Origin of needle fibre calcite (NFC) : a geochemical approach

ABSTRACTNeedle fibre calcite (NFC) is one of the most widespread habits of pedogenic calcite. It is a monocrystal of calcite, in the shape of a needle, with a diameter of one micron and a length between 4 and 103 times its width. NFC occurs in soils with different macroscopic and microscopic morphologies. Macroscopically, two main habits of NFC exist: "cotton ball'Mike clusters and as "powder" coating on pebbles inside the soil. It can also act as nucleation sites for precipitation of calcite cements of purely physicochemical origin (LCC - Late Calcitic Cement). Although many studies have been conducted on needle fibre calcite, its origin remains a subject of debate. The NFC having never been reproduced in the laboratory whatever the considered approach, the processes responsible for its precipitation as a so particular morphology remain unexplained. The shift between the length orientation of the needle crystal and the normal axis of calcite growth (c-axis) is also unresolved.Samples taken in two soils observed in quarries (Villiers and Savagnier) in the Swiss Jura Mountains are used to investigate the processes involved in the formation of these calcite crystals in pedogenic environments. Three groups of microscopic morphologies are distinguished: (i) simple needles (SN), (ii) simple needles with overgrowths (SNO), and (iii) simple needles with nanofibres (SNN), nanofibres being either organic or mineral in nature. These groups correspond to different stages in the formation and evolution of NFC.Comparison of carbon and oxygen isotope compositions of NFC with LCC, in relationship with the composition of the carbonate host rock (CHR), and the carbon isotope signature of dissolved inorganic carbon (DIC) from the soil waters, indicates that both NFC and LCC are precipitated in isotopic equilibrium with the soil solution. Similar Ô13C and Ô180 values of the elongated NFC and the rhombohedral calcite crystals of the LCC suggest that the precipitation of these different calcite habits is not due to changes in physicochemical conditions. The growth of NFC crystals inside an organic mould formed by the fungal hyphae could explain the formation of calcite ciystals in the shape of a needle in isotopic equilibrium with the local environment.Strontium and calcium isotope compositions of the three microscopic groups of NFC and LCC were also studied, in order to determine the origin of calcium (Ca2+) entrapped in the calcite lattice and to elucidate the processes responsible for the precipitation of NFC. The 87Sr/86Sr ratio of the SN is closer to the 87Sr/86Sr ratio of the carbonate host rock than the LCC, SNO, and SNN. This could be another clue for the formation of SN inside fungal hyphae, because fungi are known to dissolve the rocks to release and translocate through their hyphae nutrients necessary for their growth. SN and SNN are depleted in Sr and enriched in ^Ca compared to the LCC. In the context of Villiers quarry, where the two ciystal shapes precipitate at similar temperature (in a range of 0,6°C), such variations are the result of a slower precipitation rate of NFC, which is inconsistent with a purely physicochemically precipitated elongate crystal.Finally, NFC is enriched in major and trace elements (i.e. Fe, Zn, Cu, and Mo) compared to the LCC. This enrichment is ascribed to modification in precipitation processes between the NFC and LCC. Right now, it is not possible to preclude the influence of the particular shape of NFC or the biological influence. REEs are not fractionated in NFC, contrary to LCC. Thus, NFC does not precipitate from a percolation solution circulating downward the soil, which should lead to the fractionation of the REEs. As explained above, fungi, are able to dissolve and translocate nutrients. This kind of processes allows releasing elements in the soil solution without fractionation and could explain the particular chemical signature of NFC regarding the REEs.The geochemical approach to investigate the origin of NFC presented in this study does not allow providing direct clues to the fungal origin of NFC, but brings several new insights in the understanding of the formation of such a particular mineral, calcite needles, by precluding definitively their physicochemical origin.RESUMELa calcite en aiguilles (NFC) est l'une des formes les plus ubiquiste de calcite