Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17959498
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Traumatic brain injury (TBI) can be caused by motor vehicle accidents, falls and firearms. TBI can result in major neurological dysfunction such as chronic seizures and memory disturbances. To discover mechanisms of func...Traumatic brain injury (TBI) can be caused by motor vehicle accidents, falls and firearms. TBI can result in major neurological dysfunction such as chronic seizures and memory disturbances. To discover mechanisms of functional deficits underlying TBI, we developed a stretchable microelectrode array (SMEA),which can be used for continuous recording of neuronal function, pre-, during, and post-stretch injury. TheSMEA was fabricated on a polydimethylsiloxane (PDMS)substrate with stretchable, 100 pm wide, 25 nm thick gold electrodes patterned there on [1]. The electrodes were encapsulated with a 10-20 microm thick, photo-patternable PDMS insulation layer. Previous biocompatibility tests showed no overt necrosis or cell death caused by the SMEAs after 2 weeks in culture [2]. The electrical performance of the SMEAs was tested in electrophysiological saline solution before, during and after biaxial stretching. The results showed that the electrode impedance increased with the strain to reach 800 kL at 8.5% strain and then recovered to 10 kil after relaxation. The working noise level remained below 20 pV pp during the whole process. New methodologiesf or improving the patterning of the encapsulation layer were tested on gold electrode arrays supported on glass. With these prototype arrays, robust population spikes were recorded from organotypic hippocampal slice cultures of brain tissue. Additionally, seizure-like activity induced with 1 mM bicuculline was also recorded. Our results demonstrate that the prototype arrays have good electrical performance compatible with existing multielectrode array systems. They also indicate the ability to record neuronal activity from hippocampal slices. This novel technology will enable new studies to understand injury mechanisms leading to post-traumatic neuronal dysfunction.
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17959497
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A comparative study into two novel and diverse schemes designed to improve immobilization of biomolecules for biosensing purposes is presented. In the first method a silicon rich matrix is created using PECVD. The second...A comparative study into two novel and diverse schemes designed to improve immobilization of biomolecules for biosensing purposes is presented. In the first method a silicon rich matrix is created using PECVD. The second method involves creating nano-patterns on the sensor surface to create a large number of surface discontinuities to which the proteins will bind preferentially. The basic theory of SPR is provided to show the importance of the surface sensitive nature of this optical transduction technique. The present work suggests that both may prove both for SPR and other biosensing applications. Of the two schemes proposed, the results for nano-patterning seem to suggest that it is promoting better surface attachment of biomolecules. The results of SPR and AFM studies are presented that have shown that each of these schemes promotes improved binding of various proteins.
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17959496
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In this paper, the performance of traditional variance-based method for detection of epileptic seizures in EEG signals are compared with various methods based on nonlinear time series analysis, entropies, logistic regres...In this paper, the performance of traditional variance-based method for detection of epileptic seizures in EEG signals are compared with various methods based on nonlinear time series analysis, entropies, logistic regression,discrete wavelet transform and time frequency distributions.We noted that variance-based method in compare to the mentioned methods had the best result (100%) applied on the same database.
Li Y, Xu G, Guo L
… +5 more, Wang L, Yang S, Rao L, He R, Yan W
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17959495
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The improved Differential Evolution (DE)algorithm is proposed in this paper to solve the resistivity parameters estimation problem based on 2D real head model. Our simulations demonstrate that the improved DE algorithm i...The improved Differential Evolution (DE)algorithm is proposed in this paper to solve the resistivity parameters estimation problem based on 2D real head model. Our simulations demonstrate that the improved DE algorithm is robust in obtaining high quality reconstruction, and the convergence is much faster than the usual DE algorithm.Furthermore, the selection of the amplification parameters is much easier.
Krauledat M, Blankertz B, Dornhege G
… +3 more, Schröder M, Curio G, Müller K-
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17959494
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This paper discusses machine learning methods and their application to Brain-Computer Interfacing. A particular focus is placed on linear classification methods which can be applied in the BCI context. Finally, we provid...This paper discusses machine learning methods and their application to Brain-Computer Interfacing. A particular focus is placed on linear classification methods which can be applied in the BCI context. Finally, we provide an overview of the Berlin-Brain Computer Interface (BBCI).
