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Hand movement is controlled by a large number of muscles acting on multiple joints in the hand and forearm. In a forearm amputee the control of a hand prosthesis is traditionally depending on electromyography from the remaining forearm muscles. Technical improvements have made it possible to safely and routinely implant electrodes inside the muscles and record high-quality signals from individual muscles. In this study, we present a database of intramuscular EMG signals recorded with fine-wire electrodes alongside recordings of hand forces in an isometric setup and with the addition of spike-sorted metadata. Six forearm muscles were recorded from twelve able-bodied subjects and nine forearm muscles from two subjects. The fully automated recording protocol, based on command cues, comprised a variety of hand movements, including some requiring slowly increasing/decreasing force. The recorded data can be used to develop and test algorithms for control of a prosthetic hand. Assessment of the signals was done in both quantitative and qualitative manners., Measurement(s)muscle electrophysiology trait • muscle contractionTechnology Type(s)micro electrode • strain gaugesFactor Type(s)age • muscleSample Characteristic - OrganismHomo sapiens Machine-accessible metadata file describing the reported data: 10.6084/m9.figshare.11310011

The spatial accuracy of transcranial magnetic stimulation (TMS) may be as small as a few millimeters. Despite such great potential, navigated TMS (nTMS) mapping is still underused for the assessment of motor plasticity, particularly in clinical settings. Here, we investigate the within‐limb somatotopy gradient as well as absolute and relative reliability of three hand muscle cortical representations (MCRs) using a comprehensive grid‐based sulcus‐informed nTMS motor mapping. We enrolled 22 young healthy male volunteers. Two nTMS mapping sessions were separated by 5–10 days. Motor evoked potentials were obtained from abductor pollicis brevis (APB), abductor digiti minimi, and extensor digitorum communis. In addition to individual MRI‐based analysis, we studied normalized MNI MCRs. For the reliability assessment, we calculated intraclass correlation and the smallest detectable change. Our results revealed a somatotopy gradient reflected by APB MCR having the most lateral location. Reliability analysis showed that the commonly used metrics of MCRs, such as areas, volumes, centers of gravity (COGs), and hotspots had a high relative and low absolute reliability for all three muscles. For within‐limb TMS somatotopy, the most common metrics such as the shifts between MCR COGs and hotspots had poor relative reliability. However, overlaps between different muscle MCRs were highly reliable. We, thus, provide novel evidence that inter‐muscle MCR interaction can be reliably traced using MCR overlaps while shifts between the COGs and hotspots of different MCRs are not suitable for this purpose. Our results have implications for the interpretation of nTMS motor mapping results in healthy subjects and patients with neurological conditions.

How does the neural control of fine movements develop from childhood to adulthood? Here, we investigated developmental differences in functional corticomuscular connectivity using coherence analyses in 111 individuals from four different age groups covering the age range 8–30 y. EEG and EMG were recorded while participants performed a uni-manual force-tracing task requiring fine control of force in a precision grip with both the dominant and non-dominant hand. Using beamforming methods, we located and reconstructed source activity from EEG data displaying peak coherence with the EMG activity of an intrinsic hand muscle during the task. Coherent cortical sources were found anterior and posterior to the central sulcus in the contralateral hemisphere. Undirected and directed corticomuscular coherence was quantified and compared between age groups. Our results revealed that coherence was greater in adults (20–30 yo) than in children (8–10 yo) and that this difference was driven by greater magnitudes of descending (cortex-to-muscle), rather than ascending (muscle-to-cortex), coherence. We speculate that the age-related differences reflect maturation of corticomuscular networks leading to increased functional connectivity with age. We interpret the greater magnitude of descending oscillatory coupling as reflecting a greater degree of feedforward control in adults compared to children. The findings provide a detailed characterization of differences in functional sensorimotor connectivity for individuals at different stages of typical ontogenetic development that may be related to the maturational refinement of dexterous motor control.

