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Current Biology: CB

Matthias Stangl, Johannes Achtzehn, Karin Huber, Caroline Dietrich, Claus Tempelmann, Thomas Wolbers
A progressive loss of navigational abilities in old age has been observed in numerous studies, but we have only limited understanding of the neural mechanisms underlying this decline [1]. A central component of the brain's navigation circuit are grid cells in entorhinal cortex [2], largely thought to support intrinsic self-motion-related computations, such as path integration (i.e., keeping track of one's position by integrating self-motion cues) [3-6]. Given that entorhinal cortex is particularly vulnerable to neurodegenerative processes during aging and Alzheimer's disease [7-14], deficits in grid cell function could be a key mechanism to explain age-related navigational decline...
March 12, 2018: Current Biology: CB
Sam C Berens, Jessica S Horst, Chris M Bird
When we encounter a new word, there are often multiple objects that the word might refer to [1]. Nonetheless, because names for concrete nouns are constant, we are able to learn them across successive encounters [2, 3]. This form of "cross-situational" learning may result from either associative mechanisms that gradually accumulate evidence for each word-object association [4, 5] or rapid propose-but-verify (PbV) mechanisms where only one hypothesized referent is stored for each word, which is either subsequently verified or rejected [6, 7]...
March 10, 2018: Current Biology: CB
Lysann Wagener, Maria Loconsole, Helen M Ditz, Andreas Nieder
Endowed with an elaborate cerebral cortex, humans and other primates can assess the number of items in a set, or numerosity, from birth on [1] and without being trained [2]. Whether spontaneous numerosity extraction is a unique feat of the mammalian cerebral cortex [3-7] or rather an adaptive property that can be found in differently designed and independently evolved neural substrates, such as the avian enbrain [8], is unknown. To address this question, we recorded single-cell activity from the nidopallium caudolaterale (NCL), a high-level avian association brain area [9-11], of numerically naive crows...
March 9, 2018: Current Biology: CB
Rohit Menon, Thomas Grund, Iulia Zoicas, Ferdinand Althammer, Dominik Fiedler, Verena Biermeier, Oliver J Bosch, Yuichi Hiraoka, Katsuhiko Nishimori, Marina Eliava, Valery Grinevich, Inga D Neumann
Oxytocin (OXT)-mediated behavioral responses to social and stressful cues have extensively been studied in male rodents. Here, we investigated the capacity of brain OXT receptor (OXTR) signaling in the lateral septum (LS) to prevent social fear expression in female mice using the social-fear-conditioning paradigm. Utilizing the activated OXT system during lactation, we show that lactating mice did not express fear 24 hr after social fear conditioning. Supporting the role of OXTR signaling in the LS in attenuation of social fear, synthetic OXT infusion or overexpression of OXTR in the LS diminished social fear expression, whereas constitutive OXTR knockout severely impaired social fear extinction in virgin mice...
March 7, 2018: Current Biology: CB
Vladimir Djurdjevic, Alessio Ansuini, Daniele Bertolini, Jakob H Macke, Davide Zoccolan
Despite their growing popularity as models of visual functions, it remains unclear whether rodents are capable of deploying advanced shape-processing strategies when engaged in visual object recognition. In rats, for instance, pattern vision has been reported to range from mere detection of overall object luminance to view-invariant processing of discriminative shape features. Here we sought to clarify how refined object vision is in rodents, and how variable the complexity of their visual processing strategy is across individuals...
March 7, 2018: Current Biology: CB
Nicolas Josset, Marie Roussel, Maxime Lemieux, David Lafrance-Zoubga, Ali Rastqar, Frederic Bretzner
The mesencephalic locomotor region (MLR) has been initially identified as a supraspinal center capable of initiating and modulating locomotion. Whereas its functional contribution to locomotion has been widely documented throughout the phylogeny from the lamprey to humans, there is still debate about its exact organization. Combining kinematic and electrophysiological recordings in mouse genetics, our study reveals that glutamatergic neurons of the cuneiform nucleus initiate locomotion and induce running gaits, whereas glutamatergic and cholinergic neurons of the pedunculopontine nucleus modulate locomotor pattern and rhythm, contributing to slow-walking gaits...
March 7, 2018: Current Biology: CB
Louise P Cramer, Robert R Kay, Evgeny Zatulovskiy
Attractive and repulsive cell guidance is essential for animal life and important in disease. Cell migration toward attractants dominates studies [1-8], but migration away from repellents is important in biology yet relatively little studied [5, 9, 10]. It is widely held that cells initiate migration by protrusion of their front [11-15], yet this has not been explicitly tested for cell guidance because cell margin displacement at opposite ends of the cell has not been distinguished for any cue. We argue that protrusion of the front, retraction of the rear, or both together could in principle break cell symmetry and start migration in response to guidance cues [16]...
