1,721,031 research outputs found
Improving an open-source commercial system to reliably perform activity-dependent stimulation
No full textObjective. Activity-dependent stimulation (ADS) is designed to strengthen the connections between neuronal circuits and therefore may be a promising tool for promoting neurophysiological reorganization following a brain injury. To successfully perform this technique, two criteria must be met: (1) spikes in the extracellular electrical field potential must be detected accurately at one site of interest, and (2) stimulation pulses generated at fixed (< 1 ms jitter), low-latency (< 10ms) intervals relative to each detected spike must be delivered reliably to a second site of interest. Here, we aimed to improve noise rejection in a low-cost commercial system to reliably perform ADS in awake, behaving rats, while maintaining latency requirements. Approach. We implemented a spike detection state machine on a field-programmable gate array (FPGA). Because the accuracy of spike detection can be heavily reduced in awake and behaving animals due to biological artifacts such as movement and chewing, the state machine tracks candidate spike waveforms, checking them against multiple programmable thresholds and rejecting any spikes that fail to meet a programmed threshold criterion. Main Results. A series of offline analyses showed that our implementation was able to appropriately trigger stimulation during epochs of biological artifacts with an overall accuracy between 72% and 97%, fixed computational latency of 167 mu s, and an algorithmic latency of 300 mu s to 800 mu s. Significance. Our improvements have been made open-source and are freely available to all scientists working on closed-loop neuroprosthetic devices. Importantly, the improvements are easily incorporated into existing workflows that utilize the Intan Stimulation and Recording Controller
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Réseaux de neurones sur silicium : une approche mixte, analogique / numérique, pour l'étude des phénomènes d'adaptation, d'apprentissage et de plasticité
No full textThis work addresses the integration issues for neurominetic integrated circuits de-dicated to computationnal neuroscience, in the context of adaptive neural networks. Those circuits implement a biologically realistic model. This model is continuously solved in real time. the network adaptation is also computed in real time by digital means using sofware and or hardware material. The software part of the system is handled by a computer, interfaced to the system through the PCI bus, whereas the hardware part uses FPGAS. Three generations of the simulation system are presented, followed by a critical analysis on their performance as analog neural network simulators.Dans un contexte où l'usage de circuits neuromimétiques se généralise au sein des neurosciences, nous étudions ici leur intégration au sein de réseaux adaptatifs. Les circuits mis en oeuvre se basent sur un modèle proche de la biologie résolu en continu et en temps réel. Les calculs relatifs à l'adaptation du réseau sont réalisés en numérique temps réel, logiciel et/ou matériel. La partie logicielle est assurée par un ordinateur interfacé à travers le bus PCI, tandis que la partie matérielle utilise des EPGAS. Trois générations sont présentés avec une analyse critique sur leur utilisation comme système de simulation de réseau neuronal
Réseaux de neurones sur Silicium : une approche mixte analogique / numérique pour l'étude des phénomènes d'adaptation, d'apprentissage et de plasticité
No full textDans un contexte où l'usage de circuits neuromimétiques se généralise au sein des neurosciences, nous étudions ici leur intégration au sein de réseaux adaptatifs. Les circuits mis en oeuvre se basent sur un modèle proche de la biologie résolu en continu et en temps réel. Les calculs relatifs à l'adaptation du réseau sont réalisés en numérique temps réel, logiciel et/ou matériel. La partie logicielle est assurée par un ordinateur interfacé à travers le bus PCI, tandis que la partie matérielle utilise des EPGAS. Trois générations sont présentés avec une analyse critique sur leur utilisation comme système de simulation de réseau neuronal.This work addresses the integration issues for neurominetic integrated circuits de-dicated to computationnal neuroscience, in the context of adaptive neural networks. Those circuits implement a biologically realistic model. This model is continuously solved in real time. the network adaptation is also computed in real time by digital means using sofware and or hardware material. The software part of the system is handled by a computer, interfaced to the system through the PCI bus, whereas the hardware part uses FPGAS. Three generations of the simulation system are presented, followed by a critical analysis on their performance as analog neural network simulators
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Systems and methods for adaptive and real-time detection of biological activity
No full textL’intéraction entre la biologie et l’électronique est une discpline en pleine essort. De nom-breux systèmes électroniques tentent de s’interconnecter avec des tissus ou des cellules vivantesafin de décoder l’information biologique. Le Potentiel d’action (PA) est au coeur de codagebiologique et par conséquent il est nécéssaire de pouvoir les repérer sur tout type de signal bio-logique. Par conséquent, nous étudions dans ce manuscrit la possibilité de concevoir un circuitélectronique couplé à un système de microélectrodes capable d’effectuer une acquisition, unedétection des PAs et un enregistrement des signaux biologiques. Que ce soit en milieu bruitéou non, nous considérons le taux de détection de PA et la contrainte de temps réel commedes notions primordiales et la consommation en silicium comme un prix à payer. Initialementdéveloppés pour l’étude de signaux neuronaux et pancréatiques, ces systèmes conviennent par-faitement pour d’autres type de cellules.Interaction between biology and electronic is in expansion. Many electronic systems aretrying to interconnect with tissues or living cells to decode biological information. The ActionPotential (AP) is the heart of biological coding and therefore it is necessary to be able to locateit from any type of biological signal. Therefore, we study in this manuscript the possibility ofdesigning an electronic circuit coupled to microelectrodes capable of acquisition, detection ofPAs and recording of biological signals. Whether or not in a noisy environment, we consider thedetection rate of PA and the real time-computing constraint as an hard specificationand andsilicon area as a price to pay. Initially developed for the study of neural signals and pancreatic,these systems are ideal for other types of cells
Réseaux de neurones sur silicium : une approche mixte, analogique / numérique, pour l'étude des phénomènes d'adaptation, d'apprentissage et de plasticité
No full textThis work addresses the integration issues for neurominetic integrated circuits de-dicated to computationnal neuroscience, in the context of adaptive neural networks. Those circuits implement a biologically realistic model. This model is continuously solved in real time. the network adaptation is also computed in real time by digital means using sofware and or hardware material. The software part of the system is handled by a computer, interfaced to the system through the PCI bus, whereas the hardware part uses FPGAS. Three generations of the simulation system are presented, followed by a critical analysis on their performance as analog neural network simulators.Dans un contexte où l'usage de circuits neuromimétiques se généralise au sein des neurosciences, nous étudions ici leur intégration au sein de réseaux adaptatifs. Les circuits mis en oeuvre se basent sur un modèle proche de la biologie résolu en continu et en temps réel. Les calculs relatifs à l'adaptation du réseau sont réalisés en numérique temps réel, logiciel et/ou matériel. La partie logicielle est assurée par un ordinateur interfacé à travers le bus PCI, tandis que la partie matérielle utilise des EPGAS. Trois générations sont présentés avec une analyse critique sur leur utilisation comme système de simulation de réseau neuronal
Architecture de contrôle en temps réel pour la stimulation électrique de tissus vivants à l'aide de formes d'onde arbitraires
No full textInternational audienc
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