Papers
466.8K views | +114 today
Follow
Papers
Recent publications related to complex systems
Your new post is loading...
Your new post is loading...
Rescooped by Complexity Digest from Self-organizing, Systems and Complexity
Scoop.it!

Top-Down Self-Organization: State Logics, Substitutional Delegation, and Private Governance in Russia

This study investigates the counterintuitive emergence of self-regulation in the Russian construction sector. Despite its proclivity for centralizing political authority, the government acted as the catalyst for the delegation of regulatory powers to private industry groups. The article argues that a factor little considered in extant literature—namely, a weak and corrupt bureaucracy—is key to explaining why the normally control-oriented executive branch began to promote private governance despite industry's preference for continued state regulation. The article's signal contribution is to theoretically explain and empirically demonstrate how a government's prior inability to establish intrastate control over an ineffective and bribable public bureaucracy creates incentives for political authorities to search for alternative means for policy implementation outside of existing state agencies. These findings are important for understanding the impetus and logic behind particular regulatory shifts in countries where the state apparatus is both deficient and corrupt.


Top-Down Self-Organization: State Logics, Substitutional Delegation, and Private Governance in Russia
Masha Hedberg

Governance

http://dx.doi.org/10.1111/gove.12140 ;


Via june holley
more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

Anthropocene: The human age

Anthropocene: The human age | Papers | Scoop.it
Momentum is building to establish a new geological epoch that recognizes humanity's impact on the planet. But there is fierce debate behind the scenes.


http://www.nature.com/news/anthropocene-the-human-age-1.17085

more...
ASundberg's curator insight, March 29, 2015 9:30 AM

Brief historicization of the anthropocene discussion. 

Scooped by Complexity Digest
Scoop.it!

Conflict resolution: Wars without end

Conflict resolution: Wars without end | Papers | Scoop.it
The world is full of bloody conflicts that can drag on for decades. Some researchers are trying to find resolutions through complexity science.


http://www.nature.com/news/conflict-resolution-wars-without-end-1.17070

more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

Attention decay in science

The exponential growth in the number of scientific papers makes it increasingly difficult for researchers to keep track of all the publications relevant to their work. Consequently, the attention that can be devoted to individual papers, measured by their citation counts, is bound to decay rapidly. In this work we make a thorough study of the life-cycle of papers in different disciplines. Typically, the citation rate of a paper increases up to a few years after its publication, reaches a peak and then decreases rapidly. This decay can be described by an exponential or a power law behavior, as in ultradiffusive processes, with exponential fitting better than power law for the majority of cases. The decay is also becoming faster over the years, signaling that nowadays papers are forgotten more quickly. However, when time is counted in terms of the number of published papers, the rate of decay of citations is fairly independent of the period considered. This indicates that the attention of scholars depends on the number of published items, and not on real time.


Attention decay in science
Pietro Della Briotta Parolo, Raj Kumar Pan, Rumi Ghosh, Bernardo A. Huberman, Kimmo Kaski, Santo Fortunato

http://arxiv.org/abs/1503.01881

more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

The Molecular Clock of Neutral Evolution Can Be Accelerated or Slowed by Asymmetric Spatial Structure

Evolution is driven by genetic mutations. While some mutations affect an organism’s ability to survive and reproduce, most are neutral and have no effect. Neutral mutations play an important role in the study of evolution because they generally accrue at a consistent rate over time. This result, first discovered 50 years ago, allows neutral mutations to be used as a “molecular clock” to estimate, for example, how long ago humans diverged from chimpanzees and bonobos. We used mathematical modeling to study how the rates of these molecular clocks are affected by the spatial arrangement of a population in its habitat. We find that asymmetry in this spatial structure can either slow down or speed up the rate at which neutral mutations accrue. This effect could potentially skew our estimates of past events from genetic data. It also has implications for a number of other fields. For example, we show that the architecture of intestinal tissue can limit the rate of genetic substitutions leading to cancer. We also show that the structure of social networks affects the rate at which new ideas replace old ones. Surprisingly, we find that most Twitter networks slow down the rate of idea replacement.


Allen B, Sample C, Dementieva Y, Medeiros RC, Paoletti C, Nowak MA. (2015) The Molecular Clock of Neutral Evolution Can Be Accelerated or Slowed by Asymmetric Spatial Structure. PLoS Comput Biol 11(2): e1004108. http://dx.doi.org/10.1371/journal.pcbi.1004108 ;

more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

Predicting Epidemic Risk from Past Temporal Contact Data

Following the emergence of a transmissible disease epidemic, interventions and resources need to be prioritized to efficiently control its spread. While the knowledge of the pattern of disease-transmission contacts among hosts would be ideal for this task, the continuously changing nature of such pattern makes its use less practical in real public health emergencies (or otherwise highly resource-demanding when possible). We show that in such situations critical knowledge to assess the real-time risk of infection can be extracted from past temporal contact data. An index expressing the conservation of contacts over time is proposed as an effective tool to prioritize interventions, and its efficiency is tested considering real data on livestock movements and on human sexual encounters.


Valdano E, Poletto C, Giovannini A, Palma D, Savini L, et al. (2015) Predicting Epidemic Risk from Past Temporal Contact Data. PLoS Comput Biol 11(3): e1004152. http://dx.doi.org/10.1371/journal.pcbi.1004152 ;

more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

Manipulation and abuse on social media

The computer science research community has became increasingly interested in the study of social media due to their pervasiveness in the everyday life of millions of individuals. Methodological questions and technical challenges abound as more and more data from social platforms become available for analysis. This data deluge not only yields the unprecedented opportunity to unravel questions about online individuals' behavior at scale, but also allows to explore the potential perils that the massive adoption of social media brings to our society. These communication channels provide plenty of incentives (both economical and social) and opportunities for abuse. As social media activity became increasingly intertwined with the events in the offline world, individuals and organizations have found ways to exploit these platforms to spread misinformation, to attack and smear others, or to deceive and manipulate. During crises, social media have been effectively used for emergency response, but fear-mongering actions have also triggered mass hysteria and panic. Criminal gangs and terrorist organizations like ISIS adopt social media for propaganda and recruitment. Synthetic activity and social bots have been used to coordinate orchestrated astroturf campaigns, to manipulate political elections and the stock market. The lack of effective content verification systems on many of these platforms, including Twitter and Facebook, rises concerns when younger users become exposed to cyber-bulling, harassment, or hate speech, inducing risks like depression and suicide. This article illustrates some of the recent advances facing these issues and discusses what it remains to be done, including the challenges to address in the future to make social media a more useful and accessible, safer and healthier environment for all users.


Manipulation and abuse on social media
Emilio Ferrara

http://arxiv.org/abs/1503.03752


more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

Behavior of early warnings near the critical temperature in the two-dimensional Ising model

Among the properties that are common to complex systems, the presence of critical thresholds in the dynamics of the system is one of the most important. Recently, there has been interest in the universalities that occur in the behavior of systems near critical points. These universal properties make it possible to estimate how far a system is from a critical threshold. Several early-warning signals have been reported in time series representing systems near catastrophic shifts. The proper understanding of these early-warnings may allow the prediction and perhaps control of these dramatic shifts in a wide variety of systems. In this paper we analyze this universal behavior for a system that is a paradigm of phase transitions, the Ising model. We study the behavior of the early-warning signals and the way the temporal correlations of the system increase when the system is near the critical point.


Behavior of early warnings near the critical temperature in the two-dimensional Ising model
Irving O. Morales, Emmanuel Landa, Carlos Calderon Angeles, Juan C. Toledo, Ana Leonor Rivera, Joel Mendoza-Temis, Alejandro Frank

http://arxiv.org/abs/1502.06048

more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

Daily rhythms in mobile telephone communication

Circadian rhythms are known to be important drivers of human activity and the recent availability of electronic records of human behaviour has provided fine-grained data of temporal patterns of activity on a large scale. Further, questionnaire studies have identified important individual differences in circadian rhythms, with people broadly categorised into morning-like or evening-like individuals. However, little is known about the social aspects of these circadian rhythms, or how they vary across individuals. In this study we use a unique 18-month dataset that combines mobile phone calls and questionnaire data to examine individual differences in the daily rhythms of mobile phone activity. We demonstrate clear individual differences in daily patterns of phone calls, and show that these individual differences are persistent despite a high degree of turnover in the individuals' social networks. Further, women's calls were longer than men's calls, especially during the evening and at night, and these calls were typically focused on a small number of emotionally intense relationships. These results demonstrate that individual differences in circadian rhythms are not just related to broad patterns of morningness and eveningness, but have a strong social component, in directing phone calls to specific individuals at specific times of day.