pédogénique. Il s'agit d'un monocrystal de calcite d'un diamètre d'un micron et d'une longueur 4 à 102 fois supérieure à sa largeur. A l'échelle macroscopique, la NFC a été observée sous deux principaux aspects : l'une « cotonneuse » et l'autre formant un mince croûte autour des graviers du sol. La NFC peut également servir de support à la nucléation de ciments secondaires précipités de manière purement physico-chimique (LCC). Malgré les nombreuses études menées sur la NFC, son origine demeure encore inconnue. A ce jour, aucune expérience en laboratoire n'a permis de créer de la calcite en aiguilles, et ce, quelque soit l'approche abordée. Par conséquent, les processus précis responsables de la précipitation calcite avec une telle morphologie restent inconnus. Le décalage existant entre l'axe d'allongement des aiguilles de calcite et l'axe normal de croissance de la calcite (axe c) reste inexpliqué.Des échantillons de NFC, LCC, roche mère, eau de pluie des différents horizons du sol ont été prélevés principalement au front de deux carrières de graviers, ainsi que dans un profil de sol adjacent à ces carrières, dans le but de mieux comprendre les processus à l'origine de la précipitation de calcite en forme d'aiguille. Trois micro-morphologies ont été distinguées: les aiguilles simples (SN), les aiguilles simples avec surcroissances calcitiques (SNO) et enfin les aiguilles simples avec nanofibres (SNN), celles-ci pouvant être de minérales ou organiques. Ces groupes, d'après nos résultats et les études antérieures pourraient correspondre à différentes étapes de formation de la calcite en aiguilles.Dans un premier temps, la comparaison des signatures isotopiques de la calcite en aiguilles, du LCC, de la roche mère et du carbone inorganique dissout dans la solution du sol (CID) indique que la NFC, tout comme le LCC, précipite en équilibre avec la solution du sol. Les valeurs similaires en Ô13C et δ180 de cristaux de calcite allongés (NFC) et rhombohédriques (LCC) formés dans un même milieu suggère que ces différences morphologiques ne peuvent pas être attribuées à des modifications purement physico-chimiques. La croissance de NFC à l'intérieur d'un moule organique comme les hyphes de champignons semble être la seule hypothèse plausible permettant d'expliquer la formation de monocrystaux allongés de calcite en équilibre avec leur environnement.La composition isotopique en strontium (Sr) et calcium (Ca) des LCC et des trois micro¬morphologies de la NFC ont été étudiées également, afin de déterminer l'origine du Ca2+ présent dans le réseau cristallin de la calcite en aiguilles, ainsi que les processus responsables de la formation de NFC. Les valeurs du rapport 87Sr/86$r de la forme SN sont les plus proches de celles de la roche mère par rapport aux formes SNN et SNO et du LCC. Ceci pourrait être un nouvel indice de l'implication des champignons dans la précipitation de calcite en aiguilles, puisqu'ils sont connus pour avoir la capacité de dissoudre les roches afin de libérer les nutriments nécessaires à leur croissance, ainsi que de les transloquer par leurs hyphes. De plus, les formes SN et SNN sont appauvries en Sr et enrichies en "Ca, comparativement au LCC. Dans le sol étudié, tous les carbonates de calcium précipitent à la même température, par conséquent, de telles variations sont dues à un taux de précipitation plus lent de SN et SNN, ce qui est contradictoire avec l'hypothèse physico-chimique. Pour finir, la NFC est enrichie en certains éléments majeurs et traces (i.e. Fe, Zn, Cu et Mo) par rapport au LCC. Ceci peut être attribué à différents processus de formation entre la NFC et le LCC. Pour le moment il est impossible d'exclure l'influence de la forme particulière de la NFC ou celle du champignon. Les terres rares (REEs) ne sont pas fractionnées dans la NFC, contrairement au LCC. Ceci peut être expliqué par le fait que la NFC précipite à partir d'une solution qui n'a pas percolé à travers le sol. Les champignons en dissolvant les roches mettent en solution éléments sans les fractionner. L'approche géochimique de l'étude de la calcite en aiguilles ne permets pas de produire des preuves directes sur sa potentielle origine fongique, mais permet de mieux comprendre comment un minéral aussi singulier que la NFC peut se former. D'autre pare cette étude permets d'exclure définitivement l'hypothèse physico-chimique de l'origine de la calcite en aiguilles

