IEEE Transactions on Neural Systems and Rehabilitation Engineering (IEEE T NEUR SYS REH)

Publications in this journal

• Article: GPGPU-Enabled Synchronization Measurement of Multiple Brain Regions upon Nonlinear Interdependence Analysis

  Dan Chen, Xiaoli Li, Dong Cui, Lizhe Wang, Dongchuan Lu
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  ABSTRACT: The estimation of synchronization amongst multiple brain regions is a critical issue in understanding brain functions. There is a lack of an appropriate approach which is capable of (1) measuring the direction and strength of synchronization of activities of multiple brain regions, and (2) adapting to the quickly increasing sizes and scales of neural signals. Nonlinear Interdependence (NLI) analysis is an effective method for measuring synchronization direction and strength of bivariate neural signal. However, the method currently does not directly apply in handling multivariate signal. Its application in practice has also long been largely hampered by the ultra-high complexity of NLI algorithms. Aiming at these problems, this study (1) extends the conventional NLI to quantify the global synchronization of multivariate neural signals, and (2) develops a parallelized NLI method with general-purpose computing on the graphics processing unit (GPGPU), namely, G-NLI. The approach performs synchronization measurement in a massively parallel manner. The G-NLI has improved the runtime performance by more than 1000 times comparing to the original sequential NLI. Meanwhile, the G-NLI was employed to analyze 10-channel local field potential (LFP) recordings from a patient suffering from temporal lobe epilepsy. The results demonstrate that the proposed G-NLI method can support real-time global synchronization measurement and it could be successful in localization of epileptic focus.
  IEEE Transactions on Neural Systems and Rehabilitation Engineering 01/2014; PP(99).
• Article: Assistive technology selection: A study of participation of users with rheumatoid arthritis.

  U. Hass, H. Brodin, A. Andersson, J. Persson
  IEEE Transactions on Neural Systems and Rehabilitation Engineering 02/2013; 5:263-275.
• Article: Nanotextured flexible low-impedance 3-D microelectrode array for neural signal recording and stimulation

  S. R. I. Gabran, A. Bagheri, M. T. Salam, J. Dian, Y. El-Hayek, R. R. mansour, M. M. A. Salama, J. L. Perez Velazquez, R. Genov, P. Carlen
  IEEE Transactions on Neural Systems and Rehabilitation Engineering 10/2012;
• Article: Control of Upper Limb Prostheses: Terminology and Proportional Myoelectric Control -- A Review

  A Fougner, O Stavdahl, P Kyberd, Y Losier, P Parker
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  ABSTRACT: The recent introduction of novel multifunction hands as well as new control paradigms increase the demand for advanced prosthetic control systems. In this context, an unambiguous terminology and a good understanding of the nature of the control problem is important for efficient research and communication concerning the subject. Thus, one purpose of this paper is to suggest an unambiguous taxonomy, applicable to control systems for upper limb prostheses and also to prostheses in general. A functionally partitioned model of the prosthesis control problem is also presented along with the taxonomy. In the second half of the paper, the suggested taxonomy has been exploited in a comprehensive literature review on proportional myoelectric control of upper limb prostheses. The review revealed that the methods for system training have not matured at the same pace as the novel multifunction prostheses and more advanced intent interpretation methods. Few publications exist regarding the choice of training method and the composition of the training data set. In this context, the notion of outcome measures is essential. By definition, system training involves optimization, and the quality of the results depends heavily on the choice of appropriate optimization criteria. In order to further promote the development of proportional myoelectric control, these topics need to be addressed.
  IEEE Transactions on Neural Systems and Rehabilitation Engineering 09/2012; 20(5):663-677.
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  Article: Electrostimulation as a Prosthesis for Repair of Information Flow in a Computer Model of Neocortex

  C. C. Kerr, S. A. Neymotin, G. L. Chadderdon, C. T. Fietkiewicz, J. T. Francis, W. W. Lytton
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  ABSTRACT: Damage to a cortical area reduces not only information transmitted to other cortical areas, but also activation of these areas. This phenomenon, whereby the dynamics of a follower area are dramatically altered, is typically manifested as a marked reduction in activity. Ideally, neuroprosthetic stimulation would replace both information and activation. However, replacement of activation alone may be valuable as a means of restoring dynamics and information processing of other signals in this multiplexing system. We used neuroprosthetic stimulation in a computer model of the cortex to repair activation dynamics, using a simple repetitive stimulation to replace the more complex, naturalistic stimulation that had been removed. We found that we were able to restore activity in terms of neuronal firing rates. Additionally, we were able to restore information processing, measured as a restoration of causality between an experimentally recorded signal fed into the in silico brain and a cortical output. These results indicate that even simple neuroprosthetics that do not restore lost information may nonetheless be effective in improving the functionality of surrounding areas of cortex.
  IEEE Transactions on Neural Systems and Rehabilitation Engineering 04/2012;
• Article: Virtual Active Touch Using Randomly Patterned Intracortical Microstimulation

