Abstract The central nervous system (CNS) controls skeletal muscles by the recruitment of motor units (MUs). Understanding MU function is critical in diagnosis neuromuscular diseases, exercise physiology and sports, rehabilitation medicine. Recording analyzing MUs’ electrical depolarization basis for state-of-the-art methods. Ultrafast ultrasound a method that has potential to study MUs because depolarizations consequent mechanical twitches. In this study, we evaluate if single their...

The central nervous system coordinates movement through forces generated by motor units (MUs) in skeletal muscles. To analyze MUs function is essential sports, rehabilitation medicine applications, and neuromuscular diagnostics. their are studied using electromyography. Typically, these methods study only a small muscle volume (1 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> ) or superficial (<1 cm) of the muscle. Here we introduce...

Objective: Identifying the activity of motor neurons (MNs) non-invasively is possible by decomposing signals from muscles, e.g., surface electromyography (EMG) or ultrasound. The theoretical background MN identification convolutive blind source separation (cBSS), and different algorithms have been developed validated. Yet, existence identifiability inverse solutions corresponding estimation errors are not fully understood. Further, guidelines for selecting appropriate parameters often built...

In this study, the aim was to compare performance of four spatiotemporal decomposition algorithms (stICA, stJADE, stSOBI, and sPCA) parameters for identifying single motor units in human skeletal muscle under voluntary isometric contractions ultrafast ultrasound image sequences as an extension a previous study. The quantified using two measures: (1) similarity components' temporal characteristics against gold standard needle electromyography recordings (2) agreement detected sets components...

The smallest voluntarily controlled structure of the human body is motor unit (MU), comprised a motoneuron and its innervated fibres. MUs have been investigated in neurophysiology research clinical applications, primarily using electromyographic (EMG) techniques. Nonetheless, EMG (both surface intramuscular) has limited detection volume. A recent alternative approach to detect ultrafast ultrasound (UUS) imaging. possibility identifying MU activity from UUS shown by blind source separation...

During a voluntary contraction, motor units (MUs) fire train of action potentials, causing summation the twitch forces, resulting in fused or unfused tetanus. Twitches have been important studying whole-muscle contractile properties and differentiation between MU types. However, there are still knowledge gaps concerning force generation mechanisms. Current methods rely on spike-triggered averaging technique, which cannot track changes successive twitches' response to individual neural...

Skeletal muscles are functionally regulated by populations of so-called motor units (MUs). An MU comprises a bundle muscle fibers controlled neuron from the spinal cord. Current methods to diagnose neuromuscular diseases and monitor rehabilitation, study sports sciences rely on recording analyzing bio-electric activity MUs. However, these provide information limited part muscle. Ultrasound imaging provides large It has recently been shown that ultrafast ultrasound can be used record analyze...

Ultrasound (US) muscle image series can be used for peripheral human-machine interfacing based on global features, or even the decomposition of US images into contributions individual motor units (MUs). With respect to state-of-the-art surface electromyography (sEMG), provides higher spatial resolution and deeper penetration depth. However, accuracy current methods direct decomposition, at low forces, is relatively poor. These are linear mathematical models MUs images. Here, we test...

Recent findings have shown that imaging voluntarily activated motor units (MUs) by decomposing ultrasound-based displacement images provides estimates of unfused tetanic signals evoked spinal motoneurons' neural discharges (spikes). Two methods been suggested to estimate its spike trains: band-pass filter (BPM) and Haar wavelet transform (HWM). However, the methods' optimal parameters which method performs best are unknown. This study will answer these questions.HWM BPM were optimized using...

Individual motor units have been imaged using ultrafast ultrasound based on separating images into unit twitches (unfused tetanus) evoked by the motoneuronal spike train. Currently, train is estimated from unfused tetanic signal a Haar wavelet method (HWM). Although this technique has great potential to provide comprehensive access neural drive muscles for large population of simultaneously, limited identification rate active units. The estimation spikes partly explains limitation. Since HWM...

Abstract Ultrasound (US) muscle image series can be used for peripheral human-machine interfacing based on global features, or even the decomposition of US images into contributions individual motor units (MUs). With respect to state-of-the-art surface electromyography (sEMG), provides higher spatial resolution and deeper penetration depth. However, accuracy current methods direct decomposition, at low forces, is relatively poor. These are linear mathematical models MUs images. Here, we test...

