Comparison of filtering methods for real-time extraction of the volitional EMG component in electrically stimulated muscles

Objective Recorded electromyograms (EMG) of electrically stimulated muscles can contain both an exogenous-evoked potential (M-wave) and an endogenous, or volitional, component. This study evaluated the effectiveness of three filtering methods (i.e., high-pass, adaptive, and comb), commonly used in neurorehabilitation, in extracting the volitional component of simulated and experimental EMG during upper-limb tasks. Methods Volitional EMG and M-wave were simulated through a physiological model of muscle recruitment, comprising of a motor neuron pool and associated muscle fibres, superimposed to a stimulation artefact. Experimental EMG data during different levels of volitional muscle contraction in isometric and dynamic tasks were recorded from five unimpaired individuals. Electrical stimulation artefact was removed with different techniques (i.e., none, removing samples, blanking, and interpolation) to assess filter performance across time and frequency domains, and information content (i.e., Kolmogorov-Smirnov D-value). Results The experimental results agreed with the simulations, wherein the adaptive filter outperformed the other filters when using no artefact removal or removing artefact samples from the signal, while for the blanking and interpolation artefact removal methods, the adaptive and comb filters outperformed the high-pass filter. Conclusion The adaptive and comb filters best estimated volitional muscle activity in electrically stimulated muscles. Significance Results from this study will enable the enhanced design of real-time neuroprosthesis control.This study was supported by the Motor Accident Insurance Commission, Queensland, Australia (BioSpine project) and by a Griffith University Postgraduate Research Scholarship. The authors would like to thank Prof David Lloyd for the stimulating discussions that allowed us to refine our study design and analyses.Peer ReviewedPostprint (published version

Open Inquiry based learning experiences to understand the Nature of Science

In this paper we address the question of the efficacy of an inquiry-based learning approach, with different levels of teacher’s guidance, to introduce the students to fundamental aspects of the Nature of Science (NoS). Explicit pedagogical approaches, in which specific instruction on the topic of NoS is provided in addition to the engagement in scientific inquiry, are generally considered more effective with respect to implicit methods, where NoS conceptions are expected to develop as a natural consequence of inquiry-based learning experiences alone. In our study, we further explore the connections between scientific inquiry and implicit development of NoS conceptions, by investigating the efficacy of different kinds of inquiry approaches. Our findings confirm limited gains in developing NoS views by following a guided inquiry approach and suggest a more efficient NoS instruction by applying integrated open-inquiry-based teaching strategie

An experience of elicited inquiry elucidating the electron transport in semiconductor crystals

In this study we report the results of an inquiry-driven learning path experienced by a sample of 10 electronic engineering students, engaged to investigate the electron transport in semiconductors. The undergraduates were first instructed by following a lecture-based class on condensed matter physics and then involved into an inquiry based path of simulative explorations. The students were invited by two instructors to explore the electron dynamics in a semiconductor bulk by means of Monte Carlo simulations. The students, working in group, had to design their own procedure of exploration, as expected in a traditional guided inquiry. But they experienced several difficulties on planning and carrying out a meaningful sequence of simulative experiments, many times coming to a standstill. At this stage, the two instructors actively participated to the students’ debate on the physics governing the observed phenomena, never providing exhaustive explanations to the students, but giving comments and hints, sometimes expressly incorrect, but effective to stimulate students’ reasoning and activating a proficient scientific inquiry. The relation between this teaching intervention and student cognitive and affective development has been investigated by methods of discourse and behaviour analysis, as well as by the analysis of a student motivation/satisfaction inventory. The elicited inquiry stimulated the students to follow a question-driven path of exploration, starting from the validation of the model of electron dynamics within the semiconductor, up to performing reasoned inquiries about the observed characteristic of charge transport. Our results show that the stimulated activation of the inquiry process constitutes an efficient teaching/learning approach both to effectively engage students into an active learning and, at the same time, to clarify important experimental and technological aspects of semiconductor science, representing a viable example of integration of a traditional lecture-based teaching approach with effective learning strategies

Open Inquiry Investigations on Heat Transfer Performed by Undergraduate Engineering Students

Many researches have shown the pedagogical effectiveness of structured inquiry as a high performance tool in science education of undergraduate engineering students. In this paper we report the preliminary results of an extended investigation on the efficacy of the application of an open inquiry approach to the consolidation of the physics concepts regarding the topic of thermal energy transfer. We selected a sample of undergraduate mechanical engineering students, who passed the examination of the basic physics courses with good marks. Firstly, we investigated about resistant misconceptions in thermal physics by administrating a pre-activity questionnaire. Even the best marked students showed several deficiencies for what concerns, in particular, the practical knowledge of the physics of energy exchange by thermal radiation. Our open inquiry activity involved the students in a highly challenging learning environment, starting from the problem of projecting a thermodynamically efficient space base on Mars. Students were asked to work in groups and to perform scientific investigations regarding the best materials to use in the construction and the best design strategies to practice in order to collect as much thermal energy as possible during the Martian day. Students were stimulated to design and carry out their own laboratory activity by collecting, processing and analysing data, in order to discover new concepts and obtain more meaningful conceptual understanding of the physics underlying the process of thermal energy exchange by conduction, convection and radiation. All groups of students were invited to share the results of their explorative works within each other during the final discussion. Lastly, a final post-activity evaluation test was administered. Our open inquiry learning path has proved to be a great opportunity of enhancing the practical and reasoning skills of our engineering students. Here we discuss in detail the advantages and limits of the open inquiry-based teaching approach

