Interpersonal Synergies

We present the perspective that interpersonal movement coordination results from establishing interpersonal synergies. Interpersonal synergies are higher-order control systems formed by coupling movement system degrees of freedom of two (or more) actors. Characteristic features of synergies identified in studies of intrapersonal coordination – dimensional compression and reciprocal compensation – are revealed in studies of interpersonal coordination that applied the uncontrolled manifold approach and principal component analysis to interpersonal movement tasks. Broader implications of the interpersonal synergy approach for movement science include an expanded notion of mechanism and an emphasis on interaction-dominant dynamics

Postural Stability Variables for Dynamic Equilibrium

Source at http://www.jnsci.org/index.php.Experiments on the maintenance of postural stability on flat stationary support surfaces (quiet standing) that show only limited modes of the potential configurations of balance stability have dominated investigations of balance in quiet upright standing. Recent studies have revealed coordination properties of the whole body in maintaining dynamic postural stability with the application of moving platform paradigms. This paper examines properties of candidate collective variables for postural control within the dynamic systems framework. Evidence is discussed in this paper for: (i) self-organization properties of dynamic postural balance; (ii) enhanced variability and entropy prior to a phase transition between center of mass and center of pressure coupling; (iii) co-existence of intermittent postural control strategies that oscillate between periodic to chaotic transitions to maintain upright postural balance. These collective findings indicate postural attractor dynamic states progressively emerge to the changing task constraints of a moving platform revealing insights into the deterministic and stochastic properties of the multiple time scales of human postural behavior

Spinal circuits can accommodate interaction torques during multijoint limb movements

The dynamic interaction of limb segments during movements that involve multiple joints creates torques in one joint due to motion about another. Evidence shows that such interaction torques are taken into account during the planning or control of movement in humans. Two alternative hypotheses could explain the compensation of these dynamic torques. One involves the use of internal models to centrally compute predicted interaction torques and their explicit compensation through anticipatory adjustment of descending motor commands. The alternative, based on the equilibrium-point hypothesis, claims that descending signals can be simple and related to the desired movement kinematics only, while spinal feedback mechanisms are responsible for the appropriate creation and coordination of dynamic muscle forces. Partial supporting evidence exists in each case. However, until now no model has explicitly shown, in the case of the second hypothesis, whether peripheral feedback is really sufficient on its own for coordinating the motion of several joints while at the same time accommodating intersegmental interaction torques. Here we propose a minimal computational model to examine this question. Using a biomechanics simulation of a two-joint arm controlled by spinal neural circuitry, we show for the first time that it is indeed possible for the neuromusculoskeletal system to transform simple descending control signals into muscle activation patterns that accommodate interaction forces depending on their direction and magnitude. This is achieved without the aid of any central predictive signal. Even though the model makes various simplifications and abstractions compared to the complexities involved in the control of human arm movements, the finding lends plausibility to the hypothesis that some multijoint movements can in principle be controlled even in the absence of internal models of intersegmental dynamics or learned compensatory motor signals.This work is funded by the project "eSMCs: Extending Sensorimotor Contingencies to Cognition," FP7-ICT-2009-6 no: 270212

Effect of Visual Motor Coordination with Body Awareness Training on Balance, Coordination and Intensity of Tremor in patients with Cerebellar Ataxia

This study is to find out the effectiveness of visual motor coordination and body awareness training on balance, coordination and intensity of tremor in patients with cerebellar ataxia. Based on the selection criteria 15 subjects were selected. They were assigned into a single group, All 15 subjects were involved for pre-test assessment for balance, coordination and intensity of tremor using the Berg balance scale, Nine hole peg test and Fahn’s tremor rating scale. The 8 weeks treatment program was given for 5 days per week, 60 minutes per session. where each session consists of 5 mins of warm-up, followed by physiotherapy intervention including Proximal stability training, Balance training, Functional movement training using the principles of Visual Motor Coordination and Body Awareness Training, after the 8 weeks of the treatment program the post-test assessment for the Balance, Coordination and Intensity of Tremor was done using the outcome measures. The results were analyzed using student‘t’ test, that showed a significant improvement. Hence it can be concluded that the visual motor coordination with body awareness training is effective in patients with cerebellar ataxia

Studie zur neuromuskulären Stabilisierung des Sprunggelenkkomplexes anhand ausgewählter Muskeln

Das erfolgreiche Interagieren mit der Umwelt ist bezüglich der motorischen Kontrolle des Bewegungsapparates eine komplexe Aufgabe. Bei sich ändernden äußeren Anforderungen muss eine situationsadäquate Regulation der involvierten motorischen Strukturen erfolgen. Dazu müssen neuromuskuläre Prozesse im Sinne der Aufgabenerfüllung aufeinander abgestimmt werden, um beispielsweise ein externes Objekt sicher kontrollieren zu können. Wird die Stabilität während der Aufgabenerfüllung nicht durch die Umwelt (bzw. das Interaktionsobjekt) gesichert, muss das neuromuskuläre System diese Ausgabe übernehmen

