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Spinal cord computational model

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https://www.readbyqxmd.com/read/27843686/effect-of-spinal-cord-compression-on-local-vascular-blood-flow-and-perfusion-capacity-by-alshareef-m-krishna-v-ferdous-j-aishareef-a-kindy-m-kolachalama-vb-et-al
#1
Nancy E Epstein
BACKGROUND: Different degrees of blood flow/vascular compromise occur with anterior, posterior, or circumferential spinal cord compression/spinal cord injury (SCI). SCI is also divided into primary and secondary injury. Primary SCI refers to the original neurological damage to tissues, whereas secondary injury reflects interruption of normal blood flow leading to further inflammatory response/other local changes which contribute to additional neurological injury. METHODS: The authors developed a quantitative "3-D finite element fluid structure interaction model" of spinal cord blood flow to better document the mechanisms of secondary ischemic damage occurring in the spinal cord anteriorly, posteriorly, or circumferentially...
2016: Surgical Neurology International
https://www.readbyqxmd.com/read/27834648/epidural-stimulation-of-rat-spinal-cord-at-lumbosacral-segment-using-a-surface-electrode-a-computer-simulation-study
#2
Qi Xu, Li Kong, Hui Zhou, Jiping He
Clinical research indicates that the epidural spinal cord stimulation (ESCS) at lumbosacral segment has shown potential for promoting locomotor recovery in patients with incomplete spinal cord injury. However, the underlying neural mechanism needs to be determined by animal experiments. In order to refine experimental protocols, we used a finite element simulation to investigate the activation of nerve fibers in a rat spinal cord model. Our model is composed of a volume conductor model from L1 to S2 spinal segments and the McIntyre-Richard-Grill axon model, which is used to investigate the threshold of selected spinal fibers with different diameters at varied locations and predict the neural responses of any target fibers with bipolar electrode configuration...
November 4, 2016: IEEE Transactions on Neural Systems and Rehabilitation Engineering
https://www.readbyqxmd.com/read/27799905/cerebellar-and-spinal-direct-current-stimulation-in-children-computational-modeling-of-the-induced-electric-field
#3
Serena Fiocchi, Paolo Ravazzani, Alberto Priori, Marta Parazzini
Recent studies have shown that the specific application of transcranial direct current stimulation (tDCS) over the cerebellum can modulate cerebellar activity. In parallel, transcutaneous spinal DC stimulation (tsDCS) was found to be able to modulate conduction along the spinal cord and spinal cord functions. Of particular interest is the possible use of these techniques in pediatric age, since many pathologies and injuries, which affect the cerebellar cortex as well as spinal cord circuits, are diffuse in adults as well as in children...
2016: Frontiers in Human Neuroscience
https://www.readbyqxmd.com/read/27760818/descending-propriospinal-neurons-mediate-restoration-of-locomotor-function-following-spinal-cord-injury
#4
Katelyn N Benthall, Ryan A Hough, Andrew D McClellan
Following spinal cord injury (SCI) in the lamprey, there is virtually complete recovery of locomotion within a few weeks, but interestingly, axonal regeneration of reticulospinal (RS) neurons is mostly limited to short distances caudal to the injury site. To explain this situation, we hypothesize that descending propriospinal (PS) neurons relay descending drive from RS neurons to indirectly activate spinal central pattern generators (CPGs). In the present study, the contributions of PS neurons to locomotor recovery were tested in the lamprey following SCI...
October 19, 2016: Journal of Neurophysiology
https://www.readbyqxmd.com/read/27734100/meagre-effects-of-disuse-on-the-human-fibula-are-not-explained-by-bone-size-or-geometry
#5
A Ireland, R F Capozza, G R Cointry, L Nocciolino, J L Ferretti, J Rittweger
: Fibula response to disuse is unknown; we assessed fibula bone in spinal cord injury (SCI) patients and able-bodied counterparts. Group differences were smaller than in the neighbouring tibia which could not be explained by bone geometry. Differential adaptation of the shank bones may indicate previously unknown mechanoadaptive behaviours of bone. INTRODUCTION: The fibula supports only a small and highly variable proportion of shank compressive load (-8 to +19 %), and little is known about other kinds of stresses...