Daily rhythms in mobile telephone communication

Talayeh Aledavood, Eduardo López, Sam G. B. Roberts, Felix Reed-Tsochas, Esteban Moro, Robin I. M. Dunbar, Jari Saramäki

http://arxiv.org/abs/1502.06866

more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

The dark side of cosmology: Dark matter and dark energy

A simple model with only six parameters (the age of the universe, the density of atoms, the density of matter, the amplitude of the initial fluctuations, the scale dependence of this amplitude, and the epoch of first star formation) fits all of our cosmological data . Although simple, this standard model is strange. The model implies that most of the matter in our Galaxy is in the form of “dark matter,” a new type of particle not yet detected in the laboratory, and most of the energy in the universe is in the form of “dark energy,” energy associated with empty space. Both dark matter and dark energy require extensions to our current understanding of particle physics or point toward a breakdown of general relativity on cosmological scales.


The dark side of cosmology: Dark matter and dark energy
David N. Spergel

Science 6 March 2015:
Vol. 347 no. 6226 pp. 1100-1102
http://dx.doi.org/10.1126/science.aaa0980

more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

A sustainable model for antibiotics

Despite the alarming increase in the prevalence of drug-resistant bacterial infections, far fewer new antibiotics have been approved in the past decade than at the peak in the 1980s (1). The situation is particularly alarming for serious infections by Gram-negative bacteria, some of which are becoming untreatable by modern antibiotics (2–4). Particularly in low- and middle-income countries, untreatable infections are becoming an everyday reality in hospital and care settings (5). Increasing recognition of this problem is spurring a number of public and private initiatives on both sides of the Atlantic (6–8). To more effectively counter the threat of emerging resistance, we must increase the number of innovative new antibiotics in development and harness advances in diagnostic technology to preserve their efficacy.


A sustainable model for antibiotics
Manos Perros

Science 6 March 2015:
Vol. 347 no. 6226 pp. 1062-1064
http://dx.doi.org/10.1126/science.aaa3048

more...
No comment yet.
Suggested by Fil Menczer
Scoop.it!

Measuring Online Social Bubbles

Measuring Online Social Bubbles | Papers | Scoop.it

Social media have quickly become a prevalent channel to access information, spread ideas, and influence opinions. However, it has been suggested that social and algorithmic filtering may cause exposure to less diverse points of view, and even foster polarization and misinformation. Here we explore and validate this hypothesis quantitatively for the first time, at the collective and individual levels, by mining three massive datasets of web traffic, search logs, and Twitter posts. Our analysis shows that collectively, people access information from a significantly narrower spectrum of sources through social media and email, compared to search. The significance of this finding for individual exposure is revealed by investigating the relationship between the diversity of information sources experienced by users at the collective and individual level. There is a strong correlation between collective and individual diversity, supporting the notion that when we use social media we find ourselves inside "social bubbles". Our results could lead to a deeper understanding of how technology biases our exposure to new information.


Measuring Online Social Bubbles
Dimitar Nikolov, Diego F. M. Oliveira, Alessandro Flammini, Filippo Menczer

http://arxiv.org/abs/1502.07162


more...
No comment yet.
Suggested by Matteo Chinazzi
Scoop.it!

Knowledge-Based Trust: Estimating the Trustworthiness of Web Sources

The quality of web sources has been traditionally evaluated using exogenous signals such as the hyperlink structure of the graph. We propose a new approach that relies on endogenous signals, namely, the correctness of factual information provided by the source. A source that has few false facts is considered to be trustworthy. The facts are automatically extracted from each source by information extraction methods commonly used to construct knowledge bases. We propose a way to distinguish errors made in the extraction process from factual errors in the web source per se, by using joint inference in a novel multi-layer probabilistic model. We call the trustworthiness score we computed Knowledge-Based Trust (KBT). On synthetic data, we show that our method can reliably compute the true trustworthiness levels of the sources. We then apply it to a database of 2.8B facts extracted from the web, and thereby estimate the trustworthiness of 119M webpages. Manual evaluation of a subset of the results confirms the effectiveness of the method.


