Human Arm Movements Research Articles

Modulation of cutaneous reflexes in arm muscles during walking: further evidence of similar control mechanisms for rhythmic human arm and leg movements.

Stimulation of cutaneous nerves innervating the hand evokes prominent reflexes in many arm muscles during arm cycling. We hypothesized that the mechanisms controlling reflex modulation during the rhythmic arm swing of walking would be similar to that documented during arm cycling. Thus, we expected cutaneous reflexes to be modulated by position in the walking cycle (phase dependence) and be different when walking compared to contraction while standing (task dependence). Subjects performed static postures similar to those occurring during walking and also walked on a treadmill while the superficial radial nerve was electrically stimulated pseudorandomly throughout the step cycle. EMG was recorded bilaterally from upper limb muscles and kinematic recordings were obtained from the elbow and shoulder joints. Step cycle information was obtained from force-sensing insoles. Analysis was conducted after averaging contingent upon the occurrence of stimulation in the step cycle. Phase-dependent modulation of cutaneous reflexes at early (approximately 50-80 ms) and middle (approximately 80-120 ms) latencies was observed. Coordinated bilateral reflexes were seen in posterior deltoid and triceps brachii muscles. Task dependency was seen in that reflex amplitude was only correlated with background EMG during static contraction (75% of comparisons for both early and middle latency reflexes). During walking, no significant relationship between reflex amplitude and background EMG level was found. The results show that cutaneous reflex modulation during rhythmic upper limb movement is similar to that seen during arm cycling and to that observed in leg muscles during locomotion. These results add to the evidence that, during cyclical movements of the arms and legs, similar neural mechanisms observed only during movement (e.g. central pattern generators) control reflex output.

1P1-3F-D1 3 次元計測装置 OPTOTRAK3020 を用いた運動中における人間の上肢関節トルク計測システムの構築 : 人間とロボットの協調作業における人間の運動の定量的評価法の提案

人間とロボットによる協調作業において, 人間の腕の運動を定量的に評価するために, 人間の腕を7自由度モデルとし, 3次元計測装置を用いて各関節に生じるトルクを算出する計測システムを構築する。

525 人間の上肢と眼球運動の基礎特性

525 人間の上肢と眼球運動の基礎特性

Neural control of rhythmic human arm movement: phase dependence and task modulation of hoffmann reflexes in forearm muscles.

Although we move our arms rhythmically during walking, running, and swimming, we know little about the neural control of such movements. Our working hypothesis is that neural mechanisms controlling rhythmic movements are similar in the human lumbar and cervical spinal cord. Thus reflex modulation during rhythmic arm movement should be similar to that seen during leg movement. Our main experimental hypotheses were that the amplitude of H-reflexes in the forearm muscles would be modulated during arm movement (i.e., phase-dependent) and would be inhibited during cycling compared with static contraction (i.e., task-dependent). Furthermore, to determine the locus of any modulation, we tested the effect that active and passive movement of the ipsilateral (relative to stimulated arm) and contralateral arm had on H-reflex amplitude. Subjects performed rhythmic arm cycling on a custom-made hydraulic ergometer in which the two arms could be constrained to move together (180 degrees out of phase) or could rotate independently. Position of the stimulated limb in the movement cycle is described with respect to the clock face. H-reflexes were evoked at 12, 3, 6, and 9 o'clock positions during static contraction as well as during rhythmic arm movements. Reflex amplitudes were compared between tasks at equal M wave amplitudes and similar levels of electromyographic (EMG) activity in the target muscle. Surface EMG recordings were obtained bilaterally from flexor carpi radialis as well as from other muscles controlling the wrist, elbow, and shoulder. Compared with reflexes evoked during static contractions, movement of the stimulated limb attenuated H-reflexes by 50.8% (P < 0.005), 65.3% (P < 0.001), and 52.6% (P < 0.001) for bilateral, active ipsilateral, and passive ipsilateral movements, respectively. In contrast, movement of the contralateral limb did not significantly alter H-reflex amplitude. H-reflexes were also modulated by limb position (P < 0.005). Thus task- and phase-dependent modulation were observed in the arm as previously demonstrated in the leg. The data support the hypothesis that neural mechanisms regulating reflex pathways in the moving limb are similar in the human upper and lower limbs. However, the inhibition of H-reflex amplitude induced by contralateral leg movement is absent in the arms. This may reflect the greater extent to which the arms can be used independently.

