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Prenatal kynurenine exposure in rats: age-dependent changes in NMDA receptor expression and conditioned fear responding
No full textRationale: Levels of kynurenic acid (KYNA), an endogenous negative modulator of alpha 7 nicotinic acetylcholine receptors (α7nAChRs) and antagonist at glutamatergic N-methyl-d-aspartate receptors (NMDARs), are elevated in the brain of patients with schizophrenia (SZ). In rats, dietary exposure to KYNA’s immediate precursor kynurenine during the last week of gestation produces neurochemical and cognitive deficits in adulthood that resemble those seen in patients with SZ. Objectives: The present experiments examined whether prenatal kynurenine exposure results in age-dependent changes in the kynurenine pathway (KP), expression of selected receptors, and cognitive function. Methods: Pregnant dams were fed unadulterated mash (progeny = ECON) or mash containing kynurenine (100 mg/day; progeny = EKYN) from embryonic day (ED) 15 to 22. Male offspring were assessed as juveniles, i.e., prior to puberty (postnatal day [PD] 32), or as adults (PD70) for brain KYNA levels, α7nAChR and NMDAR gene expression, and performance on a trace fear conditioning (TFC) task. Results: KYNA levels were comparable between juvenile ECON and EKYN rats, whereas EKYN adults exhibited a ~3-fold increase in brain KYNA relative to ECONs. NR2A expression was persistently reduced (30–40 %) in EKYN rats at both ages. Compared to ECON adults, there was a 50 % reduction in NR1, and a trend toward decreased α7nAChR expression, in adult EKYN rats. Surprisingly, juvenile EKYN rats performed significantly better in the TFC paradigm than controls, whereas adult EKYN animals showed the predicted deficits. Conclusions: Collectively, our results provide evidence that KP changes in the fetal brain alter neuronal development and cause age-dependent effects on neurochemistry and cognitive performance
An analysis of locomotion, anxiety, and recognition memory in a Fetal Alcohol Spectrum Disorder rat model
No full text2015 Annual Neuroscience Undergraduate Research Forum, Forum DistinctionAlcohol consumption during pregnancy may result in Fetal Alcohol Spectrum Disorders (FASD), which are often characterized by impairments in cognition. Our laboratory employs a FASD rat model in which pups are exposed to ethanol across postnatal days (PD) 4 through 9, a period roughly comparable to the human third trimester. We previously demonstrated impaired hippocampus-dependent learning and memory in adult (PD 70) FASD rats, as assessed by fear-elicited freezing behavior. It is unclear, however, whether the deficit is due specifically to hippocampal dysfunction, aberrant input from upstream brain regions (e.g., the perirhinal cortex, PR), or altered behavioral patterns (i.e., anxiety, hyperactivity). To dissociate these variables between FASD and control rats over development we measured locomotion (open field, OF) in adolescent (PD 35) subjects, and locomotion, anxiety (passive avoidance, PA) and memory (novel object recognition, NOR) in adult rats. In the OF, quantification of gridline crossings revealed adolescent 5E rats were more active than SI rats within the periphery, and all adolescent rats became more active across the three sessions. Adolescent rats also demonstrated increased anxiety from session 1 to 3. Adult animals showed no significant differences in the OF across sessions or treatment groups, but females were more active than males. For PA, adult rats were placed in a white, brightly lit chamber separated from a black, unlit chamber and allowed to explore for 5 min. Decreased time in the brightly lit arena would indicate increased anxiety, albeit no treatment group differences were observed. Finally, in the PR-dependent NOR task subjects were exposed to two identical objects then tested on their ability to discriminate between the familiar and a novel object 20 min or 4 h later, representing short-term memory (STM) and long-term memory (LTM), respectively. Results suggest FASD rats are not impaired in the STM or LTM variants of the NOR task. Together, results imply that 5E rats are more hyperactive than SI rats as adolescents, but as adults 5E rats perform similarly to controls for locomotion, anxiety and object recognition.Arts and Sciences Undergraduate Research ScholarshipSocial and Behavioral Sciences Undergraduate Research GrantPsychology- Undergraduate Research Office Summer Research FellowshipNo embargoAcademic Major: NeuroscienceAcademic Major: Psycholog
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
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AI in International Arbitration: Need for the Human Touch
No full textTechnology is rapidly changing the way law is practiced. The legal profession, including arbitration, will feel the effect of technological advancements in AI and Legal Tech. In fact, the Covid-19 pandemic has already pushed arbitration to either be virtual in toto or hybrid in other cases. An exclusively physical arbitration hearing is currently the exception, rather than the norm. Admittedly this is a temporary and perhaps unsustainable situation, nevertheless the current landscape underscores that humans are replaceable
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
AI in International Arbitration: Need for the Human Touch
Get PDFTechnology is rapidly changing the way law is practiced. The legal profession, including arbitration, will feel the effect of technological advancements in AI and Legal Tech. In fact, the Covid-19 pandemic has already pushed arbitration to either be virtual in toto or hybrid in other cases. An exclusively physical arbitration hearing is currently the exception, rather than the norm. Admittedly this is a temporary and perhaps unsustainable situation, nevertheless the current landscape underscores that humans are replaceable
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