Hypocretin/orexin in addiction: a mediator of stress-induced reinstatement of cocaine-seeking behaviour

The importance of the lateral hypothalamus in the pursuit of reward has long been recognized. However, the hypothalamic neuronal network involved in the regulation of reward still remains partially unknown. Hypocretins (aka orexins) are neuropeptides synthesized by a few thousand neurons restricted to the lateral hypothalamus and the perifornical area. Compelling evidence indicates that hypocretin neurons receive inputs from sensory and limbic systems and drive hyper-arousal possibly through modulation of stress responses. Major advances have been made in the elucidation of the hypocretin involvement in the regulation of arousal, stress, motivation, and reward seeking, without clearly defining the role of hypocretins in addictionrelated behaviors. We have recently gathered substantial evidence that points to a previously unidentified role for hypocretin-1 in driving relapse for cocaine seeking through activation of brain stress pathways. Meanwhile, several authors published concordant observations rather suggesting a direct activation of the mesolimbic dopamine system. In particular, hypocretin-1 has been shown to be critically involved in cocaine sensitization through the recruitment of NMDA receptors in the ventral tegmental area. Overall, on can conclude from recent findings that activation of hypocretin/orexin neurons plays a critical role in the development of the addiction process, either by contributing to brain sensitization (which is thought to lead to the unmanageable desire for drug intake) or by modulating the brain reward system that, in coordination with brain stress systems, leads to a vulnerable state that may facilitate relapse for drug seeking behavior.

Speed-cohesion trade-offs in collective decision making in ants and the concept of precision in animal behaviour

In decision making, speed-accuracy trade-offs are well known and often inevitable because accuracy depends on being well informed and gathering information takes time. However, trade-offs between speed and cohesion, that is the degree to which a group remains together as a single entity, as a result of their decision making, have been comparatively neglected. We combine theory and experimentation to show that in decision-making systems, speed-cohesion trade-offs are a natural complement to speed-accuracy trade-offs and are therefore of general importance. We then analyse the decision performance of 32 rock ant, Temnothorax albipennis, colonies in experiments in which accuracy of collective decision making was held constant, but time urgency varied. These experiments reveal for the first time an adaptive speed-cohesion trade-off in collective decision making and how this is achieved. In accord with different time constraints, colonies can decide quickly, at the cost of social unity, or they can decide slowly with much greater cohesion. We discuss the similarity between cohesion and the term precision as used in statistics and engineering. This emphasizes the generality of speed versus cohesion/precision trade-offs in decision making and decision implementation in other fields within animal behaviour such as sexually selected motor displays and even certain aspects of birdsong. We also suggest that speed versus precision trade-offs may occur when individuals within a group need to synchronize their activity, and in collective navigation, cooperative hunting and in certain escape behaviours.

Geochemical compositions of Neogene phosphatic brachiopods: Implications for ancient environmental and marine conditions

Isotopic and trace element compositions of Miocene and Pliocene phosphatic brachiopods (Lingulidae and Discinidae) from southern North Sea, the Central Paratethys and the Atlantic coast of Europe were investigated in order to trace past environmental conditions and marine connections between the northern boreal and the southern subtropical-tropical marine basins. The North Sea genus Glottidia yielded low epsilon(Nd) and high delta O-18(PO4) values through the Mio-Pliocene indicating cold habitat temperature where the local seawater was dominated by the Atlantic Ocean. In contrast, the Middle Miocene Lingulidae and Discinidae of the Paratethys inhabited warm subtropical seawater with the possible influence of the Indian Ocean via the Mediterranean, as supported by their average epsilon(Nd) value of -8.3. The combined geochemical data support a thermal and marine separation of the Paratethys from the North Sea with no direct connection or major exchange of water from the Miocene onwards. The temperature in the Paratethys was very similar to that inferred from brachiopods from the Middle Miocene of western France, but the seawater epsilon(Nd) value here is identical to that of contemporaneous Atlantic Ocean. A Late Miocene lingulid brachiopod from southern Portugal has a high delta O-18(PO4), similar to the specimens investigated from the North Sea, reflecting either a deep water habitat or formation after the onset of major global cooling that resulted in an increased delta O-18 value of seawater. The epsilon(Nd) value of -8.4 for this site is compatible with an influence of Mediterranean outflow. (C) 2012 Elsevier B.V. All rights reserved.

Tectonomagmatic evolution of Western Amazonia: Geochemical characterization and zircon U-Pb geochronologic constraints from the Peruvian Eastern Cordilleran granitoids