An optimal control model of a neuromuscular system in human arm movements and its control characteristics

The joint torque which sets human limbs into motion is generated by a separate group of muscles provided for each joint. As the activation of each muscle is determined by a neural input, a neuromuscular system controlling all muscles has to be considered in order to understand human movements. In this study, an optimal control model of a neuromuscular system is investigated, and its control characteristics are examined. First, the dynamic and mechanical properties of a muscle are examined, and a neuromuscular system is formulated mathematically. Second, a performance criterion for the optimal control model is defined in order to characterize the dynamic behavior of the neuromuscular system, and a mathematical procedure for producing optimal trajectories is represented. Third, optimal trajectories in human arm movements are produced under various conditions of movement, and these trajectories are compared with experimentally observed ones. It is then verified that the optimal trajectories demonstrate human arm movements well. Finally, the behavior of individual muscles in various movements is examined quantitatively by means of simulation results, and the control characteristics of the human neuromuscular system are investigated.

Bio-mimetic trajectory generation based on human arm movements with a nonholonomic constraint

In this paper, a bio-mimetic trajectory of robots for manipulating a nonholonomic car is generated with a time base generator (TBG). In order to reveal what kind of trajectories the robots should generate for the given task, experiments with human subjects were performed. It has been shown that a human generates the trajectory with a single- or double-peaked velocity profile according to the geometrical conditions of the car. Then, bio-mimetic trajectories were generated by modeling the observed primitive profiles with the TBG and also compared with the human trajectories.

Dynamic Textures for Image-based Rendering of Fine-Scale 3D Structure and Animation of Non-rigid Motion

The problem of capturing real world scenes and then accurately rendering them is particularly difficult for finescale 3D structure. Similarly, it is difficult to capture, model and animate non-rigid motion. We present a method where small image changes are captured as a time varying (dynamic) texture. In particular, a coarse geometry is obtained from a sample set of images using structure from motion. This geometry is then used to subdivide the scene and to extract approximately stabilized texture patches. The residual statistical variability in the texture patches is captured using a PCA basis of spatial filter s. The filter s coefficients are parameterized in camera pose and object motion. To render new poses and motions, new texture patches are synthesized by modulating the texture basis. The texture is then warped back onto the coarse geometry. We demonstrate how the texture modulation and projective homography-based warps can be achieved in real-time using hardware accelerated OpenGL. Experiments comparing dynamic texture modulation to standard texturing are presented for objects with complex geometry (a flower) and non-rigid motion (human arm motion capturing the non-rigidities in the joints, and creasing of the shirt).

Estimating the efficiency of recognizing gender and affect from biological motion

It is often claimed that point-light displays provide sufficient information to easily recognize properties of the actor and action being performed. We examined this claim by obtaining estimates of human efficiency in the categorization of movement. We began by recording a database of three-dimensional human arm movements from 13 males and 13 females that contained multiple repetitions of knocking, waving and lifting movements done both in an angry and a neutral style. Point-light displays of each individual for all of the six different combinations were presented to participants who were asked to judge the gender of the model in Experiment 1 and the affect in Experiment 2. To obtain estimates of efficiency, results of human performance were compared to the output of automatic pattern classifiers based on artificial neural networks designed and trained to perform the same classification task on the same movements. Efficiency was expressed as the squared ratio of human sensitivity ( d ′) to neural network sensitivity ( d ′). Average results for gender recognition showed a proportion correct of 0.51 and an efficiency of 0.27%. Results for affect recognition showed a proportion correct of 0.71 and an efficiency of 32.5%. These results are discussed in the context of how different cues inform the recognition of movement style.

A dynamic pattern analysis of coordination between breathing and rhythmic arm movements in humans

We investigated the behavioral dynamics of human breathing–wrist movement coordination in a 1:1 frequency locking task. A pronation–supination wrist movement and a short trial duration were chosen to limit both mechanical and metabolic constraints on the respiratory system. Subjects voluntarily controlled their breathing rhythm to follow the metronome. We found that pronation–expiration and pronation–inspiration patterns coexisted as the (sole) stable fixed-point attractors of the coordination system. The pronation–expiration pattern was more stable than the pronation–inspiration pattern. Depending on the oscillation frequency, this differential stability gave rise to both absolute and relative coordination. These results show that simple behavioral laws of coordination encapsulate neural coupling dynamics evidenced from experimental research in human beings and animals. They challenge the classical view that such a coupling is not present for all imposed movement frequencies. Rather, relative coordination emerges as a result of the modification of coupling strength with frequency. These results can be accommodated by the asymmetric version of the HKB model of coordination dynamics. Thus, our data suggest that the principles and models of coordination dynamics may be taken as a reference to study the coupling of the motor and physiological subsystems involved in breathing–movement coordination.

