their paretic ankle by practising a visuo-motor ankle-tracking task? 2. Are practice effects enhanced with non-invasive brain stimulation? A carefully selected sample of chronic stroke patients able to perform the experimental task attended three data collection sessions. Facilitatory transcranial direct current stimulation (tDCS) was applied in a random order over the lower limb primary motor cortex of the lesioned hemisphere or the non-lesioned hemisphere or sham stimulation was delivered over the lesioned hemisphere. In each session, tDCS was applied as patients practiced tracking a sinusoidal waveform for 15 min using dorsiflexion-plantarflexion movements of their paretic ankle. The difference in tracking error prior to, and after, the 15 min of practice was calculated. A practice effect was revealed following sham stimulation, and this effect was enhanced with tDCS applied over the lesioned hemisphere. The practice effect observed following sham stimulation was eliminated by tDCS applied over the non-lesioned hemisphere. The study provides the first evidence that non-invasive brain stimulation applied to the lesioned motor cortex of moderate- to well-recovered stroke patients enhances voluntary control of the paretic ankle. The results provide a basis for examining whether this enhanced ankle control can be induced in patients with greater impairments and whether enhanced control of a single or multiple lower limb joints improves hemiparetic gait patterns.

    View details for DOI 10.1007/s00221-010-2511-0

    View details for Web of Science ID 000287147500002

    View details for PubMedID 21170708

  • Chiropractic students and research: assessing the research culture at a north american chiropractic college. The Journal of chiropractic education Weber Ii, K. A., He, X. 2010; 24 (1): 35-45

    Abstract

    To continue positive professional growth and boost research endeavors, chiropractic institutions need to develop a research-oriented foundation and produce a larger body of researchers. The purpose of this study was to provide a current analysis of the research culture among students at Palmer College of Chiropractic Florida. This study will gain insight toward the research contributions of the next generation of chiropractors and identify the difficulties toward participation. This will help modify current academic programs to better foster research and ensure a promising, credible future for the chiropractic profession.Participants were students at Palmer College of Chiropractic Florida enrolled in quarters 1 through 12 during the 2008 summer term. To evaluate the research culture, participants were asked to complete a 33-item web-based survey.A total of 303 students completed the survey. Forty-four percent were female, and the mean age was 26 (SD = 4.2). Ninety-nine percent of respondents agreed that research was necessary for positive growth within the chiropractic profession. A majority of students reported having research experience, and 58% planned to participate in research activities prior to graduation. Technical writing was reported as the most challenging aspect of research, and heavy academic workload was reported as the greatest deterrent to participation.This study expresses possibilities for building a strong research culture at the college. Students were aware of the necessity for research and were openly interested in conducting research. Modification of current academic policies will allow for greater student research opportunities and the development of tomorrow's researchers.

    View details for PubMedID 20480013