Large-Scale Patterns in a Minimal Cognitive Flocking Model: Incidental Leaders, Nematic Patterns, and Aggregates

Barberis, Lucas; Peruani, Fernando

doi:10.1103/physrevlett.117.248001

Cited by 133 publications

(134 citation statements)

References 60 publications

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“…However, this loop structure seems shrinking and unstable for longer time. The similar loop structure is observed transiently in the numerical simulation of the self-propelled system with the visual corn [5,46].…”

Section: Loop Formationsupporting

confidence: 73%

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Gliding filament system giving both global orientational order and clusters in collective motion

et al. 2020

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Active matter consists of self-propelled elements exhibits fascinating collective motions ranging from biological to artificial systems. Among wide varieties of active matter systems, reconstituted bio-filaments moving on molecular motor turf interacting purely by physical interactions provides the fundamental test ground for understanding biological motility. However, for the emergence of ordered patterns such as polar pattern, swirls, clusters, and density wave in actomyosin motility assay, multi-filament collisions are required instead of binary collision which is often assumed in kinetic theory. Similarly, for microtubules driven by kinesin motors to produce nematic ordered state, depletion agents or binding molecules are required to introduce strong alignment effects between filaments. Thus, whether simple physical interactions during collisions such as steric effect without depletion nor binding agents are sufficient or not for producing ordered patterns in motility assays remains still elusive. In this article, we constructed a motility assay purely consists of kinesin motor and microtubule in which the frequency of binary collision can be controlled without using depletion nor binding agents. By controlling strength of steric interaction and density of microtubules, we found different states; disordered state, long-range orientationally ordered state, liquid-gas-like phase separated state, and transitions between them. We found that a balance between cross over and aligning events in collisions controls transition from disorder to global ordered state, while excessively strong steric effect leads to the phase separated clusters. Furthermore, macroscopic chiral symmetry breaking observed as a global rotation of nematic order observed in this experiment could be attributed to the chirality at molecular level. Numerical simulations in which we change strength of volume exclusion reproduce these experimental results. Moreover, it reveals the transition from long-range alignment to nematic bands then to aggregations. This study may provide new insights into dynamic ordering by self-propelled elements through a purely physical interaction.

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Section: Loop Formationsupporting

confidence: 73%

“…When R is 200 µm, S(R) is the same as Eq. (5). At all MT densities, S(R) decayed toward each asymptotic value S 0 [ Fig.…”

Section: Long Range Order Of the Orientational Ordered Patternmentioning

confidence: 96%

Gliding filament system giving both global orientational order and clusters in collective motion

et al. 2020

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“…the projection of the environment, vision appears as a good starting point to explore the relationship between sensory information and emergent collective behaviors. Some models have attempted to relate vision and movement 8,11,13,14 . However, they use vision as a motivation to refine established social in-…”

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confidence: 99%

A model of collective behavior based purely on vision

Bastien

Romanczuk

2019

Preprint

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Classical models of collective behavior often take a "birds-eye perspective," assuming that individuals have access to social information that is not directly available (e.g., the behavior of individuals outside of their field of view). Despite the explanatory success of those models, it is now thought that a better understanding needs to incorporate of the perception of the individual, i.e. how internal and external information are acquired and processed. In particular, vision has appeared to be a central feature to gather external information and influence the collective organization of the group. Here we show that a vision based model of collective behavior is sufficient to generate organized collective behavior in the absence of spatial representation and collision. Our work suggests a novel approach for development of purely vision-based autonomous swarm robotic systems, and formulates a mathematical framework for exploration of perception-based interactions and how they differ from physical ones. Thus, it is of broader relevance for self-organization in complex systems, neuroscience, behavioral sciences and engineering. 1 Models of collective behaviour often rely on phenomenological interactions of individuals with neighbors 1-4 . However, and contrary to physical interaction, these social interactions do not have a direct physical reality, such as gravity or electromagnetism. The behavior of individuals is influenced by their representation of the environment, acquired through sensory information. Current models often suggest that individuals are responding to the state of movement of their neighbors -their (relative) positions and velocities -which are not explicitly encoded in the sensory stream. Thus such phenomenological interactions implicitly assume internal processing of the sensory input in order to extract the relevant state variables. On the other hand, neuroscience has made tremendous progress in understanding various aspects of the relation of sensory signals and movement response, yet connections to large-scale collective behavior are lacking. Although evidence has been found for neural representation of social cues in the case of mice 5 and bats 6 , yet details and role of these internal representations remain unclear, in particular in the context of coordination of movement. Collective behavior crucially depends on the sensory information available to individuals, thus ignoring perception by relying on ad-hoc rules, strongly limits our understanding of the underlying complexity of the problem. Besides, it obstructs the interdisciplinary exchange between biology, neuroscience, engineering, and physics.Recently, the visual projection field has appeared as a central feature of collective movements, in fish 7-10 , birds 11 or humans 12 . Due to the geometrical nature of vision, i.e. the projection of the environment, vision appears as a good starting point to explore the relationship between sensory information and emergent collective behaviors. Some models have attempted to relate vision and mo...