March 7, 2018: Current Biology: CB
Matthew J Paul, Clemens K Probst, Lauren M Brown, Geert J de Vries
Alongside the development of sexual characteristics and reproductive competence, adolescents undergo marked cognitive, social, and emotional development [1]. A fundamental question is whether these changes are triggered by activation of the hypothalamic-pituitary-gonadal (HPG) axis at puberty (puberty dependent) or whether they occur independently of HPG activation (puberty independent). Disentangling puberty-dependent from puberty-independent mechanisms is difficult because puberty and adolescence typically proceed concurrently...
March 6, 2018: Current Biology: CB
Eugene Jennifer Jin, Ferdi Ridvan Kiral, Mehmet Neset Ozel, Lara Sophie Burchardt, Marc Osterland, Daniel Epstein, Heike Wolfenberg, Steffen Prohaska, Peter Robin Hiesinger
Neurons are highly polarized cells that require continuous turnover of membrane proteins at axon terminals to develop, function, and survive. Yet, it is still unclear whether membrane protein degradation requires transport back to the cell body or whether degradation also occurs locally at the axon terminal, where live observation of sorting and degradation has remained a challenge. Here, we report direct observation of two cargo-specific membrane protein degradation mechanisms at axon terminals based on a live-imaging approach in intact Drosophila brains...
March 3, 2018: Current Biology: CB
John S S Denton
The mesopelagic (midwater) and deep-sea environments together comprise over 90% of the volume of the world ocean [1] and provide services that are only recently becoming recognized [2]. One of the most significant of these services relates to midwater fish biomass, recently estimated to be two orders of magnitude larger than the current worldwide fisheries catch [3, 4]. Calls to exploit midwater fish biomass have increased despite warnings about the unknown recovery potential of such organisms [2] and despite existing data suggesting that deep-sea fishes could be classified as endangered [5]...
March 3, 2018: Current Biology: CB
Vineet Choudhary, Gonen Golani, Amit S Joshi, Stéphanie Cottier, Roger Schneiter, William A Prinz, Michael M Kozlov
Lipid droplets (LDs) store fats and play critical roles in lipid and energy homeostasis. They form between the leaflets of the endoplasmic reticulum (ER) membrane and consist of a neutral lipid core wrapped in a phospholipid monolayer with proteins. Two types of ER-LD architecture are thought to exist and be essential for LD functioning. Maturing LDs either emerge from the ER into the cytoplasm, remaining attached to the ER by a narrow membrane neck, or stay embedded in the ER and are surrounded by ER membrane...
March 3, 2018: Current Biology: CB
Kelli A Fagan, Jintao Luo, Ross C Lagoy, Frank C Schroeder, Dirk R Albrecht, Douglas S Portman
Biological sex, a fundamental dimension of internal state, can modulate neural circuits to generate behavioral variation. Understanding how and why circuits are tuned by sex can provide important insights into neural and behavioral plasticity. Here we find that sexually dimorphic behavioral responses to C. elegans ascaroside sex pheromones are implemented by the functional modulation of shared chemosensory circuitry. In particular, the sexual state of a single sensory neuron pair, ADF, determines the nature of an animal's behavioral response regardless of the sex of the rest of the body...
March 3, 2018: Current Biology: CB
Anja Buttstedt, Carmen I Mureşan, Hauke Lilie, Gerd Hause, Christian H Ihling, Stefan-H Schulze, Markus Pietzsch, Robin F A Moritz
The female sex in honeybees (Apis spp.) comprises a reproductive queen and a sterile worker caste. Nurse bees feed all larvae progressively with a caste-specific food jelly until the prepupal stage. Only those larvae that are exclusively fed a large amount of royal jelly (RJ) develop into queens [1]. RJ is a composite secretion of two specialized head glands: the mandibular glands, which produce mainly fatty acids [2], and the hypopharyngeal glands, which contribute proteins, primarily belonging to the major royal jelly protein (MRJP) family [3]...
March 2, 2018: Current Biology: CB
Scott A Cairney, Anna Á Váli Guttesen, Nicole El Marj, Bernhard P Staresina
How are brief encounters transformed into lasting memories? Previous research has established the role of non-rapid eye movement (NREM) sleep, along with its electrophysiological signatures of slow oscillations (SOs) and spindles, for memory consolidation [1-4]. In related work, experimental manipulations have demonstrated that NREM sleep provides a window of opportunity to selectively strengthen particular memory traces via the delivery of auditory cues [5-10], a procedure known as targeted memory reactivation (TMR)...
