Entraining neurons via noninvasive electric stimulation improves cognition

Transcranial Alternating Current Stimulation (tACS) is a method that injects rhythmic currents into the human brain via electrodes attached to the scalp of a participant. This technique allows researchers to control naturally occurring brain rhythms and study their causal relevance for cognition. Recent findings, however, cast doubts on the effectiveness of tACS to stimulate the brain and its mode of action. Two new studies by Vieira and colleagues and Marchesotti and colleagues reported in the current issue report promising new results in showing that tACS can entrain single neuron activity and improve reading abilities in dyslexic individuals

Rôle de la Dynamique Membranaire dans la Mise en Place des Mécanismes de Défense chez le Tabac

La cryptogéine, une protéine sécrétée par l oomycète Phytophthora cryptogea, provoque la mise en place de mécanismes de défense chez le tabac, mobilisant au cours des étapes précoces de la signalisation associée, des protéines localisées dans la membrane plasmique (MP). Une fraction membranaire résistante à la solubilisation par les détergents (DIM pour Detergent Insoluble Membrane), enrichie en stérols et en sphingolipides avait été purifiée à partir de la MP de tabac : cette fraction contenait plusieurs protéines impliquées dans la cascade de signalisation induite par la cryptogéine. Chez l animal, l association dynamique de protéines à des microdomaines riches en stérols et sphingolipides en réponse à un stress biotique joue un rôle essentiel dans la régulation de la signalisation cellulaire. L objectif de ce travail était de tester l hypothèse qu un tel phénomène puisse se produire dans notre modèle d étude. La comparaison du protéome de fractions DIMs, purifiées à partir de cellules traitées ou non pendant 5 minutes à la cryptogéine a été réalisée à l aide d un marquage isotopique (15N ou 14N) et d une approche de protéomique quantitative. Le premier résultat est que l abondance de la majorité des protéines n est pas modifiée dans les DIMs en réponse à la cryptogéine. Une seule protéine est enrichie dans les DIMs, une isoforme de 14-3-3, tandis que quatre dynamines (DRPs pour Dynamin Related Proteins), impliquées dans le trafic vésiculaire, sont exclues des DIMs en réponse à la cryptogéine. L étude d une des dynamines identifiées, DRP1A, a été menée. Nous avons caractérisé les différents gènes codant DRP1A dans le génome du tabac, puis utilisé une approche ARN antisens pour altérer l expression de cette protéine et nous avons étudié sa localisation subcellulaire à l aide d anticorps spécifiques et en observant en microscopie confocale cette protéine fusionnée à la GFP. Cette approche a permis de confirmer la présence de DRP1A dans la fraction DIMs et la diminution transitoire de son association à cette fraction en réponse à la cryptogéine, suite à une dissociation de la fraction membranaire. Ces travaux constituent la première mise en évidence d une association/dissociation dynamique de protéines aux DIMs de plantes en réponse à un stimulus biologiqueCryptogein, a protein secreted by the oomycete Phytophthora cryptogea, induces defense mechanisms in tobacco. Several proteins involved in the associated signaling pathway were identified and localized on the plasma membrane (PM). A fraction resistant to solubilization by detergent named DIMs for Detergent Insoluble Membranes, enriched in sterols an sphigolipids had been isolated from tobacco PM. It was proved to contain proteins previously identified as actors of the signaling cascade triggered by cryptogein. In animal cells, the dynamic association of proteins to sterol and sphingolipid rich microdomains under the influence of a biological stimulus plays an essential role in the regulation of cellular signaling. The purpose of this work was to test the hypothesis that such a phenomenon might occur in our model. The comparison using isotopic labeling (15N or 14N) and quantitative proteomics, of the composition of DIMs extracted from tobacco cells treated or not by cryptogein, revealed that, although the association to DIMs of most proteins remained unchanged, five proteins had their relative abundance modified after 5 minutes of treatment. One of these was a signaling protein (a 14-3-3 protein) and the four others were related to cell trafficking (4 DRPs, Dynamin Related Proteins). We characterized the DRP1A gene family in tobacco, and set up an antisens RNA antisense to down-regulate the expression of this protein. We studied the intracellular localization of DRP1 using specific antibodies and a GFP fusion. The results confirmed the presence of DRP1 in DIMs and its depletion from this fraction upon cryptogein treatment, through a dissociation from the PM. This is the first evidence of a dynamic association/dissociation of proteins to microdomains in plants upon a biological stimulusDIJON-BU Doc.électronique (212319901) / SudocSudocFranceF

Constitutive expression of clathrin hub hinders elicitor-induced clathrin-mediated endocytosis and defense gene expression in plant cells

