Structural constraints on bimanual movements

Experimental Brain Research, 2006

In two experiments bimanual movements with various combinations of target directions were studied by means of the timed-response procedure. The findings revealed an adaptive modulation of intermanual interactions during direction specifications depending on particular target directions. For symmetric movements intermanual correlations of movement directions are positive, indicating a symmetric coupling. For parallel movements the positive intermanual correlations, observed at short preparation intervals, turn into negative correlations as the time available for motor preparation increases. Biases of mean directions, that can be observed for movements to targets with different eccentricities, reflect one or the other kind of coupling, symmetrical for symmetric target directions and parallel for parallel target directions. These biases are static, that is, they are present at long preparation times, and they are phasically enhanced at shorter preparation intervals. The task-adaptive modulation of intermanual interactions is superposed on a basic symmetry bias.

Journal of Experimental Psychology: Human Perception and Performance, 1996

Patterns of interlimb coordination associated with infant reaching fluctuate frequently over developmental time. This study investigated whether these fluctuations are related to coordination tendencies. Interlimb patterns were studied in reaching and nonreaching movements in 4 infants, which were followed through their 1 st year. Each week, reaching and nonreaching endpoint kinematics were recorded in both arms during multiple 14-s trials. It was found that patterns of interlimb coordination in reaching matched coordination tendencies in nonreaching. Reaching fluctuated between uni-and bimanual periods. During the bimanual periods, nonreaching interlimb activity tended to be synchronous. During the unimanual periods, nonreaching activity revealed no predominant form of interlimb coordination. It is argued that changing coordination tendencies may influence the organization of specific goal-oriented behaviors from early in life.

Psychonomic Bulletin & Review, 2015

For nearly four decades bimanual coordination, Ba prototype of complex motor skills^and apparent Bwindow into the design of the brain,^has been intensively studied. Past research has focused on describing and modeling the constraints that allow the production of some coordination patterns while limiting effective performance of other bimanual coordination patterns. More recently researchers have identified a coalition of perception-action constraints that hinder the effective production of bimanual skills. The result has been that given specially designed contexts where one or more of these constraints are minimized, bimanual skills once thought difficult, if not impossible, to effectively produce without very extensive practice can be executed effectively with little or no practice. The challenge is to understand how these contextual constraints interact to allow or inhibit the production of complex bimanual coordination skills. In addition, the factors affecting the stability of bimanual coordination tasks needs to be re-conceptualized in terms of perception-related constraints arising from the environmental context in which performance is conducted and action constraints resident in the neuromotor system.

Behavioural Brain Research, 2001

The present study addressed the status of spatial encoding during a bimanual task paradigm. This was based on the premise that patterns of contralateral interference during bimanual coordination provide a window into those movement parameters that are primarily encoded within the central nervous system. Results showed that both direction and amplitude were subject to (bilateral) interference when different specifications were to be generated simultaneously for each limb. Directional interference was found to be partially independent of the amount and pattern of underlying muscle activation, suggesting that direction is encoded at a rather abstract level in the central nervous system. The findings are consistent with single-cell recording studies that have pointed to the role of directional tuning in various brain areas. Moreover, the findings suggest that spatial parameters of movement constrain the coordination of limb movements in addition to temporal parameters.

Human Movement Science, 2002

The present study was designed to test two predictions from the coupled oscillator model of multifrequency coordination. First, it was predicted that multifrequency tasks that match the inherent manual asymmetry (i.e., the preferred hand assigned to the faster tempo) would be easier to learn than tasks that do not match the inherent dynamics (i.e., the non-preferred hand assigned to the faster tempo). Second, in the latter case acquisition of the multifrequency coordination would involve a reorganisation of the coupling dynamics such that the faster hand would exert a greater influence on the slower hand than vice versa. Sixteen right-handed volunteers received extensive training on a 2:1 coordination pattern involving a bimanual forearm pronation-supination task. Participants were randomly assigned to one of two groups: 1L:2R in which the preferred right hand performed the higher frequency, or 2L:1R in which the non-preferred left hand performed the higher frequency. The dynamic stability of the patterns was assessed by the ability of participants to maintain the coordination pattern as movement frequency was increased. Changes in the directional coupling between the hands was assessed by transition pathways and lead-lag relationship evident in a 1:1 anti-phase frequency-scaled coordination task performed prior to and following three practice sessions of the 2:1 task. The predicted differential stability between the multifrequency patterns was evident in the initial acquisition sessions but by the end of training the two patterns evidenced equivalent stability. Unexpectedly, for both groups the fast hand displayed greater variability Human Movement Science 21 www.elsevier.com/locate/humov in amplitude and movement frequency than the slow hand perhaps reflecting anchoring afforded to the slow hand by synchronising movement endpoints with the auditory pacing metronome. Analysis of pre-to post-training changes to the coupling dynamics in the 1:1 anti-phase task support the hypothesis that acquisition of the 2L:1R pattern involved reorganisation of the inherent dynamics.

