http://www.jneuroengrehab.com The latest research articles published by Journal of NeuroEngineering and Rehabilitation 2010-03-15T00:00:00Z This is an RSS newsfeed from BioMed Central It is intended to be used with an RSS reader. For more information about RSS newsfeeds from BioMed Central, visit http://www.biomedcentral.com/info/about/rss/ Background: Although robot therapy is progressively becoming an accepted method of treatment for stroke survivors, few studies have investigated how to adapt the robot/subject interaction forces in an automatic way. The paper is a feasibility study of a novel self-adaptive robot controller to be applied with continuous tracking movements. Methods: The haptic robot Braccio di Ferro is used, in relation with a tracking task. The proposed control architecture is based on three main modules: 1) a force field generator that combines a non linear attractive field and a viscous field; 2) a performance evaluation module; 3) an adaptive controller. The first module operates in a continuous time fashion; the other two modules operate in an intermittent way and are triggered at the end of the current block of trials. The controller progressively decreases the gain of the force field, within a session, but operates in a non monotonic way between sessions: it remembers the minimum gain achieved in a session and propagates it to the next one, which starts with a block whose gain is greater than the previous one. The initial assistance gains are chosen according to a minimal assistance strategy. The scheme can also be applied with closed eyes in order to enhance the role of proprioception in learning and control. Results: The preliminary results with a small group of patients (10 chronic hemiplegic subjects) show that the scheme is robust and promotes a statistically significant improvement in performance indicators as well as a recalibration of the visual and proprioceptive channels. The results confirm that the minimally assistive, self-adaptive strategy is well tolerated by severely impaired subjects and is beneficial also for less severe patients. Conclusions: The experiments provide detailed information about the stability and robustness of the adaptive controller of robot assistance that could be quite relevant for the design of future large scale controlled clinical trials. Moreover, the study suggests that including continuous movement in the repertoire of training is acceptable also by rather severely impaired subjects and confirms the stabilizing effect of alternating vision/no vision trials already found in previous studies. http://www.jneuroengrehab.com/content/7/1/13 Elena Vergaro Maura Casadio Valentina Squeri Psiche Giannoni Pietro Morasso Vittorio Sanguineti Journal of NeuroEngineering and Rehabilitation 2010, 7:13 2010-03-15T00:00:00Z doi:10.1186/1743-0003-7-13 Journal of NeuroEngineering and Rehabilitation 1743-0003 7 13 2010-03-15T00:00:00Z PDF Background: When a cell is exposed to a time-varying magnetic field, this leads to an induced voltage on the cytoplasmic membrane, as well as on the membranes of the internal organelles, such as mitochondria. These potential changes in the organelles could have a significant impact on their functionality. However, a quantitative analysis on the magnetically-induced membrane potential on the internal organelles has not been performed. Methods: Using a two-shell model, we provided the first analytical solution for the transmembrane potential in the organelle membrane induced by a time-varying magnetic field. We then analyzed factors that impact on the polarization of the organelle, including the frequency of the magnetic field, the presence of the outer cytoplasmic membrane, and electrical and geometrical parameters of the cytoplasmic membrane and the organelle membrane. Results: The amount of polarization in the organelle was less than its counterpart in the cytoplasmic membrane. This was largely due to the presence of the cell membrane, which "shielded" the internal organelle from excessive polarization by the field. Organelle polarization was largely dependent on the frequency of the magnetic field, and its polarization was not significant under the low frequency band used for transcranial magnetic stimulation (TMS). Both the properties of the cytoplasmic and the organelle membranes affect the polarization of the internal organelle in a frequency-dependent manner. Conclusions: