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The involvement of amygdala neurons and amygdaloid dopaminergic and glutamatergic receptors in the acquisition and reinstatement of fear-potentiated startle in rats.
Get PDFThe basolateral amygdala (BLA) contains NMDA, AMPA, and dopamine (DA) D1 and D2 receptors and neurobiochemical events within the amygdala mediate conditioned-fear-learning (CFL) and fear expression. Long-term potentiation (LTP) occurs in the amygdale during Pavlovian fear conditioning and is associated with fear-memory storage. CFL depends on NMDA, AMPA and dopaminergic receptor-mediated processes and enhanced amygdaloidal synaptic transmission facilitates fear-memory retrieval and makes the expression of conditioned fear possible. Since mesoamygdaloid DA receptors contribute to CFL and fear expression, Experiment 1A and 1D examined the impact of intra-BLA infusion of the DA D1 and D2 receptor antagonists SCH 23390 and raclopride L-tartrate on the acquisition of FPS in rats. Rats of the Wistar strain were bilaterally implanted with guide cannulae positioned 1.0 mm above the medial portion of the BLA. Approximately fourteen days later rats were assessed for baseline acoustic startle responding and assigned to drug-treatment groups. Forty-eight hours later rats were infused with either saline or the appropriate dopaminergic antagonist. The intra-BLA infusions occurred before five fear conditioning and testing blocks and were conducted to see if antagonism of DA receptors would prevent FPS acquisition. Retention testing for FPS took place forty-eight hours later. The results demonstrated that blockade of amygdaloid DA D1 and D2 receptors prevented the acquisition of FPS. The pretraining intra-BLA infusions of either raclopride or SCH 23390 disrupted the formation of long-term conditioned fear memories as rats treated with these DA antagonists failed to exhibit FPS on the retention test. Thus, the deficits in FPS displayed by SCH 23390 and raclopride-treated rats are likely due to the impact of these DA antagonists on associative learning and fear-memory consolidation processes. Experiment 2 demonstrated that fear-extinguished rats exposed to unsignalled footshocks displayed a reinstatement of FPS, but the exact neurobiochemicaI events involved in FPS reinstatement have not been elucidated. In contrast, fear-extinguished rats that received no unsignalled footshocks exhibited no FPS during final testing. Since unsignalled footshocks produced robust FPS reinstatement, Experiments 3A to 3D independently examined the effects of NMOA, AMPA, and DA D2 and D1 receptor antagonists on this phenomenon. Over a period of ten days, rats with cannulae targeting the BLA were base lined, fear-conditioned, pretested, fear-extinguished and then infused with either raclopride L-tartrate (8.0µg, 4.0 µg and 2.0µg), SCH 23390 (4.0 µg), (±)-2-amino-5-phosphonopentanoic acid {(APS); 2.5 µg and 1.25 µg}, 6-Cyno-7-nitroquinoxaline-2,3-dione disodium {(CNQX); 5.0 µg and 2.5 µg), or phosphate buffered saline (PBS) before exposure to five unsignalled footshocks. FPS reinstatement was assessed 24 hours later. Results from these experiments demonstrate that PBS-infused rats showed FPS reinstatement, whereas rats infused with AP5, CNQX, or the two higher doses of raclopride failed to exhibit FPS reinstatement. Intra-BLA SCH 23390 infusions did not appear to disrupt the reinstatement of FPS in Experiment 3B, however obstructed guide cannulae may have affected these results. In Experiment 3C, intra-BLA AP5 infusions made just before unsignalled footshock presentation, prevented rats from exhibiting FPS reinstatement during final testing. A similar effect on FPS reinstatement was produced by CNQX application to the BLA of rats in Experiment 3D. The overall findings of Experiment 3 suggest that DA D2 receptor antagonism and the glutamatergic receptor antagonists (AP5 and CNQX) impaired amygdaloid fear-memory reconsolidation and retrieval processes by preventing the re-excitation of neurons and pathways that had become established during fear-conditioning. It is speculated that these drugs may have interfered with excitatory synaptic transmission processes and neurobiological intracellular cascades within the amygdala and thus prevented FPS reinstatement from occurring. Two expression-control experiments (Experiments 4 and 5), revealed