A phenomenological model of the electrically stimulated auditory nerve fiber: temporal and biphasic response properties

We present a phenomenological model of electrically stimulated auditory nerve fibers (ANFs). The model reproduces the probabilistic and temporal properties of the ANF response to both monophasic and biphasic stimuli, in isolation. The main contribution of the model lies in its ability to reproduce statistics of the ANF response (mean latency, jitter, and firing probability) under both monophasic and cathodic-anodic biphasic stimulation, without changing the model's parameters. The response statistics of the model depend on stimulus level and duration of the stimulating pulse, reproducing trends observed in the ANF. In the case of biphasic stimulation, the model reproduces the effects of pseudomonophasic pulse shapes and also the dependence on the interphase gap (IPG) of the stimulus pulse, an effect that is quantitatively reproduced. The model is fitted to ANF data using a procedure that uniquely determines each model parameter. It is thus possible to rapidly parameterize a large population of neurons to reproduce a given set of response statistic distributions. Our work extends the stochastic leaky integrate and fire (SLIF) neuron, a well-studied phenomenological model of the electrically stimulated neuron. We extend the SLIF neuron so as to produce a realistic latency distribution by delaying the moment of spiking. During this delay, spiking may be abolished by anodic current. By this means, the probability of the model neuron responding to a stimulus is reduced when a trailing phase of opposite polarity is introduced. By introducing a minimum wait period that must elapse before a spike may be emitted, the model is able to reproduce the differences in the threshold level observed in the ANF for monophasic and biphasic stimuli. Thus, the ANF response to a large variety of pulse shapes are reproduced correctly by this model

CYSTORE. Valorisation écologique des ouvrages maritimes par la transplantation des algues du genre Cystoseira.

CYSTORE. Valorisation écologique des ouvrages maritimes par la transplantation des algues du genre Cystoseira

Projet GIREL - Pilote CYSTORE : Valorisation écologique lagunaire- Etat initial du site de transplantation et de prélèvement. 26 p.

Rapport scientifiqueProjet GIREL - Pilote CYSTORE : Valorisation écologique lagunaire- Etat initial du site de transplantation et de prélèvement

Projet GIREL - Pilote CYSTORE : Valorisation écologique des digues - Etat initial. 37 p.

Rapport scientifiqueProjet GIREL - Pilote CYSTORE : Valorisation écologique des digues - Etat initial

Posidonia oceanica in the Marmara Sea

The seagrass Posidonia oceanica is a stenohaline species endemic to the Mediterranean Sea, where it normally lives at a salinity of between 36.5 and 39.5 ppt. Surveys carried out at the North-eastern distribution limits revealed large beds in the Dardanelles Strait and isolated beds in the Marmara Sea, where the salinity ranges between 21.5 and 28 ppt. Microsatellite analysis of these low-salinity tolerant P. oceanica beds, show different signs of genetic isolation: excess of heterozygosity and a presence of fixed alleles. These particularities are rarely found in the whole distributional range of the species. Moreover, all the populations considered in the analysis have a very low genetic diversity in comparison with most of the meadows sampled throughout the Mediterranean Sea. Taking into consideration the genetic data, rhizome expansion rate and the actual extent of the isolated beds in the Marmara Sea and knowing the reproductive rate and dissemination characteristics of P. oceanica, we hypothesize that the isolated population of the Marmara Sea has been established since the Middle Holocene, before the catastrophic intrusion of brackish water into the Marmara Sea and the strong and persistent flow coming from the Black Sea. (c) 2008 Elsevier B.V. All rights reserved

Côtes méditerranéennes françaises : inventaire et impact des aménagements gagnés sur la mer. Ed. Lab. ECOMERS, Université Nice Sophia Antipolis. 153p.

Rapport scientifiqueCôtes méditerranéennes françaises : inventaire et impact des aménagements gagnés sur la mer

MEDAM.org : inventaire et impact des aménagements gagnés sur le domaine marin - côtes méditerranéennes françaises. Laboratoire Ecomers, Université Nice Sophia Antipolis. Publication électronique : www.medam.org.

Site internetMEDAM.org : inventaire et impact des aménagements gagnés sur le domaine marin - côtes méditerranéennes françaises. Laboratoire Ecomers, Université Nice Sophia Antipolis. Publication électronique : www.medam.org