Jurjen Bosga

Anatomical substrates of cooperative joint-action in a continuous motor task: Virtual lifting and balancing

An emerging branch of social cognitive neuroscience attempts to unravel the critical cognitive mechanisms that enable humans to engage in joint action. In the current experiment, differences in brain activity in participants engaging in solitary action and joint action were identified using whole brain fMRI while participants performed a virtual bar-balancing task either alone (S), or with the help of a partner in each of two separate joint-action conditions (isomorphic [Ji] and non-isomorphic [Jn]). Compared to the performing the task alone, BOLD signal was found to be stronger in both joint-action conditions at specific sites in the human mirror system (MNS). This activation pattern may reflect the demand on participants to simulate the actions of others, integrate their own actions with those of their partners, and compute appropriate responses. Increasing inter-dependence (complementarity) of movements being generated by cooperating individuals (Jn>Ji>S) was found to correlate with BOLD signal in the right anterior node of the MNS (pars opercularis), and the area around the right temporoparietal junction (TPJ). These data are relevant to current debates concerning the role of right IFG in complementary action, as well as evolving theories of joint action.

Joint-action coordination in transferring objects

Here we report a study of joint-action coordination in transferring objects. Fourteen dyads were asked to repeatedly reposition a cylinder in a shared workspace without using dialogue. Variations in task constraints concerned the size of the two target regions in which the cylinder had to be (re)positioned and the size and weight of the transferred cylinder. Movements of the wrist, index finger and thumb of both actors were recorded by means of a 3D motion-tracking system. Data analyses focused on the interpersonal transfer of lifting-height and movement-speed variations. Whereas the analyses of variance did not reveal any interpersonal transfer effects targeted data comparisons demonstrated that the actor who fetched the cylinder from where the other actor had put it was systematically less surprised by cylinder-weight changes than the actor who was first confronted with such changes. In addition, a moderate, accuracy-constraint independent adaptation to each other’s movement speed was found. The current findings suggest that motor resonance plays only a moderate role in collaborative motor control and confirm the independency between sensorimotor and cognitive processing of action-related information.

Coordination dynamics in horse-rider dyads

The sport of equestrianism is defined through close horse-rider interaction. However, no consistent baseline parameters currently exist describing the coordination dynamics of horse-rider movement across different equine gaits. The study aims to employ accelerometers to investigate and describe patterns of motor coordination between horse and rider across the equine gaits of walk, rising trot, sitting trot and canter. Eighteen female (N=18; mean age±SD: 37.57±13.04) Dutch horse-rider combinations were recruited to participate in the study. Horse-rider coordination was recorded using two tri-axial wireless accelerometers during a standard ridden protocol. Multiple measures of horse-rider coordination were calculated to investigate the relationship between the horse and rider, while the unpredictability of the acceleration-time series of the horse and rider during task performance were determined separately by means of approximate entropy analysis. The kinematic variables of horse-rider correlation, mean relative phase, mean standard deviation of the relative phase, approximate entropy rider, approximate entropy horse and spectral edge frequency at 95% of the power in the 0-10 Hz frequency band were examined using multiple correlational analyses and multivariate analysis of variance (MANOVA). Findings showed significantly different coordination dynamics between equine gaits, with the gait of canter allowing for the highest levels of horse-rider synchronicity. It may be concluded that accelerometers are a valuable tool to map distinct coordination patterns of horse-rider combinations.

Deliberate control of continuous motor performance

The authors examined the means by which people vary movement parameters to satisfy more than 1 constraint at a time in a repetitive motor task. The authors expected that when participants (N = 12) were simultaneously confronted with spatial and temporal constraints in an ellipse-drawing task, they would either exploit the intrinsic amplitude-frequency relationships or activate less natural control regimes to prioritize their movement goals. By focusing on local amplitude and frequency errors and parameter changes from 1 movement to the next, the authors distinguished parameter changes that reflected exploitation of biomechanics from those that required deliberate control. The findings demonstrated that at low movement speeds, participants can pursue multiple movement goals simultaneously; at higher speeds, their capacity to satisfy multiple task goals is reduced. The authors used a new method of inferring deliberate control from movement kinematics in the present study.