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17959493
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Pathological manifestations of epilepsy are generally associated with a set of clinical events that possess both spatial and temporal patterns. In this paper, based on a similar hypothesis, we study the evolution of epil...Pathological manifestations of epilepsy are generally associated with a set of clinical events that possess both spatial and temporal patterns. In this paper, based on a similar hypothesis, we study the evolution of epileptic seizures by analyzing temporal changes in the spatial bindings between various cortical structures. We propose to apply the Mantel statistics to quantitatively analyze the temporal changes in spatial-correlation matrices. The Mantel test is applied to 6 complex partial seizures of an epileptic patient. We show that, in 5 of the 6 instances, the spatial structures undergo significant connectivity changes in the 2 hours time-interval prior to the occurrence of a seizure.
Niethammer M, Estepar RS, Bouix S
… +2 more, Shenton M, Westin CF
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17959492
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In this paper we propose a formal formulation for the estimation of Diffusion Tensors in the space of symmetric positive semidefinite (PSD) tensors. Traditionally, diffusion tensor model estimation has been carried out i...In this paper we propose a formal formulation for the estimation of Diffusion Tensors in the space of symmetric positive semidefinite (PSD) tensors. Traditionally, diffusion tensor model estimation has been carried out imposing tensor symmetry without constraints for negative eigenvalues. When diffusion weighted data does not follow the diffusion model,due to noise or signal drop, negative eigenvalues may arise. An estimation method that accounts for the positive definiteness is desirable to respect the underlying principle of diffusion. This paper proposes such an estimation method and provides a theoretical interpretation of the result. A closed-form solution is derived that is the optimal data-fit in the matrix 2-norm sense,removing the need for optimization-based tensor estimation.
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17959491
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To study the role of nitric oxide (NO) in regulating oxygen consumption by vessel walls, the oxygen consumption rate of arteriolar walls in rat cremaster muscle was measured in vivo during flow-induced vasodilation and a...To study the role of nitric oxide (NO) in regulating oxygen consumption by vessel walls, the oxygen consumption rate of arteriolar walls in rat cremaster muscle was measured in vivo during flow-induced vasodilation and after inhibiting NO synthesis. The oxygen consumption rate of arteriolar was calculated based on the intra- and peri-vascular oxygen tension (P0(2)) values measured by phosphorescence quenching laser microscopy. The peri-vascular PO(2) value of the arterioles during vasodilation was significantly higher than under control conditions, although the intravascular PO(2) values under both conditions were approximately the same. On the other hand, inhibition of NO synthesis caused a significant decrease in both the intra- and peri-vascular P0(2) values of the arterioles. The inhibition of NO synthesis increased the oxygen consumption rate of the walls by 42%, whereas enhancement of flow-induced NO release decreased it by 34%. These results suggest that NO plays an important role not only as a regulator of peripheral vascular tone, but also as a modulator of tissue oxygen consumption by reducing oxygen consumption by vessel walls.
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17959489
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Automated segmentation of nerve cell in microscopic image is an important task in neural researches. We proposed a multi-scale watershed-based approach to cope with this microscopic image analysis problem. There are thre...Automated segmentation of nerve cell in microscopic image is an important task in neural researches. We proposed a multi-scale watershed-based approach to cope with this microscopic image analysis problem. There are three stages in the proposed segmentation algorithm: (1) a multi-scale watershed scheme is used to estimate an initial location of nerve cell nuclei; (2) we can identity nerve cell nuclei according to properties of nerve cell and watershed results in different scale; (3) Once the possible nerve cell is identified as a true one, a fuzzy rule based Active Contour Model (ACM) is applied to find the optimal outer contour. Our approach can segment nerve cell automatically and accurately. The cell detection rates in the experiments are above 95%. Moreover, the fuzzy rule based ACM provides flexible alternative to handle cell contour detection.
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17959488
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Cortical neural networks are responsible for identification, recognition and classification of natural signals mediated by various sensory channels. These tasks are still too complex to be accomplished by state-of-the-ar...Cortical neural networks are responsible for identification, recognition and classification of natural signals mediated by various sensory channels. These tasks are still too complex to be accomplished by state-of-the-art engineering systems. There is, therefore, a great deal of interest in the development of suitable biologically-motivated architectures which are based on a realistic model of generic neural ensembles. We present a computational architecture for classification of natural signals, such as physiological signals,based on the emergence of instant neural cliques and phase-locked attractors in liquid architectures. The emergence of instant neural cliques enables mapping of complex classes of signals onto specific spatio-temporal firing patterns. The convergence of neural cliques onto attractors, along phase-locked pathways, reveals a new type dynamic behavior of neural ensembles, which lends itself to simple discrete-output computational systems.