The work provided a theoretical framework and insights into factors affecting mitochondrial function under time-varying magnetic stimulation, and provided evidence that TMS does not affect normal mitochondrial functionality by altering its membrane potential. http://www.jneuroengrehab.com/content/7/1/12 Hui Ye Marija Cotic Eunji Kang Michael Fehlings Peter Carlen Journal of NeuroEngineering and Rehabilitation 2010, 7:12 2010-02-20T00:00:00Z doi:10.1186/1743-0003-7-12 Journal of NeuroEngineering and Rehabilitation 1743-0003 7 12 2010-02-20T00:00:00Z XML Background: As physical and cognitive rehabilitation protocols utilizing virtual environments transition from single applications to comprehensive rehabilitation programs there is a need for a new design cycle methodology. Current human-computer interaction designs focus on usability without benchmarking technology within a user-in-the-loop design cycle. The field of virtual rehabilitation is unique in that determining the efficacy of this genre of computer-aided therapies requires prior knowledge of technology issues that may confound patient outcome measures. Benchmarking the technology (e.g., displays or data gloves) using healthy controls may provide a means of characterizing the "normal" performance range of the virtual rehabilitation system. This standard not only allows therapists to select appropriate technology for use with their patient populations, it also allows them to account for technology limitations when assessing treatment efficacy. Methods: An overview of the proposed user-centered design cycle is given. Comparisons of two optical see-through head-worn displays provide an example of benchmarking techniques. Benchmarks were obtained using a novel vision test capable of measuring a user's stereoacuity while wearing different types of head-worn displays. Results from healthy participants who performed both virtual and real-world versions of the stereoacuity test are discussed with respect to virtual rehabilitation design. Results: The user-centered design cycle argues for benchmarking to precede virtual environment construction, especially for therapeutic applications. Results from real-world testing illustrate the general limitations in stereoacuity attained when viewing content using a head-worn display. Further, the stereoacuity vision benchmark test highlights differences in user performance when utilizing a similar style of head-worn display. These results support the need for including benchmarks as a means of better understanding user outcomes, especially for patient populations. Conclusions: The stereoacuity testing confirms that without benchmarking in the design cycle poor user performance could be misconstrued as resulting from the participant's injury state. Thus, a user-centered design cycle that includes benchmarking for the different sensory modalities is recommended for accurate interpretation of the efficacy of the virtual environment based rehabilitation programs. http://www.jneuroengrehab.com/content/7/1/11 Cali Fidopiastis Albert Rizzo Jannick Rolland Journal of NeuroEngineering and Rehabilitation 2010, 7:11 2010-02-19T00:00:00Z doi:10.1186/1743-0003-7-11 Journal of NeuroEngineering and Rehabilitation 1743-0003 7 11 2010-02-19T00:00:00Z XML Background: The combination of robotic tools with assistance technology determines a slightly explored area of applications and advantages for disability or elder people in their daily tasks. Autonomous motorized wheelchair navigation inside an environment, behaviour based control of orthopaedic arms or user's preference learning from a friendly interface are some examples of this new field. In this paper, a Simultaneous Localization and Mapping (SLAM) algorithm is implemented to allow the environmental learning by a mobile robot while its navigation is governed by electromyographic signals. The entire system is part autonomous and part user-decision dependent (semi-autonomous). The environmental learning executed by the SLAM algorithm and the low level behaviour-based reactions of the mobile robot are robotic autonomous tasks, whereas the mobile robot navigation inside an environment is commanded by a Muscle-Computer Interface (MCI). Methods: In this paper, a sequential Extended Kalman Filter (EKF) feature-based SLAM algorithm is implemented. The features correspond to lines and corners -concave and convex- of the environment. From the SLAM