Phase transitions and self-organized criticality in networks of stochastic spiking neurons

Ludmila Brochini, Ariadne de Andrade Costa, Miguel Abadi, Antônio C. Roque, Jorge Stolfi and Osame Kinouchi

Phase transitions and critical behavior are crucial issues both in theoretical and experimental neuroscience. We report analytic and computational results about phase transitions and self-organized criticality (SOC) in networks with general stochastic neurons. The stochastic neuron has a firing probability given by a smooth monotonic function Φ(V) of the membrane potential V, rather than a sharp firing threshold. We find that such networks can operate in several dynamic regimes (phases) depending on the average synaptic weight and the shape of the firing function Φ. In particular, we encounter both continuous and discontinuous phase transitions to absorbing states. At the continuous transition critical boundary, neuronal avalanches occur whose distributions of size and duration are given by power laws, as observed in biological neural networks. We also propose and test a new mechanism to produce SOC: the use of dynamic neuronal gains – a form of short-term plasticity probably located at the axon initial segment (AIS) – instead of depressing synapses at the dendrites (as previously studied in the literature). The new self-organization mechanism produces a slightly supercritical state, that we called SOSC, in accord to some intuitions of Alan Turing.

Opening for Web-based and mobile application design Scholarship

The Research, Innovation and Dissemination Center on Neuromathematics (NeuroMat) is offering a FAPESP scholarship for information technology professionals interested in being part of a breakthrough and innovative scientific project. The recipient will interact with researchers from USP and other NeuroMat collaborating institutions in activities of development, customization, maintenance and deployment of open software related to the scientific goals of the center.

Openings for Software Developers

The Research, Innovation and Dissemination Center on Neuromathematics (RIDC NeuroMat) is offering scholarships for information technology professionals interested in being part of a breakthrough and innovative scientific project.

Motor Coordination Correlates with Academic Achievement and Cognitive Function in Children

Valter R. Fernandes, Michelle L. Scipião Ribeiro, Thais Melo, Paulo de Tarso Maciel-Pinheiro, Thiago T. Guimarães, Narahyana B. Araújo, Sidarta Ribeiro and Andréa C. Deslandes

The relationship between exercise and cognition is an important topic of research that only recently began to unravel. Here, we set out to investigate the relation between motor skills, cognitive function, and school performance in 45 students from 8 to 14 years of age. We used a cross-sectional design to evaluate motor coordination (Touch Test Disc), agility (Shuttle Run Speed—running back and forth), school performance (Academic Achievement Test), the Stroop test, and six sub-tests of the Wechsler Intelligence Scale for Children-IV (WISC-IV). We found, that the Touch Test Disc was the best predictor of school performance (R2 = 0.20). Significant correlations were also observed between motor coordination and several indices of cognitive function, such as the total score of the Academic Achievement Test (AAT; Spearman's rho = 0.536; p ≤ 0.001), as well as two WISC-IV sub-tests: block design (R = −0.438; p = 0.003) and cancelation (rho = −0.471; p = 0.001). All the other cognitive variables pointed in the same direction, and even correlated with agility, but did not reach statistical significance. Altogether, the data indicate that visual motor coordination and visual selective attention, but not agility, may influence academic achievement and cognitive function. The results highlight the importance of investigating the correlation between physical skills and different aspects of cognition.

Second NeuroMat Workshop: New Frontiers in NeuroMathematics

The Research, Innovation and Dissemination Center for Neuromathematics (NeuroMat) will hold the Second NeuroMat Workshop: New Frontiers in NeuroMathematics, in São Paulo, from November 22 to 25, 2016. NeuroMat is hosted by the University of São Paulo and supported by the São Paulo Research Foundation (FAPESP). The event's official website is: neuromat.numec.prp.usp.br/nm2w.

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The Research, Innovation and Dissemination Center for Neuromathematics is hosted by the University of São Paulo and funded by FAPESP (São Paulo Research Foundation).

 

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