On the power spectrum of motor unit action potential trains synchronized with mechanical vibration

Objective: Provide a definitive analysis of the spectrum of a motor unit action potential train elicited by mechanical vibratory stimulation via a detailed and concise mathematical formulation. Experimental studies demonstrated that motor unit action potentials are not exactly synchronized with the vibratory stimulus but show a variable latency jitter, whose effects have not been investigated yet. Methods: Synchronized action potential train was represented as a quasi-periodic sequence of a given motor unit waveform. The latency jitter of action potentials was modeled as a Gaussian stochastic process, in accordance to previous experimental studies. Results: A mathematical expression for power spectrum of a synchronized motor unit action potential train has been derived. The spectrum comprises a significant continuous component and discrete components at the vibratory frequency and its harmonics. Their relevance is correlated to the level of synchronization: the weaker the synchronization, the more relevant the continuous spectrum. EMG rectification enhances the discrete components. Conclusion: The derived equations have general validity and well describe the power spectrum of actual EMG recordings during vibratory stimulation. Results are obtained by appropriately setting the level of synchronization and vibration frequency. Significance: This study definitively clarifies the nature of changes in spectrum of raw EMG recordings from muscles undergoing vibratory stimulation. Results confirm the need of motion artifact filtering for raw EMG recordings during stimulation and strongly suggests to avoid EMG rectification that significantly alters the spectrum characteristics

A novel approach to estimate the upper limb reaching movement in three-dimensional space

Background: In spite of the complexity that the number of redundancy levels suggests, humans show amazingly regularities when generating movement. When moving the hand between pairs of targets, subjects tended to generate roughly straight hand trajectories with single-peaked, bell-shaped speed profiles. The original minimum-jerk model, in which limb displacement is represented by a fifth order polynomial, has been shown to predict qualitative features of experimental trajectories recorded in monkeys performing intermediate speed one-joint elbow movements to a target. However, it is difficult to compare a real (experimentally measured) movement to its equivalent minimum-jerk trajectory (MJT) because the exact start and end times and positions of real movements are usually not well defined: even discrete movements usually exhibit an extended period of low (but non-zero) velocity and acceleration before and after a movement, making estimation of the exact start and end times inaccurate. Aim: The purpose of this study was to describe a method used for correctly fitting the minimum jerk trajectory to real movement data assuming that the minimum-jerk trajectory satisfies the same threshold condition as the real movement (the same position and the same percentage of maximum velocity), rather than the movements start and end at full rest. Thus, the original minimum-jerk model was revised. Materials and methods: Starting from the original minimum-jerk model, in this work is proposed a method used for correctly fitting the minimum jerk trajectory to real movement data defined by a threshold condition. This method enables users to accurately compare a minimum-jerk trajectory to real movements. The latter were recorded using APDM inertial sensors. To estimate if the ideal model fits adequately the real reaching movements we consider three kinematic indexes. Results: and Discussion: A total of 100 upper arm straight line reaching movements executed by healthy subjects were acquired. MJTs follow closely to the reaching movements when they have been computed considering the revised model. On the contrary, the MJTs do not follow the real profiles when considering the original formulation. This behaviour is confirmed when we consider the three kinematic indexes. These findings help us better understand important characteristics of movements in health. Future works will focus on the investigation of the performance of the upper arm straight line reaching movements in a larger healthy subjects sample and then in pathological conditions. Keywords: Reaching movements, Minimum jerk model, Reaching movements, Rehabilitatio

Microvascular blood flow improvement in hyperglycemic obese adult patients by hypocaloric diet

The present study was aimed to assess the changes in skin microvascular blood flow (SBF) in newly diagnosed hyperglycemic obese subjects, administered with hypocaloric diet. Adult patients were recruited and divided in three groups: NW group (n=54), NG (n=54) and HG (n=54) groups were constituted by normal weight, normoglycemic and hyperglycemic obese subjects, respectively. SBF was measured by laser Doppler perfusion monitoring technique and oscillations in blood flow were analyzed by spectral methods under baseline conditions, at 3 and 6 months of dietary treatment. Under resting conditions, SBF was lower in HG group than in NG and NW ones. Moreover, all subjects showed blood flow oscillations with several frequency components. In particular, hyperglycemic obese patients revealed lower spectral density in myogenic-related component than normoglycemic obese and normal weight ones. Moreover, postocclusive reactive hyperemia (PORH) was impaired in hyperglycemic obese compared to normoglycemic and normal weigh subjects. After hypocaloric diet, in hyperglycemic obese patients there was an improvement in SBF accompanied by recovery in myogenic-related oscillations and arteriolar responses during PORH. In conclusion, hyperglycemia markedly affected peripheral microvascular function; hypocaloric diet ameliorated tissue blood flow