Advances in sports medicine, rehabilitation applications and diagnostics of neuromuscular disorders are based on the analysis skeletal muscle contractions. Recently, medical imaging techniques have transformed study contractions, by allowing identification individual motor units' activity, within whole studied muscle. However, appropriate image-based simulation models, which would assist continued development these new methods missing. This is mainly due to a lack models that describe...

Abstract Objective. Ultrasound can detect individual motor unit (MU) activity during voluntary isometric contractions based on their subtle axial displacements. The detection pipeline, currently performed offline, is displacement velocity images and identifying the This identification preferably be made through a blind source separation (BSS) algorithm with feasibility of translating pipeline from offline to online . However, question remains how reduce computational time for BSS algorithm,...

Objective.Ultrafast ultrasound (UUS) imaging has been used to detect intramuscular mechanical dynamics associated with single motor units (MUs). Detecting MUs from sequences requires decomposing a velocity field into components, each consisting of an image and signal. These components can be putative MU activity or spurious movements (noise). The differentiation between noise accomplished by comparing the signals firings obtained needle electromyography (EMG). Here, we examined whether...

Abstract Objective Ultrasound (US) images during a muscle contraction can be decoded into individual motor unit (MU) activity, i.e., trains of neural discharges from the spinal cord. However, current decoding algorithms assume stationary mixing matrix, i.e. equal mechanical twitches at each discharge. This study aimed to investigate accuracy these approaches in non-ideal conditions when response vary over time and are partially fused tetanic contractions. Methods We performed an silico...

Non-invasive identification of motoneuron (MN) activity commonly uses electromyography (EMG). However, surface EMG (sEMG) detects only superficial sources, at less than approximately 10-mm depth. Intramuscular can detect deep but it is limited to sources within a few mm the detection site. Conversely, ultrasound (US) images have high spatial resolution across whole muscle cross-section. The MNs be extracted from US due movements that MN activation generates in innervated fibers. Current...

Abstract Muscle force generation and human movement are organised by the central nervous system executed peripheral muscle fibres through molecular electrical mechanisms. Over last half-century, attempts have been made to elucidate these mechanisms in vivo, primarily focusing on motor unit (MU) activity because of its role as smallest voluntarily contractible unit. Although it is firmly established that controls modulating MU activity, yet possible distinguish between activities slow-...

Mechanical perturbations applied to the arm can elicit reflexive actions. These rapid corrective responses include stretch reflex, which consists of different components: short-latency reflex (SLR) as well early and late long-latency (LLR). In this study, we explore how task factors dynamically influence these components in context a specific delayed-reach paradigm. Using multiple linear regression (MLR), analysed from seven muscles actuating right examine effects mechanical load,...

Abstract Objective Ultrafast ultrasound imaging has been used to measure intramuscular mechanical dynamics associated with single motor unit (MU) activations. Detecting MU activity from sequences requires decomposing a displacement velocity field into components consisting of spatial maps and temporal signals. These can be putative or spurious movements (noise). The differentiation between MUs noise accomplished by comparing the signals firings obtained needle EMG. Here, we examined whether...

Abstract This study aims to compare two methods for the identification of anatomical and mechanical motor unit (MU) properties through integration high-density surface electromyography (HDsEMG) ultrafast ultrasound (UUS). The approaches rely on a combined analysis firing pattern active MUs, identified from HDsEMG, tissue velocity sequences muscle cross-section, obtained UUS. first method is spike-triggered averaging (STA) sequence based occurrences MU firings. second spatio-temporal...

Abstract Objective Non-invasive identification of motoneuron (MN) activity is commonly done using (EMG). However, surface EMG (sEMG) signals detect only superficial sources, at less than approximately 10-mm depth. Intramuscular can deep but it limited to sources within a few mm the detection site. Conversely, ultrasound (US) images have high spatial resolution across whole muscle cross-section. The MNs be extracted from US due movements that MN activation generates in innervated fibers....

Abstract Background Human movement is generated by activating motor units (MUs), i.e., the smallest structures that can be voluntarily controlled. Recent findings have shown imaging of activated MUs using ultrafast ultrasound based on displacement velocity images and a decomposition algorithm. Given this, estimates trains twitches (unfused tetanic signals) evoked neural discharges (spikes) spinal neurons are provided. Based these signals, band-pass filter method (BPM) has been used to...

Abstract Objective Ultrasound can detect individual motor unit (MU) activity during voluntary isometric contractions based on their subtle axial displacements. The detection pipeline, currently performed offline, is displacement velocity images and identifying the This identification preferably be made through a blind source separation (BSS) algorithm with feasibility of translating pipeline from offline to online . However, question remains how reduce computational time for BSS algorithm,...