architecture, a global metric map of the environment is derived. The electromyographic signals that command the robot's movements can be adapted to the patient's disabilities. For mobile robot navigation purposes, five commands were obtained from the MCI: turn to the left, turn to the right, stop, start and exit. A kinematic controller to control the mobile robot was implemented. A low level behavior strategy was also implemented to avoid robot's collisions with the environment and moving agents. Results: The entire system was tested in a population of seven volunteers: three elder, two below-elbow amputees and two young normally limbed patients. The experiments were performed within a closed low dynamic environment. Subjects took an average time of 35 minutes to navigate the environment and to learn how to use the MCI. The SLAM results have shown a consistent reconstruction of the environment. The obtained map was stored inside the Muscle-Computer Interface. Conclusions: The integration of a highly demanding processing algorithm (SLAM) with a MCI and the communication between both in real time have shown to be consistent and successful. The metric map generated by the mobile robot would allow possible future autonomous navigation without direct control of the user, whose function could be relegated to choose robot destinations. Also, the mobile robot shares the same kinematic model of a motorized wheelchair. This advantage can be exploited for wheelchair autonomous navigation. http://www.jneuroengrehab.com/content/7/1/10 Fernando Auat Cheein Natalia Lopez Carlos Soria Fernando di Sciascio Fernando Lobo Pereira Ricardo Carelli Journal of NeuroEngineering and Rehabilitation 2010, 7:10 2010-02-17T00:00:00Z doi:10.1186/1743-0003-7-10 Journal of NeuroEngineering and Rehabilitation 1743-0003 7 10 2010-02-17T00:00:00Z PDF Background: The purpose of this study was to analyze kinematic trunk motion data in normal adults and to investigate gender effect. Methods: Kinematic trunk motion data were obtained for 20 healthy subjects (11 men and 9 women; age from 21 to 40 years) during walking a 9 m long lane at a self selected speed, namely, motions in the sagittal (tilt), coronal (obliquity), and transverse (rotation) planes, which were all expressed as motions in global (relative to the ground) and those in pelvic reference frame (relative to pelvis), i.e., tilt (G), obliquity (G), rotation (G), tilt (P), obliquity (P), rotation (P). Results: Range of tilt (G), obliquity (G) and rotation (G) showed smaller motion than that of tilt (P), obliquity (P) and rotation (P), respectively. When genders were compared, female trunks showed a 5 degree more extended posture during gait than male trunks (p=0.002), which appeared to be caused by different lumbar lordosis. Ranges of coronal and transverse plane motion appeared to be correlated. In gait cycle, the trunk motion appeared to counterbalance the lower extremity during swing phase in sagittal plane, and to reduce the angular velocity toward the contralateral side immediate before the contralateral heel strike in the coronal plane. Conclusions: Men and women showed different lumbar lordosis during normal gait, which might be partly responsible for the different prevalence of lumbar diseases between genders. However, this needs further investigation. http://www.jneuroengrehab.com/content/7/1/9 Chin Youb Chung Moon Seok Park Sang Hyeong Lee Se Jin Kong Kyoung Min Lee Journal of NeuroEngineering and Rehabilitation 2010, 7:9 2010-02-15T00:00:00Z doi:10.1186/1743-0003-7-9 Journal of NeuroEngineering and Rehabilitation 1743-0003 7 9 2010-02-15T00:00:00Z PDF Methods for the calculation and application of quantitative electromyographic (EMG) statistics for the characterization of EMG data detected from forearm muscles of individuals with and without pain associated with repetitive strain injury are presented.A classification procedure using a multi-stage application of Bayesian inference is presented that characterizes a set of motor unit potentials acquired using needle electromyography. The utility of this technique in characterizing EMG data obtained from both normal individuals and those presenting with symptoms of "non-specific arm pain" is explored and validated. The efficacy of the Bayesian technique is compared with simple voting methods.The aggregate Bayesian classifier presented is found to perform with accuracy equivalent to