October 12, 2016: Osteoporosis International
https://www.readbyqxmd.com/read/27712091/sustained-high-pressure-in-the-spinal-subarachnoid-space-while-arterial-expansion-is-low-may-be-linked-to-syrinx-development
#6
Elizabeth C Clarke, David F Fletcher, Lynne E Bilston
Syringomyelia (a spinal cord cyst) usually develops as a result of conditions that cause cerebrospinal fluid (CSF) obstruction. The mechanism of syrinx formation and enlargement remains unclear, though previous studies suggest that the fluid enters via the perivascular spaces (PVS) of the penetrating arteries of the spinal cord, and that alterations in the CSF pulse timing and pressure could contribute to enhanced PVS inflow. This study uses an idealised computational model of the PVS to investigate the factors that influence peri-arterial fluid flow...
October 7, 2016: Computer Methods in Biomechanics and Biomedical Engineering
https://www.readbyqxmd.com/read/27676678/evaluation-of-bone-cancer-pain-induced-by-different-doses-of-walker-256-mammary-gland-carcinoma-cells
#7
Changsheng Dong, RuiXin Wu, Jing Wu, Jing Guo, Fangyuan Wang, Yanli Fu, Qing Wang, Ling Xu, Juyong Wang
BACKGROUND: Cancer pain is a complex medical syndrome. Understanding its underlying mechanisms relies on the use of animal models which can mimic the human condition. A crucial component of this model is the quantity of tumor cells; however, the exact relationship between the doses of tumor cells on bone cancer pain is yet unknown. OBJECTIVE: We explored the relationship of different doses of Walker 256 carcinoma cells using a bone cancer pain model in rats, and evaluated its success and stability...
September 2016: Pain Physician
https://www.readbyqxmd.com/read/27664830/g-ratio-weighted-imaging-of-the-human-spinal-cord-in-vivo
#8
T Duval, S Le Vy, N Stikov, J Campbell, A Mezer, T Witzel, B Keil, V Smith, L L Wald, E Klawiter, J Cohen-Adad
The fiber g-ratio is defined as the ratio of the inner to the outer diameter of the myelin sheath. This ratio provides a measure of the myelin thickness that complements axon morphology (diameter and density) for assessment of demyelination in diseases such as multiple sclerosis. Previous work has shown that an aggregate g-ratio map can be computed using a formula that combines axon and myelin density measured with quantitative MRI. In this work, we computed g-ratio weighted maps in the cervical spinal cord of nine healthy subjects...
September 22, 2016: NeuroImage
https://www.readbyqxmd.com/read/27633893/central-control-of-interlimb-coordination-and-speed-dependent-gait-expression-in-quadrupeds
#9
Simon M Danner, Simon D Wilshin, Natalia A Shevtsova, Ilya A Rybak
KEY POINTS: Quadrupeds express different gaits depending on speed of locomotion. Central pattern generators (one per limb) within the spinal cord generate locomotor oscillations and control limb movements. Neural interactions between these generators define interlimb coordination and gait. We present a computational model of spinal circuits representing four rhythm generators with left-right excitatory and inhibitory commissural and fore-hind inhibitory interactions within the cord. Increasing brainstem drive to all rhythm generators and excitatory commissural interneurons induces an increasing frequency of locomotor oscillations accompanied by speed-dependent gait changes from walk to trot and to gallop and bound...
December 1, 2016: Journal of Physiology
https://www.readbyqxmd.com/read/27610400/abdomen-and-spinal-cord-segmentation-with-augmented-active-shape-models
#10
Zhoubing Xu, Benjamin N Conrad, Rebeccah B Baucom, Seth A Smith, Benjamin K Poulose, Bennett A Landman
Active shape models (ASMs) have been widely used for extracting human anatomies in medical images given their capability for shape regularization of topology preservation. However, sensitivity to model initialization and local correspondence search often undermines their performances, especially around highly variable contexts in computed-tomography (CT) and magnetic resonance (MR) images. In this study, we propose an augmented ASM (AASM) by integrating the multiatlas label fusion (MALF) and level set (LS) techniques into the traditional ASM framework...
July 2016: Journal of Medical Imaging
https://www.readbyqxmd.com/read/27561702/estimation-of-excitatory-and-inhibitory-synaptic-conductance-variations-in-motoneurons-during-locomotor-like-rhythmic-activity
#11
Ryota Kobayashi, Hiroshi Nishimaru, Hisao Nishijo
The rhythmic activity of motoneurons (MNs) that underlies locomotion in mammals is generated by synaptic inputs from the locomotor network in the spinal cord. Thus, the quantitative estimation of excitatory and inhibitory synaptic conductances is essential to understand the mechanism by which the network generates the functional motor output. Conductance estimation is obtained from the voltage-current relationship measured by voltage-clamp- or current-clamp-recording with knowledge of the leak parameters of the recorded neuron...