Slowing of human arm movements during weightlessness: the role of vision.

The human motor system responds to weightlessness by the slowing of movement. It has been suggested that deficits in visuo-motor co-ordination cause this effect. We studied the mechanisms of the slowing of movement in three long-term missions to the Russian space station Mir. In particular, the role of vision in the control of movement in microgravity has been studied in these experiments on seven cosmonauts, pre-, in-, and post-flight. The cosmonauts made arm movements to visual targets under the following conditions of visual control: no visual control, interrupted visual control, and undisturbed visual control. The results showed that the slowing of movement during weightlessness was manifested by decreases of peak velocity and peak acceleration, was not associated with a prolongation of the movement phase of deceleration, and was not affected by manipulation of the conditions of visual control. The slowing of movement tended to subside after the months of the flight and completely disappeared within days after the landing. Accuracy of the movements strictly depended on the constraints imposed on the vision and remained unaffected in-flight. The data presented demonstrate that the slowing of movement in microgravity is not directly related to deficits in sensori-motor co-ordination and is not associated with a reduction of the accuracy of movement. The strategy for motor control in microgravity seems to be directed towards the generation of smooth movements and the maintenance of their accuracy.

The Effect of Aging on the Synchronization of Human Arm Movements to External Events

The aim of this study was to analyze the synchronization of cyclical arm movements to an external event and to determine age-related differences when the coupling strength between perception and action is manipulated. A group of young and a group of older subjects had to track a moving light travelling horizontally while manipulating a lever in the same direction (in-phase) or in the opposite direction (anti-phase). The results showed a performance decrease for both age groups in the anti-phase condition as compared to the in-phase condition, yet this decrease was more pronounced for the older persons. Interestingly, this age effect disappeared with practice. Most likely the observed age-related performance decrement was due to the difficulties encountered by older people to correct on line movements when the visual information needed was not directly accessible. Nevertheless, this study also highlights the capacity of older people to regain the performance loss through training.

The emergence of movement units through learning with noisy efferent signals and delayed sensory feedback

Rapid human arm movements often have velocity profiles consisting of several bell-shaped acceleration–deceleration phases, sometimes overlapping in time and sometimes appearing separately. We show how such sub-movement sequences can emerge naturally as an optimal control policy is approximated by a reinforcement learning system in the face of uncertainty and feedback delay. The system learns to generate sequences of pulse-step commands, producing fast initial sub-movements followed by several slow corrective sub-movements that often begin before the initial sub-movement has completed. These results suggest how the nervous system might efficiently control a stochastic motor plant under uncertainty and feedback delay.

Human Arm Motion Recognition Using Silhouette Images Obtained by a Single Camera

Human Arm Motion Recognition Using Silhouette Images Obtained by a Single Camera

Evaluation of a bio-impedance method for measuring human arm movement.

This study proposes a new method for measuring upper limb movement using a bio-impedance technique. Bio-impedance and joint angle were simultaneously measured during the wrist and elbow movements of 12 normal subjects. The joint angles of the wrist and elbow were estimated by measuring the bio-impedances of the forearm and upper arm, respectively. Although the measured bio-impedances on upper limbs varied among individuals, changes in the bio-impedances and joint angles of the wrist and elbow during their extension and flexion were very highly correlated, having correlation coefficients of 0.96 +/- 0.04 and -0.98 +/- 0.02, respectively. The reproducibilities of wrist and elbow bio-impedance changes were 2.1 +/- 1.0% and 1.8 +/- 1.0%, respectively. Since the proposed method is not restricted by size or the duration of measurements, it is expected to be useful for the analysis of athletic movement.

