Efficient spike-sorting of multi-state neurons using inter-spike intervals information

We demonstrate the efficacy of a new spike-sorting method based on a Markov Chain Monte Carlo (MCMC) algorithm by applying it to real data recorded from Purkinje cells (PCs) in young rat cerebellar slices. This algorithm is unique in its capability to estimate and make use of the firing statistics as well as the spike amplitude dynamics of the recorded neurons. PCs exhibit multiple discharge states, giving rise to multimodal interspike interval (ISI) histograms and to correlations between successive ISIs. The amplitude of the spikes generated by a PC in an "active" state decreases, a feature typical of many neurons from both vertebrates and invertebrates. These two features constitute a major and recurrent problem for all the presently available spike-sorting methods. We first show that a Hidden Markov Model with 3 log-Normal states provides a flexible and satisfying description of the complex firing of single PCs. We then incorporate this model into our previous MCMC based spike-sorting algorithm (Pouzat et al, 2004, J. Neurophys. 91, 2910-2928) and test this new algorithm on multi-unit recordings of bursting PCs. We show that our method successfully classifies the bursty spike trains fired by PCs by using an independent single unit recording from a patch-clamp pipette.Comment: 25 pages, to be published in Journal of Neurocience Method

The EU trade policy is an important contribution to overcome slow economic growth in the EU countries. Challenge this point of view.

As it has been suggested EU trade policy contribution to economic growth of MSs should be considered at best moderate if not negligible – on one hand due to still extensively applied extra-tariff measures such as anti-dumping proceedings and safety and health procedures, on the other hand because of lack of direct link between liberalisation of trade in industrial commodities and stimulation of growth. All this seems quite logical if one takes under consideration the fact that EU trade policy objectives are to less extent aimed at promotion of growth rather than at achieving social and political goals

The EU trade policy is an important contribution to overcome slow economic growth in the EU countries. Challenge this point of view.

As it has been suggested EU trade policy contribution to economic growth of MSs should be considered at best moderate if not negligible – on one hand due to still extensively applied extra-tariff measures such as anti-dumping proceedings and safety and health procedures, on the other hand because of lack of direct link between liberalisation of trade in industrial commodities and stimulation of growth. All this seems quite logical if one takes under consideration the fact that EU trade policy objectives are to less extent aimed at promotion of growth rather than at achieving social and political goals

Dibutyryl Cyclic Amp-Induced Differentiation Of Epidermal Cells In Tissue Culture

Histochemical and biochemical techniques have been used to compare the effects of dibutyryl cyclic AMP on epidermal cells and dermal cells in primary tissue culture. Rhodamin B staining showed only scattered positive cells in nontreated epidermal cells and a few contaminating keratinizing cell foci in both nontreated and treated dermal cell cultures. In contrast, treated epidermal cells stained strongly and had many keratinizing cell foci. A significant increase in histidine, cystine, and arginine incorporation was noted in epidermal cells treated with dibutyryl cyclic AMP as compared to untreated epidermal cells and no dermal cell cultures both treated and untreated. Dibutyryl cyclic AMP had no significant effect on leucine and phenylalanine incorporation. These results seem to suggest that the intracellular level of cyclic AMP not only controls the synthesis of DNA by epidermal cells in culture but also induces the process of differentiation toward keratinization

« Maroc, c’est le choc ! » : vulnérabilités extrêmes et tactiques de survie des migrants d'Afrique subsaharienne