MODELLING AND PERFORMANCE ASSESSMENT OF HUMAN REACHING MOVEMENTS FOR DISEASE CLASSIFICATION

Human arm motor control has been object of great investigation for several decades, during which some issues have been identified as themes of high interest. There is a wide number of studies on human motor control supporting the theory that reaching and pointing movements are the result of sequences of discrete motion units, called sub-movements. Evidence for the existence of discrete sub-movements underlying continuous human movement has motivated many attempts to "extract" them. Moreover, to analyze the strategy of the reaching movements, gained a great appeal in the rehabilitation field. In fact, understanding movement deficits following central nervous system lesions and the relationships between these deficits and functional ability, is fundamental to the development of successful rehabilitation therapies. The goal of sub-movement extraction is to infer the sub-movement composition of a movement from kinematic data. In the tangential velocity domain, a sub-movement is represented as a uni-modal, bell-shaped function. Determining the number, relative timing, and amplitude of sub-movements that most closely reproduce the original tangential velocity data is a non-linear optimization problem difficult to solve. The experimental observations suggest that sub-movements are ubiquitous but proof of their existence and detailed quantification of their form have been elusive. Although several sub-movement extraction algorithms have been proposed previously, all of them are subject to finding local, rather than global, minima and to producing spurious decomposition results. The first section of this thesis, propose a review on the decomposition methods developed until now and the several methodologies used to extract them. Furthermore, an hybrid sub-movement decomposition method is proposed, based on a robust expectation maximization (EM) constrained algorithm and a scale-space approach capable to overcome the limitations of the EM algorithm, which is a local maximum seeker. This representation allowed to explore whether the movements are built up of elementary kinematic units by decomposing each surface into a weighted combination of Gaussian functions. Finally, is proposed a new kinematic and electromyographic assessment of robot assisted upper arm reaching in hemiparetic subjects applying successfully the sub-movement decomposition method implemented to carefully analyze their motor and muscle strategy

Comparison of low computational complexity filters suitable for real-time fluoroscopy image denoising

Fluoroscopy devices provide real-time, radiographic movies of patient and it is widely utilized as support for surgery and in diagnostic. Low X-ray dose results in intense quantum noise, which is modeled as Poisson-distributed stochastic signal. Recently, a specific filter technique was introduced to suppress quantum noise in fluoroscopy. Filter operation relies on the estimation of the relationship between noise variance and mean pixel intensity relative to the fluoroscopy device setup. By holding this information, noise suppression can be exclusively performed by averaging the only adjacent data in space and time that have high probability to belong to the noise statistics. The performances of this filter were compared to those of another filter based on the maximum a posteriori probability criterion designed for Poisson's noise suppression. The performances of the two filters, in terms of SNR and PSNR, resulted very similar, but they are a bit lower than more sophisticated filters such as BM3Dc. Nevertheless, they offer a simplicity of the algorithms that allows their realization in real-time to support interventional fluoroscopy applicatio

Bioengineering activities in proprioceptive and robotic rehabilitation at Salvatore Maugeri Foundation

Over the last decades, numerous and extensive research programs have been conducted in the field of robotic and proprioceptive rehabilitation. Robotic rehabilitation allows to record quantitative data about movement patterns that can help clinicians to better address the rehabilitation protocols providing information not captured using clinical measures, but the biome-chanical parameters proposed until today, to evaluate the quality of the movement are not yet standardized. Equally, the proprioception rehabilitation is known to play important roles in the planning and control of limb posture and movement. The Russian Academy of Sciences has recently developed the "Regent Suit" (RS), an experimental medical device derived from a suit worn by astronauts for therapeutical purposes after space flights. Although preliminary studies describe rehabilitation outcome of the RS in stroke, EMG changes induced by the suit are not known. The purpose of this paper is to review the rehabilitation activities employed at Salvatore Maugeri Foundation in the last two years, showing the main robotic and proprioceptive rehabilitation protocol developed to carefully analyse the motor strategies of the movement and of the gait in pathological conditions

Submovements composition and quality assessment of reaching movements in subjects with Parkinson's Disease