The results of a coupled, in situ laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) U-Pb study on zircon and geochemical characterization of the Eastern Cordilleran intrusives of Peru reveal 1.15 Ga of intermittent magmatism along central Western Amazonia, the Earth's oldest active open continental margin. The eastern Peruvian batholiths are volumetrically dominated by plutonism related to the assembly and breakup of Pangea during the Paleozoic-Mesozoic transition. A Carboniferous-Permian (340-285 Ma) continental arc is identified along the regional orogenic strike from the Ecuadorian border (6 degrees S) to the inferred inboard extension of the Arequipa-Antofalla terrane in southern Peru (14 degrees S). Widespread crustal extension and thinning, which affected western Gondwana throughout the Permian and Triassic resulted in the intrusion of the late- to post-tectonic La Merced-San Ramon-type anatectites dated between 275 and 220 Ma, while the emplacement of the southern Cordillera de Carabaya peraluminous granitoids in the Late Triassic to Early Jurassic (220-190 Ma) represents, temporally and regionally, a separate tectonomagmatic event likely related to resuturing of the Arequipa-Antofalla block. Volcano-plutonic complexes and stocks associated with the onset of the present Andean cycle define a compositionally bimodal alkaline suite and cluster between 180 and 170 Ma. A volumetrically minor intrusive pulse of Oligocene age (ca. 30 Ma) is detected near the southwestern Cordilleran border with the Altiplano. Both post-Gondwanide (30-170 Ma), and Precambrian plutonism (691-1123 Ma) are restricted to isolated occurrences spatially comprising less than 15% of the Eastern Cordillera intrusives. Only one remnant of a Late Ordovician intrusive belt is recognized in the Cuzco batholith (446.5 +/- 9.7 Ma) indicating that the Famatinian arc system previously identified in Peru along the north-central Eastern Cordillera and the coastal Arequipa-Antofalla terrane also existed inboard of this parautochthonous crustal fragment. Hitherto unknown occurrences of late Mesoproterozoic and middle Neoproterozoic granitoids from the south-central cordilleran segment define magmatic events at 691 +/- 13 Ma, 751 +/- 8 Ma, 985 +/- 14 Ma, and 1071-1123 +/- 23 Ma that are broadly coeval with the Braziliano and Grenville-Sunsas orogenies, respectively. Our data suggest the existence of a continuous orogenic belt in excess of 3500 km along Western Amazonia during the formation of Rodinia, its ``early'' fragmentation prior to 690 Ma, and support a model of reaccretion of the Paracas-Arequipa-Antofalla terrane to western Gondwana in the Early Ordovician with subsequent detachment of the Paracas segment in form of the Mexican Oaxaquia microcontinent in Middle Ordovician. A tectonomagmatic model involving slab detachment, followed by underplating of cratonic margin by asthenospheric mantle is proposed for the genesis of the volumetrically dominant Late Paleozoic to early Mesozoic Peruvian Cordilleran batholiths.

Body image perception and weight-related behaviour among adolescents of the Seychelles

Background: We examined one's own body image perception and its association with reported weight-related behavior among adolescents of a rapidly developing country in the African region. Methods: We conducted a school-based survey of 1432 students aged 11-17 years in the Seychelles. Weight and height were measured, and thinness, normal weight and overweight were assessed along standard criteria. A self-administered and anonymous questionnaire was administered. Perception of body image was assessed using both a closed-ended question (CEQ) and the Stunkard's pictorial silhouettes (SPS). Finally, a question assessed voluntary attempts to change weight. Results: Overall, 14.1% of the students were thin, 63.9% were normal-weight, and 22.0% were overweight or obese. There was fair agreement between actual weight status and self-perceived body image based on either CEQ or SPS. However, a substantial proportion of the overweight students did not consider themselves as overweight (SPS: 24%, CEQ: 34%) and, inversely, a substantial proportion of the normal-weight students considered themselves as too thin (SPS: 29%, CEQ: 15%). Among the overweight students, an adequate attempt to lose weight was reported more often by boys and girls who perceived themselves as overweight vs. not overweight (72-88% vs. 40-71%, p <0.05 for most comparisons). Among the normal-weight students, an inadequate attempt to gain weight was reported more often by boys and girls who perceived themselves as thin vs. not thin (27-68% vs. 11-19%, p <0.05). Girls had leaner own body ideals than boys. Conclusions: We found that substantial proportions of overweight students did not perceive themselves as overweight and/or did not want to lose weight and, inversely, that many normalweight students perceived themselves as too thin and/or wanted to gain weight: this points to forces that can drive the upwards overweight trends. Appropriate perception of one's weight was associated with adequate weight-control behavior, although not strongly, emphasizing that appropriate weight perception is only one of several factors driving adequate weight-related behavior. These findings emphasize the need to address appropriate perception of one's own weight and adequate weight-related behavior in adolescents for both individual and community weight-related interventions.