International audience; Understanding and predicting the behavior of the powered wheelchair users play an important role in developing the driver assistance systems for the intelligent wheelchair. This article presents a model of wheelchair users, from the point of view of control engineering, based on the interaction between the human hand-joystick and the lumped-parameter model of the human hand muscle system. The interaction between hand and joystick is represented by a robot arm with a four-bar closed-chain mechanism. This mechanism is operated by four musculotendon units based on Hill's muscle model. This configuration allows simulating whole motions of the joystick as well as the evolutions of muscle activities during maneuvering the powered wheelchair. The advantage of this model is the integration of the biomechanical parameters of the muscular system of the human hand, which is very useful for simulating the defects related to the degree of physical impairment of wheelchair users. To validate the proposed model, we compare the simulation outputs of the user model with the previously published experimental results in the framework of the Wheelchair Skills Test (v. 4.1). The simulation results show that the proposed model can reflect the difficulties at the biomechanical level of users in driving the wheelchair.

Currently, myoelectric prostheses lack dexterity and ease of control, in part because of inadequate schemes to extract relevant muscle features that can approximate muscle activation patterns that enable individuated dexterous finger motion. This project seeks to apply a novel algorithm pipeline that extracts muscle activation patterns from one limb, as well as from forearm muscles of the opposite limb, to predict muscle activation data of opposite limb intrinsic hand muscles, with the long-range goal of informing dexterous prosthetic control.

Transcranial magnetic stimulation (TMS) can be used to probe for the location of cortical somatomotor representations in humans. These somatomotor representations are dynamic and are perturbed following motor training, systematic intervention, and in disease. Evidence suggests that these representations are maintained by the inhibitory neurotransmitter gamma-Aminobutyric acid (GABA). In the current study, we quantified the location, outline, and variability of the first dorsal interosseous (FDI) hand muscle somatomotor representation using a novel rapid-acquisition TMS method in 14 healthy young volunteers. In addition, resting motor thresholds were measured using established protocols. TMS was also used to examine short-interval intracortical inhibition (SICI), which is thought to measure transiently activated cortical gamma-Aminobutyric acid (GABA) interneurons. Using stepwise regression, our results showed that the level of intracortical inhibition was a significant predictor of the FDI somatomotor representation suggesting that greater excitability of the hand area representation is possibly governed by greater activation of transient GABA interneurons.

Transcranial magnetic stimulation (TMS) of the precentral hand knob can evoke motor evoked potentials (MEP) in contralateral hand muscles. Biophysical modelling points to the dorsal premotor cortex (PMd) in the superficial crown-lip region as primary site of TMS-induced neuronal excitation. Here, we used a sulcus-aligned MRI-informed TMS mapping approach to determine the optimal site (hotspot) for evoking MEPs in the precentral hand knob. Individual precentral hotspot location varied along the rostro-caudal axis. Individuals with a more rostral location had longer MEP latencies. Spatiotemporal “hotspot rostrality” was associated with higher precentral myelin-related signals, stronger movement-related activation of PMd in the precentral crown, and higher temporal precision during paced finger tapping. Together, our multimodal mapping approach provides first-time evidence for behaviourally relevant, structural and functional phenotypic variation in the crown of human precentral motor hand knob. The results have important implications for physiological and interventional TMS studies targeting the precentral hand knob.

Research background. Autism is one of the most difficult wide spectrum developmental disorders. Recently, striking increase in the number of autistic children is observed. Physical activation is important for the development and physical fitness of children with autism disorder. Research object – children’s balance, muscle strength and endurance. The aim was to evaluate physical capacity and impact of physiotherapy on balance, muscle strength and endurance in 7–11-yearold children with autism disorder. Methods. The study group consisted of 10 children with autism disorder (8 boys and 2 girls), the control group consisted of 18 healthy children (15 boys and 3 girls). The average age of the study group was 8.90 ± 1.4 years; in the control group 8.94 ± 1.0 years. Balance of children was assessed by Berg Balance Scale, hand grip – by dynamometry, leg muscle strength – by long jump test and squat test, and endurance of abdominal muscle – by sit up test. The results showed that physical condition of children with autism disorder was significantly poorer compared to healthy children: the balance – 43.9 ± 7.82 v. s. 55.4 ± 0.9 points; right hand muscle strength of 5.9 ± 2.06 kg v. s. 12.2 ± 3.43 kg; left – 5.3 ± 1.87 kg v. s 12.1 ± 3.43; long jump 43.0 ± 25.25 cm v. s 132.6 ± 31.87 cm; endurance of abdominal muscles 7.3 ± 2.01 v. s 19.6 ± 4.06 times per 30 s; squats 9.1 ± 4.36 v. s 27.6 ± 7.07 times per 30 s. After applying physical therapy results of all performed tests in children with autism improved significantly: balance to 49.9 ± by 5.45 points, right hand muscle strength to 7.9 ± 2.49 kg, left – 7.5 ± 2.31 kg, long jump to 79.2 ± 39.87 cm, crunches to 11.8 ± 4.54 times, squats to 14.8 ± 4.83 times, but they did not reach the results of healthy children. Conclusion. Balance, muscle strength and endurance of children with autism disorder were significantly lower than those in healthy children. Physical therapy significantly improved physical capacity of autistic children, but the level of healthy children was not reached.Keywords: autism, children, physiotherapy.