that of majority voting on the test data, with an overall accuracy greater than 0.85. Theoretical foundations of the technique are discussed, and are related to the observations found.Aggregation of motor unit potential conditional probability distributions estimated using quantitative electromyographic analysis, may be successfully used to perform electrodiagnostic characterization of "non-specific arm pain." It is expected that these techniques will also be able to be applied to other types of electrodiagnostic data. http://www.jneuroengrehab.com/content/7/1/8 Andrew Hamilton-Wright Linda McLean Daniel Stashuk Kristina Calder Journal of NeuroEngineering and Rehabilitation 2010, 7:8 2010-02-15T00:00:00Z doi:10.1186/1743-0003-7-8 Journal of NeuroEngineering and Rehabilitation 1743-0003 7 8 2010-02-15T00:00:00Z PDF Peripheral nerves possess the capacity of self-regeneration after traumatic injury but the extent of regeneration is often poor and may benefit from exogenous factors that enhance growth. The use of cellular systems is a rational approach for delivering neurotrophic factors at the nerve lesion site, and in the present study we investigated the effects of enwrapping the site of end-to-end rat sciatic nerve repair with an equine type III collagen membrane enriched or not with N1E-115 pre-differentiated neural cells. After neurotmesis, the sciatic nerve was repaired by end-to-end suture (End-to-End group), end-to-end suture enwrapped with an equine collagen type III membrane (End-to-EndMemb group); and end-to-end suture enwrapped with an equine collagen type III membrane previously covered with neural cells pre-differentiated in vitro from N1E-115 cells (End-to-EndMembCell group). Along the postoperative, motor and sensory functional recovery was evaluated using extensor postural thrust (EPT), withdrawal reflex latency (WRL) and ankle kinematics. After 20 weeks animals were sacrificed and the repaired sciatic nerves were processed for histological and stereological analysis. Results showed that enwrapment of the rapair site with a collagen membrane, with or without neural cell enrichment, did not lead to any significant improvement in most of functional and stereological predictors of nerve regeneration that we have assessed, with the exception of EPT which recovered significantly better after neural cell enriched membrane employment. It can thus be concluded that this particular type of nerve tissue engineering approach has very limited effects on nerve regeneration after sciatic end-to-end nerve reconstruction in the rat. http://www.jneuroengrehab.com/content/7/1/7 Sandra Amado Jorge Rodrigues Ana Luis Paulo Armada-da-Silva Marcia Vieira Andrea Gartner Maria Simoes Antonio Veloso Michele Fornaro Stefania Raimondo Artur Varejao Stefano Geuna Ana Mauricio Journal of NeuroEngineering and Rehabilitation 2010, 7:7 2010-02-11T00:00:00Z doi:10.1186/1743-0003-7-7 Journal of NeuroEngineering and Rehabilitation 1743-0003 7 7 2010-02-11T00:00:00Z XML Background: Previous research has shown that body weight support (BWS) has the potential to improve gait speed for individuals post-stroke. However, body weight support also reduces the optimal walking speed at which energy use is minimized over the gait cycle indicating that BWS should reduce walking speed capability. Methods: Nonimpaired subjects and subjects post-stroke walked at a self-selected speed over a 15 m walkway. Body weight support (BWS) was provided to subjects at 0%, 10%, 20%, 30%, and 40% of the subject's weight while they walked overground using a robotic body weight support system. Gait speed, cadence, and average step length were calculated for each subject using recorded data on their time to walk 10 m and the number of steps taken. Results: When subjected to greater levels of BWS, self-selected walking speed decreased for the nonimpaired subjects. However, subjects post-stroke showed an average increase of 17% in self-selected walking speed when subjected to some level of BWS compared to the 0% BWS condition. Most subjects showed this increase at the 10% BWS level. Gait speed increases corresponded to an increase in step length, but not cadence. Conclusions: The BWS training environment results in decreased self-selected walking speed in nonimpaired individuals, however self-selected overground walking speed is facilitated when provided with a small percentage of body weight support for people