KINEMATICS OF THE AXIAL SKELETON DURING ONE-MAN RUGBY UNION SCRUMS

Understanding kinematics and movement variability (MV) of the axial skeleton (head, thorax, spine, and pelvis) during scrums in Rugby Union is important from a performance and injury prevention perspective. The aim of this study was to investigate repeatability (or MV) of axial skeleton kinematics during one-man simulated scrums. Nine front row players performed scrums against a scrum machine. Results showed high levels of repeatability. The outcomes of this study suggest that the difficulty in performing scrums well might not reside in the basic technique, but be more associated with external factors, such as the interaction between players in a full scrum. Therefore, the results suggest that expert movement may better be achieved by practicing scrums under more realistic conditions than against a scrum machine

Multi-level personalization of neuromusculoskeletal models to estimate physiologically plausible knee joint contact forces in children

Neuromusculoskeletal models are a powerful tool to investigate the internal biomechanics of an individual. However, commonly used neuromusculoskeletal models are generated via linear scaling of generic templates derived from elderly adult anatomies and poorly represent a child, let alone children with a neuromuscular disorder whose musculoskeletal structures and muscle activation patterns are profoundly altered. Model personalization can capture abnormalities and appropriately describe the underlying (altered) biomechanics of an individual. In this work, we explored the effect of six different levels of neuromusculoskeletal model personalization on estimates of muscle forces and knee joint contact forces to tease out the importance of model personalization for normal and abnormal musculoskeletal structures and muscle activation patterns. For six children, with and without cerebral palsy, generic scaled models were developed and progressively personalized by (1) tuning and calibrating musculotendon units' parameters, (2) implementing an electromyogram-assisted approach to synthesize muscle activations, and (3) replacing generic anatomies with image-based bony geometries, and physiologically and physically plausible muscle kinematics. Biomechanical simulations of gait were performed in the OpenSim and CEINMS software on ten overground walking trials per participant. A mixed-ANOVA test, with Bonferroni corrections, was conducted to compare all models' estimates. The model with the highest level of personalization produced the most physiologically plausible estimates. Model personalization is crucial to produce physiologically plausible estimates of internal biomechanical quantities. In particular, personalization of musculoskeletal anatomy and muscle activation patterns had the largest effect overall. Increased research efforts are needed to ease the creation of personalized neuromusculoskeletal models

A muscle synergy-based method to estimate muscle activation patterns of children with cerebral palsy using data collected from typically developing children

Preparing children with cerebral palsy prior to gait analysis may be a challenging and time-intensive task, especially when large number of sensors are involved. Collecting minimum number of electromyograms (EMG) and yet providing adequate information for clinical assessment might improve clinical workflow. The main goal of this study was to develop a method to estimate activation patterns of lower limb muscles from EMG measured from a small set of muscles in children with cerebral palsy. We developed and implemented a muscle synergy extrapolation method able to estimate the full set of lower limbs muscle activation patterns from only three experimentally measured EMG. Specifically, we extracted a set of hybrid muscle synergies from muscle activation patterns of children with cerebral palsy and their healthy counterparts. Next, those muscle synergies were used to estimate activation patterns of muscles, which were not initially measured in children with cerebral palsy. Two best combinations with three (medial gastrocnemius, semi membranous, and vastus lateralis) and four (lateral gastrocnemius, semi membranous, sartorius, and vastus medialis) experimental EMG were able to estimate the full set of 10 muscle activation patterns with mean (+/- standard deviation) variance accounted for of 79.93 (+/- 9.64)% and 79.15 (+/- 6.40)%, respectively, using only three muscle synergies. In conclusion, muscle activation patterns of unmeasured muscles in children with cerebral palsy can be estimated from EMG measured from three to four muscles using our muscle synergy extrapolation method. In the future, the proposed muscle synergy-based method could be employed in gait clinics to minimise the required preparation time

Long term stability of learning outcomes in undergraduates after an open-inquiry instruction on thermal science

This paper investigates the efficacy of an open-inquiry approach to achieve a long term stability of physics instruction. This study represents the natural continuation of a research project started four years ago when a sample of thirty engineering undergraduates, having already attended traditional university physics instruction, were involved in a six-week long learning experience of open-inquiry research activities within the highly motivating context of developing a thermodynamically efficient space base on Mars. Four years later, we explore the effectiveness of that learning experience by analyzing the outcomes that the students achieved by answering again the same questionnaire that was administered them both prior to and immediately after those activities. As we did in the first work, students’ answers were classified within three epistemological profiles. Now, a comparison among students’ outcomes during the three phases, namely, preinstruction, postinstruction, and after four years has been carried out. Immediately after the open-inquiry experience, the students obtained significant benefits in terms of the strengthening of their practical and reasoning abilities, by proficiently applying the learned concepts to face and solve real-world problem situations. In this study, the students’ answers do not highlight any significant regress towards their preinstruction profiles. The global robustness of the teaching strategy adopted four years ago is confirmed by a statistically significant comparison with a control group of students who experienced the same curricular instruction except for the open inquiry-based workshop. Nevertheless, some changes have been observed and discussed in the light of the answers the students provided to a short interview regarding their studying or working experiences across the four-year temporal window