October 29, 2016: Neuroscience
https://www.readbyqxmd.com/read/27534535/integrated-analysis-of-omics-data-using-microrna-target-mrna-network-and-ppi-network-reveals-regulation-of-gnai1-function-in-the-spinal-cord-of-ews-ewsr1-ko-mice
#12
Chai-Jin Lee, Hongryul Ahn, Sean Bong Lee, Jong-Yeon Shin, Woong-Yang Park, Jong-Il Kim, Junghee Lee, Hoon Ryu, Sun Kim
BACKGROUND: Multifunctional transcription factor (TF) gene EWS/EWSR1 is involved in various cellular processes such as transcription regulation, noncoding RNA regulation, splicing regulation, genotoxic stress response, and cancer generation. Role of a TF gene can be effectively studied by measuring genome-wide gene expression, i.e., transcriptome, in an animal model of Ews/Ewsr1 knockout (KO). However, when a TF gene has complex multi-functions, conventional approaches such as differentially expressed genes (DEGs) analysis are not successful to characterize the role of the EWS gene...
2016: BMC Medical Genomics
https://www.readbyqxmd.com/read/27509542/spinal-cord-inflammation-molecular-imaging-after-thoracic-aortic-ischemia-reperfusion-injury
#13
Hassan Albadawi, John W Chen, Rahmi Oklu, Yue Wu, Gregory Wojtkiewicz, Benjamin Pulli, John D Milner, Richard P Cambria, Michael T Watkins
Purpose To evaluate whether noninvasive molecular imaging technologies targeting myeloperoxidase (MPO) can reveal early inflammation associated with spinal cord injury after thoracic aortic ischemia-reperfusion (TAR) in mice. Materials and Methods The study was approved by the institutional animal care and use committee. C57BL6 mice that were 8-10 weeks old underwent TAR (n = 55) or sham (n = 26) surgery. Magnetic resonance (MR) imaging (n = 6) or single photon emission computed tomography (SPECT)/computed tomography (CT) (n = 15) studies targeting MPO activity were performed after intravenous injection of MPO sensors (bis-5-hydroxytryptamide-tetraazacyclododecane [HT]-diethyneletriaminepentaacetic acid [DTPA]-gadolinium or indium 111-bis-5-HT-DTPA, respectively)...
August 10, 2016: Radiology
https://www.readbyqxmd.com/read/27465752/cardiometabolic-syndrome-in-people-with-spinal-cord-injury-disease-guideline-derived-and-nonguideline-risk-components-in-a-pooled-sample
#14
Mark S Nash, Rochelle E Tractenberg, Armando J Mendez, Maya David, Inger H Ljungberg, Emily A Tinsley, Patricia A Burns-Drecq, Luisa F Betancourt, Suzanne L Groah
OBJECTIVE: To assess cardiometabolic syndrome (CMS) risk definitions in spinal cord injury/disease (SCI/D). DESIGN: Cross-sectional analysis of a pooled sample. SETTING: Two SCI/D academic medical and rehabilitation centers. PARTICIPANTS: Baseline data from subjects in 7 clinical studies were pooled; not all variables were collected in all studies; therefore, participant numbers varied from 119 to 389. The pooled sample included men (79%) and women (21%) with SCI/D >1 year at spinal cord levels spanning C3-T2 (American Spinal Injury Association Impairment Scale [AIS] grades A-D)...
October 2016: Archives of Physical Medicine and Rehabilitation
https://www.readbyqxmd.com/read/27403420/inverse-kinematics-for-upper-limb-compound-movement-estimation-in-exoskeleton-assisted-rehabilitation
#15
Camilo Cortés, Ana de Los Reyes-Guzmán, Davide Scorza, Álvaro Bertelsen, Eduardo Carrasco, Ángel Gil-Agudo, Oscar Ruiz-Salguero, Julián Flórez
Robot-Assisted Rehabilitation (RAR) is relevant for treating patients affected by nervous system injuries (e.g., stroke and spinal cord injury). The accurate estimation of the joint angles of the patient limbs in RAR is critical to assess the patient improvement. The economical prevalent method to estimate the patient posture in Exoskeleton-based RAR is to approximate the limb joint angles with the ones of the Exoskeleton. This approximation is rough since their kinematic structures differ. Motion capture systems (MOCAPs) can improve the estimations, at the expenses of a considerable overload of the therapy setup...