Soft-Assembled Multilevel Dynamics of Tactical Behaviors in Soccer

This study aimed to identify the tactical patterns and the timescales of variables during a soccer match, allowing understanding the multilevel organization of tactical behaviors, and to determine the similarity of patterns performed by different groups of teammates during the first and second halves. Positional data from 20 professional male soccer players from the same team were collected using high frequency global positioning systems (5 Hz). Twenty-nine categories of tactical behaviors were determined from eight positioning-derived variables creating multivariate binary (Boolean) time-series matrices. Hierarchical principal component analysis (PCA) was used to identify the multilevel structure of tactical behaviors. The sequential reduction of each set level of principal components revealed a sole principal component as the slowest collective variable, forming the global basin of attraction of tactical patterns during each half of the match. In addition, the mean dwell time of each positioning-derived variable helped to understand the multilevel organization of collective tactical behavior during a soccer match. This approach warrants further investigations to analyze the influence of task constraints on the emergence of tactical behavior. Furthermore, PCA can help coaches to design representative training tasks according to those tactical patterns captured during match competitions and to compare them depending on situational variables

Analyzing Whole-Body Pose Transitions in Multi-Contact Motions

When executing whole-body motions, humans are able to use a large variety of support poses which not only utilize the feet, but also hands, knees and elbows to enhance stability. While there are many works analyzing the transitions involved in walking, very few works analyze human motion where more complex supports occur. In this work, we analyze complex support pose transitions in human motion involving locomotion and manipulation tasks (loco-manipulation). We have applied a method for the detection of human support contacts from motion capture data to a large-scale dataset of loco-manipulation motions involving multi-contact supports, providing a semantic representation of them. Our results provide a statistical analysis of the used support poses, their transitions and the time spent in each of them. In addition, our data partially validates our taxonomy of whole-body support poses presented in our previous work. We believe that this work extends our understanding of human motion for humanoids, with a long-term objective of developing methods for autonomous multi-contact motion planning.Comment: 8 pages, IEEE-RAS International Conference on Humanoid Robots (Humanoids) 201

Changes in movement control and coordination with increasing skill in females and males

In comparisons between the sexes on movement tasks, performance outcome is emphasised with little focus upon the coordination process that underpins this. Motor skills develop through practice; differences between the sexes may therefore reflect differences in the volume of experience with a task. The first study compared groups with increasing surfing experience performing a drop-landing. Sex differences in joint angle measures were accounted for at least in part by experience. Study two investigated whether females and males achieve similar improvement from an equal volume of practice using a slalom-skiing simulator task. Over five days of practice there were no differences in rate of learning for any measure. Performance differences in some cases were attributable to anthropometric differences between the sexes that interacted with the task apparatus. Most importantly, frequency for both sexes moved towards their calculated optimal, given the task constraint meaning performance was comparable. Overall males and females showed similar initial and final performance outcomes and achieved similar gains from an equal volume of practice. The basis of coordinative structure is the coupling and correlation between elements in the motor system. Principal component analysis (PCA) can quantify these relations. A recently developed technique in PCA incorporating overall coherence was applied to kinematic and EMG signals to provide further insight into the changes in coordination that occurred with practice. There were no differences between the male and female performers again supporting the idea that with equal practice, performance is similar despite any differences in anthropometrics. Whole body movement on the skiing-simulator could be defined in a low dimensional space that was further reduced over the course of practice. Previous studies had failed to show this; hidden structure was best revealed when PCA incorporating correlation in the frequency domain was employed

Coordination between hand and trunk movements in a Fitts\u27 Law task

It has been shown that limb movements are coupled in space and time in a bimanual Fitts\u27 task. The present study was designed to examine whether coordination of hand and trunk share some sets of coordinative principles with bimanual coordination. Participants (n = 28) were required to perform a Fitts\u27 task with the dominant hand and a Fitts\u27 task with the trunk. These tasks were performed separately or together. The task required moving the trunk, the dominant hand or both, such that the cursor/cursors on a computer screen was/were moved from the starting position/positions to the designated target/targets as fast and as accurately as possible. When the hand and the trunk moved in the same direction, hand movement and trunk movement were initiated and executed in a synchronized fashion, and the velocity was coupled. In contrast, when the hand and the trunk moved in the opposite directions, hand movement and trunk movement were not synchronized and the velocity was not coupled, as though they moved independently. The distinctions were further confirmed when the results were compared across different combinations of movement directions. Hand movement and trunk movement were more synchronized and the velocity was more coupled when they moved in the same direction than when they moved in the opposite directions. In addition, hand movement and trunk movement were initiated sooner and executed faster when they moved in the same direction than when they moved in the opposite directions. Therefore, the coordination between hand and trunk when they moved in the same direction showed the same coordinative patterns as the bimanual coordination, but not when they moved in the opposite directions. It is argued that the interaction between biomechanical and task constraints played an important role in determining optimal coordinative patterns. In conclusion, the coordinative patterns are not determined solely by the muscular skeletal structure involved in the coordination, but are determined by the interaction of biomechanical constraints and task constraints imposed on the action of the effectors. The central nervous system controls the formation of synergies to optimize the coordinative patterns also depending on the constraints. These findings support the idea that coordination is the result of the constraints imposed on the action of the effectors