35 research outputs found

    Coordinated population activity underlying texture discrimination in rat barrel cortex

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    Rodents can robustly distinguish fine differences in texture using their whiskers, a capacity that depends on neuronal activity in primary somatosensory \u201cbarrel\u201d cortex. Here we explore how texture was collectively encoded by populations of three to seven neuronal clusters simultaneously recorded from barrel cortex while a rat performed a discrimination task. Each cluster corresponded to the single-unit or multiunit activity recorded at an individual electrode. To learn how the firing of different clusters combines to represent texture, we computed population activity vectors across moving time windows and extracted the signal available in the optimal linear combination of clusters. We quantified this signal using receiver operating characteristic analysis and compared it to that available in single clusters. Texture encoding was heterogeneous across neuronal clusters, and only a minority of clusters carried signals strong enough to support stimulus discrimination on their own. However, jointly recorded groups of clusters were always able to support texture discrimination at a statistically significant level, even in sessions where no individual cluster represented the stimulus. The discriminative capacity of neuronal activity was degraded when error trials were included in the data, compared to only correct trials, suggesting a link between the neuronal activity and the animal's performance. These analyses indicate that small groups of barrel cortex neurons can robustly represent texture identity through synergistic interactions, and suggest that neurons downstream to barrel cortex could extract texture identity on single trials through simple linear combination of barrel cortex responses

    Caracterización de depósitos carbonáticos ligados a paleosurgencias en el sector de Batallones-Malcovadeso (Neógeno de la Cuenca de Madrid)

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    En la zona de canteras de Valdeinfierno, en el sector de Batallones-Malcovadeso, parte centro-meridional de la Cuenca de Madrid, se ha reconocido una serie de depósitos carbonáticos que presentan geometría dómica y estructura interna columnar. Dentro de estos depósitos de carbonato se distinguen dos unidades. La inferior (U2) es mayoritariamente dolomítica y de estructura brechoide, y petrográficamente consiste en dolomicritas con cemento calcítico. La superior (U3) está formada tanto por dolomita como por calcita, y se caracteriza por el desarrollo de morfologías columnares de aspecto travertínico. Petrográficamente, los depósitos de esta unidad consisten en caliza con texturas alveolar y biogénica. Entre las columnas de carbonato se distinguen abundantes masas arcillosas. Hacia la base de estas unidades carbonáticas se sitúa una unidad detrítica (U1), formada por arenas feldespáticas y a su techo se dispone un conjunto lutítico con alguna intercalación carbonática de composición dolomítica (Unidad U4) y, por encima de estas lutitas, un conjunto calizo (Unidad U5). Las arcillas presentes en la unidad U3 tienen una composición (sepiolita > esmectita trioctaédrica ± illita) netamente diferente a las de la unidad U4 (esmectita dioctaédrica > illita ± caolinita). La composición isotópica de los carbonatos de las unidades U2 y U3, así como de los niveles carbonatados de la unidad U4, es bastante similar en el caso de la dolomita, con valores δ13C que oscilan entre –6,21 y –7,78‰ y entre –3,23 y –4,05‰ para el δ18O. Por otro lado, desde un punto de vista de su composición isotópica, se diferencian los carbonatos de la unidad 4 y del techo de la unidad 2, exclusivamente calcíticos, en los que los valores de δ13C oscilan entre –8,07 y –11,75‰, y los de δ18O entre –5,27 y –7,35‰. La calcita existente en los niveles dolomíticos presenta valores intermedios entre los dos grupos anteriores. Los rasgos de la sucesión sedimentaria y los resultados analíticos obtenidos indican una fase de expansión lacustre en la zona estudiada con un cambio en la química de las aguas, todo ello favorecido por la entrada de aguas subterráneas a través de surgencias.Este trabajo se ha realizado dentro del Proyecto de investigación CGL2005-03900/BTE financiado por el Ministerio de Educación y Ciencia.Peer reviewe

    Astronomical forcing of sedimentary cycles in the middle to late Miocene continental Calatayud Basin (NE Spain)

