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Neural Systems and Rehabilitation Engineering, IEEE Transactions on

Issue 4 • Date Dec. 2007

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Displaying Results 1 - 18 of 18
  • Table of contents

    Page(s): C1 - C4
    Save to Project icon | Request Permissions | PDF file iconPDF (149 KB)  
    Freely Available from IEEE
  • IEEE Transactions on Neural Systems and Rehabilitation Engineering publication information

    Page(s): C2
    Save to Project icon | Request Permissions | PDF file iconPDF (36 KB)  
    Freely Available from IEEE
  • Brain–Computer Communication: Motivation, Aim, and Impact of Exploring a Virtual Apartment

    Page(s): 473 - 482
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1523 KB) |  | HTML iconHTML  

    The step away from a synchronized or cue-based brain-computer interface (BCI) and from laboratory conditions towards real world applications is very important and crucial in BCI research. This work shows that ten naive subjects can be trained in a synchronous paradigm within three sessions to navigate freely through a virtual apartment, whereby at every junction the subjects could decide by their own, how they wanted to explore the virtual environment (VE). This virtual apartment was designed similar to a real world application, with a goal-oriented task, a high mental workload, and a variable decision period for the subject. All subjects were able to perform long and stable motor imagery over a minimum time of 2 s. Using only three electroencephalogram (EEG) channels to analyze these imaginations, we were able to convert them into navigation commands. Additionally, it could be demonstrated that motivation is a very crucial factor in BCI research; motivated subjects perform much better than unmotivated ones. View full abstract»

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  • Interaction Between Rhythms in the Human Basal Ganglia: Application of Bispectral Analysis to Local Field Potentials

    Page(s): 483 - 492
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1675 KB) |  | HTML iconHTML  

    The application of deep brain stimulation (DBS) for the treatment of Parkinson's disease offered a direct ldquoinsightrdquo into the human electrical activity in subcortical structures. The analysis of the oscillatory activity [local field potentials (LFPs)] disclosed the importance of rhythms and of interactions between rhythms in the human basal ganglia information processing. The aim of this study was to investigate the existence of possible nonlinear interactions between LFP rhythms characterizing the output structure of the basal ganglia, the globus pallidus internus, by means of bispectral analysis. The results of this study disclosed that the rhythms expressed in the globus pallidus internus of the untreated parkinsonian patient are not independent and, in particular, the low-beta (13-20 Hz) band generates harmonics that are included in the high-beta (20-35 Hz) band. Conversely, in the dystonic globus pallidus, as well as in the parkinsonian globus pallidus after dopaminergic medication (i.e., in the more ldquonormalrdquo condition), the rhythms are substantially independent and characterized by a strong activity in the low-frequency band that generates a second harmonic (4-14 Hz), mostly included in the same band. The interactions between rhythms in the human globus pallidus are therefore different in different pathologies and in different patient's states. The interpretation of these interactions is likely critical for fully understanding the role of LFP rhythms in the pathophysiology of human basal ganglia. View full abstract»

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  • Thermal Impact of an Active 3-D Microelectrode Array Implanted in the Brain

    Page(s): 493 - 501
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1346 KB) |  | HTML iconHTML  

    A chronically implantable, wireless neural interface device will require integrating electronic circuitry with the interfacing microelectrodes in order to eliminate wired connections. Since the integrated circuit (IC) dissipates a certain amount of power, it will raise the temperature in surrounding tissues where it is implanted. In this paper, the thermal influence of the integrated 3-D Utah electrode array (UEA) device implanted in the brain was investigated by numerical simulation using finite element analysis (FEA) and by experimental measurement in vitro as well as in vivo. The numerically calculated and experimentally measured temperature increases due to the UEA implantation were in good agreement. The experimentally validated numerical model predicted that the temperature increases linearly with power dissipation through the UEA, with a slope of 0.029degC/mW over the power dissipation levels expected to be used. The influences of blood perfusion, brain metabolism, and UEA geometry on tissue heating were also investigated using the numerical model. View full abstract»

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  • Poly (3,4-Ethylenedioxythiophene) for Chronic Neural Stimulation

    Page(s): 502 - 508
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1853 KB) |  | HTML iconHTML  

    Chronic neural stimulation using microelectrode arrays requires highly stable and biocompatible electrode materials with high charge injection capability. Conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT) was electrochemically deposited on thin film Pt electrodes of stimulation electrode arrays to evaluate its properties for chronic stimulation. The coated electrodes demonstrated much lower impedance than thin film Pt due to the high surface area and high ion conductivity across the film. The PEDOT film also presents intrinsic redox activity which contributes to the low impedance as well as a much higher charge storage capacity. The charge injection limit of PEDOT electrode was found to be 2.3 mC/cm2 , comparable to IrOx and much higher than thin film Pt. Under biphasic stimulation, the coated electrodes exhibited lower voltage and linear voltage excursion. Well-coated PEDOT electrodes were stable under chronic stimulation conditions, suggesting that PEDOT is a promising electrode material to be further developed for chronic neural stimulation applications. View full abstract»