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“…Somewhat surprisingly, this generic fore-aft asymmetry has not been much investigated per se. It is explicitly mentioned in some works [6], and implicitly present in a number of models, see, e.g. [7], and the rather complicated escape-pursuit mechanisms introduced in [8,9] to describe marching locusts, or the 'motion guided attention' of [10].…”

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confidence: 99%

Fore-aft asymmetric flocking

et al. 2017

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We show that fore-aft asymmetry, a generic feature of living organisms and some active matter systems, can have a strong influence on the collective properties of even the simplest flocking models. Specifically, an arbitrarily weak asymmetry favoring front neighbors changes qualitatively the phase diagram of the Vicsek model. A region where many sharp traveling band solutions coexist is present at low noise strength, below the Toner-Tu liquid, at odds with the phase-separation scenario well describing the usual isotropic model. Inside this region, a 'banded liquid' phase with algebraic density distribution coexists with band solutions. Linear stability analysis at the hydrodynamic level suggests that these results are generic and not specific to the Vicsek model.Non-reciprocal (effective) interactions are interesting but rather rare in physical systems [1]. They are, however, likely to be more common in active matter. A nice example of action-reaction symmetry breaking was given recently by Soto and Golestanian for catalytically active colloids [2]. A strong case is that of self-propelled objects interacting solely via volume exclusion: their shape governs their effective interaction (e.g. aligning or not) and thus their collective behavior [3]. In the context of animal and human collective motion, asymmetric interactions are quite generic, and this asymmetry lies mostly in the relative position and weight of neighbors: the importance and quality of the information perceived by living organisms usually varies with its origin: In animal groups one often -but not always, cf. the cannibalistic behavior of locusts in [4,5]-expects that frontal stimuli such as neighbor positions matter more to an individual than events taking place in its back. Somewhat surprisingly, this generic fore-aft asymmetry has not been much investigated per se. It is explicitly mentioned in some works [6], and implicitly present in a number of models, see, e.g. [7], and the rather complicated escape-pursuit mechanisms introduced in [8,9] to describe marching locusts, or the 'motion guided attention' of [10]. It can even be found in variants of simple flocking models such as the Vicsek model, where local alignment of constantspeed particles competes with noise [22][23][24]. In [15][16][17][18][19], the introduction of a limited angle of vision was shown to have an influence on the shape of cohesive moving groups, on the degree of ordering, etc. Asymmetric interactions are also present in 'metric-free' models introduced in the context of bird flocks [11][12][13][14].In all cases mentioned above, it was not shown that fore-aft asymmetry alone can lead to qualitatively new collective phenomena. Recently, though, the influence of fore-aft asymmetric neighbors was investigated in the context of flocking models incorporating fast 'inertial spin' variables [20,21]. Both these works argue that the combination of asymmetric neighbors and fast variables induces new collective behavior.In this Letter, we show that fore-aft asymmetry alone has a strong i...

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Large-Scale Patterns in a Minimal Cognitive Flocking Model: Incidental Leaders, Nematic Patterns, and Aggregates

Cited by 133 publications

References 60 publications

Gliding filament system giving both global orientational order and clusters in collective motion

Gliding filament system giving both global orientational order and clusters in collective motion

A model of collective behavior based purely on vision

Fore-aft asymmetric flocking

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