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Neural Systems and Rehabilitation Engineering, IEEE Transactions on

Issue 2 • Date June 2004

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Displaying Results 1 - 21 of 21
  • Table of contents

    Publication Year: 2004 , Page(s): c1 - c4
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  • IEEE Transactions on Neural Systems and Rehabilitation Engineering publication information

    Publication Year: 2004 , Page(s): c2
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  • Theory and design of an orthotic device for full or partial gravity-balancing of a human leg during motion

    Publication Year: 2004 , Page(s): 157 - 165
    Cited by:  Papers (20)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (577 KB) |  | HTML iconHTML  

    Gravity balancing is often used in industrial machines to decrease the required actuator efforts during motion. In the literature, a number of methods have been proposed for gravity balancing that include counterweights, springs, and auxiliary parallelograms that determine the center of mass. However, these concepts have not yet been seriously applied to rehabilitation machines. This paper presents the underlying theory and design of an orthosis for the human leg that can fully or partially balance the human leg over the range of its motion. This design combines the use of auxiliary parallelograms to determine the center of mass along with springs to achieve a full or partial gravity balanced orthosis design. A first prototype has been constructed to demonstrate the effectiveness of the idea. Future prototypes will have parameters that will be tuned to the geometry and inertia of a human subject and be tailored to an individual's needs. View full abstract»

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  • Evidence for force-feedback inhibition in chronic stroke

    Publication Year: 2004 , Page(s): 166 - 176
    Cited by:  Papers (4)
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    The presence of force-feedback inhibition was explored during reflex responses in five subjects with known incidence of stroke. Using constant velocity stretches, it was previously found that after movement onset, active reflex force progressively increases with increasing joint angle, at a rate proportional to a fractional exponent of the speed of stretch. However, after the reflex force magnitude exceeds a particular level, it begins rolling off until maintaining a steady-state value. The magnitudes of these force plateaus are correlated with the speed of stretch, such that higher movement speeds result in higher steady-state forces. Based upon these previous studies, we hypothesized that force plateau behavior could be explained by a force-feedback inhibitory pathway. To help facilitate an understanding of this stretch reflex force roll off, a simple model representing the elbow reflex pathways was developed. This model contained two separate feedback pathways, one representing the monosynaptic stretch reflex originating from muscle spindle excitation, and another representing force-feedback inhibition arising from force sensitive receptors. It was found that force-feedback inhibition altered the stretch reflex response, resulting in a force response that followed a sigmoidal shape similar to that observed experimentally. Furthermore, simulated reflex responses were highly dependent on force-feedback gain, where predicted reflex force began plateauing at decreasing levels with increases in this force-feedback gain. The parameters from the model fits indicate that the force threshold for force-sensitive receptors is relatively high, suggesting that the inhibition may arise from muscle free nerve endings rather than Golgi tendon organs. The experimental results coupled with the simulations of elbow reflex responses suggest the possibility that after stroke, the effectiveness of force-feedback inhibition may increase to a level that has functional significance. Prac- - tical implications of these findings are discussed in relation to muscle weakness commonly associated with stroke. View full abstract»

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  • The effects of trunk stimulation on bimanual seated workspace

    Publication Year: 2004 , Page(s): 177 - 185
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (469 KB) |  | HTML iconHTML  