Être une femme ou un homme étranger et noir et souffrir du froid, de la faim et de l’absence de sécurité, ne pas avoir d'existence sociale reconnue : telle est l’expérience des personnes migrantes suivies durant cette enquête au Maroc. Leur point commun est de n’avoir, à certains moments de leur séjour, plus qu'une seule et ultime ressource : leur propre corps. À partir d’une enquête ethnographique menée entre 2016 et 2020 et de l’analyse de corpus biographiques, cet article propose de revenir sur l’expérience vécue de la vulnérabilité extrême et sur les tactiques envisagées pour y faire face. Il présente une analyse centrée sur les corps des migrants conçus comme des surfaces sur lesquelles des « régimes de vérité » s’inscrivent, en tant que lieu de domination et de résistance créative.Being a foreign, black woman or man, suffering from cold, hunger and lack of security, with no recognized social existence: this is the experience of the migrants we followed during this survey in Morocco. What they have in common is that, at certain points in their stay, they have only one ultimate resource left: their own bodies. Based on an ethnographic survey conducted between 2016 and 2020 and the analysis of biographical material, this article proposes to revisit the lived experience of extreme vulnerability and the tactics considered to cope with it. It presents an analysis centered on migrants’ bodies conceived as surfaces on which “regimes of truth” are inscribed, as sites of domination and creative resistance

"Se connecter sans être reliés" : des effets ambigus de l’hyper-connectivité d’immigrés noirs au Maroc

Au Maroc, les migrants originaires d’Afrique centrale et de l’Ouest font un usage ambivalent des réseaux sociaux. L’obligation de réussite qui pèse sur eux les contraint à réduire la communication sur leurs difficultés pour ne pas inquiéter ou décevoir leurs familles. Exposés à de multiples violences socio-raciales, certains privilégient les sociabilités numériques pour ne pas s’exposer dans l’espace public. Ce faisant, ces migrants laissent entrevoir la face sombre de leur vie connectée et contribuent à une distorsion de la réalité sur leur pays de résidence

Spike detection and sorting: combining algebraic differentiations with ICA

International audienceA new method for action potentials detection is proposed. The method is based on a numerical differentiation, as recently intro- duced from operational calculus. We show that it has good performance as compared to existing methods. We also combine the proposed method with ICA in order to obtain spike sorting

Making neurophysiological data analysis reproducible. Why and how?

Manuscript submitted to "The Journal of Physiology (Paris)". Second version.Reproducible data analysis is an approach aiming at complementing classical printed scientific articles with everything required to independently reproduce the results they present. ''Everything'' covers here: the data, the computer codes and a precise description of how the code was applied to the data. A brief history of this approach is presented first, starting with what economists have been calling replication since the early eighties to end with what is now called reproducible research in computational data analysis oriented fields like statistics and signal processing. Since efficient tools are instrumental for a routine implementation of these approaches, a description of some of the available ones is presented next. A toy example demonstrates then the use of two open source software for reproducible data analysis: the ''Sweave family'' and the org-mode of emacs. The former is bound to R while the latter can be used with R, Matlab, Python and many more ''generalist'' data processing software. Both solutions can be used with Unix-like, Windows and Mac families of operating systems. It is argued that neuroscientists could communicate much more efficiently their results by adopting the reproducible research paradigm from their lab books all the way to their articles, thesis and books

The Owen Ridge uplift in the Arabian Sea: Implications for the sedimentary record of Indian monsoon in Late Miocene

International audienceThe pelagic cover of the Owen Ridge in the Arabian Sea recorded the evolution of the Indian monsoon since the Middle Miocene. The uplift of the Owen Ridge resulted from tectonic processes along the previously unidentified Miocene India-Arabia plate boundary. Based on seismic reflection data tied with deep-sea drilling to track the Miocene India-Arabia plate boundary, we propose a new timing for the uplift of the Owen Ridge and highlight its impact on the record of climate changes in pelagic sediments. The new dataset reveals a fracture zone east of the Owen Ridge corresponding to the fossil plate boundary, and documents that the main uplift of the Owen Ridge occurred close to ∼8.5 Ma, and is coeval with a major uplift of the east Oman margin. Late Miocene deformation at the India-Arabia plate boundary is also coeval with the onset of intra-plate deformation in the Central Indian Ocean, suggesting a kinematic change of India and surrounding plates in the Late Miocene. The uplift of the Owen Ridge above the lysocline at ∼8.5 Ma accounts for a better preservation of Globigerina bulloides in the pelagic cover, previously misinterpreted as the result of a monsoon intensification event