To design comfortable and efficient hand tools, an objective measurement such as using surface electromyography (sEMG) is required, where the ergonomic design tries to find the most optimal and most fit design of hand-tool that doesn't cause stress on the hand muscles. The hand tool design optimization will be demonstrated in this study on designing shampoo bottles, where the design of bottle and its compatibility with the slippery watery area, in addition to the aesthetic considerations are important issues that must be taking by the manufacturers concerned with such industries. Six different designs of shampoo bottles, as outcomes of industrial design graduation project in the department of Industrial design at our university, were used in this study. The new designs, together with other traditionally bottle designs, were evaluated in simulated shampoo pouring task in the laboratory. Several important parameters extracted from the sEMG signal in both temporal domain and frequency domain provide useful information about the tested designs. Twenty healthy university students (10 males and 10 females; mean age of 21 ± 2 years) were included in this study. Each subject was asked to handle the bottle and simulate the shampoo pouring activity in gentle and delicate manner using the grasp pattern that is found most comfort for him/her. Muscular behavior during bottle holding and shampoo pouring tasks show that male and female have different preferences in dealing with different bottle design, where male have less hand stress with designs that achieve the best fit of their full hand, while female have less hand stress with designs that achieve the best fit of their fingertips, and therefore, the end-user gender must be considered in designs of such industries. Keywords: Surface electromyography, Ergonomic design, Hand-tools, Hand stress, Mean frequency, Euclidean distance, Root mean square, Gender considerations

The objective is to determine the age peculiarities of higher education students’ functional and motor preparedness.Materials and methods. The participants in the study were male students of the 1st year (n = 98), 2nd year (n = 69), 3rd year (n = 56), 4th year (n = 32), and 5th year (n = 46) of training.The following research methods were used to solve the tasks set within the study: analysis of scientific literature, pedagogical observation, pedagogical testing; the index method and biomedical methods. The pedagogical methods were used to study the peculiarities of the functional state of the organism and the motor abilities in higher education students of the 1st-5th years of trtaining; methods of mathematical statistics were used to processing the data.Results. The first and second-year students demonstrated statistically reliable dynamics in the indicators of their functional and motor preparedness. Thus, at the age of 19, the students show a decrease in the Ruffier index (9.7 – “good heart”), the static equilibrium (12 sec. – “satisfactory”), and the standing long jump (Р

Introduction. “Man-in-the-barrel syndrome” is a neurological phenotype with brachial diplegia, normal sensation, and preserved motor function of the lower limb. It has been described in various neuropathological conditions affecting the cerebral hemispheres, pons, upper spinal cord, and peripheral neurons. Severe hypotension leading to watershed infarctions leading to this phenotype has been reported. We describe the first case of “man-in-the-barrel syndrome” in a patient with a precipitous drop in blood pressure following oral antihypertensive medications. Case Presentation. A 75-year-old Sri Lankan male presented following a generalized tonic-clonic seizure to a tertiary care hospital. Upon recovery, he was noted to have severe brachia diplegia affecting shoulder movements with preserved hand muscle power and motor functions of the lower limb. The previous day, he was newly diagnosed with markedly elevated blood pressure without acute end organ involvement. Treatment with three antihypertensives had been initiated. Noncontrast CT of the brain revealed watershed infarctions affecting both cerebral hemispheres. Conclusion. It is generally unwise to lower blood pressure very rapidly, as ischemic damage can occur in vascular beds that are habituated to high levels of blood pressure in the brain. Ischemic damage caused by rapid lowering of blood pressure may rarely result in “man-in-the-barrel syndrome” leading to severe functional disability.