    This study explores the effects of functional electrical stimulation (FES) of the lumbar trunk extensors on the seated posture and bimanual workspace of subjects with spinal cord injury (SCI). Four subjects with motor complete SCI with implanted intramuscular stimulating electrodes to activate the lumbar erector spinae were studied. The positions of markers on the pelvis, trunk, and hands were monitored by a motion capture system during bimanual reaching maneuvers. To define three-dimensional functional workspace boundaries, subjects swept their hands through the extremes of their range of motion without losing balance while sitting. To characterize forward reach, subjects reached to targets in the sagittal plane while carrying various masses with and without FES. Reaching trials were rated on the seven-point usability rating scale to determine effort and subject preference and change in pelvic angle with stimulation was monitored. There was a consistent change in the seated posture with FES in all subjects that resulted in significant forward or upward (6.85 cm ± 2.15 cm) shifts in the workspace. Workspace volumes increased for two of the four subjects tested. FES caused significant anterior rotation of the pelvis to restore a more natural lumbar curve without a backrest (19.81° ± 8.75°). With a backrest, the change in posture with FES allowed individuals with SCI to reach further in the sagittal plane and carry heavier masses by shifting the trunk, allowing increased elbow extension, or a combination of the two mechanisms. Reaching with FES was consistently preferred over reaching without FES. This preliminary study is encouraging for future research on trunk stability and reaching ability with FES. View full abstract»

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  • Evidence for improved muscle activation patterns after retraining of reaching movements with the MIME robotic system in subjects with post-stroke hemiparesis

    Publication Year: 2004 , Page(s): 186 - 194
    Cited by:  Papers (66)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (645 KB) |  | HTML iconHTML  

    Previously, we reported that chronic stroke subjects had significant improvements in isometric strength, free reaching extent, and clinical evaluations of function after training in the mirror-image movement enabler (MIME) robotic device. Our primary goal in this analysis was to investigate the hypothesis that the robotic training promoted improved muscle activation patterns. To this end, we examined the interaction forces, kinematics, and electromyograms recorded during training of eight different movement patterns in active-constrained mode. In this mode, the robot constrained the reaching movements to be toward the target, and the movement velocity was proportional to the force produced along the trajectory. Thirteen chronic stroke subjects trained in MIME for 24 1-h sessions over an eight-week period. Work output was significantly increased by week five in all eight movement patterns. Low-level subjects increased their extent of reach, while high-level subjects increased their speed. Directional errors in force production were reduced in six of eight movement patterns. Electromyographic data provided evidence for improved muscle activation patterns in the four movement patterns that started at tabletop level and ended at shoulder level. In contrast, there was no evidence of improved muscle activation patterns in any of the tabletop movements, with increased activation of antagonists in two movement patterns. This dichotomy may have been related to compensation at the shoulder girdle during movements that remained at tabletop level. A simple biomechanical model will be introduced to demonstrate the likelihood of this possibility. View full abstract»

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  • Arrays for chronic functional microstimulation of the lumbosacral spinal cord

    Publication Year: 2004 , Page(s): 195 - 207
    Cited by:  Papers (28)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (901 KB)  

    Our objective is to develop neural prostheses based on an array of microelectrodes implanted into the sacral spinal cord, that will allow persons with spinal cord injuries to regain control of their bladder and bowels. For our chronic cat model, we have developed two microelectrode arrays, one type containing nine discrete activated iridium microelectrodes and the second utilizing silicon substrate probes with multiple electrode sites on each probe. Both types can elicit an increase in the pressure within the urinary bladder of more than 40-mm Hg and/or relaxation of the urethral sphincter. A stimulus of 100 μA and 400 μs/ph at 20 Hz (charge-balanced pulses) was required to induce a large increase in bladder pressure or relaxation of the urethral sphincter. We found that 24 h of continuous stimulation with these parameters induced tissue injury (disrupted neuropil, infiltration of inflammatory cells, and loss of neurons close to the tip sites). However, a neural prosthesis that is intended to restore bladder control after spinal cord injury would not operate continuously. Thus, when this stimulus was applied for 24 h, at a 10% duty cycle (1 min of stimulation, then 9 min without stimulation) only minimal histologic changes were observed. View full abstract»

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  • Interleaved, multisite electrical stimulation of cat sciatic nerve produces fatigue-resistant, ripple-free motor responses

    Publication Year: 2004 , Page(s): 208 - 215
    Cited by:  Papers (36)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (356 KB) |  | HTML iconHTML  