Knowledge-Based Trust: Estimating the Trustworthiness of Web Sources
Xin Luna Dong, Evgeniy Gabrilovich, Kevin Murphy, Van Dang, Wilko Horn, Camillo Lugaresi, Shaohua Sun, Wei Zhang

http://arxiv.org/abs/1502.03519v1

more...
No comment yet.
Suggested by Segismundo
Scoop.it!

Fast and asymptotic computation of the fixation probability for Moran processes on graphs

Population genetics studies the genetic composition of biological populations, and the changes in this composition that result from the action of four different processes: natural selection, random drift, mutation and migration. The modern evolutionary synthesis combines Darwin's thesis on natural selection and Mendel's theory of inheritance.
more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

Defining the Anthropocene

Time is divided by geologists according to marked shifts in Earth’s state. Recent global environmental changes suggest that Earth may have entered a new human-dominated geological epoch, the Anthropocene. Here we review the historical genesis of the idea and assess anthropogenic signatures in the geological record against the formal requirements for the recognition of a new epoch. The evidence suggests that of the various proposed dates two do appear to conform to the criteria to mark the beginning of the Anthropocene: 1610 and 1964. The formal establishment of an Anthropocene Epoch would mark a fundamental change in the relationship between humans and the Earth system.


Defining the Anthropocene
Simon L. Lewis & Mark A. Maslin

Nature 519, 171–180 (12 March 2015) http://dx.doi.org/10.1038/nature14258 ;

more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

Co-evolutionary Dynamics of Collective Action with Signaling for a Quorum

From humans to social insects and bacteria, decision-making is often influenced by some form of collective signaling, be it quorum, information exchange, pledges or announcements. Here we investigate how such signaling systems evolve when collective action entails a public good, and how meanings co-evolve with individual choices, given Nature’s most prevalent states. We find a rich scenario, showing how natural selection is able to evolve a costly quorum signaling system that allows individuals to coordinate their action so as to provide the appropriate response to different states of Nature. We show that signaling robustly and selectively promotes cooperative collective action when coordinated action is most needed. In light of our results, and despite the complexity that collective action relying on quorum signaling may entail, it is not so surprising how signaling is a ubiquitous property of the living world.


Pacheco JM, Vasconcelos VV, Santos FC, Skyrms B (2015) Co-evolutionary Dynamics of Collective Action with Signaling for a Quorum. PLoS Comput Biol 11(2): e1004101. http://dx.doi.org/10.1371/journal.pcbi.1004101 ;

more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

Ten Simple Rules for Lifelong Learning, According to Hamming

Rule 1. Cultivate Lifelong Learning as a “Style of Thinking” That Concentrates on Fundamental Principles Rather Than on Facts
Rule 2. Structure Your Learning to Ride the Information Tsunami Rather Than Drown in It
Rule 3. Be Prepared to Compete and Interact with a Greater and More Rapidly Increasing Number of Scientists Than at Any Time in the Past
Rule 4. Focus on the Future but Don’t Ignore the Past
Rule 5. Look for the Personal Angle
Rule 6. Learn from the Successes of Others
Rule 7. Use Trial and Error to Find the Style of Learning That Suits You
Rule 8. No Matter How Much Advice You Get and How Much Talent You Possess, It Is Still You Who Must Do the Learning and Put in the Time
Rule 9. Have a Vision to Give You a General Direction
Rule 10. Make Your Life Count: Struggle for Excellence


Erren TC, Slanger TE, Groß JV, Bourne PE, Cullen P (2015) Ten Simple Rules for Lifelong Learning, According to Hamming. PLoS Comput Biol 11(2): e1004020. http://dx.doi.org/10.1371/journal.pcbi.1004020 

more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

Modeling infectious disease dynamics in the complex landscape of global health

Despite some notable successes in the control of infectious diseases, transmissible pathogens still pose an enormous threat to human and animal health. The ecological and evolutionary dynamics of infections play out on a wide range of interconnected temporal, organizational, and spatial scales, which span hours to months, cells to ecosystems, and local to global spread. Moreover, some pathogens are directly transmitted between individuals of a single species, whereas others circulate among multiple hosts, need arthropod vectors, or can survive in environmental reservoirs. Many factors, including increasing antimicrobial resistance, increased human connectivity and changeable human behavior, elevate prevention and control from matters of national policy to international challenge. In the face of this complexity, mathematical models offer valuable tools for synthesizing information to understand epidemiological patterns, and for developing quantitative evidence for decision-making in global health.


