More adult-born dentate gyrus neurons to weaken cocaine-related retrograde memories: an in vivo strategy employing exogenous lysophosphatidic acid

The post-training enhancement of adult hippocampal neurogenesis (AHN) has been receiving growing interest as a potential method to manipulate retrograde memories. Recent hypothesis suggest that the addition of adult-born dentate granule cells might promotes remodeling of pre-existing hippocampal circuits, which might both clear cocaine-related memories and facilitate the learning of new adaptive information. Here, we study the effect of stimulating AHN in vivo with exogenous lysophosphatidic acid (LPA) on the maintenance of retrograde cocaine-contextual associative memories. Male C57BL/6J mice trained in a cocaine-induced Conditioned Place Preference (CPP) model were later submitted to repeated intracerebroventricular (i.c.v.) injections of LPA, Ki16425 or vehicle solution during withdrawal. Afterwards, the long-term persistence of the cocaine-CPP was assessed and the mediational role of AHN in this process was evaluated. In addition, wild-type and mice lacking the LPA1 receptor received a single i.c.v. injection of LPA, Ki16425 or vehicle to assess the role of the LPA1 receptor in the LPA-induced increase of AHN. Our results revealed that the chronic administration of LPA decreased the retention of a previously acquired cocaine-induced CPP. This effect was mediated by an LPA-induced increase of AHN. In contrast, mice treated with Ki16425 showed reduced cocaine-CPP retention, but they increased their preference for the cocaine-paired compartment throughout CPP extinction. Besides, no effects of Ki16425 on AHN were found. Immunohistochemical studies suggested that LPA stimulated cell proliferation and promoted neuronal maturation with a key role of the LPA1 receptor. These findings emphasize the relevance of LPA and its LPA1 receptor as an in vivo modulator of AHN and the utility of the post-training increase of adult-born hippocampal neurons to weaken cocaine-context associations.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

On Shifting a Nations Collective Memory: The Role of Ahn Jung-geun in South Koreas Foreign Policy

This article revisits the role that Ahn Jung-geun plays in Korean collective memory today and contrasts this with the Moon administrations foreign policy. An analysis of Korean collective memory shows that Ahns assassination of Ito Hirobumi is heavily emphasized but Ahns ultimate goal of bringing peace to Northeast Asia is overlooked. This emphasis is understood through Jan Assmanns model of collective memory. Based on Aleida Assmann and Linda Shortts proposition, it is argued that the historical figure of Ahn can instead play a constructive role. Shifting the focus of collective memory toward Ahns ambition for peace in Northeast Asia may serve as a positive nudge for Seouls Japan policy, thus helping to ameliorate Korea-Japan relations in the medium term

Bier-bearing Inferiors and the Skin of the Community in Modern and Contemporary Village Society: Cases from Southern Gyeonggi Province

In this paper I analyze what bier–bearers did for the village community, mainly based on the fieldwork interviews carried out in southern Gyeonggi area. Focused on the bier–shouldering practice, those interviews illuminate the role of the inferiors (sangnom 常–, hain 下人, and jungin 中人) who resided in the social border area of the village community. It was their job to perform the lowly work both in ritual and ordinary practices, so they could not escape from social disdain. I begin this article by tracing how sachon gye (四寸契), one of the modern rural organizations for bier–bearing, developed and elucidate its social and cultural meanings, which were consistently under the influence of the yangban-commoner relationship. I then extend the analysis to outline a number of incidents in the southern Gyeonggi area. The final section classifies the southern Gyeonggi cases into two sociohistorical groups to discuss the social and cultural meanings of the abolition of the discriminatory bier–shouldering practices and address debates about immunity and the other community

PCA consistency in high dimension, low sample size context

Principal Component Analysis (PCA) is an important tool of dimension reduction especially when the dimension (or the number of variables) is very high. Asymptotic studies where the sample size is fixed, and the dimension grows [i.e., High Dimension, Low Sample Size (HDLSS)] are becoming increasingly relevant. We investigate the asymptotic behavior of the Principal Component (PC) directions. HDLSS asymptotics are used to study consistency, strong inconsistency and subspace consistency. We show that if the first few eigenvalues of a population covariance matrix are large enough compared to the others, then the corresponding estimated PC directions are consistent or converge to the appropriate subspace (subspace consistency) and most other PC directions are strongly inconsistent. Broad sets of sufficient conditions for each of these cases are specified and the main theorem gives a catalogue of possible combinations. In preparation for these results, we show that the geometric representation of HDLSS data holds under general conditions, which includes a $\rho$-mixing condition and a broad range of sphericity measures of the covariance matrix.Comment: Published in at http://dx.doi.org/10.1214/09-AOS709 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

A note on constrained degree reduction of polynomials in Bernstein–Bézier form over simplex domain

AbstractIn the paper [H.S. Kim, Y.J. Ahn, Constrained degree reduction of polynomials in Bernstein–Bézier form over simplex domain, J. Comput. Appl. Math. 216 (2008) 14–19], Kim and Ahn proved that the best constrained degree reduction of a polynomial over d-dimensional simplex domain in L2-norm equals the best approximation of weighted Euclidean norm of the Bernstein–Bézier coefficients of the given polynomial. In this paper, we presented a counterexample to show that the approximating polynomial of lower degree to a polynomial is virtually non-existent when d≥2. Furthermore, we provide an assumption to guarantee the existence of solution for the constrained degree reduction

Reduction of adult neurogenesis by temozolomide inhibits intrinsic preference for exploring complex objects in mice

Póster de congresoIntrinsic exploratory bias is an innate tendency to prefer certain types of stimuli or environments over others. For example, mice would genuinely spent more time exploring perceptually complex objects (i.e. with edges and concavities) than simpler objects without irregularities. Intrinsic exploratory bias are relevant as they may be associated to cognitive, emotional and even personality-like traits. However, their neurobiological basis are scarcely investigated. Adult hippocampal neurogenesis (AHN) is a key neuroplastic phenomenon for the processing of spatial and contextual stimuli in rodents, being involved in novelty recognition, spatial navigation and spatial pattern separation tasks. Therefore, here we studied whether a pharmacological inhibition of AHN influences intrinsic motivation for exploring complex objects. Twenty male young adult C57BL/6J mice (∼3 months old) received vehicle or the DNA alkylating agent temozolomide (TMZ) for four weeks. Bromodeoxyuridine (BrdU) was administered weekly, confirming a reduction of AHN-related markers by TMZ. After the pharmacological treatment, mice were tested for behavior. TMZ did not impair mice’s health nor their general exploratory and anxiety-like responses. Unlike control mice, the TMZ-treated mice did not prefer exploring a complex (i.e. irregular) object over a simple (i.e. non-irregular) object of similar size presented at once. Nevertheless, they were able to discriminate a novel complex object from a familiar complex object. This suggest that the lack of intrinsic preference for complexity could be explained by motivational and not by cognitive variables. Future studies should investigate a new role of AHN in modulating exploratory bias.Universidad de Málaga; Project PID2020-114374RB-I00 funded by MCIN/AEI/10.13039/501100011033/ Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech