1,720,963 research outputs found
Sex differences shape memory capacity declining during ageing: rescue effects of voluntary exercise
Full text linkAlzheimer’s Disease (AD) has higher incidence in women compared to men, but the biological bases of this increased vulnerability is still unknown. The aim of this study is to identify early markers of aging in female subjects to discover early disease’ mechanisms that make them more prone to develop dementia.
Memory Capacity (MC) is the amount of information that can be hold in memory for a specific time interval. MC declines with ageing and its decline is a form of mild cognitive impairment with high predictive value for conversion to dementia.
Using the Different/Identical Object Recognition Task (DOT/IOT) thatwe have developed to study MC in rodents, we found that in conditions of high load female mice do not consolidate information into long-term memory.
Here we report that this early highly specific deficit in memory consolidation predisposes female mice to an accelerated aging in memory performance; furthermore, we show that this MC deficits is related to estrogen-dependent impairment in GluA1 trafficking in the hippocampus, which we have previously shown to be important for MC in male mice (Sannino et al 2012, Olivito et al 2014). One-month voluntary exercise training, which is known to stimulate hippocampal function (Colcombe et al 2003), strikingly rescued the performance of aging female mice.
In conclusion, we identified a cognitive marker of early aging in females, whose mechanisms may be at the base of their major vulnerability to AD. Furthermore, we show that this deficit is sensitive to exercise training, which makes it a valid model to study the molecular pathway underlying its therapeutic efficacy
Loffredo V., Torromino G., Esposito F., Carboncino A., Cecere A., Mele A., De Leonibus E. "Sex regulates memory capacity"
No full textMemory Capacity (MC) is the number of information maintained in memory. MC is regulated by fronto-striatal dopamine circuit and hippocampus (HP).
Using a modified version of the object recognition task, the DOT/IOT, we have recently showed that adult naïve male mice could discriminate 3,4,6 but not 9 different objects after a 1 min or 24 hrs delay. Moreover, it has been reported that male mice use the HP, as well as humans, to solve the task (Sannino et al 2012, Olivito et al 2014; Sugita et al 2015).
To report sex differences influencing MC, we have challenged 3 months old mice (males and females) with the 6-DOT (highest memory load), testing them at different time points.
We have found that 3 months old female mice properly perform the 6-DOT when tested at 1 min delay (Short Term Memory, STM), but they are impaired when tested 24 hr later (Long Term Memory, LTM). Female mice properly perform the 6-IOT (lowest memory load) independently on the delay.
We hypothesized that the impairment in LTM could reflect sex regulated differences in the use of different neuronal circuits to solve the task. Therefore, we are performing c-fos immunohistochemical analysis as an index of stimuli-induced neuronal activation on the HP and the prefrontal cortex, at different time points after exposing the animals to the 6-DOT. Preliminary data show that female mice, differently from males, do not activate the HP.
Sex-regulated neuronal activation might be relevant to understand the higher impact of dementia in women as compared to men
Sex differences shape memory capacity decline with ageing
No full textMemory capacity (MC) is the number of information that can be retained in memory for a short (working memory capacity – WMC) or a long (long-term memory capacity – LTMC) time interval. Its decline has been observed in many psychiatric and neurodegenerative diseases, and in physiological ageing. Although gender differences in MC are reported, less is known about the biological mechanisms at the basis.
Using the Different/Identical Object Recognition Task (DOT/IOT), we found that adult male mice have a WMC of about six objects, like humans, and that only in high memory load conditions the hippocampus (HP) is recruited to solve the task.
Female subjects have the same WMC as males, but they are impaired in consolidating information when challenged with high memory load conditions. This impairment in memory consolidation correlates with recruitment of different brain circuitries in the two sexes, with the HP hypoactivated in female compared to male mice. Using a chemogenetic approach, we demonstrated that reverting HP hypoactivation rescues the memory consolidation impairment in females.
In parallel, we characterized MC decline during ageing in males and females at 6 and 12 months. We found that female mice have a load- and delay-dependent earlier decay of MC compared to males. These findings might be relevant in understanding the higher impact of dementia in women population compared to men, and we propose the different circuitry recruitment as a mechanism responsible for female’s higher vulnerability to age-dependent memory decay
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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
- …