Modeling infectious disease dynamics in the complex landscape of global health
Hans Heesterbeek, et al.

Science 13 March 2015:
Vol. 347 no. 6227
http://dx.doi.org/10.1126/science.aaa4339 ;

more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

The Evolution of Popular Music: USA 1960-2010

In modern societies, cultural change seems ceaseless. The flux of fashion is especially obvious for popular music. While much has been written about the origin and evolution of pop, most claims about its history are anecdotal rather than scientific in nature. To rectify this we investigate the US Billboard Hot 100 between 1960 and 2010. Using Music Information Retrieval (MIR) and text-mining tools we analyse the musical properties of ~17,000 recordings that appeared in the charts and demonstrate quantitative trends in their harmonic and timbral properties. We then use these properties to produce an audio-based classification of musical styles and study the evolution of musical diversity and disparity, testing, and rejecting, several classical theories of cultural change. Finally, we investigate whether pop musical evolution has been gradual or punctuated. We show that, although pop music has evolved continuously, it did so with particular rapidity during three stylistic "revolutions" around 1964, 1983 and 1991. We conclude by discussing how our study points the way to a quantitative science of cultural change.


The Evolution of Popular Music: USA 1960-2010
Matthias Mauch, Robert M. MacCallum, Mark Levy, Armand M. Leroi

http://arxiv.org/abs/1502.05417

more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

Quantum Criticality at the Origin of Life

Why life persists at the edge of chaos is a question at the very heart of evolution. Here we show that molecules taking part in biochemical processes from small molecules to proteins are critical quantum mechanically. Electronic Hamiltonians of biomolecules are tuned exactly to the critical point of the metal-insulator transition separating the Anderson localized insulator phase from the conducting disordered metal phase. Using tools from Random Matrix Theory we confirm that the energy level statistics of these biomolecules show the universal transitional distribution of the metal-insulator critical point and the wave functions are multifractals in accordance with the theory of Anderson transitions. The findings point to the existence of a universal mechanism of charge transport in living matter. The revealed bio-conductor material is neither a metal nor an insulator but a new quantum critical material which can exist only in highly evolved systems and has unique material properties.


Quantum Criticality at the Origin of Life
Gabor Vattay, Dennis Salahub, Istvan Csabai, Ali Nassimi, Stuart A. Kaufmann

http://arxiv.org/abs/1502.06880

more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

Self-organized pattern formation in coastal barrier washover deposits

Storm-driven overwash is a sediment-transport process fundamental to the evolution of low-lying coastal environments. Physical insight into overwash morphodynamics is crucial for improved risk assessment and hazard forecasting in vulnerable coastal zones. Spatially extended observations of washover deposits have shown that back-barrier shoreline planforms can be quasi-periodic. These rhythmic patterns have been attributed to the influence of a forcing template in bathymetry or topography, or as inherent in the forcing itself. With an alternative to this prevailing explanation, we present results of a physical experiment and numerical model in which quasi-periodic patterns in washover deposits are self-organized, arising from interactions between barrier topography, routing of overwash flow, and sediment flux.


Self-organized pattern formation in coastal barrier washover deposits
Eli D. Lazarus and Scott Armstrong

Geology

http://geology.gsapubs.org/content/early/2015/02/26/G36329.1.abstract

more...
No comment yet.
Suggested by Kazutoshi Sasahara
Scoop.it!

Selection for Representation in Higher-Order Adaptation

Selection for Representation in Higher-Order Adaptation

By Solvi Arnold, Reiji Suzuki, Takaya Arita

 

A theory of the evolution of mind cannot be complete without an explanation of how cognition became representational. Artificial approximations of cognitive evolution do not, in general, produce representational cognition. We take this as an indication that there is a gap in our understanding of what drives evolution towards representational solutions, and propose a theory to fill this gap. We suggest selection for learning and selection for second order learning as the causal factors driving the emergence of innate and acquired forms of representation, respectively. Cognition is commonly viewed as a “black box”—selection works on externally visible behaviour alone, with little regard for implementation structure. Yet even if implementation structure is not constrained by selection on behaviour, implementation structure does affect how easy or difficult it is to make specific modifications to the behaviour. Hence selection for learning can affect the implementation structure of behaviour. Similarly, the implementation structure of learning ability itself is not under direct selection, but selection for second order learning can affect the implementation structure of first order learning. We argue that these indirect selection effects guide evolution towards representational implementations, as structural alignment between implementation structure and environment structure guarantees that simple changes in the environment can be met with simple changes in implementation. We illustrate the theory with examples of computational investigations, and discuss how the theory may help put representational cognition within reach of purely connectionist AI.