Neural control of rhythmic, cyclical human arm movement: task dependency, nerve specificity and phase modulation of cutaneous reflexes

Neural control of rhythmic, cyclical human arm movement: task dependency, nerve specificity and phase modulation of cutaneous reflexes

Neural control of rhythmic, cyclical human arm movement: task dependency, nerve specificity and phase modulation of cutaneous reflexes.

1. The organization and pattern of cutaneous reflex modulation during rhythmic cyclical movements of the human upper limbs has received much less attention than that afforded the lower limb. Our working hypothesis is that control mechanisms underlying the modulation of cutaneous reflex amplitude during rhythmic arm movement are similar to those that control reflex modulation in the leg. Thus, we hypothesized that cutaneous reflexes would show task dependency and nerve specificity in the upper limb during rhythmic cyclical arm movement as has been demonstrated in the human lower limb. 2. EMG was recorded from 10 muscles crossing the human shoulder, elbow and wrist joints while bilateral whole arm rhythmic cyclical movements were performed on a custom-made, hydraulic apparatus. 3. Cutaneous reflexes were evoked with trains (5 x 1.0 ms pulses at 300 Hz) of electrical stimulation delivered at non-noxious intensities (approximately 2 x threshold for radiating parasthesia) to the superficial radial, median and ulnar nerves innervating the hand. 4. Cutaneous reflexes were typically modulated with the movement cycle (i.e. phase dependency was observed). There was evidence for nerve specificity of cutaneous reflexes during rhythmic movement of the upper limbs. Task-dependent modulation was also seen as cutaneous reflexes were of larger amplitude or inhibitory (reflex reversal) during arm cycling as compared to static contraction. 5. While there are some differences in the patterns of cutaneous reflex modulation seen between the arms and legs, it is concluded that cutaneous reflexes are modulated similarly in the upper and lower limbs implicating similar motor control mechanisms.

Learning human arm movements by imitation:: Evaluation of a biologically inspired connectionist architecture

This paper evaluates a model of human imitation of abstract, two-arm movements. The model consists of a hierarchy of artificial neural networks, which are abstractions of brain regions involved in visuo-motor control. The model is validated in a biomechanical simulation of a 37 degree of freedom (DOF) humanoid. Input to the model are data from human arm movements recorded using video and marker-based tracking systems. Results show a high qualitative and quantitative agreement with human data. The model’s reproduction is better or comparable to that of human subjects imitating the same movements.

Compensation of hand movement for patients by assistant force: relationship between human hand movement and robot arm motion.

As some functional diseases in the brain, such as cerebellum dysfunction and Parkinson's disease, cause the disability related to human movement control, a compensation method was developed for improving the performance of hand movement. The compensation can be carried out by adding assistant force, which is generated from artificial equipment attached to a human arm. From the experiment of visual target tracking, the tracking trajectories recorded from both healthy persons and patients with movement disability were analyzed. It was found that the tracking trajectories were represented sufficiently by a dynamic model of a robot arm in which the differences between healthy persons and patients were characterized by the model parameters. Based on the model, it was demonstrated that the hand movement of patients could be improved by introducing an appropriate compensation. The effectiveness of the proposed compensation method was verified from a simulation study of a robot arm. The design of artificial equipment for compensating the hand movement was also presented and discussed.

A computational trajectory formation model for the human sagittal plane movement at various motion durations

We have confirmed from human arm movement measurement on the sagittal plane that the highest position in the vertical direction where the hand passes through changes according to the motion duration. In this paper, we propose an estimation algorithm of the position where the hand passes through according to the variation in the motion duration. We add the algorithm into the hardware of the trajectory formation model, i.e., the forward inverse relaxation model, which is the trajectory formation model based on the minimum commanded torque change criterion. Finally, we show that the model can reproduce the same trajectories as the human trajectories at various motion durations on the sagittal plane.

An examination of a relation between hand height position and motion duration on the human sagittal plane movement based on the minimization principle

We confirmed from human arm movement measurement on the sagittal plane that the highest position in the vertical direction where the hand passes through changes according to the motion duration. The minimum commanded torque change criterion is one of the optimal criteria for a trajectory formation in a reaching movement. We examined whether the criterion can explain the highest position change on the sagittal plane movement for various motion durations. This shows the possibility that the position where the hand passes through, which changes according to the motion duration, can be estimated by using the differential coefficient of the criterion with respect to the hand height with the amount of change in the hand height of measurement trajectory.