1,720,959 research outputs found
Behavioral Analysis of Mice in a Virtual Navigation Decision Task
No full textMice were trained on an accumulation of evidence task in a virtual reality, in which
they had to integrate evidence of left and right cues presented in the cue zone of
a straight runway. After a short memory zone, in which cues were absent, they
had to turn into either a left or right branch at the end of the maze depending on
which side had previously more cues. Mice were trained in two different versions
of the task. The version with the shorter cue zone as well as shorter memory
zone and total length enabled more mice to accomplish the task by advancing to
the goal maze. A logistic regression model predicted how mice weighed cues in
different sections of the cue zone was and showed that mice do not integrate over
all cues equally. The mouse data was then analyzed with regard to the Signal
Detection Theory Model, previously developed by Scott and Constantinople et al.
[26]. The Signal Detection Theory assumes a Gaussian probability distribution for
what the mouse perceives the number of cues to be [10]. The standard deviation
of this Gaussian was found to scale linearly to the number of cues for rats [26].
A similar analysis was conducted for mouse data and the standard deviation was
furthermore found to scale linearly to the number of cues for mice. . .
The neuropeptide FLP-11 induces and self-inhibits sleep through the receptor DMSR-1 in Caenorhabiditis elegans
Get PDFhttp://dx.doi.org/10.13039/501100000781 European Research Councilhttp://dx.doi.org/10.13039/501100010563 Baillet Latour Fundhttp://dx.doi.org/10.13039/501100001659 German Research Foundatio
Sleep neuron depolarization promotes protective gene expression changes and FOXO activation
Get PDFSleep is an essential state that allows for recuperation and survival processes. Disturbing sleep triggers stress responses that promote protective gene expression. Sleep and its deprivation grossly impact gene expression, but little is known about how normal or disturbed sleep control gene expression. Central to the induction of sleep are sleep-active neurons, which inhibit wakefulness and promote survival. Sleep and sleep-active neurons are highly conserved. In Caenorhabditis elegans, the sleep-active RIS neuron is crucial for sleep and survival. Here, we show that RIS depolarization promotes the protective gene expression response that occurs during developmental arrest. This response includes the activation of FOXO/DAF-16 and expression of DAF-16 target genes such as HSP-12.6, a small heat-shock protein that is required for starvation survival. Disturbing sleep by mechanical stimulation increases RIS depolarization. RIS activation in turn activates DAF-16 and other genes required for survival. Hence, during normal sleep, RIS depolarization promotes protective gene expression. When sleep is disturbed, protective gene expression gets further increased by raised RIS depolarization. We thus link sleep-active neuron depolarization to protective gene expression changes and suggest that the cellular stress response following sleep deprivation could be understood as a safeguarding process that is caused by the overactivation of sleep-active neurons
A sleep-active neuron can promote survival while sleep behavior is disturbed
Get PDFSleep is controlled by neurons that induce behavioral quiescence and physiological restoration. It is not known, however, how sleep neurons link sleep behavior and survival. In Caenorhabditis elegans, the sleep-active RIS neuron induces sleep behavior and is required for survival of starvation and wounding. Sleep-active neurons such as RIS might hypothetically promote survival primarily by causing sleep behavior and associated conservation of energy. Alternatively, RIS might provide a survival benefit that does not depend on behavioral sleep. To probe these hypotheses, we tested how activity of the sleep-active RIS neuron in Caenorhabditis elegans controls sleep behavior and survival during larval starvation. To manipulate the activity of RIS, we expressed constitutively active potassium channel (twk-18gf and egl-23gf) or sodium channel (unc-58gf) mutant alleles in this neuron. Low levels of unc-58gf expression in RIS increased RIS calcium transients and sleep. High levels of unc-58gf expression in RIS elevated baseline calcium activity and inhibited calcium activation transients, thus locking RIS activity at a high but constant level. This manipulation caused a nearly complete loss of sleep behavior but increased survival. Long-term optogenetic activation also caused constantly elevated RIS activity and a small trend towards increased survival. Disturbing sleep by lethal blue-light stimulation also overactivated RIS, which again increased survival. FLP-11 neuropeptides were important for both, induction of sleep behavior and starvation survival, suggesting that FLP-11 might have divergent roles downstream of RIS. These results indicate that promotion of sleep behavior and survival are separable functions of RIS. These two functions may normally be coupled but can be uncoupled during conditions of strong RIS activation or when sleep behavior is impaired. Through this uncoupling, RIS can provide survival benefits under conditions when behavioral sleep is disturbed. Promoting survival in the face of impaired sleep might be a general function of sleep neurons
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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