Panescu D, Rao L, Ding C
… +4 more, Sun H, Youker KA, Nagueh SF, Khoury DS
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17959487
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INTRODUCTION: The study tested the feasibility of differentiating radiofrequency ablation lesions from normal myocardium and quantifying their dimensions by myocardial contrast echocardiography (MCE). METHODS AND RESULTS...INTRODUCTION: The study tested the feasibility of differentiating radiofrequency ablation lesions from normal myocardium and quantifying their dimensions by myocardial contrast echocardiography (MCE). METHODS AND RESULTS: In 11 normal dogs, we created 14 focal and 4 linear lesions at different left ventricular sites.MCE was performed both before and after ablation by using an intracardiac echocardiography catheter (9 MHz)and infusing contrast microbubbles through the left coronary artery. An independent observer examined the lesion pathology. We found that intracardiac echocardiography alone could not delineate lesion dimensions. However, after ablation, MCE localized the lesions as well-defined, low-contrast areas within the normally opacified myocardium. Lesion dimensions byMCE immediately after ablation and 30 minutes later were similar. In 12 focal lesions, the average maximum depth (5.55 +/- 1.38 mm) and average maximum diameter(10.38 +/- 2.09 mm) by MCE were in excellent agreement with the pathologic depth (5.20 +/- 1.45 mm) and diameter(10.61 +/- 1.67 mm). Two focal lesions could not be detected by MCE and later were found to be superficial. Three-dimensional MCE correctly reconstructed the extent and shape of linear lesions compared to pathology (length: 18.7+/- 5.7 vs 18.5 +/- 5.6 mm; maximum longitudinal cross-sectional area: 81.2 +/- 9.6 vs 76.0 +/-10.3 mm(2)). CONCLUSION: MCE accurately localized and quantified radiofrequency ablation lesions in the normal leftv entricle. This new application of MCE may advance'ablation for managing ventricular arrhythmias that involve intramural or epicardial regions by providing instantaneous anatomic feedback on the effects of ablation during catheterization.
Ishisaka T, Sato H, Akiyama Y
… +2 more, Furukawa Y, Morishima K
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17959486
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A novel bio hybrid micro power generator using cardiomyocytes on a polymer wire is proposed. Cultured cardiomyocytes convert chemical energy into kinetic energy efficiently and beat themselves autonomously. PZT fiber was...A novel bio hybrid micro power generator using cardiomyocytes on a polymer wire is proposed. Cultured cardiomyocytes convert chemical energy into kinetic energy efficiently and beat themselves autonomously. PZT fiber was utilized for cell immobilized substrate and electro-mechanical coupling material. In this paper, two preliminary experimental results were shown to prove this principle.
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17959485
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Voltammetry has been used as a method to measure the concentration of monoaminergic neurotransmitters in-vivo. The standard electrode used with voltammetry has been carbon fiber microelectrodes. Despite the advantages of...Voltammetry has been used as a method to measure the concentration of monoaminergic neurotransmitters in-vivo. The standard electrode used with voltammetry has been carbon fiber microelectrodes. Despite the advantages of using carbon as a sensing element, carbon fiber microelectrodes have only one site to record the extracellular concentration of neurotransmitters. Studies have shown that the concentration of neurotransmitters, such as dopamine, varies across small regions of the brain (less than Imm). To study the varying concentration of dopamine, the recording sites of a ceramic-based multi-site electrode was coated with carbon and deployed in the somatosensory cortex of a rat. Known concentrations of dopamine were pressure injected and the diffusion curve, which is the change in concentration over time, was recorded. From the falling phase of the diffusion curve, the initial rate of clearance was measured. The initial rates of clearance from the different recording sites in the somatosensory cortex were compared to a model that used the standard diffusion equation with uptake. The results show that the in-vivo data does not follow the prediction of the model providing an interesting insight to the uptake of monoamines across the different layers of the somatosensory cortex.
