Patterns Of Interlimb Coordination Research Articles

Decentralized control mechanism for limb steering in quadruped robot walking

Quadrupedal mammals adaptively change their direction, and their behavior is remarkable when they initiate such turns. They flexibly alter their interlimb coordination patterns when transitioning from forward to turning motion. However, the turning performance of quadruped robots is low compared to that of animals. We attempted to understand the control mechanism underlying the animal's flexible turning behavior by developing a simple robot model. We hypothesize that animals achieve lateral acceleration during transitions by adjusting the position of their limbs sideways at ground contact. On this basis, we proposed a decentralized control model for limb steering in quadrupedal turning behavior. The results obtained from the robot simulation demonstrated that either a turn initiated by the medial forelimb or the lateral forelimb occurred depending on the timing of the turn command. The fact that the proposed control algorithm could reproduce the behavior observed in animals suggests that a mechanism similar to the algorithm may exist in animals. Biological verification is expected in the future.

Homing tasks performed using variations of crawling gait patterns reveal a role for attention in podokinetic path integration.

Self-motion can be perceived via podokinetic information, that is, based upon the movements of the legs during legged locomotion. This information can be integrated in order to perceive a path of travel through the environment (i.e., via podokinetic path integration). Two types of podokinetic information have been distinguished by analyzing the patterns of bias that result from manipulating the gait patterns used in direct-route homing tasks. Each type of podokinetic information has been associated specific groupings of gaits that support equivalent perceptual measurements of self-motion. Specifically, gaits are grouped if they can be varied across the outbound and inbound phases of a homing task (e.g., walking outbound and jogging inbound) and the accuracy of homing task performances does not differ from matched-gait control conditions. Recently, it was theorized that different types of podokinetic information are related to the differences in the kinematic form of limb motions in these groupings of gaits. Here we test an alternative hypothesis, namely that attention plays a role in selecting the type of podokinetic information. In three experiments, we manipulated the crawling gait patterns used in direct-route homing tasks. Consistent with our hypotheses, we observe that self-motion is equivalently measured via crawling movement patterns that (1) have distinct kinematic forms, but that similarly direct participants' attention onto controlling the swing phase trajectories of their arms, and (2) have distinct inter-limb coordination patterns (i.e., pace vs. trot), but do not require attention to be specifically focused upon swing phase arm trajectories.

An Analysis of Lower Limb Coordination Variability in Unilateral Tasks in Healthy Adults: A Possible Prognostic Tool.

Interlimb coordination variability analysis can shed light into the dynamics of higher order coordination and motor control. However, it is not clear how the interlimb coordination of people with no known injuries change in similar activities with increasing difficulty. This study aimed to ascertain if the interlimb coordination variability range and patterns of healthy participants change in different unilateral functional tasks with increasing complexity and whether leg dominance affects the interlimb coordination variability. In this cross-sectional study fourteen younger participants with no known injuries completed three repeated unilateral sit-to-stands (UniSTS), step-ups (SUs), and continuous-hops (Hops). Using four inertial sensors mounted on the lower legs and thighs, angular rotation of thighs and shanks were recorded. Using Hilbert transform, the phase angle of each segment and then the continuous relative phase (CRP) of the two segments were measured. The CRP is indicative of the interlimb coordination. Finally, the linear and the nonlinear shank-thigh coordination variability of each participant in each task was calculated. The results show that the linear shank-thigh coordination variability was significantly smaller in the SUs compared to both UniSTS and Hops in both legs. There were no significant differences found between the latter two tests in their linear coordination variability. However, Hops were found to have significantly larger nonlinear shank-thigh coordination variability compared to the SUs and the UniSTS. This can be due to larger vertical and horizontal forces required for the task and can reveal inadequate motor control during the movement. The combination of nonlinear and linear interlimb coordination variability can provide more insight into human movement as they measure different aspects of coordination variability. It was also seen that leg dominance does not affect the lower limb coordination variability in participants with no known injuries. The results should be tested in participants recovering from lower limb injuries.

Interlimb Coordination Performance in Seated Position in Persons With Multiple Sclerosis: Reduced Amplitude Over 6 min and Higher Coordination Variability in Persons With Walking Fatigability.