that the observed blockade of FPS reinstatement in Experiment 3 could not be attributed to the drugs simply blocking fear expression since infusion of raclopride, AP5, or CNQX into the BLA of non-extinguished rats 24 hours before final testing did not prevent rats from expressing FPS. Electrical stimulation (ES) of the human amygdala and temporal lobe region produces emotionally charged memory flash-backs and behaviours indicative of a central fear-state. ES of the rat amygdala is known to elevate acoustic startle amplitudes and enhance emotionality in rats and kindling of the rat amygdala exaggerates FPS and produces a variety of autonomic and behavioural
fear responses. In rats, conditioned fear and LTP are induced by ES of amygdaloid afferents so it is possible that electrical excitation of BLA neurons can trigger FPS reinstatement. Experiments 7A and 7B were conducted to test the hypothesis that ES of BLA neurons can restore FPS responding in fear-extinguished rats. Thus, rats with bipolar electrodes implanted unilaterally in the BLA were baselined, fear conditioned, pretested and then assigned to one of five groups matched on FPS. Rats then received fear-extinction or no-extinction training, followed 48 hours later by either 100 unsignalled electrical stimulations of the BLA or no stimulation. Experimental groups included; [Extinction + Stimulation (N=12), Extinction + No stimulation (N=12), No Extinction + No stimulation
(N= 12), No Extinction + Stimulation (N=11) and Extinction + Stimulation out of context (N=12)]. FPS reinstatement was assessed 24 hours later and BLA AD-current threshold were recorded four days after FPS reinstatement testing was completed. Experiment 7A demonstrated that all experimental groups exhibited FPS except the Extinction + No stimulation control group which displayed a robust extinction effect. Most importantly, the Extinction + Stimulation group exhibited statistically significant FPS reinstatement after ES of the amygdala. Experiment 7B demonstrated that ES of the amygdala in a context different to the startle apparatus also produced FPS reinstatement in fear-extinguished rats.
However, the magnitude of this FPS reinstatement effect was much smaller than that obtained when rats received ES of the amygdala in the startle testing apparatus. The overall finding that ES of the BLA causes FPS reinstatement in fear-extinguished rats suggests that ES of the BLA resensitised fear-memory systems and restored FPS responding. This effect was likely achieved by exciting amygdaloid neurons and pathways containing the memory-trace of the CS-UCS association originally established during Pavlovian fear conditioning. Experiments 8 to 10 used the same protocol as Experiment 7A and investigated whether ES of other brain regions that share reciprocal connections with the amygdala would trigger FPS reinstatement in fear-extinguished rats. Rats in Experiments 8 to 10 had bipolar electrodes unilaterally implanted in the perirhinal/insular cortex (PRh/IC), dorsal periaqueductal gray (dPAG), ventral tegmental area (VTA) and ventral periaqueductal gray (vPAG). Experiment 8 revealed that ES of the PRh/IC produced a positive trend towards FPS reinstatement. Experiment 9 examined the impact of dPAG and VTA ES on FPS reinstatement. This experiment demonstrated that VTA but not dPAG ES produced a FPS reinstatement effect. This finding seems to support the research evidence that highlights the importance of mesoamygdaloid systems in mediating conditioned fear and stress responses. Experiment 10 assessed the impact of vPAG ES on
FPS reinstatement and discovered that stimulation of this region did not trigger a restoration of FPS in fear-extinguished rats but it did seem to elevate overall acoustic startle responding during final testing, This finding would seem to indicate that ES of the vPAG likely increased contextual fear but not cue specific fear since acoustic startle amplitudes during both the noise-alone and the CS + noise conditions were elevated, The key finding that ES of the amygdala produces robust FPS reinstatement provides further proof that the amygdala and its afferent and efferent neural circuits are essential for fear-memory reconsolidation and conditioned fear expression and reinstatement
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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