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  • Influence of Pedaling Rate on Muscle Mechanical Energy in Low Power Recumbent Pedaling Using Forward Dynamic Simulations

    Page(s): 509 - 516
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (533 KB) |  | HTML iconHTML  

    An understanding of the muscle power contributions to the crank and limb segments in recumbent pedaling would be useful in the development of rehabilitative pedaling exercises. The objectives of this work were to 1) quantify the power contributions of the muscles to driving the crank and limb segments using a forward dynamic simulation of low-power pedaling in the recumbent position, and 2) determine whether there were differences in the muscle power contributions at three different pedaling rates. A forward dynamic model was used to determine the individual muscle excitation amplitude and timing to drive simulations that best replicated experimental kinematics and kinetics of recumbent pedaling. The segment kinematics, pedal reaction forces, and electromyograms (EMG) of 10 muscles of the right leg were recorded from 16 subjects as they pedaled a recumbent ergometer at 40, 50, and 60 rpm and a constant 50 W workrate. Intersegmental joint moments were computed using inverse dynamics and the muscle excitation onset and offset timing were determined from the EMG data. All quantities were averaged across ten cycles for each subject and averaged across subjects. The model-generated kinematic and kinetic quantities tracked almost always within 1 standard deviation (SD) of the experimental data for all three pedaling rates. The uniarticular hip and knee extensors generated 65% of the total mechanical work in recumbent pedaling. The triceps surae muscles transferred power from the limb segments to the crank and the bi-articular muscles that crossed the hip and knee delivered power to the crank during the leg transitions between flexion and extension. The functions of the individual muscles did not change with pedaling rate, but the mechanical energy generated by the knee extensors and hip flexors decreased as pedaling rate increased. By varying the pedaling rate, it is possible to manipulate the individual muscle power contributions to the crank and limb segments in recumbe- - nt pedaling and thereby design rehabilitative pedaling exercises to meet specific objectives. View full abstract»

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  • Finite Element Analysis for Evaluation of Pressure Ulcer on the Buttock: Development and Validation

    Page(s): 517 - 525
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1399 KB) |  | HTML iconHTML  

    The interface pressure is currently the only clinical tool to estimate the risk of sitting-related pressure ulcers. However, it provides little information on the loading condition in deep tissues. We present a comprehensive 3-D finite element (FE) model for human buttocks with the consideration of the joint configuration and realistic boundary conditions in a sitting posture. Sitting induced soft tissue deformation, internal pressure, and von-Mises stress were computed. The FE model was well validated qualitatively using actual displacement obtained from magnetic resonance imaging (MRI) images. FE analysis demonstrated that the deformation induced by sitting pressure was substantially different among muscle, fat, and skin. The deformation of the muscle varied with location and the maximum was seen in the regions underneath the bony prominence of ischial tuberosity. In these regions, the range of compressive pressure was 65-80 kPa, 50-60 kPa, and 55-65 kPa, for skin, fat, and muscle, respectively. The von-Mises stress distribution had a similar pattern. In conclusion, this study suggests a new methodology for the development and validation of FE models for investigating the risk of sitting-related soft tissue injury. The proposed model may provide researchers and therapists with a powerful technique for evaluating the effectiveness of various postural modulations in preventing deep tissue ulcers. View full abstract»

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  • Strength and Coordination in the Paretic Leg of Individuals Following Acute Stroke

    Page(s): 526 - 534
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (910 KB) |  | HTML iconHTML  

    The goal of this study was to determine whether acute stroke survivors demonstrate abnormal synergy patterns in their affected lower extremity. During maximum isometric contractions with subjects in a standing position, joint torques generated simultaneously at the knee and hip were measured, along with associated muscle activation patterns in eight lower limb muscles. Ten acute stroke survivors and nine age-match controls participated in the study. For all joints tested, stroke subjects demonstrated significantly less maximum isometric torque than age-matched control subjects. However, the synergistic torques generated in directions different than the direction that was being maximized were not significantly different between the two groups. According to electromyography (EMG) data, it was found that stroke subjects activated antagonistic muscle groups significantly higher than the control group subjects, suggesting that deficits in joint torque may be at least partially attributable to co-contraction of antagonistic muscles. Our findings suggest that a primary contributor to lower limb motor impairment in acute hemiparetic stroke is poor volitional torque generating capacity, which is at least partially attributable to co-contraction of antagonistic muscles. Furthermore, while we did not observe abnormal torque synergy patterns commonly found in the upper limbs, muscle activation patterns differed between groups for many of the directions tested indicating changes in the motor control strategies of acute stroke survivors. View full abstract»