post-stroke. http://www.jneuroengrehab.com/content/7/1/6 Jamie Burgess Gwendolyn Weibel David Brown Journal of NeuroEngineering and Rehabilitation 2010, 7:6 2010-02-11T00:00:00Z doi:10.1186/1743-0003-7-6 Journal of NeuroEngineering and Rehabilitation 1743-0003 7 6 2010-02-11T00:00:00Z XML Background: Aspects of afferent inputs, generally termed proprioception, are being increasingly studied. Extraneous factors such as cutaneous inputs can dramatically interfere while trying to design studies in order to determine the participation of the different structures involved in proprioception in the wrist position sense. We tried to determine validity and repeatability of a new wrist joint position measurement device using methodology designed to minimize extraneous factors and isolate muscle and joint inputs. Methods: In order to test the reliability of the system, eighty young-adult subjects without musculoskeletal or neurologic impairments affecting the right upper extremity were tested using a custom made motion tracking system. Testing consisted of two conditions: active reproduction of active placement and passive reproduction of passive placement. Subjects performed two repetitions of each target position (10, 20, and 30° of flexion and extension) presented in a random order. Test- retest reliability was then tested. Results: The average constant error in the passive condition was -0.7° ± 4.7° as compared to the active condition at 3.7° ± 5.1°. Average absolute error in the passive condition was 4.9° ± 2.9° compared to the active condition in which absolute error was 5.9° ± 3.5°.DiscussionTest-retest repeatability in both conditions was less than the 5° magnitude typical of clinical goniometry. Errors in the active condition (less than 2°) were slightly smaller than the passive condition, and the passive condition was also associated with poorer consistency between apparatus sensors and skin sensors. Conclusions: The current system for measurement of wrist joint proprioception allows the researcher to decrease extraneous influences that may affect joint position sense awareness, and will help in future study aiming to determine precisely the role of the different structure involved in proprioception. http://www.jneuroengrehab.com/content/7/1/5 Andre Gay Kimberly Harbst Kenton Kaufman Diana Hansen Edward Laskowski Richard Berger Journal of NeuroEngineering and Rehabilitation 2010, 7:5 2010-02-10T00:00:00Z doi:10.1186/1743-0003-7-5 Journal of NeuroEngineering and Rehabilitation 1743-0003 7 5 2010-02-10T00:00:00Z XML Background: The aim of this study was to evaluate a method based on a single accelerometer for the assessment of gait symmetry and regularity in subjects wearing lower limb prostheses. Methods: Ten transfemoral amputees and ten healthy control subjects were studied. For the purpose of this study, subjects wore a triaxial accelerometer on their thorax, and foot insoles. Subjects were asked to walk straight ahead for 70 m at their natural speed, and at a lower and faster speed. Indices of step and stride regularity (Ad1 and Ad2, respectively) were obtained by the autocorrelation coefficients computed from the three acceleration components. Step and stride durations were calculated from the plantar pressure data and were used to compute two reference indices (SI1 and SI2) for step and stride regularity. Results: Regression analysis showed that both Ad1 well correlates with SI1 (R2 up to 0.74), and Ad2 well correlates with SI2 (R2 up to 0.52). A ROC analysis showed that Ad1 and Ad2 has generally a good sensitivity and specificity in classifying amputee's walking trial, as having a normal or a pathologic step or stride regularity as defined by means of the reference indices SI1 and SI2. In particular, the antero-posterior component of Ad1 and the vertical component of Ad2 had a sensitivity of 90.6% and 87.2%, and a specificity of 92.3% and 81.8%, respectively. Conclusions: The use of a simple accelerometer, whose components can be analyzed by the autocorrelation function method, is adequate for the assessment of gait symmetry and regularity in transfemoral amputees. http://www.jneuroengrehab.com/content/7/1/4 Andrea Tura Michele Raggi Laura Rocchi Andrea Cutti Lorenzo Chiari Journal of NeuroEngineering and Rehabilitation 2010, 7:4 2010-01-19T00:00:00Z doi:10.1186/1743-0003-7-4 Journal of NeuroEngineering and Rehabilitation 1743-0003 7 4 2010-01-19T00:00:00Z XML