tutorial surface emg detection in space and time best practices

Abstract This tutorial is aimed to non-engineers using, or planning to use, surface electromyography (sEMG) as an assessment tool in the prevention, monitoring and rehabilitation fields. Its first purpose is to address the issues related to the origin and nature of the signal and to its detection (electrode size, distance, location) by one-dimensional (bipolar and linear arrays) and two-dimensional (grids) electrode systems while avoiding advanced mathematical, physical or physiological issues. Its second purpose is to outline best practices and provide general guidelines for proper signal detection. Issues related to the electrode-skin interface, signal conditioning and interpretation will be discussed in subsequent tutorials

Tortura, trattamenti inumani e degradanti e detenzioni arbitrarie: il caso della Corea del Nord.

Il presente elaborato intende affrontare la tematica della tortura, dei trattamenti inumani e degradanti e delle detenzioni arbitrarie nella Repubblica Popolare Democratica di Corea. Il tema viene introdotto tramite un’analisi degli avvenimenti storici che hanno contribuito alla formazione politica ed ideologica dell’attuale Corea del Nord, avvenimenti percepiti ancora oggi come estremamente importanti per il Paese. Nel secondo capitolo sono analizzati ordinamento interno e normativa nazionale in un confronto diretto con le previsioni maggiormente rilevanti del Patto Internazionale sui Diritti Civili e Politici (ICCPR), del Patto Internazionale sui Diritti Economici, Sociali e Culturali (ICESCR), della Convenzione sui diritti dell’Infanzia e dell’adolescenza (CRC) e della Convenzione contro ogni forma di discriminazione contro le donne (CEDAW), mentre è nel terzo capitolo che viene effettuata una disamina approfondita delle testimonianze e dei documenti prodotti dalla Commissione d’inchiesta (COI) del Consiglio dei Diritti Umani (HRC) sulla Tortura, sui trattamenti inumani e degradanti e sulle detenzioni arbitrarie, in combinazione con le risorse prodotte direttamente dalle organizzazioni governative, semi-governative e non governative le quali hanno avuto un ruolo di preminenza nella ricerca e nello sviluppo delle informazioni relative all’ordinamento nordcoreano. Il quarto e ultimo capitolo è infine dedicato alle conclusioni della Commissione d’Inchiesta, nell’ottica di una possibile responsabilità istituzionale ed individuale per crimini contro l’umanità in base allo Statuto di Roma nonché alla normativa consuetudinaria legata alle opinioni giurisprudenziali, comprensiva altresì dei suggerimenti diretti al Consiglio di Sicurezza, alla luce della sistematicità e della diffusione di un attacco diretto alla popolazione portato avanti dal governo tramite un’alta coordinazione dei poteri

Specificity of surface EMG recordings for gastrocnemius during upright standing.

The relatively large pick-up volume of surface electrodes has for long motivated the concern that muscles other than that of interest may contribute to surface electromyograms (EMGs). Recent findings suggest however the pick-up volume of surface electrodes may be smaller than previously appreciated, possibly leading to the detection of surface EMGs insensitive to muscle activity. Here we combined surface and intramuscular recordings to investigate how comparably action potentials from gastrocnemius and soleus are represented in surface EMGs detected with different inter-electrode distances. We computed the firing instants of motor units identified from intramuscular EMGs detected from gastrocnemius and soleus while five participants stood upright. We used these instants to trigger and average surface EMGs detected from multiple skin regions along gastrocnemius. Results from 66 motor units (whereof 31 from gastrocnemius) revealed the surface-recorded amplitude of soleus action potentials was 6% of that of gastrocnemius and did not decrease for inter-electrode distances smaller than 4 cm. Gastrocnemius action potentials were more likely detected for greater inter-electrode distances and their amplitude increased steeply up to 5 cm inter-electrode distance. These results suggest that reducing inter-electrode distance excessively may result in the detection of surface EMGs insensitive to gastrocnemius activity without substantial attenuation of soleus crosstalk

Using High Density EMG to Proportionally Control 3D Model of Human Hand

Control of human hand using surface electromyography (EMG) is already established in various mechanisms, but proportionally controlling magnitudes degrees of freedom (DOF) of humanoid hand model is still highly developed in recent years. This paper proposes another method to achieve a proportional estimation and control of human’s hand multiple DOFs. Gestures in the form of American Sign Language (ABCDFIKLOW) were chosen as the targets, of which ten alphabetical gestures were specifically used following their clarity on its 3D model. Then the dataset of the movements gestures was simultaneously recorded using High-density electromyography (HD-EMG) and motion capture system. Sensor placements were on intrinsic - extrinsic muscles for HD-EMG and finger joints for the motion capture system. To derive the proportional control in time series between both datasets (HD-EMG and kinematics data), neural network (NN) and k-Nearest Neighbour were used. The models produced around 70-95 % (R index) accuracy for the eleven DOFs in four healthy subjects’ hand. kNN’s performance was better than NN, even if the input features were reduced either using manual selections or principal component analysis (PCA). The time series controls could also identify most sign language gestures (9 of 10), with difficulty was given on O gesture. The false interpretation was because of nearly identical muscle’s EMG and kinematics data between O and C. This paper intends to extend its conference version [1] by adding more in-depth Results and Discussion along making other sections more comprehensive

