References of "Franci, Alessio"
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See detailDynamic Input Conductances Shape Neuronal Spiking
Drion, Guillaume ULg; Franci, Alessio ULg; Dethier, Julie ULg et al

in eNeuro (2015)

Assessing the role of biophysical parameter variations in neuronal activity is critical to the understanding of modulation, robustness and homeostasis of neuronal signaling. The paper proposes that this ... [more ▼]

Assessing the role of biophysical parameter variations in neuronal activity is critical to the understanding of modulation, robustness and homeostasis of neuronal signaling. The paper proposes that this question can be addressed through the analysis of dynamic input conductances. Those voltage-dependent curves aggregate the concomitant activity of all ion channels in distinct timescales. They are shown to shape the current-voltage dynamical relationships that determine neuronal spiking. We propose an experimental protocol to measure dynamic input conductances in neurons. In addition, we provide a computational method to extract dynamic input conductances from arbitrary conductance-based models and to analyze their sensitivity to arbitrary parameters. We illustrate the relevance of the proposed approach for modulation, compensation and robustness studies in a published neuron model based on data of the stomatogastric ganglion of the crab Cancer borealis. [less ▲]

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See detailModeling the Modulation of Neuronal Bursting: A Singularity Theory Approach
Franci, Alessio ULg; Drion, Guillaume ULg; Sepulchre, Rodolphe ULg

in SIAM Journal on Applied Dynamical Systems (2014), 13(2), 798-829

Exploiting the specific structure of neuron conductance-based models, the paper investigates the mathematical modeling of neuronal bursting modulation. The proposed approach combines singularity theory ... [more ▼]

Exploiting the specific structure of neuron conductance-based models, the paper investigates the mathematical modeling of neuronal bursting modulation. The proposed approach combines singularity theory and geometric singular perturbations to capture the geometry of multiple time-scale attractors in the neighborhood of high-codimension singularities. We detect a three–time-scale bursting attractor in the universal unfolding of the winged cusp singularity and discuss the physiological relevance of the bifurcation and unfolding parameters in determining a physiological modulation of bursting. The results suggest generality and simplicity in the organizing role of the winged cusp singularity for the global dynamics of conductance-based models. [less ▲]

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See detailHomeostatic principles are consistent with sensitivity analysis of neuronal rhythmicity
Franci, Alessio ULg; O'Leary, Timothy; Drion, Guillaume ULg et al

Poster (2013, November)

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See detailFirst spike latency sensitivity of spiking neuron models
Trotta, Laura ULg; Franci, Alessio ULg; Sepulchre, Rodolphe ULg

Poster (2013, July 08)

First spike latency is the long-lasting period preceding the first spike of a neuron submitted to a super-threshold stimulus. It has been suggested that this latency could code for stimulus recognition in ... [more ▼]

First spike latency is the long-lasting period preceding the first spike of a neuron submitted to a super-threshold stimulus. It has been suggested that this latency could code for stimulus recognition in several sensory systems. To encode information reliably, first spike latency should be sensitive to sensory inputs but robust to external perturbations. This paper studies the robustness of the first spike latency in spiking neuron models. We show the interplay between bistability, first spike latency and a type of neuronal excitability called regenerative excitability. [less ▲]

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See detailSingularly perturbed phase response curves
Sacré, Pierre ULg; Franci, Alessio ULg; Sepulchre, Rodolphe ULg

Conference (2013, March 26)

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See detailA Balance Equation Determines a Switch in Neuronal Excitability
Franci, Alessio ULg; Drion, Guillaume ULg; Seutin, Vincent ULg et al

in PLoS Computational Biology (2013)

We use the qualitative insight of a planar neuronal phase portrait to detect an excitability switch in arbitrary conductance-based models from a simple mathematical condition. The condition expresses a ... [more ▼]

We use the qualitative insight of a planar neuronal phase portrait to detect an excitability switch in arbitrary conductance-based models from a simple mathematical condition. The condition expresses a balance between ion channels that provide a negative feedback at resting potential (restorative channels) and those that provide a positive feedback at resting potential (regenerative channels). Geometrically, the condition imposes a transcritical bifurcation that rules the switch of excitability through the variation of a single physiological parameter. Our analysis of six di erent published conductance based models always nds the transcritical bifurcation and the associated switch in excitability, which suggests that the mathematical predictions have a physiological rel- evance and that a same regulatory mechanism is potentially involved in the excitability and signaling of many neurons. [less ▲]

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See detailA novel phase portrait for neuronal excitability
Drion, Guillaume ULg; Franci, Alessio ULg; Seutin, Vincent ULg et al

in PLoS ONE (2012), 7(8),

Fifty years ago, FitzHugh introduced a phase portrait that became famous for a twofold reason: it captured in a physiological way the qualitative behavior of Hodgkin-Huxley model and it revealed the power ... [more ▼]

Fifty years ago, FitzHugh introduced a phase portrait that became famous for a twofold reason: it captured in a physiological way the qualitative behavior of Hodgkin-Huxley model and it revealed the power of simple dynamical models to unfold complex firing patterns. To date, in spite of the enormous progresses in qualitative and quantitative neural modeling, this phase portrait has remained a core picture of neuronal excitability. Yet, a major difference between the neurophysiology of 1961 and of 2011 is the recognition of the prominent role of calcium channels in firing mechanisms. We show that including this extra current in Hodgkin-Huxley dynamics leads to a revision of FitzHugh-Nagumo phase portrait that affects in a fundamental way the reduced modeling of neural excitability. The revisited model considerably enlarges the modeling power of the original one. In particular, it captures essential electrophysiological signatures that otherwise require non-physiological alteration or considerable complexification of the classical model. As a basic illustration, the new model is shown to highlight a core dynamical mechanism by which calcium channels control the two distinct firing modes of thalamocortical neurons. [less ▲]

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See detailA Novel Phase Portrait to Understand Neuronal Excitability
Drion, Guillaume ULg; Franci, Alessio ULg; Seutin, Vincent ULg et al

Conference (2012, March)

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See detailAn Organizing Center in a Planar Model of Neuronal Excitability
Franci, Alessio ULg; Drion, Guillaume ULg; Sepulchre, Rodolphe ULg

in SIAM Journal on Applied Dynamical Systems (2012), 11(4), 1698-1722

The paper studies the excitability properties of a generalized FitzHugh-Nagumo model. The model differs from the purely competitive FitzHugh-Nagumo model in that it accounts for the effect of cooperative ... [more ▼]

The paper studies the excitability properties of a generalized FitzHugh-Nagumo model. The model differs from the purely competitive FitzHugh-Nagumo model in that it accounts for the effect of cooperative gating variables such as activation of calcium currents. Excitability is explored by unfolding a pitchfork bifurcation that is shown to organize five different types of excitability. In addition to the three classical types of neuronal excitability, two novel types are described and distinctly associated to the presence of cooperative variables. [less ▲]

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