more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

A century of general relativity: Astrophysics and cosmology

One hundred years after its birth, general relativity has become a highly successful physical theory in the sense that it has passed a large number of experimental and observational tests and finds extensive application to a wide variety of cosmic phenomena. It remains an active area of research as new tests are on the way, epitomized by the exciting prospect of detecting gravitational waves from merging black holes. General relativity is the essential foundation of the standard model of cosmology and underlies our description of the black holes and neutron stars that are ultimately responsible for the most powerful and dramatic cosmic sources. Its interface with physics on the smallest and largest scales will continue to provide fertile areas of investigation in its next century.


A century of general relativity: Astrophysics and cosmology
R. D. Blandford

Science 6 March 2015:
Vol. 347 no. 6226 pp. 1103-1108
http://dx.doi.org/10.1126/science.aaa4033

more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

Citizen CyberScience ─ New Directions and Opportunities for Human Computation

“There are already hundreds of thousands of people actively contributing to citizen cyberscience - we want to reach tens of millions.” ― Francois Grey, Citizen Cyberscience Centre Coordinator
“Citizen Cyberscience offers people around the world the opportunity to contribute to cutting- edge scientific research that may be of fundamental significance, as well as having applications relevant to their own lives.” ― John Ellis, CERN and James Clerk Maxwell Professor of Theoretical Physics at Kings College London
“Citizen Cyberscience has great potential not only for scientific researchers, but also for those working in the humanities and cultural heritage.” ― Mark Hedges, Deputy Director of the Centre for e-Research at King’s College London
“The power of the Internet and the growing public availability of scientific and other data have made possible the involvement of a wide variety of communities and citizens in a range of activities that... break new ground in public awareness and direct participation in important areas of scientific research.” ― Professor John Darlington, Director of the London e-Science Centre


Citizen CyberScience ─ New Directions and Opportunities for Human Computation
GREG NEWMAN

Human Computation (2014) 1:2:103-109 © 2014, Newman. CC-BY-3.0 ISSN: 2330-8001, DOI: 10.15346/hc.v1i2.2

more...
No comment yet.
Suggested by Joseph Lizier
Scoop.it!

Information flow through a model of the C. elegans klinotaxis circuit

Understanding how information about external stimuli is transformed into behavior is one of the central goals of neuroscience. Here we characterize the information flow through a complete sensorimotor circuit: from stimulus, to sensory neurons, to interneurons, to motor neurons, to muscles, to motion. Specifically, we apply a recently developed framework for quantifying information flow to a previously published ensemble of models of salt klinotaxis in the nematode worm C. elegans. The models are grounded in the neuroanatomy and currently known neurophysiology of the worm. The unknown model parameters were optimized to reproduce the worm's behavior. Information flow analysis reveals several key principles underlying how the models operate: (1) Interneuron class AIY is responsible for integrating information about positive and negative changes in concentration, and exhibits a strong left/right information asymmetry. (2) Gap junctions play a crucial role in the transfer of information responsible for the information symmetry observed in interneuron class AIZ. (3) Neck motor neuron class SMB implements an information gating mechanism that underlies the circuit's state-dependent response. (4) The neck carries non-uniform distribution about changes in concentration. Thus, not all directions of movement are equally informative. Each of these findings corresponds to an experimental prediction that could be tested in the worm to greatly refine our understanding of the neural circuit underlying klinotaxis. Information flow analysis also allows us to explore how information flow relates to underlying electrophysiology. Despite large variations in the neural parameters of individual circuits, the overall information flow architecture circuit is remarkably consistent across the ensemble, suggesting that information flow analysis captures general principles of operation for the klinotaxis circuit.

 

"Information flow through a model of the C. elegans klinotaxis circuit"
Eduardo J. Izquierdo, Paul L. Williams, Randall D. Beer
arXiv:1502.04262, 2015
http://arxiv.org/abs/1502.04262

more...
No comment yet.