Current Directions in Psychological Science, 2008

The motor-program concept, emphasizing how actions are represented in the brain, helped bring the study of motor control into the realm of cognitive psychology. However, interest in representational issues was in limbo for much of the past 30 years, during which time the focus was on biomechanical and abstract accounts of the constraints underlying coordinated movement. We review recent behavioral and neuroscientific evidence that highlights multiple levels of constraints in bimanual coordination, with an emphasis on work demonstrating that a primary source of constraint arises from the manner in which action goals are represented.

Acta Psychologica, 2008

Bimanual coordination dynamics have been conceived as the outcome of a global coordinative system, and coordination stability properties and theories of underlying processes have often been generalized over various bimanual tasks. In unimanual timing tasks it has been shown that different timing processes are involved according to tasks, yielding distinctive correlation properties in the within-hand temporal patterns. In this study we compare unimanual with bimanual, tapping with oscillation, and self-paced with externally paced tasks, and we analyze the correlation properties of temporal patterns at both the component level and the coordinative level. Results show that the distinctive signatures of event-based versus emergent, and self-paced versus synchronization timing control known from unimanual tasks persist in the corresponding bimanual coordination tasks. Accordingly, we argue that these different timing processes, and related temporal patterns at the component level, constitute a task-dependent background on which coordination builds. One direct implication of these results is that the bimanual coordination paradigm should be considered multifaceted and not governed by some unitary generic principle. We discuss the need to assess the relationship between temporal patterns at the component level and the collective level, and to integrate serial (long-range) correlation properties into bimanual coordination models. Finally, we test whether the architectures of current bimanual coordination models can account for the experimentally observed serial correlations.

Human Movement Science, 1996

This article addresses the contribution of inherent (arising from the structure of the neuromuscular-skeletal system) and incidental (arising from specific features of a task or environment) constraints/resources to intentional modifications of coordination dynamics. An experiment was conducted to determine the extent to which the organization of voluntary transitions between locally stable modes of bimanual coordination was influenced by the frequency of movement, and by the provision and phase of external auditory pacing. Subjects performed rhythmic pronation and supination movements of the forearm in four bimanual patterns. In two in-phase patterns, either maximum pronation (inphase pronation) or maximum supination (inphase supination) was synchronised with each beat of an auditory metronome. In two antiphase patterns, either maximum excursion to the left (antiphase left) or to the right (antiphase right) was synchronised with the metronome. In an initial session, mean (spontaneous) transition frequencies (MTF) were established. In a second session pacing was provided at MTF -0.5 Hz, MTF -0.25 Hz, MTF and MTF + 0.25 Hz. A visual signal presented early or late in the trial indicated that subjects were to switch to the opposite mode of coordination. On some trials, metronome pacing was removed following an induction period. Transition durations decreased in a linear fashion with increases in pacing frequency, both when the metronome was present and when it had been removed prior to the imperative signal, suggesting that movement frequency acts as an inherent constraint upon the coordination dynamics. Transitions were of greater mean duration when the metronome was present than when it was absent, indicating that external pacing signals may impose incidental * SO 167-9457 00028-O 566 R.G. Carson et al./ Human Mwement Science I5 (19%) 565-589

Journal of Neurophysiology, 2005

The present study addressed the interactions between interlimb and intralimb constraints during the control of bimanual multijoint movements. Participants performed eight coordination tasks involving bilateral shoulder-elbow (Experiment I) and shoulder-wrist (Experiment II) movements. Three principal findings were obtained. First, the principle of muscle homology (in-phase coordination), giving rise to mirror symmetrical movements with respect to the mid-sagittal plane, had a powerful influence on the quality of interlimb coordination. In both experiments, the accuracy and stability of inter-and/or-intralimb coordination deteriorated as soon as the anti-phase mode was introduced in one or both joint pairs. However, the mutual influences between bilateral distal and proximal joint pairs varied across coordination tasks and effectors. Second, the impact of intralimb coordination modes on the quality of intralimb coordination was inconsistent between adjacent (Experiment I) and nonadjacent joint (Experiment II) combinations. Third, the mode of interlimb coordination affected the quality of intralimb coordination whereas strong support for the converse effect was not obtained. Taken together, these observations point to a hierarchical control structure whereby interlimb coordination constraints have a stronger impact on the global coordination of the system than intralimb constraints, whose impact is rather effector-and task-dependent. The finding that intralimb coordination is subordinate to interlimb coordination during the production of bimanual multijoint coordination patterns indicates that symmetry is a major organizational principle in the neural control of complex movement.

Neuroscience Letters, 2004

Following earlier work by Mechsner et al. (Nature 414 (2001) 69), the purpose of this experiment was to determine the perceptual and motoric contributions to bimanual coordination. Twenty right-handed, healthy, young adults performed continuous, horizontal, linear movements of both upper limbs at frequencies of 1.5 and 2.0 Hz. The goal was to control the spatial-temporal displacement of two flags by coordinating upper limb movements in two perceptual conditions. In a congruent condition, the movement of the flags matched the movement of the upper limbs. In an incongruent condition, the movement of the flags was opposite to the movement of the upper limbs. Measures of error in coordination provided support primarily for a motor view of bimanual coordination, and failed to replicate the earlier findings of Mechsner et al. q 2004 Published by Elsevier Ireland Ltd.