The segmentation of seemingly continuous movements into segments has been theorized for many years. These segments may be considered as 'primitive' movements, or building blocks of more complex movements. The existence of these fragments, or sub-movements as they are called, has been supported by a wide range of studies over the past 100 years. Evidence for the existence of discrete sub-movements underlying continuous human movement has motivated many attempts to 'extract' them. Recently, the sub-movement theory gained a great appeal in the rehabilitation field. In fact, understanding movement deficits following CNS lesions, and the relationships between these deficits and functional ability, is fundamental to the development of successful rehabilitation therapies. So, here a novel sub-movements decomposition method is proposed; it is based on a constrained-Expectation-Maximization. This representation allowed us to explore whether the movements are built up of elementary kinematic units by decomposing each signal into a weighted combination of 2D Gaussian functions. These can be used to assess the quality of reaching movements in subjects with Parkinson's Disease

Comparison between clinical and instrumental assessing using Wii Fit system on balance control

The use of low-cost, commercial gaming systems for rehabilitation has received substantial attention in the last few years. Systems such as the Nintendo Wii encourage players to use natural actions to play games. The Wii systems has been integrated into rehabilitation programs and has gained the support of occupational therapists because it is easy to use and has a wide variety of games available. In this study we compare the benefits on balance control of Wii Fit use with traditional rehabilitation therapy in 15 patients (study group) with Spinal Cord Injuries (SCI) and in 15 normal subjects (control group). The performance on balance control of each subject was evaluate by the Berg Balance Scale(BBS) in order to establish the baseline. Similar measurement was repeated at the discharge. Moreover, we assess the improvements induced by the use of Wii Fit platform with quantitative posturographic analysis by means of parameters and objective metric indexes such as COP Area and Sway Path. Comparison between two groups was performed by means of paired t test and Mann Whitney test. Both groups showed improvements in the BBS and in the posturographic indexes at the discharge. Very interesting is to note that the wii fit training appears to improve much more the balance of the study group compared to the study group. �� 2014 IEEE

Comparison of measured and predicted reaching movements with a robotic rehabilitation device

As has been frequently observed, single-joint movements are characterized by single-peaked, bell-shaped speed profiles. This findings and the tendency of natural movements to be characteristically smooth and graceful led to suggest that motor coordination can be mathematically modeled by postulating that voluntary movements are made, at least in the absence of any other overriding concerns, to be as smooth as possible. Particularly the goal of the central nervous system (CNS) is to maximize smoothness and one measure of this feature is the integrated mean squared magnitude of jerk. Although in the past have been explored kinematic characteristics of reaching movements recorded with actigrafi or goniometric systems and potentiometers, few studies have evaluated the kinematic characteristics of these movements obtained with the new rehabilitative technologies, such as robot mediated therapy. In this paper we tested the applicability of the minimum-jerk model proposed to one join goal directed horizontal reaching movements performed by healthy subjects with a robotic shoulder rehabilitation device. Results show a good qualitative agreement between the measured trajectories and the predicted ones by the model. ?????? 2014 IEEE

Computerised simulation of fetal heart rate signals

Scopus Search Sources Alerts Lists SciVal Register Document details Back to results Previous 10of192 Next Export Download Print E-mail Save to PDF Add to List More... SFX Get it!(opens in a new window)View at Publisher 2017 E-Health and Bioengineering Conference, EHB 2017 28 July 2017, Article number 7995392, Pages 185-188 6th IEEE International Conference on E-Health and Bioengineering, EHB 2017; Grigore T. Popa University of Medicine and PharmacySinaia; Romania; 22 June 2017 through 24 June 2017; Category numberCFP1703P-ART; Code 129704 Computerised simulation of fetal heart rate signals(Conference Paper) Romano, M.abEmail Author, Iuppariello, L.bcEmail Author, D'Addio, G.bEmail Author, Clemente, F.dEmail Author, Amato, F.aEmail Author, Cesarelli, M.bcEmail Author aDMSC, University Magna Graecia, Cǎtanzaro, Italy bFondazione S. Maugeri, Clinica Del Lavoro e della Riabilitazione, Telese Terme (BN), Italy cDIETI, University Federico II, Napoli, Italy View additional affiliations Abstract View references (24) Computerized systems employed for the analysis of cardiotocographic signals have become almost indispensable tools in fetal monitoring, for which evaluation of fetal heart rate signals plays a key role. Consequently to the diffusion of these systems, new software and complex signal processing methodologies are spreading and are gaining more and more interest. For testing the performances of new software and/or techniques, the availability of synthetic signals with a-priori known characteristics can be very helpful. In this paper we describe an updating of a procedure previously published for the computerized simulation of fetal heart rate signals, realized in order to obtain more realistic signals. Obtained results, analyzed by a team of experts, are satisfying, in that new simulated signals appear less regular and more complex, and hence more similar to real signals. Nevertheless, further research is necessary for obtaining very realistic signals. The future research will be initially focused on the study of floatingline and uterine contractions simulation