Objective: The aim of this study was to analyze finger strength and effects of muscle fatigue on the ability to shoot. Background: The finger and hand muscles of soldiers are subject to high loads. For example, the trigger pull of military pistols can amount up to 58 N (≈6 kg) and could cause muscle fatigue in the trigger finger. For soldiers, however, maintaining the ability to shoot is essential for self-defense and survival. Method: The marksmanship training of 30 German soldiers (15 female) ages 18 to 40 years was evaluated. Three consecutive exercises with a total of 60 rounds were fired from target ranges of 5 and 10 m, equally using a single-action and double-action trigger mode. Maximum voluntary isometric contraction of the index finger (MVCIF) was measured before and after each of the three firing exercises. Results: Shooting reduced MVCIF in female (88.2 ± 15.8 N to 67.3 ± 17.7 N, p < .001) and male soldiers (145.8 ± 21.7 N to 112.7 ± 26.6 N, p < .001). Of the 30 subjects, 23 were unable to shoot due to fatigue, including 15 of 15 female soldiers. The higher MVCIF was at rest, the less commonly (r = .73, p < .001) and the later (r = 0.82, p < .001) task failure occurred. Two intermissions of approximately 6 min did not suffice for a significant recovery. Conclusion: Excessive trigger pull weight causes muscle fatigue of the index finger and can ultimately lead to task failure during pistol marksmanship training. Short breaks are insufficient for the recovery of finger muscles. Application: This study presents a new perspective on ideal trigger pull weight, which should be carefully considered by manufacturers to allow repetitive firing and simultaneously ensure safe handling., publishedVersion

Regaining the function of an impaired limb is highly desirable in paralyzed individuals. One possible avenue to achieve this goal is to bridge the interrupted pathway between preserved neural structures and muscles using a brain–computer interface. Here, we demonstrate that monkeys with subcortical stroke were able to learn to use an artificial cortico-muscular connection (ACMC), which transforms cortical activity into electrical stimulation to the hand muscles, to regain volitional control of a paralysed hand. The ACMC induced an adaptive change of cortical activities throughout an extensive cortical area. In a targeted manner, modulating high-gamma activity became localized around an arbitrarily-selected cortical site controlling stimulation to the muscles. This adaptive change could be reset and localized rapidly to a new cortical site. Thus, the ACMC imparts new function for muscle control to connected cortical sites and triggers cortical adaptation to regain impaired motor function after stroke., Monkeys were trained to use an artificial cortico-muscular connection (ACMC) to regain control over a paralyzed hand following subcortical stroke. Control over the paralyzed hand was accompanied by the appearance of localized high-gamma modulation in the cortex, which could be rapidly reset and relocalized to a different cortical site to reactivate motor control.

Neurons in the primate motor cortex, including identified pyramidal tract neurons projecting to the spinal cord, respond to the observation of others’ actions, yet this does not cause movement in the observer. Here, we investigated changes in spinal excitability during action observation by monitoring short latency electromyographic responses produced by single shocks delivered directly to the pyramidal tract. Responses in hand and digit muscles were recorded from two adult rhesus macaques while they performed, observed or withheld reach-to-grasp and hold actions. We found modest grasp-specific facilitation of hand muscle responses during hand shaping for grasp, which persisted when the grasp was predictable but obscured from the monkey’s vision. We also found evidence of a more general inhibition before observed movement onset, and the size of this inhibition effect was comparable to the inhibition after an explicit NoGo signal. These results confirm that the spinal circuitry controlling hand muscles is modulated during action observation, and this may be driven by internal representations of actions. The relatively modest changes in spinal excitability during observation suggest net corticospinal outflow exerts only minor, sub-threshold changes on hand motoneuron pools, thereby preventing any overflow of mirror activity into overt movement.