Background: Walking fatigability is prevalent in MS and can be measured by a percentage distance decline during a 6-min walking test. Walking is characterized by an accurate and consistent interlimb antiphase coordination pattern. A decline in coordination each minute during a 6-min walking test is observed in persons with MS (pwMS). Measuring coordination during a 6-min seated coordination task with minimized balance and strength requirements, is assumed to examine a more fundamental interlimb antiphase coordination pattern in pwMS. This research aimed to answer the following research question: How does interlimb antiphase coordination pattern change during a seated coordination task in pwMS with walking fatigability (WF), non-walking fatigability (NWF) and Healthy Controls (HC)?Methods: Thirty-five pwMS and 13 HC participated. Interlimb coordination was assessed by a seated 6-min coordination task (6MCT) with the instruction to perform antiphase lower leg movements as fast as possible. Outcomes were Phase Coordination Index (PCI) and movement parameters (amplitude, frequency).Results: Mixed models revealed a significant effect of time for the the variability of generating interlimb movements, with a difference in mean values between WF and HC. A significant group∗time interaction effect was found for movement amplitude, represented by a significant decrease in movement amplitude in the WF group from minute 1 to the end of the task.Conclusion: The higher variability in interlimb coordination and decrease in movement amplitude over time during the 6MCT in the WF group could be an indicator of decreased control of fundamental antiphase coordination pattern in pwMS with walking fatigability.Clinical Trial Registration: www.clinicaltrials.gov, identifier NCT04142853 (registration date: October 29, 2019) and NCT03938558 (registration date: May 6, 2019).

Sprinting kinematics and inter-limb coordination patterns at varying slope inclinations

ABSTRACT Uphill training is applied to induce specific overload on the musculoskeletal system to improve sprinting mechanics. This study aimed to identify unique kinematic features of uphill sprinting at different slopes and to suggest practical implications based on comparisons we early stance phase. At take-off, steeper slopes induced significantly more extended joint angles and higher ROMs during the late stance phase. Compared with moderate slopes, more anti-phase coordination patterns were detected at steeper slopes. Thus, uphill sprinting at steeper slopes shares essential kinematic features with the early acceleration phase of level sprinting. Moderate inclinations induce biomechanical adaptations similar to those in the late acceleration phase of level sprinting. Hence, the specific transfer of uphill sprinting to acceleration depends on the slope inclinations.

Lower limb coordination during gait in people with moderate Parkinson's disease

Background/Aims Parkinson's disease interferes with the control of movement, which can cause changes in coordination. The aim of this study was to compare intralimb and interlimb coordination during gait in people with Parkinson's disease and in typically healthy people. Methods Participants were split into two groups. A total of 10 participants with Parkinson's disease were in the study group and 10 typically healthy participants were in the control group. All participants underwent a clinical evaluation, a gait kinematic evaluation for spatiotemporal variables and joint angle range of motion and an intralimb and interlimb coordination analysis. Results The duration of the stride, stance and swing phases of the gait cycle were longer in individuals with Parkinson's disease, who also displayed shorter stride length, slower speed and reduced cadence and joint range of motion than participants in the control group. Intralimb and interlimb coordination did not differ significantly between the groups. Conclusions Participants with Parkinson's disease presented with alterations in spatiotemporal variables and joint range of motion but were able to adapt to the limitations imposed by the disease and accomplish a functional gait without undermining their intralimb and interlimb coordination pattern.

Interlimb Coordination During a Combined Gait and Prehension Task.

Reaching and grasping are often completed while walking, yet the interlimb coordination required for such a combined task is not fully understood. Previous studies have produced contradictory evidence regarding preference for support of the lower limb ipsilateral or contralateral to the upper limb when performing a reaching task. This coordinative aspect of the combined task provides insight into whether the two tasks are mutually modified or if the reach is superimposed upon normal arm swinging. Collectively, 18 right-handed young adults walked slower, took shorter steps, and spent more time in double support during the combined task compared with walking alone. The peak grasp aperture was larger in walking reach-to-grasp trials compared with standing trials. There was not a strong trend for lower limb support preferences at the reach initiation or object contact. The participants could begin walking with either foot and demonstrated variability of preferred gait initiation patterns. There was a range of interlimb coordination patterns, none of which could be generalized to all young adults. The variability with which healthy right-handed young adults execute a combined walking reach-to-grasp task suggests that the cyclical (walking) and discrete (prehension) motor tasks may have separate motor control mechanisms, as proposed in the two primitives theory.

