Functional Interdependence in Coupled Dissipative Structures: Physical Foundations of Biological Coordination.

Coordination within and between organisms is one of the most complex abilities of living systems, requiring the concerted regulation of many physiological constituents, and this complexity can be particularly difficult to explain by appealing to physics. A valuable framework for understanding biological coordination is the coordinative structure, a self-organized assembly of physiological elements that collectively performs a specific function. Coordinative structures are characterized by three properties: (1) multiple coupled components, (2) soft-assembly, and (3) functional organization. Coordinative structures have been hypothesized to be specific instantiations of dissipative structures, non-equilibrium, self-organized, physical systems exhibiting complex pattern formation in structure and behaviors. We pursued this hypothesis by testing for these three properties of coordinative structures in an electrically-driven dissipative structure. Our system demonstrates dynamic reorganization in response to functional perturbation, a behavior of coordinative structures called reciprocal compensation. Reciprocal compensation is corroborated by a dynamical systems model of the underlying physics. This coordinated activity of the system appears to derive from the system's intrinsic end-directed behavior to maximize the rate of entropy production. The paper includes three primary components: (1) empirical data on emergent coordinated phenomena in a physical system, (2) computational simulations of this physical system, and (3) theoretical evaluation of the empirical and simulated results in the context of physics and the life sciences. This study reveals similarities between an electrically-driven dissipative structure that exhibits end-directed behavior and the goal-oriented behaviors of more complex living systems.

Capturing and quantifying the dynamics of valenced emotions and valenced events of the organism-environment system.

The events we encounter and the emotions we experience are valenced-they are positively or negatively charged. Although these occurrences seem to be distributed irregularly throughout the day, the two experiments presented here reveal systematicity in the temporal dynamics of affective experience using a variety of time-series analyses. In Experiment 1, participants used a portable button to respond to event valence (the positive or negative charge of an event in the environment) or affective valence (one's positive or negative feeling at the time of responding). This methodology yields signed response durations, indexing the valence and intensity of an occurrence, and inter-response intervals, indexing their distribution. These measures revealed that valenced occurrences are correlated with both temporally proximal and remote occurrences. Experiment 2 validated the methodology employed in Experiment 1 using artificial, laboratory-created event structures. Implications of dynamical approaches to understanding emotion are discussed.

Oscillatory dynamics of an electrically driven dissipative structure.

Physical systems open to a flow of energy can exhibit spontaneous symmetry breaking and self-organization. These nonequilibrium self-organized systems are known as dissipative structures. We study the oscillatory mode of an electrically driven dissipative structure. Our system consists of aluminum beads in shallow oil, which, when subjected to a high voltage, self-organize into connected 'tree' structures. The tree structures serve as pathways for the conduction of charge to ground. This system shows a variety of spatio-temporal behaviors, such as oscillating movement of the tree structures. Utilizing a dynamical systems model of the electromagnetic phenomena, we explore a potential mechanism underlying the system's behavior and use the model to make additional empirical predictions. The model reproduces the oscillatory behavior observed in the real system, and the behavior of the real system is consistent with predictions from the model under various constraints. From the empirical results and the mathematical model, we observe a tendency for the system to select modes of behavior with increased dissipation, or higher rates of entropy production, in accord with the proposed Maximum Entropy Production (MEP) Principle.

Effects of visual and auditory guidance on bimanual coordination complexity.

Perceptual guidance of movement with simple visual or temporal information can facilitate performance of difficult coordination patterns. Guidance may override coordination constraints that usually limit stability of bimanual coordination to only in-phase and anti-phase. Movement dynamics, however, might not have the same characteristics with and without perceptual guidance. Do visual and auditory guidance produce qualitatively different dynamical organization of movement? An anti-phase wrist flexion and extension coordination task was performed under no specific perceptual guidance, under temporal guidance with a metronome, and under visual guidance with a Lissajous plot. For the time series of amplitudes, periods and relative phases, temporal correlations were measured with Detrended Fluctuation Analysis and complexity levels were measured with multiscale entropy. Temporal correlations of amplitudes and relative phases deviated from the typical 1/f variation towards more random variation under visual guidance. The same was observed for the series of periods under temporal guidance. Complexity levels for all time series were lower in visual guidance, but higher for periods under temporal guidance. Perceptual simplification of the task's goal may produce enhancement of performance, but it is accompanied by changes in the details of movement organization that may be relevant to explain dependence and poor retention after practice under guidance.

Environmental coupling modulates the attractors of rhythmic coordination.

A simple instance of coupling behavior to the environment is oscillating the hands in pace with metronome beats. This environmental coupling can be weaker (1 beat per cycle) or stronger (2 beats per cycle). The authors examined whether strength of environmental coupling enhanced the stability of in-phase bimanual coordination. Detuning by manipulanda that produced different left and right eigenfrequencies shifted the relative phase angle from 0 degrees, with the size of the shift larger for higher movement frequencies. Stronger environmental coupling was found to decrease this relative-phase shift, with accompanying increase and reduction, respectively, in recurrence quantification measures related to coordination stability and coordination noise. Stronger environmental coupling also increased oscillation amplitude. Results are considered from the perspective of parametric stabilization.

Effects of intention and learning on attention to information in dynamic touch.

The current research distinguishes two types of attention shifts: those entailed by perceptual learning and those entailed by changing intention. In perceptual learning, participants given feedback have been shown to gradually shift attention toward the optimal (i.e., specifying) information variable for the task. A shift in variable use is also expected when intention changes, because an intention to perceive some property entails attunement to information about that property. We compared the effects of feedback and intention in a dynamic (kinesthetic) touch task by representing both as changes of locus in an information space of inertial variables. Participants wielded variously sized, unseen, rectangular parallelepipeds and made length or width judgments about them. When given feedback, participants made gradual attentional shifts toward the optimal variable, which demonstrates the education of attention. When asked to report a new property, participants made large attentional jumps to the ballpark of the optimal variable for the new property. Exploratory movements were measured on 6 participants and were found to differ as a function of intention and to change with learning.

Distinguishing the noise and attractor strength of coordinated limb movements using recurrence analysis.

The variability of coupled rhythmic limb movements is assumed to be a consequence of the strength of a movement's attractor dynamic and a constant stochastic noise process that continuously perturbs the movement system away from this dynamic. Recently, it has been suggested that the nonlinear technique of recurrence analysis can be used to index the effects of noise and attractor strength on movement variability. To test this, three experiments were conducted in which the attractor strength of bimanual wrist-pendulum movements (using coordination mode, movement frequency and detuning), as well as the magnitude of stochastic perturbations affecting the variability of these movements (using a temporally fluctuating visual metronome) was manipulated. The results of these experiments demonstrate that recurrence analysis can index parametric changes in the attractor strength of coupled rhythmic limb movements and the magnitude of metronome induced stochastic perturbations independently. The results of Experiments 1 and 2 also support the claim that differences between the variability of inphase and antiphase coordination, and between slow and fast movement frequencies are due to differences in attractor strength. In contrast to the standard assumption that the noise that characterizes interlimb coordination remains constant for different magnitudes of detuning (Delta omega) the results of Experiment 3 suggest that the magnitude of noise increases with increases in |Delta omega|.