    We studied the use of physiologically based, multisite, intrafascicular electrical stimulation of the sciatic nerve to achieve ripple-free contractions and sustained, fatigue-resistant forces over a physiological range of forces in cat gastrocnemius muscle. Electrode arrays containing 100, 0.5-1.5-mm-long penetrating microelectrodes were inserted into the sciatic nerves of cats, and forces generated by gastrocnemius muscles in response to stimulation of the nerves were monitored via a force transducer attached to the tendons. In single-electrode stimulation, responses evoked by low-frequency [15 pulses/second, (p/s)] stimulation exhibited greater fatigue resistance than did responses evoked by higher frequency stimulation (30 and 60 p/s), but showed far more ripple within each response. We compared interleaved 15 p/s stimulation of four electrodes (100 μs biphasic pulses, 750-ms pulse trains) that produced a net stimulation frequency of 60 p/s with multielectrode 60 p/s quasi-simultaneous stimulation protocols. Across a broad range of forces (10% to 80% of maximum), responses evoked by multielectrode 15 p/s interleaved stimulation exhibited substantially less fatigue than did responses evoked by 60 p/s quasi-simultaneous stimulation, and less ripple than responses evoked by single-electrode 15 p/s stimulation. The effectiveness of this physiologically based stimulation paradigm encourages its application in the field of motor neuroprosthetics. View full abstract»

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  • Optimal halftoning for tactile imaging

    Publication Year: 2004 , Page(s): 216 - 227
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (970 KB) |  | HTML iconHTML  

    Reading of text and understanding images by touch is an important alternative and additional source of information when sight is absent or lost. Tactile graphics and models such as edge maps, binary output, etc., are the solution for simple access to images for blind persons. This paper introduces an approach to model the human tactile system based on the responses produced by stimuli on microcapsule paper. This system is utilized for the purpose of generating optimum halftone patterns on microcapsule paper that can be utilized for the effective generation of tactile graphics. View full abstract»

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  • The smart house for older persons and persons with physical disabilities: structure, technology arrangements, and perspectives

    Publication Year: 2004 , Page(s): 228 - 250
    Cited by:  Papers (60)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (942 KB) |  | HTML iconHTML  

    Smart houses are considered a good alternative for the independent life of older persons and persons with disabilities. Numerous intelligent devices, embedded into the home environment, can provide the resident with both movement assistance and 24-h health monitoring. Modern home-installed systems tend to be not only physically versatile in functionality but also emotionally human-friendly, i.e., they may be able to perform their functions without disturbing the user and without causing him/her any pain, inconvenience, or movement restriction, instead possibly providing him/her with comfort and pleasure. Through an extensive survey, this paper analyzes the building blocks of smart houses, with particular attention paid to the health monitoring subsystem as an important component, by addressing the basic requirements of various sensors implemented from both research and clinical perspectives. The paper will then discuss some important issues of the future development of an intelligent residential space with a human-friendly health monitoring functional system. View full abstract»

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  • Selective and independent activation of four motor fascicles using a four contact nerve-cuff electrode

    Publication Year: 2004 , Page(s): 251 - 257
    Cited by:  Papers (38)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (314 KB) |  | HTML iconHTML  

    Any one of the four motor nerves in the cat sciatic nerve could be activated selectively and independently, from threshold to saturation, using a self-sizing spiral cuff electrode containing four radially placed monopolar contacts. These studies were carried out in nine adult cats with acute implants. Of the 36 possible fascicles, 23 fascicles could be activated selectively with current stimuli applied to a single contact and ten of the remaining fascicles could be activated selectively with current stimuli applied to two contacts, "field steering." In three experiments, time constraints precluded attempting selective activation through "field steering" techniques. In eight of the ten cases where "field steering" was used, a positive and a negative current source (anodic steering) were required to achieve the desired fascicle and in the remaining two cases, two negative current sources (cathodic steering) were required. The relative distance from the electrode contacts to each fascicle was well correlated to the order in which each fascicle was activated. In seven experiments, carried out in two animals, selective activation was verified by collision block techniques. The results of these experiments support the hypothesis that selective and independent activation of any of four motor fascicles in the cat sciatic nerve is possible using a four contact self-sizing spiral cuff electrode. Furthermore, in a more general case, these results support the concept of a "tunable" electrode that is capable of "steering" the excitation from an undesirable location to a preferred location. View full abstract»