Substantiation of the study. There is a lack of literature about the efficiency of Kinesio Taping methods which improve recovery of arm functions for patients after stroke in the early stage of rehabilitation. The aim of the study was to determine the effect of Kinesio Taping on the recovery of the affected arm function in stroke patients during the early stage of rehabilitation. Subjects and methods. Forty stroke patients were divided into two groups. Inclusion criteria for the subjects were: age under 75 years, affected arm muscle strength – at least 2 points, and cognitive function – at least 11 points according Mini mental state exam (moderate cognitive impairment). The patients of the frst group had only exercise therapy, while to the patients of the second group exercised together with the applied Kinesio Taping method. Patients’ affected hand strength was measured using a dynamometer, arm function was assessed by Wolf Motor test, a modifed Motor Assessment Scale and modifed Fugl-Meyer motor function impairment test. Results. After physiotherapy procedures, the evaluation of arm function with Wolf and Fugl-Meyer tests showed signifcant improvement in the both groups: in the frst group of patients, Wolf test results indicated the change and the estimated values were 49.4 ± 1.3 points, in the second group – 23.1 ± 2.0 points, Fugl-Meyer test – 31.3 ± 0.3 and 21.9 ± 0 6 points (p < 0.05). In the frst group of patients, hand muscle strength improved signifcantly by 26.2 ± 2.2 kg, in the second group – 12.2 ± 1.8 kg (p < 0.05). In the frst group of patients, shoulder motion recovery by JVS improved by 3.0 ± 0.1 points, in the second group – 2.1 ± 0.1 points, hand movements recovery – by 2.6 ± 0.1 and 1.7 ± 0.1 points, complex hand movements – by 2.8 ± 0.1 and 1.4 ± 0.1 points (p < 0.05). Conclusions. The effect of exercises with Kinesio Taping on the affected arm function in stroke patients was signifcantly more pronounced (p < 0.05) than the effect of exercises only.Keywords: stroke, arm function, Kinesio Taping, physiotherapy

Motor-evoked potentials (MEPs), elicited by Transcranial Magnetic Stimulation (TMS) over the motor cortex, are reduced during the preparatory period in delayed response tasks. Here we examine how MEP suppression varies as a function of the anatomical organization of the motor cortex. MEPs were recorded from a left index muscle while participants prepared a hand or leg movement in Experiment 1, or prepared an eye or mouth movement in Experiment 2. In this manner, we assessed if the level of MEP suppression in a hand muscle varied as a function of the anatomical distance between the agonist for the forthcoming movement and the muscle targeted by TMS. MEPs suppression was attenuated when the cued effector was anatomically distant from the hand (e.g., leg or facial movement compared to finger movement). A similar effect was observed in Experiment 3 in which MEPs were recorded from a muscle in the leg and the forthcoming movement involved the upper limb or face. These results demonstrate an important constraint on preparatory inhibition: It is sufficiently broad to be manifest in a muscle that is not involved in the task, but is not global, showing a marked attenuation when the agonist muscle belongs to a different segment of the body.New & NoteworthyUsing TMS, we examine changes in corticospinal excitability as people prepare to move. Consistent with previous work, we observe a reduction in excitability during the preparatory period, an effect observed in both task relevant and task irrelevant muscles. However, this preparatory inhibition is anatomically constrained, attenuated in muscles belonging to a different body segment than the agonist of the forthcoming movement.

Contraction of a muscle modulates not only the corticospinal excitability (CSE) of the contracting muscle but also that of different muscles. We investigated to what extent the CSE of a hand muscle is modulated during preparation and execution of teeth clenching and ipsilateral foot dorsiflexion either separately or in combination. Hand-muscle CSE was estimated based on motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS) and recorded from the first dorsal interosseous (FDI) muscle. We found higher excitability during both preparation and execution of all the motor tasks than during mere observation of a fixation cross. As expected, the excitability was greater during the execution phase than the preparation one. Furthermore, both execution and preparation of combined motor tasks led to higher excitability than individual tasks. These results extend our current understanding of the neural interactions underlying simultaneous contraction of muscles in different body parts.

Background. Secondary-progressive multiple sclerosis (SPMS) patients have structural cortical damage resulting in increased compensatory cortical activity during (submaximal) performance. However, functional effects of changed cortical output are difficult to measure. The interpolated-twitch technique allows for measurement of voluntary activation (VA) necessary for force production. This study aimed to determine VA, force, and muscle fatigue during brief and sustained contractions in SPMS patients. Because fatigue effects are not confined to the motor system, we additionally examined fatiguing effects on cognitive performance. Methods. Twenty-five SPMS and 25 sex-, age-, and education-matched participants performed brief (5 seconds) and sustained (2 minutes) maximal index finger abductions. To evaluate VA, double-pulse twitches were evoked before, during, and after contractions. Additionally, data were compared with data obtained in relapsing–remitting multiple sclerosis (RRMS) patients. Subjects also performed choice-reaction time tasks before and after the sustained contraction. Results. During brief contractions, VA (85% vs 94%, P = .004) and force (25 N vs 32 N, P = .011) were lower for SPMS patients than controls. During sustained contractions, VA ( P = .001) was also lower, resulting in greater force decline (73% vs 63%, P < .001) and reduced peripheral fatigue (19% vs 50%, P < .001). Comparisons with RRMS resulted in lower VA, greater force decline, and greater estimated central fatigue in SPMS. SPMS patients were slower ( P < .001) and made more errors ( P < .001) than controls, but neither group reduced their performance after the sustained contraction. Conclusion. SPMS patients had lower VA than RRMS patients and controls. The importance of voluntary activation for muscle force and fatigability warrants targeted rehabilitation strategies.