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    A high-resolution cyclostratigraphic and magnetostratigraphic study was carried out on cyclically bedded successions of middle Miocene lacustrine to distal alluvial fan-floodplain deposits from the Calatayud basin, in northeast Spain. Eight (partially overlapping) subsections near the village of Orera are correlated in detail using distinct sedimentary cycle patterns or by following marker beds in the field. Together they form the Orera Composite Section (OCS). Sedimentary cycles are recognised on at least two different scales. The basic small-scale cycles in the OCS consist of an alternation of grey and, occasionally, red clays with white, dolomite-rich, carbonate beds. They are arranged in largerscaled, so-called large-scale cycles based on repetitive changes in the overall carbonate-clay lithology. Two other, but less distinct, types of intermediate scale cyclicity are also recognised. In terms of depositional environment, the cycle hierarchy is interpreted to represent periodic lake expansion over the palaeo-alluvial fan-floodplain area. The palaeomagnetic results yield a reliable magnetostratigraphic record, which confirms the cyclostratigraphic correlations between the subsections in detail. Rock magnetic experiments reveal that haematite is the main magnetic carrier of the primary component. The magnetostratigraphy of the OCS is correlated straightforwardly with the geomagnetic polarity time scale. This resulted in an age of 10.7^12.8 Ma for the entire succession, which is supported by fossil micromammal findings. In addition, it also reveals the presence of two, possibly three, short new polarity intervals. Based on the number of cycles in the OCS the average periodicity of the basic small-scale cycles is approximately 23 000 yr, while the large-scale cycle indicates a periodicity of 400 000 yr. This suggests that these sedimentary cycles are controlled by astronomically induced climate changes causing lake-level fluctuations and thus resulting in the deposition of carbonate-clay cycles. The continental sequences of the OCS provide a unique opportunity to extend the astronomical polarity time scale into the middle Miocene. The overlap of such continental sequences in the Mediterranean area with time-equivalent astronomically induced marine sequences is fundamental for establishing marine^continental, bed-tobed, correlations and for understanding regional climate change

    Depósitos de magnesita en la Cuenca de Calatayud: facies y asociaciones mineralógicas

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    Sedimentary magnesite is largely present in the Miocene evaporite formations (Lower and Intermediate units) of the Calatayud Basin (NE Spain). Magnesite deposits are forming part of sedimentary sequences corresponding to hypersaline and moderate-to-high concentrated saline lakes. Both field and mineralógica! studies show that magnesite is associated with a wide range of lithofacies, but most commonly with phyllosilicates and gypsum. Trioctahedral clay minerals (Mg-smectites) were identified in mudflat environments of the hypersaline Lower Unit, probably formed by transformation of inherited phases in Mg and Si-rich saline-alkaline environments. Moderate to well ordered smectites (diocta-trioctahedral) in green clay lithofacies in absence of magnesite suggest a genetic competition forming magnesite or Mg-smectite. In contrast, the exclusive presence of illite associated with interestratified illite/smectite in sequences that correspond to moderate-to-high concentrated saline lakes could result from illitization processes of smectites in Mg-K-rich environments, under periodical dry/wet cycles

    Depopulation impacts on ecosystem services in Mediterranean rural areas

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    Despite the exponential increase in human population at global scale, some rural areas have experienced a progressive abandonment over the last decades. Under particular socioecological and policy contexts, changes in demography may promote land-use changes and, consequently, alter ecosystem services (ES) supply. However, most studies on this topic have targeted urban population increase, whereas depopulation has been rarely addressed. Here, we examined how shifts in demographic variables (human population, population density, and number of villages) affect provisioning (water supply, food and biomass production) and regulating (soil retention, water and nutrient regulation) ES in Mediterranean rural areas with contrasting environmental, so-cioeconomic and land-use contexts. When depopulation results in underuse of socio-ecological systems, we ex-pected a decrease of provisioning and an increase of regulating ES, whereas we expected the opposite pattern when it results in land-use intensification. To test this hypothesis, we compared demographic data and ES estimated with Soil and Water Assessment Tool (SWAT) linked to land-use changes between the 1950s and 2000s in three rural areas of Arag ́on (NE Spain). Generalized Additive Mixed Models and Linear Mixed-Effect Models were used to analyze demographic trends, ES changes and the relationship between them. We found severe depopulation (− 42% inhabitants) and associated land-use changes in the three areas, which was particularly evident in isolated mountainous zones (− 63% inhabitants). Depopulation trends significantly affected land use and, consequently, all of the ES evaluated. In mountainous depopulated areas, land abandonment and rewilding resulted in the increase in water regulation (>1000%) and soil retention (>400%). In contrast, agriculture was intensified in more fertile and easy-to-access lowland areas, boosting the food production service (>600%). Accordingly, the interactions among depopulation, crop production and regulating ES should be considered in the management schemes and policies targeting rural areas for a balanced and sustainable supply of ES in the long term

    Resultados del estudio geológico a escala 1/25.000 del término municipal de Madrid.