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17959484
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Electrical impedance tomography (EIT) is a new functional imaging technique in the biomedical engineering. A multi-frequency hardware EIT system based on digital signal processor (DSP) has been developed, and the system...Electrical impedance tomography (EIT) is a new functional imaging technique in the biomedical engineering. A multi-frequency hardware EIT system based on digital signal processor (DSP) has been developed, and the system also has been designed using modular structure. Some experiments in vitro tissue are done and their images are generated with the filtered back-projection algorithm using this system in real time. The results show that this system is feasible, stable, convenient and extended.
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17959483
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We present forward modeling and measurement of spatially modulated illumination in layered turbid tissue systems. This technique is used to provide quantitative, depth-resolved functional physiologic information with app...We present forward modeling and measurement of spatially modulated illumination in layered turbid tissue systems. This technique is used to provide quantitative, depth-resolved functional physiologic information with applications in layered tissues including cortex, retina and skin.
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17959482
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We present a method for simulation of DNA-laden flows in complex microscale geometries. In this method an incompressible Newtonian fluid is discretized with a finite difference method in the interior of the domain and a...We present a method for simulation of DNA-laden flows in complex microscale geometries. In this method an incompressible Newtonian fluid is discretized with a finite difference method in the interior of the domain and a Cartesian grid embedded boundary/volume-of-fluid method is used near the boundary. The DNA is represented by a bead-rod polymer model. The fluid and polymer are fully coupled through a body force representing hydrodynamic drag. The main objective in this work is to implement short range forces to properly model polymer-polymer and polymer-surface interactions. We will discuss two methods for these interactions: (1) a new rigid constraint algorithm whereby rods elastically bounce off one another, and (2) a classical (smooth) potential acting between rods. In addition, a smooth potential for the polymer-surface interactions is also implemented for comparison to the same interactions currently modeled by elastic collision.
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17959481
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Muscle synergies were extracted using non-negative matrix factorization from muscle activation patterns in six lower limb muscles during normal gait. Greater than 70% of the variance in the muscle activations was describ...Muscle synergies were extracted using non-negative matrix factorization from muscle activation patterns in six lower limb muscles during normal gait. Greater than 70% of the variance in the muscle activations was described by four extracted synergies and greater than 90% was described by five synergies. Considering the timing of synergy activation, the extracted synergies appear to be related to functional divisions of the gait cycle.
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17959480
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The incidence of joint fractures is increasing and has become one of the major health problems in developed countries. Our low-cost motivated rehabilitation system enables clinicians to prescribe, demonstrate and monitor...The incidence of joint fractures is increasing and has become one of the major health problems in developed countries. Our low-cost motivated rehabilitation system enables clinicians to prescribe, demonstrate and monitor patient rehabilitation protocols during and between clinical visits. With its unique biofeedback feature it is useful for continuous patient's motivation. The proposed system can be used in wide spectrum of rehabilitation scenarios by simply downloading appropriate protocols. The hardware and software architecture(communication protocols, power management policies and application-level control) have been tuned to optimize cost,battery autonomy and real-time performance required for this application. The main advantages of the proposed system is home-based rehabilitation, low-cost and good user acceptability.
Conf Proc IEEE Eng Med Biol Soc
· 2006 · PMID 17959479
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Two papers, Legal and Ethical Issues in the Regulation and Development of Engineering Achievements in Medical Technology parts I and II were written in 1990 by three authors of diverse backgrounds and published in the IE...Two papers, Legal and Ethical Issues in the Regulation and Development of Engineering Achievements in Medical Technology parts I and II were written in 1990 by three authors of diverse backgrounds and published in the IEEE Engineering in Medicine and Biology Magazine in March of the same year. Part I of the paper discusses the existing Food and Drug Administration (FDA) requirements that existed in 1990 to regulate the clinical trial process for medical devices, obtaining Marketing Approval and exceptions that may allow the use of unapproved devices. The paper discusses how the FDA has loosened some of the stringent regulations to further its goal of encouraging new development while protecting public health and maintaining ethical standards. Part H of the paper focuses on the ethical implications of the process of introducing a new technology to the market place, specifically in the usage of unapproved technologies for emergency use and feasibility studies. This paper discusses the topics covered in the two papers and the changes that have been made to the FDA guidelines since their publication in 1990.