Mimicry, the tendency to spontaneously and unconsciously copy others' behaviour, plays an important role in social interactions. It facilitates rapport between strangers, and is flexibly modulated by social signals, such as eye contact. However, little is known about the development of this phenomenon in infancy, and it is unknown whether mimicry is modulated by social signals from early in life. Here we addressed this question by presenting 4-month-old infants with videos of models performing facial actions (e.g., mouth opening, eyebrow raising) and hand actions (e.g., hand opening and closing, finger actions) accompanied by direct or averted gaze, while we measured their facial and hand muscle responses using electromyography to obtain an index of mimicry (Experiment 1). In Experiment 2 the infants observed the same stimuli while we used functional near-infrared spectroscopy to investigate the brain regions involved in modulating mimicry by eye contact. We found that 4-month-olds only showed evidence of mimicry when they observed facial actions accompanied by direct gaze. Experiment 2 suggests that this selective facial mimicry may have been associated with activation over posterior superior temporal sulcus. These findings provide the first demonstration of modulation of mimicry by social signals in young human infants, and suggest that mimicry plays an important role in social interactions from early in life. [Abstract copyright: Copyright © 2018 The Author(s). Published by Elsevier Ltd.. All rights reserved.]

A voluntary contraction of muscles with one arm increases the excitability of corticospinal projections to the contralateral resting arm, a phenomenon known as crossed facilitation. Although many motor tasks engage simultaneous activation of the arm and trunk, interactions between corticospinal projections targeting these segments remain largely unknown. Using transcranial magnetic stimulation over the trunk representation of the primary motor cortex, we examined motor-evoked potentials (MEPs) in the resting erector spinae (ES) muscle when the contralateral arm remained at rest or performed 20% of isometric maximal voluntary contraction (MVC) into index finger abduction, thumb abduction, elbow flexion, and elbow extension. We found that MEP size in the ES increased during all voluntary contractions, with greater facilitation occurring during elbow flexion and index finger abduction. To further examine the origin of changes in MEP size, we measured short-interval intracortical inhibition (SICI) and cervicomedullary MEPs (CMEPs) in the ES muscle during elbow flexion and index finger abduction and when the arm remained at rest. Notably, SICI decreased and CMEPs remained unchanged in the ES during both voluntary contractions compared with rest, suggesting a cortical origin for the effects. Our findings reveal crossed facilitatory interactions between trunk extensor and proximal and distal arm muscles, particularly for elbow flexor and index finger muscles, likely involving cortical mechanisms. These interactions might reflect the different role of these muscles during functionally relevant arm and trunk movements. NEW & NOTEWORTHY Many of the tasks of daily life involve simultaneous activation of the arm and trunk. We found that responses in the erector spinae muscles evoked by motor cortical stimulation increased in size during elbow flexion and extension and during index finger abduction and thumb abduction. Crossed facilitation with the trunk was more pronounced during elbow flexion and index finger abduction. These results might reflect the different role of these muscles during arm and trunk movements.

When humans voluntarily activate a muscle, intracortical inhibition decreases. Such a decrease also occurs in the presence of a postural challenge and more so with increasing age. Here, we examined age-related changes in motor cortical activity during postural and non-postural contractions with varying levels of postural challenge. Fourteen young (age 22) and twelve old adults (age 70) performed three conditions: (1) voluntary contraction of the soleus muscle in sitting and (2) leaning forward while standing with and (3) without being supported. Subthreshold transcranial magnetic stimulation was applied to the soleus motor area suppressing ongoing EMG, as an index of motor cortical activity. The area of EMG suppression was similar to 60% smaller (p 0.05). Even though in absolute terms young compared with old adults leaned farther (p = 0.018), there was no age effect or an age by condition interaction in EMG suppression. Leaning closer to the maximum without support correlated with less EMG suppression (rho = -0.44, p = 0.034). We conclude that the critical factor inmodulating motor cortical activity was postural challenge and not contraction aim or posture. Age did not affect the motor control strategy as quantified by the modulation of motor cortical activity, but the modulation appeared at a lower task difficulty with increasing age. (C) 2015 Elsevier Inc. All rights reserved.