Place illusion and plausibility can lead to realistic behaviour in immersive virtual environments

In this paper address we the question as to why participants tend to respond realistically to situations and events portrayed within an Immersive Virtual Reality (IVR) system. The idea is put forward, based on experience of a large number of experimental studies, that there are two orthogonal components that contribute to this realistic response. The first is"being there", often called"presence", the qualia of having a sensation of being in a real place. We call this Place Illusion (PI). Second, Plausibility Illusion (Psi) refers to the illusion that the scenario being depicted is actually occurring. In the case of both PI and Psi the participant knows for sure that that they are not"there" and that the events are not occurring. PI is constrained by the sensorimotor contingencies afforded by the virtual reality system. Psi is determined by the extent to which the system can produce events that directly relate to the participant, and the overall credibility of the scenario being depicted in comparison with expectations. We argue that when both PI and Psi occur, participants will respond realistically to the virtual reality.

Performance analysis of software run-time behaviour using 3D-visualisation

Monimutkaisen tietokonejärjestelmän suorituskykyoptimointi edellyttää järjestelmän ajonaikaisen käyttäytymisen ymmärtämistä. Ohjelmiston koon ja monimutkaisuuden kasvun myötä suorituskykyoptimointi tulee yhä tärkeämmäksi osaksi tuotekehitysprosessia. Tehokkaampien prosessorien käytön myötä myös energiankulutus ja lämmöntuotto ovat nousseet yhä suuremmiksi ongelmiksi, erityisesti pienissä, kannettavissa laitteissa. Lämpö- ja energiaongelmien rajoittamiseksi on kehitetty suorituskyvyn skaalausmenetelmiä, jotka edelleen lisäävät järjestelmän kompleksisuutta ja suorituskykyoptimoinnin tarvetta. Tässä työssä kehitettiin visualisointi- ja analysointityökalu ajonaikaisen käyttäytymisen ymmärtämisen helpottamiseksi. Lisäksi kehitettiin suorituskyvyn mitta, joka mahdollistaa erilaisten skaalausmenetelmien vertailun ja arvioimisen suoritusympäristöstä riippumatta, perustuen joko suoritustallenteen tai teoreettiseen analyysiin. Työkalu esittää ajonaikaisesti kerätyn tallenteen helposti ymmärrettävällä tavalla. Se näyttää mm. prosessit, prosessorikuorman, skaalausmenetelmien toiminnan sekä energiankulutuksen kolmiulotteista grafiikkaa käyttäen. Työkalu tuottaa myös käyttäjän valitsemasta osasta suorituskuvaa numeerista tietoa, joka sisältää useita oleellisia suorituskykyarvoja ja tilastotietoa. Työkalun sovellettavuutta tarkasteltiin todellisesta laitteesta saatua suoritustallennetta sekä suorituskyvyn skaalauksen simulointia analysoimalla. Skaalausmekanismin parametrien vaikutus simuloidun laitteen suorituskykyyn analysoitiin.

Consumers' use of nutrition-related endorsement symbol to help their purchase decisions: An extension of the theory of planned behaviour

Tutkimuksessa haluttiin selvittää, mitkä tekijät vaikuttavat ravintoon liittyvän suositusmerkin käyttöön kuluttajan ostopäätöksen apuna. Tutkimuksen viitekehyksen pohjaksi valittiin suunnitellun toiminnan teoria, joka on osoittautunut selittämään hyvin useaa ravintoon- ja terveyteen liittyvää käyttäytymistä. Tutkimustoteutettiin kyselytutkimuksella, jonka aineisto kerättiin Internetissä julkaistulla kyselylomakkeella. Tulokset osoittivat, että kuluttajan aikomus käyttää suositusmerkkiä oli mallin vahvin selittäjä. Lisäksi merkin käyttöä selitti kuluttajan kokema sisäinen kontrolli, johon ulkoinen kontrolli vahvasti vaikuttaa. Ostopäätössitoutumisen havaittiin vaikuttavan aikomuksen ja todellisen merkin käytön väliseen yhteyteen. Yleisesti tulokset osoittivat, että kuluttajilla on aikomusta käyttää merkkiä, mutta todellinen käyttö on huomattavasti vähäisempää.