  J. E. O'Doherty, M. A. Lebedev, Z. Li, M. A. L. Nicolelis
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  ABSTRACT: Intracortical microstimulation (ICMS) has promise as a means for delivering somatosensory feedback in neuroprosthetic systems. Various tactile sensations could be encoded by temporal, spatial, or spatiotemporal patterns of ICMS. However, the applicability of temporal patterns of ICMS to artificial tactile sensation during active exploration is unknown, as is the minimum discriminable difference between temporally modulated ICMS patterns. We trained rhesus monkeys in an active exploration task in which they discriminated periodic pulse-trains of ICMS (200 Hz bursts at a 10 Hz secondary frequency) from pulse trains with the same average pulse rate, but distorted periodicity (200 Hz bursts at a variable instantaneous secondary frequency). The statistics of the aperiodic pulse trains were drawn from a gamma distribution with mean inter-burst intervals equal to those of the periodic pulse trains. The monkeys distinguished periodic pulse trains from aperiodic pulse trains with coefficients of variation 0.25 or greater. Reconstruction of movement kinematics, extracted from the activity of neuronal populations recorded in the sensorimotor cortex concurrent with the delivery of ICMS feedback, improved when the recording intervals affected by ICMS artifacts were removed from analysis. These results add to the growing evidence that temporally patterned ICMS can be used to simulate a tactile sense for neuroprosthetic devices.
  IEEE Transactions on Neural Systems and Rehabilitation Engineering 02/2012;
• Article: Vibrotactile Sensory Substitution for Object Manipulation: Amplitude Versus Pulse Train Frequency Modulation

  C.E. Stepp, Y. Matsuoka
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  ABSTRACT: Incorporating sensory feedback with prosthetic devices is now possible, but the optimal methods of providing such feedback are still unknown. The relative utility of amplitude and pulse train frequency modulated stimulation paradigms for providing vibrotactile feedback for object manipulation was assessed in 10 participants. The two approaches were studied during virtual object manipulation using a robotic interface as a function of presentation order and a simultaneous cognitive load. Despite the potential pragmatic benefits associated with pulse train frequency modulated vibrotactile stimulation, comparison of the approach with amplitude modulation indicates that amplitude modulation vibrotactile stimulation provides superior feedback for object manipulation.
  IEEE Transactions on Neural Systems and Rehabilitation Engineering 02/2012;
• Article: Functional Near Infrared Spectroscopy Study of Age-Related Difference in Cortical Activation Patterns During Cycling With Speed Feedback

  Pei-Yi Lin, Sang-I Lin, J.J. Chen
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  ABSTRACT: Functional decline of lower-limb affects the ability of locomotion and the age-related brain differences have been elucidated among the elderly. Cycling exercise is a common training program for restoring motor function in the deconditioned elderly or stroke patients. The provision of speed feedback has been commonly suggested to clinical therapists for facilitating learning of controlled cycling performance and maintaining motivation in training programs with elderly participants. However, the cortical control of pedaling movements and the effect of external feedback remain poorly understanding. This study investigated the regional cortical activities detected by functional near infrared spectroscopy (fNIRS) in 12 healthy young and 13 healthy elderly subjects under conditions of cycling without-(free cycling) and with feedback (target cycling). The elderly exhibited predominant activation of the sensorimotor cortex during free cycling similar to young subjects but with poorer cycling performance. The cycling performance improved in both groups, and the elderly showed increased brain activities of the supplementary motor area and premotor cortex under target cycling condition. These findings demonstrated age-related changes in the cortical control in processing external feedback and pedaling movements. Use of fNIRS to evaluate brain activation patterns after training may facilitate brain-based design of tailored therapeutic rehabilitation strategies.
  IEEE Transactions on Neural Systems and Rehabilitation Engineering 02/2012;
• Article: Validation of a Selective Ensemble-BasedClassification Scheme for Myoelectric ControlUsing a Three Dimensional Fitts’ Law Test

  Erik Scheme, Kevin Englehart
  IEEE Transactions on Neural Systems and Rehabilitation Engineering 01/2012; PP(99):1.
• Article: A Bilateral Ankle Manipulator to Investigate Human Balance Control

