English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Zendy Open

Presents the pdf analysis as premium feature

PDF Analysis

Insights

Presents the summarisation as premium feature

Summarisation

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the zaia usage as premium feature

ZAIA

Zendy Tools

Zendy Plus

Presents the access of premium content as premium feature

Premium Content

We investigate the cognitive control in polyrhythmic hand movements as a model paradigm for bimanual coordination. Using a symbolic coding of the recorded time series, we demonstrate the existence of qualitative transitions induced by experimental manipulation of the tempo. A nonlinear model with delayed feedback control is proposed, which accounts for these dynamical transitions in terms of bifurcations resulting from variation of the external control parameter. Furthermore, it is shown that transitions can also be observed due to fluctuations in the timing control level. We conclude that the complexity of coordinated bimanual move- ments results from interactions between nonlinear control mechanisms with delayed feedback and stochastic The analysis of dynamical processes underlying brain functioning and behavior has evolved into a field of exten- sive research. In particular, the theory of complex systems @1# is a promising contribution to these problems from the viewpoint of theoretical physics. This approach is based on the notion of qualitative changes induced by variation of a control parameter of the system. As a prominent example, the Haken-Kelso-Bunz model @2# emphasizes the importance of qualitative transitions for the understanding of the dynam- ics in the control of motor behavior. Timing of bimanual movements is an ideal experimental framework for the study of cognitive motor control. The analysis of bimanual polyrhythmic movement tasks may be looked upon as a case study for the more general problem of bimanual coordination @3#. Numerous studies have shown that bimanual coordination is subject to strong performance constraints @4#. Experimental variation of external param- eters, like manipulating the required speed of performance or the difficulty of the movement pattern, permits the system- atic study of how the human movement control system adapts to these external and its own internal constraints. The use of performance tempo as an external control parameter in the experiment under consideration @5# yields the finding of transitions between qualitatively different dynamical re- gimes. A crucial problem for the analysis of complex natural systems is the comparison of theoretical models with experi- mental data. Different from most experiments in physics, key observables in living systems are more restrictively pre- scribed by the measurement procedure and their functional state can be controlled to a much lower extent. By using symbolic dynamics @6# we demonstrate that, nevertheless, the comparison of theory and experiment can be achieved even at the level of individual subjects based on short and noisy time series. The analysis of physiological and psychological systems using nonlinear methods of data analysis @7,8# is promising for gaining new insight into the complex interactions be- tween subsystems and the resulting dynamical behavior. The more traditional approach to the analysis of human move- ment timing has employed linear models of covariance struc- tures between the produced time intervals @5,9,10#. Related methods rest on strong statistical assumptions which are of- ten violated and also require data aggregation to a degree that precludes investigation of interesting qualitative phe- nomena on the basis of individual performance which is an important advantage of our methods of time series analysis. A considerable number of studies has focused on the vari- ability in the control of movements. In the framework of timer-motor or two-level models ~for review cf. @10#! ,i t has been shown that the observed variability can be exploited to analyze the organization of control structures in the brain. At the same time nonlinear dynamical models have explained the occurrence of phase transitions in behavior @1#, at least at a qualitative level. The typical approach to the study of the stability of rhyth- mic performance is the analysis of dynamical transitions which occur when high-order polyrhythms, e.g., 3:8, fall apart in response to increasing external tempo constraints during performance @11-14#. Related experiments were de- signed for the observation of transitions between poly- rhythms of different order. In contrast to this we demonstrate here the existence of qualitative changes in the stable pro- duction of the same polyrhythm when it is performed at dif- ferent tempi. The concepts of nonlinear dynamics and timer- motor models are combined. We propose a stochastic timer for the control of cycle durations in combination with deter- ministic feedback control. In Sec. II we present the design of our experiment. The analysis of the corresponding data, in particular the observa- tion of qualitative transitions, is given in Sec. III. Our non- linear model, which is introduced in Sec. IV, reproduces these dynamical transitions. Furthermore, it permits the in- clusion of realistic random fluctuations in timing.

Tempo-induced transitions in polyrhythmic hand movements