AbstractEndocytosis has been recently implicated in the signaling network associated with the recognition of microbes by plants. In a previous study, we showed that the elicitor cryptogein was able to induce clathrin-mediated endocytosis (CME) in tobacco suspension cells. Herein, we investigate further the induced CME by means of a GFP-tagged clathrin light chain and a CME inhibitor, the hub domain of clathrin heavy chain. Hub constitutive expression does affect neither cell growth nor constitutive endocytosis but abolishes cryptogein-induced CME. Such an inhibition has no impact on early events in the cryptogein signaling pathway but reduces the expression of defense-associated genes

Stimulation of the left dorsolateral prefrontal cortex with slow rTMS enhances verbal memory formation

Encoding of episodic memories relies on stimulus-specific information processing and involves the left prefrontal cortex. We here present an incidental finding from a simultaneous EEG-TMS experiment as well as a replication of this unexpected effect. Our results reveal that stimulating the left dorsolateral prefrontal cortex (DLPFC) with slow repetitive transcranial magnetic stimulation (rTMS) leads to enhanced word memory performance. A total of 40 healthy human participants engaged in a list learning paradigm. Half of the participants (N = 20) received 1 Hz rTMS to the left DLPFC, while the other half (N = 20) received 1 Hz rTMS to the vertex and served as a control group. Participants receiving left DLPFC stimulation demonstrated enhanced memory performance compared to the control group. This effect was replicated in a within-subjects experiment where 24 participants received 1 Hz rTMS to the left DLPFC and vertex. In this second experiment, DLPFC stimulation also induced better memory performance compared to vertex stimulation. In addition to these behavioural effects, we found that 1 Hz rTMS to DLPFC induced stronger beta power modulation in posterior areas, a state that is known to be beneficial for memory encoding. Further analysis indicated that beta modulations did not have an oscillatory origin. Instead, the observed beta modulations were a result of a spectral tilt, suggesting inhibition of these parietal regions. These results show that applying 1 Hz rTMS to DLPFC, an area involved in episodic memory formation, improves memory performance via modulating neural activity in parietal regions

Observations of gas flows inside a protoplanetary gap

Gaseous giant planet formation is thought to occur in the first few million years following stellar birth. Models predict that giant planet formation carves a deep gap in the dust component (shallower in the gas). Infrared observations of the disk around the young star HD142527, at ~140pc, found an inner disk ~10AU in radius, surrounded by a particularly large gap, with a disrupted outer disk beyond 140AU, indicative of a perturbing planetary-mass body at ~90 AU. From radio observations, the bulk mass is molecular and lies in the outer disk, whose continuum emission has a horseshoe morphology. The vigorous stellar accretion rate would deplete the inner disk in less than a year, so in order to sustain the observed accretion, matter must flow from the outer-disk into the cavity and cross the gap. In dynamical models, the putative protoplanets channel outer-disk material into gap-crossing bridges that feed stellar accretion through the inner disk. Here we report observations with the Atacama Large Millimetre Array (ALMA) that reveal diffuse CO gas inside the gap, with denser HCO+ gas along gap-crossing filaments, and that confirm the horseshoe morphology of the outer disk. The estimated flow rate of the gas is in the range 7E-9 to 2E-7 Msun/yr, which is sufficient to maintain accretion onto the star at the present rate

ALMA observations of Elias 2–24: a protoplanetary disk with multiple gaps in the Ophiuchus molecular cloud