  A.C. Schouten, T.A. Boonstra, F. Nieuwenhuis, S.F. Campfens, H. van der Kooij
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  ABSTRACT: The ankles play an important role in human balance. In most studies investigating balance control the contribution of the left and right leg is not separated. However, in certain pathologies such as stroke and Parkinson's disease, balance control can be asymmetric. Here, a bilateral ankle perturbator (BAP) is presented, which applies support surface rotations to both ankles independently. The device consists of two small foot-size support surfaces, which are independently actuated. The BAP device can operate in either angle or torque control mode. The device is able to apply support surface rotations up to 8.6^° with a bandwidth of 42 Hz. Additionally the platforms can be replaced by 6-DoF force plates to measure the center of pressure underneath each foot. With the optional force plates the bandwidth decreases to 16 Hz as a result of the additional weight. Two possible applications of the device to investigate human balance control are demonstrated: ankle stiffness by applying minimum jerk profiles and sensory reweighting of the proprioceptive information. In conclusion, we developed a bilateral ankle perturbator which is able to apply support surface rotations to both ankles independently. The major application of the device will be to investigate the contribution of both ankles to human balance control, and the interactions in balance control between both legs.
  IEEE Transactions on Neural Systems and Rehabilitation Engineering 01/2012;
• Article: The Impact of Loss of Control on Movement BCIs

  B. Reuderink, M. Poel, A. Nijholt
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  ABSTRACT: Brain-computer interfaces (BCIs) are known to suffer from spontaneous changes in the brain activity. If changes in the mental state of the user are reflected in the brain signals used for control, the behavior of a BCI is directly influenced by these states. We investigate the influence of a state of loss of control in a variant of Pacman on the performance of BCIs based on motor control. To study the effect a temporal loss of control has on the BCI performance, BCI classifiers were trained on electroencephalography (EEG) recorded during the normal control condition, and the classification performance on segments of EEG from the normal and loss of control condition was compared. Classifiers based on event-related desynchronization unexpectedly performed significantly better during the loss of control condition; for the event-related potential classifiers there was no significant difference in performance.
  IEEE Transactions on Neural Systems and Rehabilitation Engineering 01/2012;
• Article: Object Manipulation Improvements Due to Single Session Training Outweigh the Differences Among Stimulation Sites During Vibrotactile Feedback

  C.E. Stepp, Y. Matsuoka
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  ABSTRACT: Most hand prostheses do not provide intentional haptic feedback about movement performance; thus users must rely almost completely on visual feedback. This paper focuses on understanding the effects of learning and different stimulation sites when vibrotactile stimulation is used as the intentional haptic feedback. Eighteen unimpaired individuals participated in this study with a robotic interface to manipulate a virtual object with visual and vibrotactile feedback at four body sites (finger, arm, neck, and foot) presented in a random order. All participants showed improvements in object manipulation performance with the addition of vibrotactile feedback. Specifically, performance showed a strong learning effect across time, with learning transferring across different sites of vibrotactile stimulation. The effects of learning over the experiment overshadowed the effects of different stimulation sites. The addition of a cognitive task slowed participants and increased the subjective difficulty. User preference ratings showed no difference in their preference among vibrotactile stimulation sites. These findings indicate that the stimulation site may not be as critical as ensuring adequate training with vibrotactile feedback during object manipulation. Future research to identify improvements in vibrotactile-based feedback parameters with amputees is warranted.
  IEEE Transactions on Neural Systems and Rehabilitation Engineering 01/2012;
• Article: Kinesthetic Motor Imagery Modulates Intermuscular Coherence

  C.E. Stepp, N. Oyunerdene, Y. Matsuoka
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  ABSTRACT: Intermuscular coherence can identify oscillatory coupling between two electromyographic (EMG) signals, measuring common presynaptic drive to motor neurons. Beta band oscillations (15-30 Hz) are hypothesized to originate largely from primary motor cortex, and are reduced during dynamic relative to static motor tasks. It has yet to be established whether motor imagery modulates beta intermuscular coherence. Using visual feedback, 10 unimpaired participants completed eighteen trials of pinching their right thumb and index finger at a constant force. During the 60-second trials, participants simultaneously engaged in one of three types of kinesthetic imagery: the right thumb and index finger executing a constant force pinch (static), the fingers of the right hand sequentially flexing and extending (dynamic), and the right foot pushing down with constant force (foot). Motor imagery of a dynamic motor task resulted in significantly lower intermuscular beta coherence than imagery of a static motor pinch task, without any difference in task performance or root-mean-square EMG. Thus, motor imagery affects intermuscular coherence in the beta band, even while measures of task performance remain constant. This finding provides insight for incorporation of beta band intermuscular coherence in future motor rehabilitation schemes and brain computer interface design.
  IEEE Transactions on Neural Systems and Rehabilitation Engineering 01/2012;
• Article: An Analysis of the Accuracy of Wearable Sensors for Classifying the Causes of Falls in Humans