BACKGROUND Exercise reduces blood glucose levels, improves cardio-respiratory fitness and increases muscle mass. Many studies have been conducted on different types of exercise training and their effects on glycemic control. Most of the studies include exercises involving large group of muscles like the leg muscles or whole body muscles. There is no data regarding only the hand muscle exercises and their effect on blood glucose levels. In this study, young healthy adult subjects are made to do a single bout of short duration hand exercise (Involving forearm and digital muscles) and its effect on blood glucose levels are checked. MATERIALS AND METHODS Normal healthy young adults of both sexes and age between 18–25 years were included in the study. Capillary blood glucose (CBG) level was measured using a glucometer. Digitalized hand grip dynamometer was used for the upper limb exercise. CBG levels were compared before and after exercise. Statistical analysis was done using Microsoft Excel and GraphPad Prism version 5. Mean values of CBG before and after exercise were compared by Students paired T test. RESULTS CBG was reduced following the exercise in most of the subjects and it was found to be statistically significant. CONCLUSION Exercise involving small muscles like the forearm and digital muscles were also able to reduce the blood glucose levels significantly. This study may be extended and done on patients with T2DM.

How changes in anatomy affect joint biomechanics can be studied using musculoskeletal modelling, making it a valuable tool to explore joint function in healthy and pathological joints. However, gathering the anatomical, geometrical and physiological data necessary to create a model can be challenging. Very few integrated datasets exist and even less raw data is openly available to create new models. Therefore, the goal of the present study is to create an integrated digital forearm and make the raw data available via an open-access database. An un-embalmed cadaveric arm was digitized using 7T MRI and CT scans. 3D geometrical models of bones, cartilage, muscle and muscle pathways were created. After MRI and CT scanning, physiological muscle parameters (e.g. muscle volume, mass, length, pennation angle, physiological cross-sectional area, tendon length) were obtained via detailed dissection. After dissection, muscle biopsies were fixated and confocal microscopy was used to visualize and measure sarcomere lengths. This study provides an integrated anatomical dataset on which complete and accurate musculoskeletal models of the hand can be based. By creating a 3D digital human forearm, including all relevant anatomical parameters, a more realistic musculoskeletal model can be created. Furthermore, open access to the anatomical dataset makes it possible for other researchers to use these data in the development of a musculoskeletal model of the hand. ispartof: Journal of Anatomy vol:233 issue:5 pages:557-566 ispartof: location:England status: published

Among the cognitive strategies that can facilitate motor performance in sport and physical practice, a prominent role is played by the direction of the focus of attention and the placebo effect. Consistent evidence converges in indicating that these two cognitive functions can influence the motor outcome, although no study up-to-now tried to study them together in the motor domain. In this explorative study, we combine for the first time these approaches, by applying a placebo procedure to increase force and by manipulating the focus of attention with explicit verbal instructions. Sixty healthy volunteers were asked to perform abduction movements with the index finger as strongly as possible against a piston and attention could be directed either toward the movements of the finger (internal focus, IF) or toward the movements of the piston (external focus, EF). Participants were randomized in 4 groups: two groups underwent a placebo procedure (Placebo-IF and Placebo-EF), in which an inert treatment was applied on the finger with verbal information on its positive effects on force; two groups underwent a control procedure (Control-IF and Control-EF), in which the same treatment was applied with overt information about its inefficacy. The placebo groups were conditioned about the effects of the treatment with a surreptitious amplification of a visual feedback signalling the level of force. During the whole procedure, we recorded actual force, subjective variables and electromyography from the hand muscles. The Placebo-IF group had higher force levels after the procedure than before, whereas the Placebo-EF group had a decrease of force. Electromyography showed that the Placebo-IF group increased the muscle units recruitment without changing the firing rate. These findings show for the first time that the placebo effect in motor performance can be influenced by the subject’s attentional focus, being enhanced with the internal focus of attention.