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    Se exponen de forma abreviada los rasgos en cuanto a metodología y conclusiones del estudio geológico a escala 1/25000 realizado en el Municipio de Madrid en los años 1982/83. Las diferentes unidades expresadas en la cartografiase describen en función de las pautas mayores observables en los materiales que forman cada una de ellas, analizándose sus relaciones estratigráficas. El Proyecto «Estudio Geológico a escala 1/25000 del Término Municipal de Madrid ha sido llevado a cabo a lo largo de los años 1982-83 como resultado de la colaboración científica entre diversos organismos de la Administración (Facultad de CC. Geológicas-Universidad Complutense, Instituto Geológico y Minero. Ayuntamiento de Madrid, Instituto de Geología de Madrid-CSIC, y otros). Constituye una de las áreas de actuación definidas dentro del Convenio de Colaboración Técnica y Cultural para el conocimiento de las Características del Suelo y Subsuelo de Madrid», propiciado y patrocinado por el Excmo. Ayuntamiento. La financiación del proyecto especifico de Geología ha sido realizada íntegramente por el IGME, organismo encargado además de su supervisión. El desarrollo del Proyecto tiene un marcado carácter interdisciplinar, fruto del trasvase de información entre los distintos grupos que abarca el Convenio general (aparte de los ya referidos, el SGOP, COPLACO, Laboratorio «José Luis Escario» siendo precisamente uno de los objetivos del trabajo el servir de apoyo a las restantes áreas de investigación. Los estudios geológicos realizados se plasman en un total de siete mapas a escala 1/25000 elaborados según la normativa Magna de cartografía geológica mapas que toman como referencia, aunque en algunos casos no las completan y en otros adosan porciones de hojas adyacentes, las hojas 1/25000 de Madrid, Alcorcón, El Pardo, San Femando de Henares, Pozuelo de Alarcón, Alcobendas y Castillo de Viñuelas

    Sedimentation and biomineralization processes in Las Eras Lake (Coca-Olmedo wetland)

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    La Laguna de Las Eras es uno de los pequeños y someros cuerpos de agua, que forman el humedal de la zona Coca-Olmedo (cuenca del Duero), caracterizado por su elevada alcalinidad, lo que constituye un rasgo singular dentro de Europa. La laguna presenta una salmuera de tipo Na-Mg-ClSO4 y su superficie está colonizada por tapices microbianos, donde se desarrollan estructuras sedimentarias inducidas por los microorganismos (MISS). Se reconocen diversos minerales autigénicos asociados a los tapices: thenardita, hidromagnesita,sulfatos y fosfatos magnésicos, azufre y halita. Junto a éstos destacan, por ser carbonatos atípicos en Europa, natrón y trona. El estudio petrográfico de los precipitados revela que éstos guardan una estrecha relación con las estructuras microbianas, sugiriendo cierta influencia de los microorganismos en la precipitación mineral.Los tapices microbianos de la laguna de Las Eras constituyen buenos análogos para comprender los procesos geobiológicos y ahondar en la reconstrucción paleoambiental de los lagos alcalinos que han existido desde el Arcaico.Las Eras Lake is one of the small and shallow bodies of water, which form the highly alkaline Coca-Olmedo wetland (Duero Basin), a unique feature within Europe. The lake brine is a Na-Mg-Cl-SO4 type. The lake hosts benthic microbial mats and its surface shows microbially influenced sedimentary structures (MISS). Associated with the microbial mats, several authigenic minerals are recognized such as thenardite, hydromagnesite, magnesium-bearing sulphate and phosphate, halite and sulphur.Among these we highlight the occurrence of natron and trona because the sodium-bearing carbonates are uncommon in the european region. The scanning electron microscopy study reveals that the minerals are closely related to microbial structures,suggesting some influence of microorganisms in the mineral precipitation. Recent microbial mats as those hosted in Las Eras Lake are good analogues for understanding geobiological processes. Knowledge of these processes provides a model for paleoenvironmental reconstruction of alkaline endorheic lakes that have existed since the Archean.Depto. de Biodiversidad, Ecología y EvoluciónFac. de Ciencias BiológicasTRUEMinisterio de Economía y Competitividad (MINECO)pu

    Development and analysis of the Soil Water Infiltration Global database.

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    In this paper, we present and analyze a novel global database of soil infiltration measurements, the Soil Water Infiltration Global (SWIG) database. In total, 5023 infiltration curves were collected across all continents in the SWIG database. These data were either provided and quality checked by the scientists who performed the experiments or they were digitized from published articles. Data from 54 different countries were included in the database with major contributions from Iran, China, and the USA. In addition to its extensive geographical coverage, the collected infiltration curves cover research from 1976 to late 2017. Basic information on measurement location and method, soil properties, and land use was gathered along with the infiltration data, making the database valuable for the development of pedotransfer functions (PTFs) for estimating soil hydraulic properties, for the evaluation of infiltration measurement methods, and for developing and validating infiltration models. Soil textural information (clay, silt, and sand content) is available for 3842 out of 5023 infiltration measurements (~76%) covering nearly all soil USDA textural classes except for the sandy clay and silt classes. Information on land use is available for 76% of the experimental sites with agricultural land use as the dominant type (~40%). We are convinced that the SWIG database will allow for a better parameterization of the infiltration process in land surface models and for testing infiltration models. All collected data and related soil characteristics are provided online in *.xlsx and *.csv formats for reference, and we add a disclaimer that the database is for public domain use only and can be copied freely by referencing it. Supplementary data are available at https://doi.org/10.1594/PANGAEA.885492 (Rahmati et al., 2018). Data quality assessment is strongly advised prior to any use of this database. Finally, we would like to encourage scientists to extend and update the SWIG database by uploading new data to it
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