Neural motor control differs between bimanual common-goal vs. bimanual dual-goal tasks.

Coordinating bimanual movements is essential for everyday activities. Two common types of bimanual tasks are common goal, where two arms share a united goal, and dual goal, which involves independent goals for each arm. Here, we examine how the neural control mechanisms differ between these two types of bimanual tasks. Ten non-disabled individuals performed isometric force tasks of the elbow at 10% of their maximal voluntary force in both bimanual common and dual goals as well as unimanual conditions. Using transcranial magnetic stimulation, we concurrently examined the intracortical inhibitory modulation (short-interval intracortical inhibition, SICI) as well as the interlimb coordination strategies utilized between common- vs. dual-goal tasks. Results showed a reduction of SICI in both hemispheres during dual-goal compared to common-goal tasks (dominant hemisphere: P = 0.04, non-dominant hemisphere: P = 0.03) and unimanual tasks (dominant hemisphere: P = 0.001, non-dominant hemisphere: P = 0.001). For the common-goal task, a reduction of SICI was only seen in the dominant hemisphere compared to unimanual tasks (P = 0.03). Behaviorally, two interlimb coordination patterns were identified. For the common-goal task, both arms were organized into a cooperative "give and take" movement pattern. Control of the non-dominant arm affected stabilization of bimanual force (R2 = 0.74, P = 0.001). In contrast, for the dual-goal task, both arms were coupled together in a positive fashion and neither arm affected stabilization of bimanual force (R2 = 0.31, P = 0.1). The finding that intracortical inhibition and interlimb coordination patterns were different based on the goal conceptualization of bimanual tasks has implications for future research.

Investigation on Inter-Limb Coordination and Motion Stability, Intensity and Complexity of Trunk and Limbs during Hands-Knees Crawling in Human Adults.

This study aimed to investigate the inter-limb coordination pattern and the stability, intensity, and complexity of the trunk and limbs motions in human crawling under different speeds. Thirty healthy human adults finished hands-knees crawling trials on a treadmill at six different speeds (from 1 km/h to 2.5 km/h). A home-made multi-channel acquisition system consisting of five 3-axis accelerometers (ACC) and four force sensors was used for the data collection. Ipsilateral phase lag was used to represent inter-limb coordination pattern during crawling and power, harmonic ratio, and sample entropy of acceleration signals were adopted to depict the motion intensity, stability, and complexity of trunk and limbs respectively. Our results revealed some relationships between inter-limb coordination patterns and the stability and complexity of trunk movement. Trot-like crawling pattern was found to be the most stable and regular one at low speed in the view of trunk movement, and no-limb-pairing pattern showed the lowest stability and the greatest complexity at high speed. These relationships could be used to explain why subjects tended to avoid no-limb-pairing pattern when speed was over 2 km/h no matter which coordination type they used at low speeds. This also provided the evidence that the central nervous system (CNS) chose a stable inter-limb coordination pattern to keep the body safe and avoid tumbling. Although considerable progress has been made in the study of four-limb locomotion, much less is known about the reasons for the variety of inter-limb coordination. The research results of the exploration on the inter-limb coordination pattern choice during crawling from the standpoint of the motion stability, intensity, and complexity of trunk and limbs sheds light on the underlying motor control strategy of the human CNS and has important significance in the fields of clinical diagnosis, rehabilitation engineering, and kinematics research.