The human hand is well known for its unique dexterity which is largely facilitated by a highly mobile, long and powerful thumb that enables both tool manufacturing and use, a key component of human evolution. The bonobo (Pan paniscus), the closest extant relative to modern humans together with the chimpanzee (Pan troglodytes), also possesses good manipulative capabilities but with a lower level of dexterity compared with modern humans. Despite the close phylogenetic relationship between bonobos and humans, detailed quantitative data of the bonobo forelimb musculature remains largely lacking. To understand how morphology may influence dexterity, we investigated the functional anatomy of the bonobo hand using a unique sample of eight bonobo cadavers, along with one chimpanzee and one human (Homo sapiens) cadaver. We performed detailed dissections of unembalmed specimens to collect quantitative datasets of the extrinsic and intrinsic hand musculature, in addition to qualitative descriptions of the forelimb muscle configurations, allowing estimation of force-generating capacities for each functional group. Furthermore, we used medical imaging to quantify the articular surface of the trapeziometacarpal joint to estimate the intra-articular pressure. Our results show that the force-generating capacity for most functional groups of the extrinsic and intrinsic hand muscles in bonobos is largely similar to that of humans, with differences in relative importance of the extensors and rotators. The bonobo thumb musculature has a lower force-generating capacity than observed in the human specimen, but the estimated maximal intra-articular pressure is higher in bonobos. Most importantly, bonobos show a higher degree of functional coupling between the muscles of the thumb, index and lateral fingers than observed in humans. It is conceivable that differentiation and individualization of the hand muscles rather than relative muscle development explain the higher level of dexterity of humans compared with that of bonobos. ispartof: Journal of Anatomy vol:233 issue:3 pages:328-340 ispartof: location:England status: published

We investigate the relation between grip force and grip stiffness for the human hand with and without voluntary cocontraction. Apart from gaining biomechanical insight, this issue is particularly relevant for variable-stiffness robotic systems, which can independently control the two parameters, but for which no clear methods exist to design or efficiently exploit them. Subjects were asked in one task to produce different levels of force, and stiffness was measured. As expected, this task reveals a linear coupling between force and stiffness. In a second task, subjects were then asked to additionally decouple stiffness from force at these force levels by using cocontraction. We measured the electromyogram from relevant groups of muscles and analyzed the possibility to predict stiffness and force. Optical tracking was used for avoiding wrist movements. We found that subjects were able to decouple grip stiffness from force when using cocontraction on average by about 20% of the maximum measured stiffness over all force levels, while this ability increased with the applied force. This result contradicts the force–stiffness behavior of most variable-stiffness actuators. Moreover, we found the thumb to be on average twice as stiff as the index finger and discovered that intrinsic hand muscles predominate our prediction of stiffness, but not of force. EMG activity and grip force allowed to explain 72 ± 12% of the measured variance in stiffness by simple linear regression, while only 33 ± 18% variance in force. Conclusively the high signal-to-noise ratio and the high correlation to stiffness of these muscles allow for a robust and reliable regression of stiffness, which can be used to continuously teleoperate compliance of modern robotic hands.

Paired associative stimulation (PAS) protocols induce plastic changes within the motor cortex. The objectives of this study were to investigate PAS effects targeting the tibialis anterior (TA) muscle using a biphasic transcranial magnetic stimulation (TMS) pulse form and, to determine whether a reduced intensity of this pulse would lead to significant changes as has been reported for hand muscles using a monophasic TMS pulse. Three interventions were investigated: (1) suprathreshold PAbi-PAS (n = 11); (2) suprathreshold PAmono-PAS (n = 11) where PAS was applied using a biphasic or monophasic pulse form at 120% resting motor threshold (RMT); (3) subthreshold PAbi-PAS (n = 10) where PAS was applied as for (1) at 95% active motor threshold (AMT). The peak-to-peak motor evoked potentials (MEPs) were quantified prior to, immediately following, and 30 min after the cessation of the intervention. TA MEP size increased significantly for all interventions immediately post (61% for suprathreshold PAbi-PAS, 83% for suprathreshold PAmono-PAS, 55% for subthreshold PAbi-PAS) and 30 min after the cessation of the intervention (123% for suprathreshold PAbi-PAS, 105% for suprathreshold PAmono-PAS, 80% for subthreshold PAbi-PAS. PAS using a biphasic pulse form at subthreshold intensities induces similar effects to conventional PAS.