Global slowing of network oscillations in mouse neocortex by diazepam

SCHEFFZUK, C. , KUKUSHKA, V. , VYSSOTSKI, A. L. , DRAGUHN, A. , TORT, A. B. L. , BRANKACK, J. . Global slowing of network oscillations in mouse neocortex by diazepam. Neuropharmacology , v. 65, p. 123-133, 2013.

Undersampled Critical Branching Processes on Small-World and Random Networks Fail to Reproduce the Statistics of Spike Avalanches

The power-law size distributions obtained experimentally for neuronal avalanches are an important evidence of criticality in the brain. This evidence is supported by the fact that a critical branching process exhibits the same exponent t~3=2. Models at criticality have been employed to mimic avalanche propagation and explain the statistics observed experimentally. However, a crucial aspect of neuronal recordings has been almost completely neglected in the models: undersampling. While in a typical multielectrode array hundreds of neurons are recorded, in the same area of neuronal tissue tens of thousands of neurons can be found. Here we investigate the consequences of undersampling in models with three different topologies (two-dimensional, small-world and random network) and three different dynamical regimes (subcritical, critical and supercritical). We found that undersampling modifies avalanche size distributions, extinguishing the power laws observed in critical systems. Distributions from subcritical systems are also modified, but the shape of the undersampled distributions is more similar to that of a fully sampled system. Undersampled supercritical systems can recover the general characteristics of the fully sampled version, provided that enough neurons are measured. Undersampling in two-dimensional and small-world networks leads to similar effects, while the random network is insensitive to sampling density due to the lack of a well-defined neighborhood. We conjecture that neuronal avalanches recorded from local field potentials avoid undersampling effects due to the nature of this signal, but the same does not hold for spike avalanches. We conclude that undersampled branching-process-like models in these topologies fail to reproduce the statistics of spike avalanches.

Global slowing of network oscillations in mouse neocortex by diazepam

SCHEFFZUK, C. , KUKUSHKA, V. , VYSSOTSKI, A. L. , DRAGUHN, A. , TORT, A. B. L. , BRANKACK, J. . Global slowing of network oscillations in mouse neocortex by diazepam. Neuropharmacology , v. 65, p. 123-133, 2013.

Undersampled Critical Branching Processes on Small-World and Random Networks Fail to Reproduce the Statistics of Spike Avalanches

The power-law size distributions obtained experimentally for neuronal avalanches are an important evidence of criticality in the brain. This evidence is supported by the fact that a critical branching process exhibits the same exponent t~3=2. Models at criticality have been employed to mimic avalanche propagation and explain the statistics observed experimentally. However, a crucial aspect of neuronal recordings has been almost completely neglected in the models: undersampling. While in a typical multielectrode array hundreds of neurons are recorded, in the same area of neuronal tissue tens of thousands of neurons can be found. Here we investigate the consequences of undersampling in models with three different topologies (two-dimensional, small-world and random network) and three different dynamical regimes (subcritical, critical and supercritical). We found that undersampling modifies avalanche size distributions, extinguishing the power laws observed in critical systems. Distributions from subcritical systems are also modified, but the shape of the undersampled distributions is more similar to that of a fully sampled system. Undersampled supercritical systems can recover the general characteristics of the fully sampled version, provided that enough neurons are measured. Undersampling in two-dimensional and small-world networks leads to similar effects, while the random network is insensitive to sampling density due to the lack of a well-defined neighborhood. We conjecture that neuronal avalanches recorded from local field potentials avoid undersampling effects due to the nature of this signal, but the same does not hold for spike avalanches. We conclude that undersampled branching-process-like models in these topologies fail to reproduce the statistics of spike avalanches.

Determinantes de competitividade de destinos turísticos aplicados aos roteiros regionais: uma avaliação do roteiro Seridó/RN

The tourism industry is gaining representation by move and stimulate the economy, especially by allowing the generation of employment and income, thus allowing growth opportunities for localities where tourism develops. Therefore, the present study entitled determinants of competitiveness of tourist destinations applied to regional routes: an evaluation of the Route of Seridó/RN, discusses the issue of competitiveness in tourism and tries to understand the scenery of this Route. The main objective of the study is to assess the conditions of competitiveness in the Route of Seridó/RN according to benchmarks and global determinants of competitiveness for tourist destinations. The study has also as specifics objectives: define dimensions of the reference model for use in evaluating the competitiveness of the Route of Seridó/RN; identify levels of governance and competitiveness in the municipalities that make up the sample set above the Route, and analyze to what extent the competitiveness of the Route correspond to the global reference of competitiveness of tourism destinations. Regarding the methodology, it is a search for an exploratory- descriptive and used a combination of quantitative and qualitative research method as expected and required in the implementation of the evaluation tool called Compet&enible Model. For data collection, it has been taken technical visits and also analysis of documents and materials. Data analysis was based on the records and documents and the use of simple descriptive statistics for the scores of the elements offered by Compet&enible Model. The results allowed us to know the real conditions of competitiveness of the Seridó/RN Route forward to the attributes of tourist destinations for global competitiveness: the dimension I, Governance, reached 17 points, classified as "in structuring" and dimension II, Competitiveness, reached 10 points, ranking "weak". These results highlight the need for greater involvement of the actors in the supply chain of tourism in Polo Seridó/RN for the actions, programs and projects are put into practice. It is expected that tourism is considered an important activity for the local and global development, serving as a reference for the future management of Seridó/RN Route, guiding new policy guidelines, planning and organization to better competitiveness