Intrinsic limb morpho‐dynamics and the early development of interlimb coordination of walking in a quadrupedal primate

AbstractWe question the developmental changes of the temporal aspects of quadrupedal walking and how these relate to the intrinsic morphological (size, shape) and dynamical (inertia) properties of the limbs and body. Indeed, during ontogeny of altricial species, a dependent infant develops toward autonomy. Interlimb coordination is likely to be mediated by the neurological system (central pattern generators and/or supraspinal control), whereas the mechanical parameters of limbs and body appear to influence the locomotor optimization of gaits. We studied six captive baboons at two instants in their development, when they just begin foraging independently and when they are autonomous, in order to collect, in parallel, morphometrics and temporal parameters of voluntary quadrupedal walking. The natural pendular period (NPP) is put forward to represent the limb's intrinsic morpho‐dynamics; the position of the body center of mass as the morpho‐dynamics of the body. The main results reveal that fore‐ and hindlimbs, at the level of the convergence of the NPP, have a significant and positive impact on the interlimb coordination pattern. This probably facilitates, very early in development, the control of the coordination. Nevertheless, because an improved control of the interlimb coordination points at a proceeding neuromotor maturation as well, neuromotor control appears to become gradually important relatively to the intrinsic morpho‐dynamics of the limbs during infancy. These findings are of importance in the context of the evolution of the locomotor developmental processes in primates.

Observational learning of a new motor skill: The effect of different model demonstrations

A central question in observational learning is which information is picked-up by the observers from a demonstration. Visual perception perspective suggested that relative motion information, such as those highlighted in point-light or stick-figure demonstrations, is extracted and used for reproducing the modeled action. This study was designed to examine this assumption by using a baseball-pitch as to-be-learnt motor task. Forty-one novice female and male adults were randomly assigned to three demonstration groups (video, stick-figure, and point-light) and a control group. Participants performed 5 trials in pretest, three blocks of 10 trial in acquisition phase, and two retention tests of 5 trials in 10 min and 7 days after last acquisition block. Intra- and inter-limb coordination patterns and movement time were measured at level of overall movement and individual movement phases as dependent variables. Results show that participants improved their coordination performance from pretest to acquisition blocks and retention tests, however, regardless of model observation. No significant difference was observed between groups in two retention tests. Analysis of movement phases showed a significant improvement in stride phase from pretest to acquisition blocks. Results are interpreted in terms of theoretical and methodological backgrounds. Further perspectives in research on observational learning are presented.

Passive Dynamics Explain Quadrupedal Walking, Trotting, and Tölting.

This paper presents a simplistic passive dynamic model that is able to create realistic quadrupedal walking, tölting, and trotting motions. The model is inspired by the bipedal spring loaded inverted pendulum (SLIP) model and consists of a distributed mass on four massless legs. Each of the legs is either in ground contact, retracted for swing, or is ready for touch down with a predefined angle of attack. Different gaits, that is, periodic motions differing in interlimb coordination patterns, are generated by choosing different initial model states. Contact patterns and ground reaction forces (GRFs) evolve solely from these initial conditions. By identifying appropriate system parameters in an optimization framework, the model is able to closely match experimentally recorded vertical GRFs of walking and trotting of Warmblood horses, and of tölting of Icelandic horses. In a detailed study, we investigated the sensitivity of the obtained solutions with respect to all states and parameters and quantified the improvement in fitting GRF by including an additional head and neck segment. Our work suggests that quadrupedal gaits are merely different dynamic modes of the same structural system and that we can interpret different gaits as different nonlinear elastic oscillations that propel an animal forward.

Spinal mediation of motor learning and memory in the rat fetus.

Fetal rats can alter patterns of interlimb coordination after experience with a yoke that links two legs together. Yoke training results in a pronounced increase in conjugate limb movements (CLM). To determine whether yoke motor learning is mediated by spinal cord circuitry, fetal subjects at embryonic Day 20 (E20) received yoke training after mid-thoracic spinal cord transection or sham surgery. Both spinal and sham-treated fetuses exhibited an increase in CLM during training. In a second experiment, fetuses received initial yoke training, then were transected or sham treated before a 2nd training. Spinal and sham fetuses that were yoked during both training sessions exhibited a more rapid rise in CLM than those yoked only in the later session. These findings indicate that motor learning in fetal rats can be supported by spinal cord circuitry alone, and that savings implies a form of motor memory localized in the spinal cord.

