Sex differences: From mental rotation to object location memory, an ERP study

Sex differences in cognition have been largely investigated. The most consistent sex differences favoring females are observed in object location memory involving the left hemisphere whereas the most consistent sex differences favoring males are observed in tasks that require mental rotation involving the right hemisphere. Here we used a task involving these two abilities to see the impact of mental rotation on object location memory. To that end we used a combination of behavioral and event-related potential (ERP) electroencephalography (EEG) measures.A computer screen displayed a square frame of 4 pairs of images (a "teddy" bear, a shoe, an umbrella and a lamp) randomly arranged around a central fixation cross. After a 10-second interval for memorization, images disappeared and were replaced by a test frame with no image but a random pair of two locations marked in black. In addition, this test frame was randomly displayed either in the original orientation (0° rotation) or in the rotated one (90° clockwise - CW - or 90° counterclockwise - CCW). Preceding the test frame, an arrow indicating the presence or the absence of rotation of the frame was displayed on the screen. The task of the participants (15 females and 15 males) was to determine if two marked locations corresponded or not to a pair of identical images. Each response was followed by feedback.Findings showed no significant sex differences in the performance of the original orientation. In comparison with this position, the rotation of the frame produced an equal decrease of male and female performance. In addition, this decrease was significantly higher when the rotation of the frame was in a CCW direction. We further assessed the ERP when the arrow indicated the direction of rotation as stimulus-onset, during four time windows representing major components C1, P1, N1 and N2. Although no sex differences were observed in performance, brain activities differed according to sex. Enhanced amplitudes were found for the CCW compared to CW rotation over the right posterior areas for the P1, N1 and N2 components for men as well as for women. Major topographical differences related to sex were measured for the CW rotation condition as marked lateralized amplitude: left-hemisphere amplitude larger than right one was measured during P1 time range for men. These similar patterns prolonged from P1 to N1 for women. Early distinctions were found in interaction with sex between CCW and CW waveform amplitudes, expressing over anterior electrode sites during C1 time range (0-50 ms post-stimulus).In conclusion (i) women do not outperform men in object location memory in this study (absence of rotation condition); (ii) mental rotation, in particular the direction of rotation, influences performance on object location memory; (iii) CCW rotation is associated with activity in the right parietal hemisphere whereas the CW rotation involves the left parietal hemisphere; (iv) this last effect is less pronounced in males, which could explain why greater involvement of right parietal areas in men and of bilateral posterior areas in women is generally reported in mental rotation tasks; and (v) the early distinctions between both directions of rotation located over anterior sites could be related to sex differences in their respective involvement of control mechanisms.

c-Cbl expression levels regulate the functional responses of human central and effector memory CD4 T cells.

The biochemical mechanisms controlling the diverse functional outcomes of human central memory (CM) and effector memory (EM) T-cell responses triggered through the T-cell receptor (TCR) remain poorly understood. We implemented reverse phase protein arrays to profile TCR signaling components in human CD8 and CD4 memory T-cell subsets isolated ex vivo. As compared with CD4 CM cells, EM cells express statistically significant increased amounts of SLP-76 and reduced levels of c-Cbl, Syk, Fyn, and LAT. Moreover, in EM cells reduced expression of negative regulator c-Cbl correlates with expression of c-Cbl kinases (Syk and Fyn), PI3K, and LAT. Importantly, consistent with reduced expression of c-Cbl, EM cells display a lower functional threshold than CM cells. Increasing c-Cbl content of EM cells to the same level as that of CM cells using cytosolic transduction, we impaired their proliferation and cytokine production. This regulatory mechanism depends primarily on c-Cbl E3 ubiquitin ligase activity as evidenced by the weaker impact of enzymatically deficient c-Cbl C381A mutant on EM cell functions. Our study reports c-Cbl as a critical regulator of the functional responses of memory T cell subsets and identifies for the first time in humans a mechanism controlling the functional heterogeneity of memory CD4 cells.

Civil conflict and human capital accumulation: The long-term effects of political violence in Perú

This paper provides empirical evidence of the persistent effect of exposure to political violence on humancapital accumulation. I exploit the variation in conflict location and birth cohorts to identify the longandshort-term effects of the civil war on educational attainment. Conditional on being exposed toviolence, the average person accumulates 0.31 less years of education as an adult. In the short-term,the effects are stronger than in the long-run; these results hold when comparing children within thesame household. Further, exposure to violence during early childhood leads to permanent losses. I alsoexplore the potential causal mechanisms.