2016: BioMed Research International
https://www.readbyqxmd.com/read/27378844/bio-inspired-controller-on-an-fpga-applied-to-closed-loop-diaphragmatic-stimulation
#16
Adeline Zbrzeski, Yannick Bornat, Brian Hillen, Ricardo Siu, James Abbas, Ranu Jung, Sylvie Renaud
Cervical spinal cord injury can disrupt connections between the brain respiratory network and the respiratory muscles which can lead to partial or complete loss of ventilatory control and require ventilatory assistance. Unlike current open-loop technology, a closed-loop diaphragmatic pacing system could overcome the drawbacks of manual titration as well as respond to changing ventilation requirements. We present an original bio-inspired assistive technology for real-time ventilation assistance, implemented in a digital configurable Field Programmable Gate Array (FPGA)...
2016: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/27334441/real-time-estimation-of-fes-induced-joint-torque-with-evoked-emg-application-to-spinal-cord-injured-patients
#17
Zhan Li, David Guiraud, David Andreu, Mourad Benoussaad, Charles Fattal, Mitsuhiro Hayashibe
BACKGROUND: Functional electrical stimulation (FES) is a neuroprosthetic technique for restoring lost motor function of spinal cord injured (SCI) patients and motor-impaired subjects by delivering short electrical pulses to their paralyzed muscles or motor nerves. FES induces action potentials respectively on muscles or nerves so that muscle activity can be characterized by the synchronous recruitment of motor units with its compound electromyography (EMG) signal is called M-wave. The recorded evoked EMG (eEMG) can be employed to predict the resultant joint torque, and modeling of FES-induced joint torque based on eEMG is an essential step to provide necessary prediction of the expected muscle response before achieving accurate joint torque control by FES...
2016: Journal of Neuroengineering and Rehabilitation
https://www.readbyqxmd.com/read/27331657/cacna1h-missense-mutations-associated-with-amyotrophic-lateral-sclerosis-alter-cav3-2-t-type-calcium-channel-activity-and-reticular-thalamic-neuron-firing
#18
Yuriy Rzhepetskyy, Joanna Lazniewska, Iulia Blesneac, Roger Pamphlett, Norbert Weiss
Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that affects nerve cells in the brain and the spinal cord. In a recent study by Steinberg and colleagues, 2 recessive missense mutations were identified in the Cav3.2 T-type calcium channel gene (CACNA1H), in a family with an affected proband (early onset, long duration ALS) and 2 unaffected parents. We have introduced and functionally characterized these mutations using transiently expressed human Cav3.2 channels in tsA-201 cells...
November 2016: Channels
https://www.readbyqxmd.com/read/27292055/organization-of-flexor-extensor-interactions-in-the-mammalian-spinal-cord-insights-from-computational-modelling
#19
Natalia A Shevtsova, Ilya A Rybak
KEY POINTS: Alternation of flexor and extensor activity in the mammalian spinal cord is mediated by two classes of genetically identified inhibitory interneurons, V1 and V2b. The V1 interneurons are essential for high-speed locomotor activity. They secure flexor-extensor alternations in the intact cord but lose this function after hemisection, suggesting that they are activated by inputs from the contralateral side of the cord. The V2b interneurons are involved in flexor-extensor alternations in both intact cord and hemicords...
November 1, 2016: Journal of Physiology
https://www.readbyqxmd.com/read/27276391/biomechanical-behaviors-in-three-types-of-spinal-cord-injury-mechanisms
#20
Batbayar Khuyagbaatar, Kyungsoo Kim, Won Man Park, Yoon Hyuk Kim
Clinically, spinal cord injuries (SCIs) are radiographically evaluated and diagnosed from plain radiographs, computed tomography (CT), and magnetic resonance imaging. However, it is difficult to conclude that radiographic evaluation of SCI can directly explain the fundamental mechanism of spinal cord damage. The von-Mises stress and maximum principal strain are directly associated with neurological damage in the spinal cord from a biomechanical viewpoint. In this study, the von-Mises stress and maximum principal strain in the spinal cord as well as the cord cross-sectional area (CSA) were analyzed under various magnitudes for contusion, dislocation, and distraction SCI mechanisms, using a finite-element (FE) model of the cervical spine with spinal cord including white matter, gray matter, dura mater with nerve roots, and cerebrospinal fluid (CSF)...
August 1, 2016: Journal of Biomechanical Engineering
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