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  • Continuous EEG classification during motor imagery-simulation of an asynchronous BCI

    Publication Year: 2004 , Page(s): 258 - 265
    Cited by:  Papers (72)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (214 KB) |  | HTML iconHTML  

    Nearly all electroencephalogram (EEG)-based brain-computer interface (BCI) systems operate in a cue-paced or synchronous mode. This means that the onset of mental activity (thought) is externally-paced and the EEG has to be analyzed in predefined time windows. In the near future, BCI systems that allow the user to intend a specific mental pattern whenever she/he wishes to produce such patterns will also become important. An asynchronous BCI is characterized by continuous analyzing and classification of EEG data. Therefore, it is important to maximize the hits (true positive rate) during an intended mental task and to minimize the false positive detections in the resting or idling state. EEG data recorded during right/left motor imagery is used to simulate an asynchronous BCI. To optimize the classification results, a refractory period and a dwell time are introduced. View full abstract»

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  • Design and implementation of haptic virtual environments for the training of the visually impaired

    Publication Year: 2004 , Page(s): 266 - 278
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1315 KB) |  | HTML iconHTML  

    This paper presents a haptic virtual reality (VR) tool developed for the training of the visually impaired. The proposed approach focuses on the development of a highly interactive and extensible haptic VR training system (the ENORASI VR training system) that allows visually impaired, to study and interact with various virtual objects in specially designed virtual environments, while allowing designers to produce and customize these configurations. Based on the system prototype and the use of the CyberGrasp haptic device, a number of custom applications have been developed. An efficient collision detection algorithm is also introduced, by extending the proximity query package (PQP) algorithm to handle five points of contact (a case studied with the use of CyberGrasp). Two test categories were identified and corresponding tests were developed for each category. The training scenarios include: object recognition and manipulation and cane simulation, used for performing realistic navigation tasks. Twenty-six blind persons conducted the tests and the evaluation results have shown the degree of acceptance of the technology and the feasibility of the proposed approach. View full abstract»

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  • Performance of epimysial stimulating electrodes in the lower extremities of individuals with spinal cord injury

    Publication Year: 2004 , Page(s): 279 - 287
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (435 KB) |  | HTML iconHTML  

    This study describes the performance of surgically-implanted epimysial stimulating electrodes in the muscles of the lower extremities for use in functional neuromuscular stimulation (FNS) systems for standing after spinal cord injury. A total of 86 epimysial electrodes were implanted in 13 volunteers with low tetraplegia or paraplegia receiving the Case Western Reserve University/Veteran Affairs (CWRU/VA)-implanted standing/transfer neuroprosthesis. The neuroprosthesis consisted of bilateral epimysial electrodes in the knee and hip extensors (vastus lateralis, gluteus maximus, and adductor magnus or semimembranosus) and intramuscular electrodes at the T12/L1 or L1/L2 spinal roots for trunk extension. Recruitment properties, stimulated knee and hip extension moments, standing performance, and mechanical integrity over time were measured for a period up to four years post-implantation. Stimulated thresholds were stable and recruitment was sufficient to generate joint moments adequate for standing, with up to 97% body weight supported by the legs. Four mechanical failures were observed, all in the posterior muscles of the thigh, leaving 95% of all electrodes operational at all followup intervals. Probability of 24-month survival is estimated to be 93% plateauing to a steady state of 90% at four years. These results indicate that epimysial designs are appropriate for long-term clinical use in the large muscles of the lower extremities with implanted motor system neuroprostheses. View full abstract»