We present ALMA 1.3 mm continuum observations at 0. 2 (25 au) resolution of Elias 2–24, one of the largest and brightest protoplanetary disks in the Ophiuchus Molecular Cloud, and we report the presence of three partially resolved concentric gaps located at ∼20, 52, and 87 au from the star. We perform radiative transfer modeling of the disk to constrain its surface density and temperature radial profile and place the disk structure in the context of mechanisms capable of forming narrow gaps such as condensation fronts and dynamical clearing by actively forming planets. In particular, we estimate the disk temperature at the locations of the gaps to be 23, 15, and 12 K (at 20, 52, and 87 au, respectively), very close to the expected snowlines of CO (23–28 K) and N2 (12–15 K). Similarly, by assuming that the widths of the gaps correspond to 4–8× the Hill radii of forming planets (as suggested by numerical simulations), we estimate planet masses in the range of 0.2 1.5 – MJup, 1.0 8.0 – MJup, and 0.02 0.15 – MJup for the inner, middle, and outer gap, respectively. Given the surface density profile of the disk, the amount of “missing mass” at the location of each one of these gaps (between 4 and 20 MJup) is more than sufficient to account for the formation of such planets.Fil: Cieza, Lucas A.. Universidad Diego Portales; ChileFil: Casassus, Simon. Universidad de Chile; ChileFil: Pérez, Sebastian. Universidad de Chile; ChileFil: Hales, Antonio. Alma Observatory; ChileFil: Cárcamo, Miguel. Universidad de Chile; ChileFil: Ansdell, Megan. University of California at Berkeley; Estados UnidosFil: Avenhaus, Henning. Universitat Zurich; SuizaFil: Bayo, Amelia. Universidad de Valparaiso; ChileFil: Bertrang, Gesa H.-M.. Universidad Diego Portales; ChileFil: Cánovas, Hector. Agencia Espacial Europea; EspañaFil: Christiaens, Valentin. Universidad de Chile; ChileFil: Dent, William. Alma Observatory; ChileFil: Ferrero, Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Gamen, Roberto Claudio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Olofsson, Johan. Universidad de Valparaiso; ChileFil: Orcajo, Santiago. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Osses, Axel. Universidad de Chile; ChileFil: Peña Ramirez, Karla. Universidad de Antofagasta; ChileFil: Principe, David. Massachusetts Institute of Technology; Estados UnidosFil: Ruíz Rodríguez, Dary. Rochester Institute Of Technology; Estados UnidosFil: Schreiber, Matthias R.. Universidad de Valparaiso; ChileFil: Plas, Gerrit van der. Univ. Grenoble Alpes; SuizaFil: Williams, Jonathan P.. Institute For Astronomy, University Of Hawaii; Estados UnidosFil: Zurlo, Alice. Universidad Diego Portales; Chil

Multi-stage semantic segmentation quantifies fragmentation of small habitats at a landscape scale

Land cover (LC) maps are used extensively for nature conservation and landscape planning, but low spatial resolution and coarse LC schemas typically limit their applicability to large, broadly defined habitats. In order to target smaller and more-specific habitats, LC maps must be developed at high resolution and fine class detail using automated methods that can efficiently scale to large areas of interest. In this work, we present a Machine Learning approach that addresses this challenge. First, we developed a multi-stage semantic segmentation approach that uses Convolutional Neural Networks (CNNs) to classify LC across the Peak District National Park (PDNP, 1439 km2) in the UK using a detailed, hierarchical LC schema. High-level classes were predicted with 95% accuracy and were subsequently used as masks to predict low-level classes with 72% to 92% accuracy. Next, we used these predictions to analyse the degree and distribution of fragmentation of one specific habitat—wet grassland and rush pasture—at the landscape scale in the PDNP. We found that fragmentation varied across areas designated as primary habitat, highlighting the importance of high-resolution LC maps provided by CNN-powered analysis for nature conservation

Warm molecular gas and kinematics in the disc around HD 100546

The disc around the Herbig Ae/Be star HD 100546 is one of the most extensively studied discs in the southern sky. Although there is a wealth of information about its dust content and composition, not much is known about its gas and large scale kinematics. We detect and study the molecular gas in the disc at spatial resolution from 7.7" to 18.9" using the APEX telescope. The lines 12CO J=7-6, J=6-5, J=3-2, 13CO J=3-2 and [C I] 3P2-3P1 are observed, diagnostic of disc temperature, size, chemistry, and kinematics. We use parametric disc models that reproduce the low-J 12CO emission from Herbig~Ae stars and vary the basic disc parameters - temperature, mass and size. Using the molecular excitation and radiative transfer code RATRAN we fit the observed spectral line profiles. Our observations are consistent with more than 0.001 Msun of molecular gas in a disc of approximately 400 AU radius in Keplerian rotation around a 2.5 Msun star, seen at an inclination of 50 degrees. The detected 12CO lines are dominated by gas at 30-70~K. The non-detection of the [C I] line indicates excess ultraviolet emission above that of a B9 type model stellar atmosphere. Asymmetry in the 12CO line emission suggests that one side of the outer disc is colder by 10-20~K than the other, possibly due to a shadow by a warped geometry of the inner disc. Pointing offsets, foreground cloud absorption and asymmetry in the disc extent are excluded scenarios. Efficient heating of the outer disc ensures that low- and high-J 12CO lines are dominated by the outermost disc regions, indicating a 400 AU radius. The 12CO J=6--5 line arises from a disc layer higher above disc midplane, and warmer by 15-20~K than the layer emitting the J=3--2 line. The existing models of discs around Herbig Ae stars, assuming a B9.5 type model stellar atmosphere overproduce the [CI] 3P2--3P1 line intensity from HD 100546 by an order of magnitude.Comment: 9pages, 3figures, Accepted for publication in Astronomy & Astrophysic