Structured chaos shapes spike-response noise entropy in balanced neural networks

Large networks of sparsely coupled, excitatory and inhibitory cells occur throughout the brain. A striking feature of these networks is that they are chaotic. How does this chaos manifest in the neural code? Specifically, how variable are the spike patterns that such a network produces in response to an input signal? To answer this, we derive a bound for the entropy of multi-cell spike pattern distributions in large recurrent networks of spiking neurons responding to fluctuating inputs. The analysis is based on results from random dynamical systems theory and is complimented by detailed numerical simulations. We find that the spike pattern entropy is an order of magnitude lower than what would be extrapolated from single cells. This holds despite the fact that network coupling becomes vanishingly sparse as network size grows -- a phenomenon that depends on ``extensive chaos," as previously discovered for balanced networks without stimulus drive. Moreover, we show how spike pattern entropy is controlled by temporal features of the inputs. Our findings provide insight into how neural networks may encode stimuli in the presence of inherently chaotic dynamics.Comment: 9 pages, 5 figure

Alien Registration- Thivierge, Paul (Van Buren, Aroostook County)

https://digitalmaine.com/alien_docs/32281/thumbnail.jp

Matrix Operators in Georgian Indexical Shift

This paper examines indexical shift in Georgian (South Caucasian), which has been noted but understudied in the literature. I argue that its matrix-level shift provides evidence in favour of the shifty operator theory (Anand and Nevins, 2004; Shklovsky and Sudo, 2014; Deal, 2020, i.a.). In these approaches, an embedded indexical is interpreted against a non-utterance context whose parameters are determined by an operator. Crucially, this operator is distinct from the verb that introduces it, which logically allows for the operator to merge freely in the structure. This prediction is evidenced by shifted indexicals in Georgian matrix clauses

Le profil d'application Normetic, version 1.1

Tiré de l'écran-titre (visionné le 27 juin 2017).Normetic est un profil d’application du standard IEEE 1484.12.1-2002 (LOM) (Learning Object Metadata)1 portant sur les métadonnées pour la description des ressources d’enseignement et d’apprentissage (REA). Nous définissons ces REA comme toute entité, numérique ou non numérique, conçue ou pouvant être utilisée pour des fins d’apprentissage, d’éducation et de formation2. Le profil d’application Normetic est une sélection d’éléments du standard LOM formant un sous-ensemble adapté aux besoins communs clairement définis par divers acteurs du domaine de l’éducation et de la formation

Étude de l'impact des droits de propriété intellectuelle sur les investissements directs étrangers: le cas des multinationales américaines

Rapport de rechercheNuméro de référence interne originel : a1.1 g 104

Note clinique sur le traitement pharmacologique de l’autisme

Cet article fait le point sur la pharmacologie de l'autisme et en survole rapidement l'utilité, F historique et les nouveautés. L'« autisme » ne fait référence à aucune pathophysiologie présentement connue. Et aucun médicament ou classe de médicaments ne peut prétendre guérir cette maladie, qui en recouvre plusieurs. Avant d'user de médicaments, efficaces pour soulager certains symptômes, il importe souvent de considérer le recours à des approches comportementales. Les développements en recherche font espérer que des médicaments pourront guérir ou prévenir cette maladie du cerveau.This article reviews the pharmacology of autism and briefly overviews its use, history and novelties. "Autism" does not refer to any pathophysiology currently known. And no drug or class of drugs can cure this illness which includes many. Before using drugs, efficient in relieving symptoms, it is important to consider the potential benefit of behavioral approaches. Developments in research give hope that drugs will cure or prevent this brain illness.Este articulo pone el acento en la farmacologia del autismo y râpidamente sobrevuela la utilidad, la historia y las novedades. El "autismo" no se refiere a ninguna fisiopatologia conocida en este momento. Ningún medicamento o clase de medicamentos puede pretender curar esta enfermedad, que encubre varias. Antes de usar medicamentos, eficaces para aliviar ciertos sintomas, conviene considerar el recurso a las terapéuticas ya probadas. Los desarrollos de la investigacion dejan créer que los medicamentos podrân curar o prévenir esta enfermedad cerebral

Revisiting chaos in stimulus-driven spiking networks: signal encoding and discrimination

Highly connected recurrent neural networks often produce chaotic dynamics, meaning their precise activity is sensitive to small perturbations. What are the consequences for how such networks encode streams of temporal stimuli? On the one hand, chaos is a strong source of randomness, suggesting that small changes in stimuli will be obscured by intrinsically generated variability. On the other hand, recent work shows that the type of chaos that occurs in spiking networks can have a surprisingly low-dimensional structure, suggesting that there may be "room" for fine stimulus features to be precisely resolved. Here we show that strongly chaotic networks produce patterned spikes that reliably encode time-dependent stimuli: using a decoder sensitive to spike times on timescales of 10's of ms, one can easily distinguish responses to very similar inputs. Moreover, recurrence serves to distribute signals throughout chaotic networks so that small groups of cells can encode substantial information about signals arriving elsewhere. A conclusion is that the presence of strong chaos in recurrent networks does not prohibit precise stimulus encoding.Comment: 8 figure

Lien social et développement économique : l’économie sociale au Bas-St-Laurent

La première partie de ce cahier sera centrée sur la trame conceptuelle de notre réflexion au travers de laquelle nous remettrons en perspective la distinction communauté/société. Les limites de cette distinction, la crise contemporaine de la modernité s’accompagnant d’une crise de la solidarité et des liens sociaux, nous amèneront sur le terrain de l’émergence possible de nouvelles formes communautaires. En deuxième partie, en nous appuyant sur de nombreuses données empiriques de recherche, nous chercherons à décrire comment l’économie sociale produit elle-même du lien social et économique. En cela, et ce sera la troisième et dernière partie, les pratiques contemporaines d’économie sociale seront envisagées comme le terreau de l’apparition de nouvelles formes de liens communautaires

Statistical Evaluation of Waveform Collapse Reveals Scale-Free Properties of Neuronal Avalanches

Neural avalanches are a prominent form of brain activity characterized by network-wide bursts whose statistics follow a power-law distribution with a slope near 3/2. Recent work suggests that avalanches of different durations can be rescaled and thus collapsed together. This collapse mirrors work in statistical physics where it is proposed to form a signature of systems evolving in a critical state. However, no rigorous statistical test has been proposed to examine the degree to which neuronal avalanches collapse together. Here, we describe a statistical test based on functional data analysis, where raw avalanches are first smoothed with a Fourier basis, then rescaled using a time-warping function. Finally, an F ratio test combined with a bootstrap permutation is employed to determine if avalanches collapse together in a statistically reliable fashion. To illustrate this approach, we recorded avalanches from cortical cultures on multielectrode arrays as in previous work. Analyses show that avalanches of various durations can be collapsed together in a statistically robust fashion. However, a principal components analysis revealed that the offset of avalanches resulted in marked variance in the time-warping function, thus arguing for limitations to the strict fractal nature of avalanche dynamics. We compared these results with those obtained from cultures treated with an AMPA/NMDA receptor antagonist (APV/DNQX), which yield a power-law of avalanche durations with a slope greater than 3/2. When collapsed together, these avalanches showed marked misalignments both at onset and offset time-points. In sum, the proposed statistical evaluation suggests the presence of scale-free avalanche waveforms and constitutes an avenue for examining critical dynamics in neuronal systems