  O. Aziz, S.N. Robinovitch
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  ABSTRACT: Falls are the number one cause of injury in older adults. Wearable sensors, typically consisting of accelerometers and/or gyroscopes, represent a promising technology for preventing and mitigating the effects of falls. At present, the goal of such “ambulatory fall monitors” is to detect the occurrence of a fall and alert care providers to this event. Future systems may also provide information on the causes and circumstances of falls, to aid clinical diagnosis and targeting of interventions. As a first step towards this goal, the objective of the current study was to develop and evaluate the accuracy of a wearable sensor system for determining the causes of falls. Sixteen young adults participated in experimental trials involving falls due to slips, trips, and “other” causes of imbalance. Three-dimensional acceleration data acquired during the falling trials were input to a linear discriminant analysis technique. This routine achieved 96% sensitivity and 98% specificity in distinguishing the causes of a falls using acceleration data from three markers (left ankle, right ankle, and sternum). In contrast, a single marker provided 54% sensitivity and two markers provided 89% sensitivity. These results indicate the utility of a three-node accelerometer array for distinguishing the cause of falls.
  IEEE Transactions on Neural Systems and Rehabilitation Engineering 01/2012;
• Article: Detecting the Onset of Urinary Bladder Contractions Using an Implantable Pressure Sensor

  J. Melgaard, N.J.M. Rijkhoff
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  ABSTRACT: This study investigates whether signals obtained from an implantable pressure sensor placed in the urinary bladder wall could be used to detect the onset of bladder contractions. The sensor assembly was custom made using a small piezoresistive sensor die. The die was mounted on ceramic substrate (8 mm × 8 mm) and encapsulated in silicone by a two-part moulding process. The final sensor was lens shaped with a diameter of 13.6 mm and height of 2.0 mm. Experiments were performed in six pigs that had one or more sensors placed in the bladder wall. An external reference sensor was used to simultaneously monitor intravesical pressure via a transurethral catheter. Bladder contractions were evoked by unilateral electrical stimulation of the pelvic nerve. Onset latency was computed using both signals. In addition, the correlation between wall pressure and intravesical pressure was calculated. On average, the onset latency was -307 ms using the wall sensors compared to the intravesical pressure, i.e., the detection occurred earlier using the wall sensors than the intravesical sensor. In 91 of 114 recordings the correlation coefficient was above 0.90. In conclusion, the implantable sensor performs similar to the reference sensor when used to detect the onset of bladder contractions.
  IEEE Transactions on Neural Systems and Rehabilitation Engineering 01/2012;
• Article: Impedance as a Method to Sense Proximity at the Electrode-Retina Interface

  A. Ray, L.L. Chan, A. Gonzalez, M.S. Humayun, J.D. Weiland
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  ABSTRACT: Precise positioning of a stimulating electrode in the eye is not possible by simple visualization. However, reliable measurement of responses to retinal stimulation requires consistent positioning. The present study focuses on impedance measurement techniques to sense the proximity of the electrode to the retina. A platinum-iridium stimulation electrode was placed inside the rat eye and impedance was recorded at different positions of the stimulating electrode relative to the retina. The presence of robust electrically evoked response in the superior colliculus indicates that the electrode may not have to be in absolute contact in order to elicit a neural response. Optical coherence tomography imaging confirmed the distance-impedance relationship.
  IEEE Transactions on Neural Systems and Rehabilitation Engineering 01/2012;
• Article: Preliminary Evaluation of a Powered Lower Limb Orthosis to Aid Walking in Paraplegic Individuals

  R.J. Farris, H.A. Quintero, M. Goldfarb
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  ABSTRACT: This paper describes a powered lower-limb orthosis that is intended to provide gait assistance to spinal cord injured (SCI) individuals by providing assistive torques at both hip and knee joints. The orthosis has a mass of 12 kg and is capable of providing maximum joint torques of 40 Nm with hip and knee joint ranges of motion from 105^° flexion to 30 ^° extension and 105 ^° flexion to 10 ^° hyperextension, respectively. A custom distributed embedded system controls the orthosis with power being provided by a lithium polymer battery which provides power for one hour of continuous walking. In order to demonstrate the ability of the orthosis to assist walking, the orthosis was experimentally implemented on a paraplegic subject with a T10 complete injury. Data collected during walking indicates a high degree of step-to-step repeatability of hip and knee trajectories (as enforced by the orthosis) and an average walking speed of 0.8 km/hr. The electrical power required at each hip and knee joint during gait was approximately 25 and 27 W, respectively, contributing to the 117 W overall electrical power required by the device during walking. A video of walking corresponding to the aforementioned data is included in the supplemental material.
  IEEE Transactions on Neural Systems and Rehabilitation Engineering 01/2012;