Intentional control and biomechanical exploitation in preparatory handwriting

In this study it was investigated how primary school children perform a graphomotor task which required them to simultaneously achieve multiple movement goals. Thirty-four 1st-grade primary school children were asked to produce with an electronic ink pen loop patterns varying in height (3, 6, 9 and 12 mm) on preprinted sheets of paper attached to a digitizer tablet. The task was paced by means of an acoustic signal of either 1, 2 or 3 Hz. The children were instructed to attain both the imposed amplitude and frequency. By focusing on how local parameter errors changed from one movement to the next, exploitation of biomechanics when the children respected the inverse relationship between movement amplitude and frequency was distinguished from deliberate, cognitive control when the children succeeded in overriding the inverse relationship between movement amplitude and frequency. The results show that children, like adults, exploit biomechanics to a considerable extent. Coupling strength between the acoustic pacing signal and the pen-tip movements increased with age, whereas the temporal errors decreased. The study shows that preparatory writers can pursue multiple movement goals simultaneously at lower speeds but at higher speeds their capacity to do so is reduced.

Developing Movement Efficiency Between 7 and 9 Years of Age

This longitudinal study examined the movement efficiency of typically developing children between 7 and 9 years of age by scrutinizing their movement amplitudes and frequencies as they settled into a loop-writing task in which both parameters were prescribed. It was hypothesized that during the first three grades at primary school children would show increasing efficiency in exploiting the inverse relationship between movement amplitude and frequency when adjusting their movement errors. Whereas a clear developmental trend showed increasing efficiency with respect to the way in which the primary school children met the amplitude constraints, a more variable pattern was found for the age-dependent adjustments to the frequency requirements. At the level of parameter-error corrections from one cycle to the next, a marginal developmental trend was observed. Results are discussed in terms of contrasting effects between educational targets and movement-efficiency principles.

Solution space: Monitoring the dynamics of motor rehabilitation

ABSTRACT This article presents and discusses a perspective on the concept of “solution space” in physiotherapy. The model is illustrated with a subjective assessment of the way movements are performed and an objective quantification of the dynamics of the recovery process for a patient with a knee injury. Based on insights from the domain of human motor control, solution space is a key concept in our recovery model that explains the emergence of a variety of adaptive changes that may occur in the movement system recovering from an injury. The three dimensions that span the solution space are: (1) information and control processes; (2) time; and (3) degrees of freedom. Each dimension is discussed within the context of feasible physiotherapeutic assessments to identify and facilitate desirable behavioral patterns or bypass emerging but undesirable behavioral patterns that could impede both short- and long-term recovery. Central to this article is our view on the relationship between the recovery process and the three dimensions of the solution space, which determines the model’s usefulness as a motor-rehabilitation monitoring tool.

De betekenis van de flexibiliteit van het neuromotorisch systeem voor de fysiotherapie

SamenvattingEen goed ontwikkelde wetenschap is in staat om twee fundamentele vragen te beantwoorden. De eerste vraag is hoe de fenomenen die zij bestudeert in elkaar zitten en de tweede vraag is waarom deze fenomenen zich voordoen. Omdat in tegenstelling tot de levenloze natuur het menselijk handelen gekenmerkt wordt door doelgerichtheid (Feigenberg, 1998) zullen de humane wetenschappen zich nog over een derde vraag moeten buigen, namelijk wat is het doel van de verschijnselen die zij bestudeert. Voor het toepassen van wetenschappelijke kennis in bijvoorbeeld de fysiotherapie moet zelfs op een vierde vraag antwoord worden gegeven, namelijk hoe kunnen de antwoorden op de gestelde vragen vertaald worden naar toepassingen die de dienstverlening verbeteren (Winstein, Wing & Whitall, 2003). In dit artikel zullen we aan de hand van de zojuist gestelde vragen een brug slaan tussen neurowetenschap en fysiotherapie. Daarbij beperken we ons tot het in de praktijk onderbelichte fenomeen van de flexibiliteit van het neuromotorische systeem, dat wil zeggen de eigenschap van het systeem om onder wisselende omstandigheden op een slimme en snelle manier adaptieve of creatieve keuzes te maken om de bewegingstaak succesvol uit te voeren.