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  • Real-Time Classification of Forearm Electromyographic Signals Corresponding to User-Selected Intentional Movements for Multifunction Prosthesis Control

    Page(s): 535 - 542
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (580 KB) |  | HTML iconHTML  

    Pattern recognition-based multifunction prosthesis control strategies have largely been demonstrated with subsets of typical able-bodied hand movements. These movements are often unnatural to the amputee, necessitating significant user training and do not maximally exploit the potential of residual muscle activity. This paper presents a real-time electromyography (EMG) classifier of user-selected intentional movements rather than an imposed subset of standard movements. EMG signals were recorded from the forearm extensor and flexor muscles of seven able-bodied participants and one congenital amputee. Participants freely selected and labeled their own muscle contractions through a unique training protocol. Signals were parameterized by the natural logarithm of root mean square values, calculated within 0.2 s sliding and non overlapping windows. The feature space was segmented using fuzzy C-means clustering. With only 2 min of training data from each user, the classifier discriminated four different movements with an average accuracy of 92.7% plusmn 3.2%. This accuracy could be further increased with additional training data and improved user proficiency that comes with practice. The proposed method may facilitate the development of dynamic upper extremity prosthesis control strategies using arbitrary, user-preferred muscle contractions. View full abstract»

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  • Locomotor Function in the Early Stage of Parkinson's Disease

    Page(s): 543 - 551
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1097 KB) |  | HTML iconHTML  

    The cardinal motor symptoms of Parkinson's disease (PD) have been widely investigated with particular reference to abnormalities of steady-state walking. The great majority of studies, however are related to severe forms of PD patients (phases of Hoehn and Yahr scale), where locomotor abnormalities are clearly manifested. Goal of the present study was to quantitatively describe locomotor symptoms in subjects with mild PD. Accordingly, a multitask protocol involving instrumental analysis of steady-state linear walking, initiation of gait, and turning while walking was applied to a group of patients with idiopathic PD in their early clinical stage (phases 1 and 2 of Hoehn and Yahr scale), as well as in age-matched elderly controls. Kinematic, kinetic, and myoelectric measures were obtained by optoelectronic motion analysis, force platform, and telemetric electromyography. Results in PD patients showed a tendency to bradykinetic gait, with reduction of walking speed and cadence. Impairments of gait initiation consisted in reduction of the backward shift of the center of pressure (CoP) and prolongation of the stepping phase. Alterations of the turning task were more consistent and included delayed reorientation of the head toward the new direction, altered head-upper trunk rotational strategy, and adoption of a greater number of steps to complete the turning. It is concluded that patients in the early stage of PD reveal mild alterations of steady-state linear walking and more significant anomalies in the transitional conditions, especially during changes in the travel direction. Quantitative analysis of nonstationary locomotor tasks might be a potentially useful starting point for further studies on the pathophysiology of PD. View full abstract»

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  • Mechanical Behavior of the Human Ankle in the Transverse Plane While Turning

    Page(s): 552 - 559
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (912 KB) |  | HTML iconHTML  

    In order to better rehabilitate lower limb amputees, prosthetic technology needs to facilitate turning gait by providing torsional control in the transverse plane. This paper characterizes biological ankle function in the transverse plane during turning gait with simple mechanical elements to assist in the design of a biomimetic prosthetic ankle joint. Motion capture data was collected from ten subjects performing left and right turns through a 90 hallway corner. The initiation, apex, and termination steps of the turn were investigated. The data for each step was separated into several states, and passive elements were chosen to model the ankle in each state. During the first state of each turning step, the ankle behaved similarly to straight steps by limiting the kinetic energy of the foot prior to foot flat. During the subsequent states of each turning step, the ankle altered its characteristic properties to accommodate the curved trajectory of the body center of mass. The results suggest controlling transverse plane stiffness with a finite state control system will suffice to mimic biological function during a turn. View full abstract»

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  • Design, Implementation and Clinical Tests of a Wire-Based Robot for Neurorehabilitation

    Page(s): 560 - 569
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1159 KB) |  | HTML iconHTML  