Diving capacity and foraging behaviour of the water shrew (Neomys fodiens)

With regard to semi-aquatic mammals, Schröpfer & Stubbe (1992) distinguished three riparian guilds: the herbivores with the water vole and the beaver; the megacarnivores with the mink and the otter; and the macrocarnivores with water shrews and desmans. Among water shrews, the evolution of aquatic foraging behaviour occurred several times: Nectogale and Chimarrogale in Asia, several species of the genus Sorex in America, and Neomys in Eurasia (Churchfield, 1990). The fairly common European water shrew N. fodiens is the best known. However, the reports on the degree of adaptation to the water habitat are conflicting. Therefore some important findings from the literature are reviewed in this introduction, whereas new data are presented in the following sections. The swimming locomotion of water shrews was analysed by Ruthardt & Schröpfer (1985) and Köhler (1991), and the related morphological adaptation were reviewed by Hutterer (1985) and Churchfield (this volume pp. 49-51). They obviously present a compromise between the requirements for activity on land and in the water. Thermoregulation is a major problem for semi-aquatic mammals, because heat conductance in water is 25-fold greater than in air (Calder, 1969). According to this author, the body temperature of immersed American Sorex palustris dropped by a rate of 2.8 °C per min. However, this may be an experimental artefact, because Neomys fodiens can maintain its body temperature at 37 °C during an immersion of 6 min (Vogel, 1990).

Courtship and mating behaviour of the Mediterranean corn borer, Sesamia nonagrioides (Lepidoptera: Noctuidae)

Se describe la secuencia de cortejo y apareamiento de machos y hembras de Sesamia nonagrioides (Lefèbvre) en el laboratorio. Esta secuencia no varió en presencia o ausencia de plantas de maíz. Se estudió la capacidad de atracción de un sexo sobre el otro atando el individuo de un sexo y dejando libre al complementario. La secuencia de cortejo y apareo de las hembras atadas fue la misma que la de las no atadas, pero los machos atados permanecieron absolutamente inactivos. La edad de los adultos (1 día versus 2 días) no afectó al porcentaje de apareamiento. Se encontraron diferencias en la hora del inicio de la llamada de las hembras y en la edad de las hembras en la primera llamada entre la población estudiada y lo descrito para una población griega, diferencias que podrían estar relacionadas con el origen geográfico. Se discute el papel de los penachos abdominales de los machos en el vuelo de cortejo, rechazándose que estimulen el comportamiento de llamada de las hembras o que las atraigan. Cuando no se aplicaron feromonas, el porcentaje de apareamiento en el laboratorio o en el campo no varió cuando aumentó la densidad de la población. Sin embargo, en los campos en que se aplicó confusión sexual, el porcentaje de apareamiento aumentó al aumentar la densidad de adultos. En la discusión se aportan algunas consecuencias para la investigación de la composición de las feromonas y su uso para el seguimiento de plagas y el control mediante confusión sexual.

Effects of a post-weaning cafeteria diet in young rats: metabolic syndrome, reduced activity and low anxiety-like behaviour.

Among adolescents, overweight, obesity and metabolic syndrome are rapidly increasing in recent years as a consequence of unhealthy palatable diets. Animal models of diet-induced obesity have been developed, but little is known about the behavioural patterns produced by the consumption of such diets. The aim of the present study was to determine the behavioural and biochemical effects of a cafeteria diet fed to juvenile male and female rats, as well as to evaluate the possible recovery from these effects by administering standard feeding during the last week of the study. Two groups of male and female rats were fed with either a standard chow diet (ST) or a cafeteria (CAF) diet from weaning and for 8 weeks. A third group of males (CAF withdrawal) was fed with the CAF diet for 7 weeks and the ST in the 8th week. Both males and females developed metabolic syndrome as a consequence of the CAF feeding, showing overweight, higher adiposity and liver weight, increased plasma levels of glucose, insulin and triglycerides, as well as insulin resistance, in comparison with their respective controls. The CAF diet reduced motor activity in all behavioural tests, enhanced exploration, reduced anxiety-like behaviour and increased social interaction; this last effect was more pronounced in females than in males. When compared to animals only fed with a CAF diet, CAF withdrawal increased anxiety in the open field, slightly decreased body weight, and completely recovered the liver weight, insulin sensitivity and the standard levels of glucose, insulin and triglycerides in plasma. In conclusion, a CAF diet fed to young animals for 8 weeks induced obesity and metabolic syndrome, and produced robust behavioural changes in young adult rats, whereas CAF withdrawal in the last week modestly increased anxiety, reversed the metabolic alterations and partially reduced overweight.