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  • Combination of variable frequency train stimulation and K+ channel blockade to augment skeletal muscle force

    Publication Year: 2004 , Page(s): 288 - 294
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (150 KB) |  | HTML iconHTML  

    Several innovative approaches are being used to optimize the input-output relationship of muscle, including nonlinear stimulation paradigms and altering muscle membrane ion channel conductances. We tested the hypothesis that the combination of the K+ channel blocker, 3,4-diaminopyridine (DAP), and variable frequency train (VFT) stimulation improves muscle force to a greater extent than either modality alone. Studies were done in vitro on rat diaphragm muscle and contractions were quantified with respect to peak force, mean force, and force area. DAP increased all three force parameters by >50% during conventional 10-20-Hz stimulation, whereas VFT stimulation improved contractile performance for peak force only. When combined, DAP and VFT stimulation augmented peak force to a significantly greater extent than either modality alone. However, this came at a cost of a moderate decline in force area relative to DAP alone, although mean force was preserved. These force increases were generally well-maintained over the course of short-term repetitive stimulation. Thus, VFT stimulation and K+ channel blockade interact in a complex manner to modulate skeletal muscle force. The utility of the combined intervention for functional electrical stimulation may be greatest for mechanical tasks requiring high force levels early during the contraction. View full abstract»

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  • A real-time articulated human motion tracking using tri-axis inertial/magnetic sensors package

    Publication Year: 2004 , Page(s): 295 - 302
    Cited by:  Papers (102)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (281 KB) |  | HTML iconHTML  

    A basic requirement in virtual environments is the tracking of objects, especially humans. A real time motion-tracking system was presented and evaluated in this paper. System sensors were built using tri-axis microelectromechanical accelerometers, rate gyros, and magnetometers. A Kalman-based fusion algorithm was applied to obtain dynamic orientations and further positions of segments of the subject's body. The system with the proposed algorithm was evaluated via dynamically measuring Euler orientation and comparing with other two conventional methods. An arm motion experiment was demonstrated using the developed system and algorithm. The results validated the effectiveness of the proposed method. View full abstract»

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  • The effect of joint angle on the timing of muscle contractions elicited by neuromuscular electrical stimulation

    Publication Year: 2004 , Page(s): 303 - 306
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (151 KB)  

    Neuromuscular electrical stimulation was used to evoke isometric knee extension contractions in seven individuals with spinal cord injury (SCI) and the time for knee extension torque to rise and fall was measured across a range of knee angles. The stimulated muscles took more than twice as long to develop 50% of maximum torque at an angle of 15°, compared to an angle of 90°. This time difference comprised both an increased delay before torque rose above resting levels (31 ± 3 ms at 90°, 67 ± 24 ms at 15°), and a prolonged duration over which torque was rising (72 ± 14 ms at 90°, 140 ± 62 ms at 15°). There was no change, however, in the time taken for torque to fall after cessation of stimulation at different knee angles (58 ± 5-ms delay, 60 ± 11-ms fall time). The difference in torque rise time with joint angle has implications for modeling functional activities that differ greatly in their joint angles. This study provides regression equations whereby activation times for the quadriceps muscles of individuals with SCI can be predicted for specific angles of knee flexion. View full abstract»

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  • 26th Annual International Conference of the IEEE Engineering in Medicine and Biology Society

    Publication Year: 2004 , Page(s): 307 - 310
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  • Join the IEEE Engineering in Medicine and Biology Society

    Publication Year: 2004 , Page(s): 311
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  • Join IEEE

    Publication Year: 2004 , Page(s): 312
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  • IEEE Transactions on Neural Systems and Rehabilitation Engineering Information for authors

    Publication Year: 2004 , Page(s): c3
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Aims & Scope

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

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Paul Sajda
Columbia University