March 2, 2018: Current Biology: CB
Michael Turelli, Brandon S Cooper, Kelly M Richardson, Paul S Ginsberg, Brooke Peckenpaugh, Chenling X Antelope, Kevin J Kim, Michael R May, Antoine Abrieux, Derek A Wilson, Michael J Bronski, Brian R Moore, Jian-Jun Gao, Michael B Eisen, Joanna C Chiu, William R Conner, Ary A Hoffmann
Maternally transmitted Wolbachia, Spiroplasma, and Cardinium bacteria are common in insects [1], but their interspecific spread is poorly understood. Endosymbionts can spread rapidly within host species by manipulating host reproduction, as typified by the global spread of wRi Wolbachia observed in Drosophila simulans [2, 3]. However, because Wolbachia cannot survive outside host cells, spread between distantly related host species requires horizontal transfers that are presumably rare [4-7]. Here, we document spread of wRi-like Wolbachia among eight highly diverged Drosophila hosts (10-50 million years) over only about 14,000 years (5,000-27,000)...
March 2, 2018: Current Biology: CB
Carlos Eduardo Pereira Nunes, Pietro Kiyoshi Maruyama, Marianne Azevedo-Silva, Marlies Sazima
Nursery pollination involves pollinators that lay eggs on the flowers they pollinate and have their brood fed on flower parts or developing ovules [1-4]. Active pollination, a ritualistic behavioral sequence shown by nursery pollinators when transferring pollen from anthers to stigmas, is known in only four plant lineages [5-8], including the classical examples of fig trees-fig wasps and yuccas-yucca moths [5, 6]. We report in detail a system in which weevils actively pollinate orchids prior to having their larvae fed on the developing fruits...
March 1, 2018: Current Biology: CB
Yuanwei Fan, Graham M Burkart, Ram Dixit
The contribution of microtubule tip dynamics to the assembly and function of plant microtubule arrays remains poorly understood. Here, we report that the Arabidopsis SPIRAL2 (SPR2) protein modulates the dynamics of the acentrosomal cortical microtubule plus and minus ends in an opposing manner. Live imaging of a functional SPR2-mRuby fusion protein revealed that SPR2 shows both microtubule plus- and minus-end tracking activity in addition to localization at microtubule intersections and along the lattice...
February 28, 2018: Current Biology: CB
Rosemary G Gillespie, Suresh P Benjamin, Michael S Brewer, Malia Ana J Rivera, George K Roderick
Insular adaptive radiations in which repeated bouts of diversification lead to phenotypically similar sets of taxa serve to highlight predictability in the evolutionary process [1]. However, examples of such replicated events are rare. Cross-clade comparisons of adaptive radiations are much needed to determine whether similar ecological opportunities can lead to the same outcomes. Here, we report a heretofore uncovered adaptive radiation of Hawaiian stick spiders (Theridiidae, Ariamnes) in which different species exhibit a set of discrete ecomorphs associated with different microhabitats...
February 27, 2018: Current Biology: CB
Lei Li, Xiaolong Feng, Zheng Zhou, Huiqi Zhang, Qianqian Shi, Zhuogui Lei, Peilei Shen, Qingning Yang, Binghao Zhao, Shuran Chen, Lin Li, Yulin Zhang, Pengjie Wen, Zhonghua Lu, Xiang Li, Fuqiang Xu, Liping Wang
Defensive responses to threatening stimuli are crucial to the survival of species. While expression of these responses is considered to be instinctive and unconditional, their magnitude may be affected by environmental and internal factors. The neural circuits underlying this modulation are still largely unknown. In mice, looming-evoked defensive responses are mediated by the superior colliculus (SC), a subcortical sensorimotor integration center. We found that repeated stress caused an anxiety-like state in mice and accelerated defensive responses to looming...
February 26, 2018: Current Biology: CB
Aude Retailleau, Genela Morris
Incentives drive goal-directed behavior; however, how they impact the formation and stabilization of goal-relevant hippocampal maps remains unknown. Since dopamine is involved in reward processing, affects hippocampal-dependent behavior, and modulates hippocampal plasticity, we hypothesized that local dopaminergic transmission in the hippocampus serves to mold the formation and updating of hippocampal cognitive maps to adaptively represent reward-predicting space of sensory inputs. We recorded CA1 place cells of rats throughout training on a spatial extra-dimensional set-shift task...
February 26, 2018: Current Biology: CB
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