Coordination pattern variability provides functional adaptations to constraints in swimming performance.

In a biophysical approach to the study of swimming performance (blending biomechanics and bioenergetics), inter-limb coordination is typically considered and analysed to improve propulsion and propelling efficiency. In this approach, 'opposition' or 'continuous' patterns of inter-limb coordination, where continuity between propulsive actions occurs, are promoted in the acquisition of expertise. Indeed a 'continuous' pattern theoretically minimizes intra-cyclic speed variations of the centre of mass. Consequently, it may also minimize the energy cost of locomotion. However, in skilled swimming performance there is a need to strike a delicate balance between inter-limb coordination pattern stability and variability, suggesting the absence of an 'ideal' pattern of coordination toward which all swimmers must converge or seek to imitate. Instead, an ecological dynamics framework advocates that there is an intertwined relationship between the specific intentions, perceptions and actions of individual swimmers, which constrains this relationship between coordination pattern stability and variability. This perspective explains how behaviours emerge from a set of interacting constraints, which each swimmer has to satisfy in order to achieve specific task performance goals and produce particular task outcomes. This overview updates understanding on inter-limb coordination in swimming to analyse the relationship between coordination variability and stability in relation to interacting constraints (related to task, environment and organism) that swimmers may encounter during training and performance.

Visual Multifrequency Entrainment: Can 1:2, 2:3, and 3:4 Coordination Occur Spontaneously?

ABSTRACT. Complex patterns of interlimb coordination, such as multifrequency relationships of 1:2, 2:3, or 3:4, are difficult to perform intentionally without extensive practice. The current study investigated whether these patterns might nonetheless occur spontaneously given an appropriate balance between the movement frequencies, or oscillatory periods, of an individual's movements and a visual-environmental stimulus. In order to test this, participants swung a fixed-period wrist-pendulum while observing an oscillating computer-generated stimulus. Results indicated that at given differences in period, 1:2, 2:3, and 3:4 coordination patterns emerged between the participant and stimulus. This suggests that large period differences do not altogether prevent the emergence of rhythmic visuomotor coordination, but instead provide the opportunity for complex patterns of coordination to emerge spontaneously.

Neurobiological Degeneracy and Affordance Perception Support Functional Intra-Individual Variability of Inter-Limb Coordination during Ice Climbing

This study investigated the functional intra-individual movement variability of ice climbers differing in skill level to understand how icefall properties were used by participants as affordances to adapt inter-limb coordination patterns during performance. Seven expert climbers and seven beginners were observed as they climbed a 30 m icefall. Movement and positioning of the left and right hand ice tools, crampons and the climber’s pelvis over the first 20 m of the climb were recorded and digitized using video footage from a camera (25 Hz) located perpendicular to the plane of the icefall. Inter-limb coordination, frequency and types of action and vertical axis pelvis displacement exhibited by each climber were analysed for the first five minutes of ascent. Participant perception of climbing affordances was assessed through: (i) calculating the ratio between exploratory movements and performed actions, and (ii), identifying, by self-confrontation interviews, the perceptual variables of environmental properties, which were significant to climbers for their actions. Data revealed that experts used a wider range of upper and lower limb coordination patterns, resulting in the emergence of different types of action and fewer exploratory movements, suggesting that effective holes in the icefall provided affordances to regulate performance. In contrast, beginners displayed lower levels of functional intra-individual variability of motor organization, due to repetitive swinging of ice tools and kicking of crampons to achieve and maintain a deep anchorage, suggesting lack of perceptual attunement and calibration to environmental properties to support climbing performance.