Signing up to motor signatures: a unique link to action

No abstract availabl

Identifying Representative Synergy Matrices for Describing Muscular Activation Patterns During Multidirectional Reaching in the Horizontal Plane

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Recruitment of motor units in the medial gastrocnemius muscle during human quiet standing: is recruitment intermittent? What triggers recruitment?

The recruitment and the rate of discharge of motor units are determinants of muscle force. Within a motoneuron pool, recruitment and rate coding of individual motor units might be controlled independently, depending on the circumstances. In this study, we tested whether, during human quiet standing, the force of the medial gastrocnemius (MG) muscle is predominantly controlled by recruitment or rate coding. If MG control during standing was mainly due to recruitment, then we further asked what the trigger mechanism is. Is it determined internally, or is it related to body kinematics? While seven healthy subjects stood quietly, intramuscular electromyograms were recorded from the MG muscle with three pairs of wire electrodes. The number of active motor units and their mean discharge rate were compared for different sway velocities and positions. Motor unit discharges occurred more frequently when the body swayed faster and forward (Pearson R = 0.63; P < 0.0001). This higher likelihood of observing motor unit potentials was explained chiefly by the recruitment of additional units. During forward body shifts, the median number of units detected increased from 3 to 11 (P < 0.0001), whereas the discharge rate changed from 8 ± 1.1 (mean ± SD) to 10 ± 0.9 pulses/s (P = 0.001). Strikingly, motor units did not discharge continuously throughout standing. They were recruited within individual, forward sways and intermittently, with a modal rate of two recruitments per second. This modal rate is consistent with previous circumstantial evidence relating the control of standing to an intrinsic, higher level planning proces

Physiological recruitment of motor units by high-frequency electrical stimulation of afferent pathways

Neuromuscular electrical stimulation (NMES) is commonly used in rehabilitation, but\ua0electrically evoked muscle activation is in several ways different from\ua0voluntary muscle contractions. These differences lead to challenges in\ua0the use of NMES for restoring muscle function. We investigated the\ua0use of low-current, high-frequency nerve stimulation to activate the\ua0muscle via the spinal motoneuron (MN) pool to achieve more natural\ua0activation patterns. Using a novel stimulation protocol, the H-reflex\ua0responses to individual stimuli in a train of stimulation pulses at 100\ua0Hz were reliably estimated with surface EMG during low-level\ua0contractions. Furthermore, single motor unit recruitment by afferent\ua0stimulation was analyzed with intramuscular EMG. The results\ua0showed that substantially elevated H-reflex responses were obtained\ua0during 100-Hz stimulation with respect to a lower stimulation frequency. Furthermore, motor unit recruitment using 100-Hz stimulation was not fully synchronized, as it occurs in classic NMES, and the\ua0discharge rates differed among motor units because each unit was\ua0activated only after a specific number of stimuli. The most likely\ua0mechanism behind these observations is the temporal summation of\ua0subthreshold excitatory postsynaptic potentials from Ia fibers to the\ua0MNs. These findings and their interpretation were also verified by a\ua0realistic simulation model of afferent stimulation of a MN population.\ua0These results suggest that the proposed stimulation strategy may allowgeneration of considerable levels of muscle activation b

Development of functional organization within the sensorimotor network across the perinatal period

In the mature human brain, the neural processing related to different body parts is reflected in patterns of functional connectivity, which is strongest between functional homologs in opposite cortical hemispheres. To understand how this organization is first established, we investigated functional connectivity between limb regions in the sensorimotor cortex in 400 preterm and term infants aged across the equivalent period to the third trimester of gestation (32–45 weeks postmenstrual age). Masks were obtained from empirically derived functional responses in neonates from an independent data set. We demonstrate the early presence of a crude but spatially organized functional connectivity, that rapidly matures across the preterm period to achieve an adult-like configuration by the normal time of birth. Specifically, connectivity was strongest between homolog regions, followed by connectivity between adjacent regions (different limbs but same hemisphere) already in the preterm brain, and increased with age. These changes were specific to the sensorimotor network. Crucially, these trajectories were strongly dependent on age more than age of birth. This demonstrates that during the perinatal period the sensorimotor cortex undergoes preprogrammed changes determining the functional movement organization that are not altered by preterm birth in absence of brain injury