    This paper presents the development of and clinical tests on NeReBot (NEuroREhabilitation roBOT): a three degrees-of-freedom (DoF), wire-driven robot for poststroke upper-limb rehabilitation. Basically, the robot consists of a set of three wires independently driven by three electric motors. The wires are connected to the patient's upper limb by means of a splint and are supported by a transportable frame, located above the patient. By controlling wire length, rehabilitation treatment (based on the passive or active-assistive spatial motion of the limb) can be delivered over a wide working space. The arm trajectory is set by the therapist through a very simple teaching-by-showing procedure, enabling most common ldquohands onrdquo therapy exercises to be reproduced by the robot. Compared to other rehabilitation robots, NeReBot offers the advantages of a low-cost mechanical structure, intrinsically safe treatment thanks to the use of wires, high acceptability by the patient, who does not feel constrained by an ldquoindustrial-likerdquo robot, transportability (it can be easily placed aside a hospital bed and/or a wheelchair), and a good trade-off between low number of DoF and spatial performance. These features and the very encouraging results of the first clinical trials make the NeReBot a good candidate for adoption in the rehabilitation treatment of subacute stroke survivors. Clinical trials were performed with a 12-patient experimental group and a 12-patient control group. Resulted that the patients who received robotic therapy in addition to conventional therapy showed greater reductions in motor impairment (in terms of Medical Research Council score, the upper limb subsection of the Fugl-Meyer score, and the Motor Status Score) and improvements in functional abilities (as measured by the Functional Independence Measure and its motor component). No adverse effects occurred and the robotic approach was very well accepted. According to these results, the NeReBot t- - herapy may efficaciously complement standard poststroke multidisciplinary rehabilitation and offer novel therapeutic strategies for neurological rehabilitation. View full abstract»

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  • A Haptic Force Feedback Device for Virtual Reality-fMRI Experiments

    Page(s): 570 - 576
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (334 KB) |  | HTML iconHTML  

    Simulation of real-world tasks using virtual reality (VR) and measurement of associated neural activity by functional magnetic resonance imaging (fMRI) have potential utility in research and clinical stroke applications. However, development of fMRI-compatible sensory feedback technology is required. Presented here is the development of a prototype force feedback device for VR-fMRI. Experiments validated device performance in terms of force output, interaction bandwidth, transmission delay, and fMRI-compatibility. A subsequent VR-fMRI experiment involved six participants touching a virtual object and verified modulation of brain activity with force feedback versus no force feedback. This device may facilitate further experiments to clarify the effect of haptics in VR, and may be adapted for characterizing brain function and behaviour associated with stroke-related hand paresis. View full abstract»

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  • Recruitment and Comfort of BION Implanted Electrical Stimulation: Implications for FES Applications

    Page(s): 577 - 586
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1230 KB) |  | HTML iconHTML  

    Restoration of motor function to paralyzed limbs by functional electrical stimulation (FES) has been hampered by the lack of precise and gradual control over muscle recruitment. A suitable interface should provide selective stimulation of individual muscles with graded recruitment of force. The BION was developed to enable neuromuscular stimulation through a miniature, self-contained implant designed to be injected in or near muscles and peripheral nerves. In this study, recruitment properties and comfort of the BION implanted electrical stimulation were systematically evaluated in subjects who participated in a clinical trial. Recruitment properties were qualitatively similar to other methods of implanted neuromuscular stimulation: thresholds and steepness of recruitment were negatively correlated and depended on stimulus charge (product of pulse current and duration). Perceived comfort was not affected by the choice of stimulus parameters, thus their choice can be based purely on technical considerations such as efficiency or resolution of recruitment. View full abstract»

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  • Wavelet-Based Feature Extraction for Support Vector Machines for Screening Balance Impairments in the Elderly

    Page(s): 587 - 597
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (776 KB) |  | HTML iconHTML  

    Trip related falls are a prevalent problem in the elderly. Early identification of at-risk gait can help prevent falls and injuries. The main aim of this study was to investigate the effectiveness of a wavelet based multiscale analysis of a gait variable [minimum foot clearance (MFC)] in comparison to MFC histogram plot analysis in extracting features for developing a model using support vector machines (SVMs) for screening of balance impairments in the elderly. MFC during walking on a treadmill was recorded on 13 healthy elderly and 10 elderly with a history of tripping falls. Features extracted from MFC histogram and then multiscale exponents between successive wavelet coefficient levels after wavelet decomposition of MFC series were used as inputs to the SVM to classify two gait patterns. The maximum accuracy of classification was found to be 100% for a SVM using a subset of selected wavelet based features, compared to 86.95% accuracy using statistical features. For estimating the relative risk of falls, the posterior probabilities of SVM outputs were calculated. These results suggest superior performance of SVM in the detection of balance impairments based on wavelet-based features and it could also be useful for evaluating for falls prevention intervention. View full abstract»

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  • 2007 Index IEEE Transactions on Neural Systems and Rehabilitation Engineering Vol. 15

    Page(s): 598 - 608
    Save to Project icon | Request Permissions | PDF file iconPDF (136 KB)  
    Freely Available from IEEE
  • IEEE Transactions on Neural Systems and Rehabilitation Engineering Information for authors

    Page(s): C3
    Save to Project icon | Request Permissions | PDF file iconPDF (26 KB)  
    Freely Available from IEEE

Aims & Scope

IEEE Transactions on Neural Systems and Rehabilitation Engineering focuses on the rehabilitative and neural aspects of biomedical engineering.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Paul Sajda
Columbia University