Emergence and stability of interlimb coordination patterns in children with developmental coordination disorder

The purpose of this study was to investigate the emergence and stability of coordination patterns in children with developmental coordination disorder (DCD) when performing a rhythmic interlimb coordination task on rigid (floor) and elastic (mini-trampoline) surfaces. Twelve typically developing (TD) children and 12 children with DCD were required to clap while jumping under different conditions: in a chosen pattern - Free; when the feet touched the surface - Clapping-surface; when the body reached the maximum jumping height - Clapping-jump; and when the feet touched the surface and the body reached the maximum jumping height - Clapping-both. The results showed that the coordination pattern of children with DCD was more variable in the Free, Clapping-surface, and Clapping-jumping conditions and more variable on the mini-trampoline than on the floor under the Free condition when compared with the TD children. Clapping-jumping was more difficult to perform than Clapping-surface for both groups. These findings suggest that the children with DCD were less capable of rhythmically coordinating the jumping-clapping task because they used a type of exploratory strategy regarding the physical properties of the surfaces, whereas the TD children used a type of adaptive strategy displaying behavior that was more consistent across the tasks/environmental demands.

Noise, variability, and motor performance in developmental coordination disorder

Variability and noise are a natural part of the neuromuscular system, and can occur at multiple levels. However, excessive neural noise in the motor system makes the problem of control much harder. Disruption of basic sensory inputs will exacerbate the problem, impacting one's sense of position in space (or body schema) and the ability of the motor system to predict its own dynamics. So-called predictive control is fundamental to movement efficiency and accuracy, but has been shown to be poorly developed in children with motor problems like developmental coordination disorder. These children manifest a core deficit in predictive control, which is expressed by high levels of variability across tasks, and at the level of movement kinematics, for example patterns of inter-limb coordination. As such, they rely heavily on feedback mechanisms to exert control, the outcome being slower and more laboured movements, and reduced responsiveness to changes in the environment. We discuss these issues of high variability and noise in developmental coordination disorder in relation to motor prediction, and with an eye to remediation. Issues of task scheduling and use of augmented feedback are important considerations for therapists when treating these children.

Interlimb coordination during forward walking is largely preserved in backward walking in children with cerebral palsy

ObjectiveLimb kinematics in backward walking (BW) are essentially those of forward walking (FW) in reverse. It has been argued that subcortical mechanisms could underlie both walking modes. MethodsTherefore, we tested whether participants with supraspinal/cortical deficits (i.e. cerebral palsy) show the kinematic reversal from FW to BW. 3D gait analysis was performed in 15 children with diplegia and 11 children with hemiplegia to record elevation angles of upper arm, lower arm, upper leg, lower leg, and foot, and were compared to those of 23 control subjects. Coordination patterns were compared between FW and BW, and elevation angle traces of BW were reversed in time (revBW) and correlated to FW traces. ResultsThe interlimb coordination pattern during BW was largely preserved for all groups. The kinematic reversal of the limbs was also present in children with cerebral palsy (represented by high correlation coefficients between FW and revBW kinematics). ConclusionsThe neural control mechanism of FW leading to BW, is preserved in persons with cortical deficits (as in cerebral palsy). SignificanceThe current results support previous evidence suggesting that interlimb locomotor coordination depends mostly on the coupling between spinal pattern generators, coordinated by brainstem mechanisms, rather than primarily on cortical structures.

Spatio-temporal gait characteristics during transitions from trot to canter in horses

Gaits can be defined based upon specific interlimb coordination patterns characteristic of a limited range of speeds, with one or more defining variables changing discontinuously at a transition. With changing speed, horses perform a repertoire of gaits (walk, trot, canter and gallop), with transitions between them. Knowledge of the series of kinematic events necessary to realize a gait is essential for understanding the proximate mechanisms as well as the control underlying gait transitions. We studied the kinematics of the actual transition from trot to canter in miniature horses. The kinematics were characterized at three different levels: the whole-body level, the spatio-temporal level of the foot falls and the level of basic limb kinematics. This concept represents a hierarchy: the horse's center of mass (COM) moves forward by means of the coordinated action of the limbs and changes in the latter are the result of alterations in the basic limb kinematics. Early and short placement of the fore limb was observed before the dissociation of the footfalls of one of the diagonal limb pairs when entering the canter. Dissociation coincided with increased amplitude and wavelength of the oscillations of the trunk in the sagittal plane. The increased amplitude cannot be explained solely by the passive effects of acceleration or by neck and head movements which are inconsistent with the timing of the transition. We propose that the transition is initiated by the fore limb followed by subsequent changes in the hind limbs in a series of kinematic events that take about 2.5 strides to complete.