The political cost of reforms

This paper formalizes in a fully-rational model the popular idea that politiciansperceive an electoral cost in adopting costly reforms with future benefits and reconciles it with the evidence that reformist governments are not punished by voters.To do so, it proposes a model of elections where political ability is ex-ante unknownand investment in reforms is unobservable. On the one hand, elections improve accountability and allow to keep well-performing incumbents. On the other, politiciansmake too little reforms in an attempt to signal high ability and increase their reappointment probability. Although in a rational expectation equilibrium voters cannotbe fooled and hence reelection does not depend on reforms, the strategy of underinvesting in reforms is nonetheless sustained by out-of-equilibrium beliefs. Contrary tothe conventional wisdom, uncertainty makes reforms more politically viable and may,under some conditions, increase social welfare. The model is then used to study howpolitical rewards can be set so as to maximize social welfare and the desirability of imposing a one-term limit to governments. The predictions of this theory are consistentwith a number of empirical regularities on the determinants of reforms and reelection.They are also consistent with a new stylized fact documented in this paper: economicuncertainty is associated to more reforms in a panel of 20 OECD countries.

Turnout, political preferences and information: Experimental evidence from Perú

Electoral institutions that encourage citizens to vote are widely used around the world. Yet littleis known about the effects of such institutions on voter participation and the composition of the electorate.In this paper, I combine a field experiment with a change in Peruvian voting laws to identify theeffect of monetary (dis-)incentives on voting. Using the random variation in the fine for abstention andan objective measure of turnout at the individual level, I estimate the elasticity of voting with respectto cost to be -0.21. Consistent with the theoretical model presented, the reduction in turnout inducedby the reduction in the fine is driven by voters who (i) are in the center of the political spectrum, (ii)are less interested in politics, and (iii) hold less political information. However, voters who respondto changes in the cost of abstention do not have different preferences for policies than those who voteregardless of the cost. Further, involvement in politics, as measured by the decision to acquire politicalinformation, seems to be independent of the level of the fine. Additional results indicate that thereduction in the fine does not affect the incidence of vote buying, but increases the price paid for avote.

Inflation, political instability and stockmarket volatility in interwar Germany

What determined the volatility of asset prices in Germany between thewars? This paper argues that the influence of political factors has beenoverstated. The majority of events increasing political uncertainty hadlittle or no effect on the value of German assets and the volatility ofreturns on them. Instead, it was inflation (and the fear of it) that islargely responsible for most of the variability in asset returns.

The 'new political economy': Two recent books

This paper reviews two recent books on Political Economy by Allan Drazen and Torsten Persson and Guido Tabellini. It discusses some problems of the recent Political Economy literature.

How political parties, rather than member-states, are building the European Union

Political party formation and coalition building in the European Parliament is being a driving force for making governance of the highly pluralistic European Union relatively effective and consensual. In spite of successive enlargements and the very high number of electoral partiesobtaining representation in the European Union institutions, the number of effective European Political Groups in the European Parliament has decreased from the first direct election in 1979 to the fifth in 1999. The formal analysis of national party¹s voting power in different Europeanparty configurations can explain the incentives for national parties to join large European Political Groups instead of forming smaller nationalistic groupings. Empirical evidence shows increasing cohesion of European Political Groups and an increasing role of the European Parliament in EU inter-institutional decision making. As a consequence of this evolution, intergovernmentalism is being replaced with federalizing relations. The analysis can support positive expectations regarding the governability of the European Union after further enlargements provided that new member states have party systems fitting the European PoliticalGroups.

TCR signaling requirements for activating T cells and for generating memory.

Over the last two decades the molecular and cellular mechanisms underlying T cell activation, expansion, differentiation, and memory formation have been intensively investigated. These studies revealed that the generation of memory T cells is critically impacted by a number of factors, including the magnitude of the inflammatory response and cytokine production, the type of dendritic cell [DC] that presents the pathogen derived antigen, their maturation status, and the concomitant provision of costimulation. Nevertheless, the primary stimulus leading to T cell activation is generated through the T cell receptor [TCR] following its engagement with a peptide MHC ligand [pMHC]. The purpose of this review is to highlight classical and recent findings on how antigen recognition, the degree of TCR stimulation, and intracellular signal transduction pathways impact the formation of effector and memory T cells.

Political representation in Switzerland : democratic or plutocratic ?

Les inégalités économiques se traduisent-elles dans des inégalités politiques à travers le processus de représentation électorale? Telle est la question centrale de cette thèse qui s'attache, par ailleurs, à investiguer les mécanismes qui tendent à produire une représentation biaisée des préférences politiques des citoyens en fonction de leur statut économique. Focalisé sur le cas de la Suisse et faisant usage des données de l'enquête postélectorale Selects de 2007, ce travail démontre que sur les rares sujets qui divisent les citoyens selon des clivages économiques - la redistribution des richesses et la sécurité sociale en particulier - les élus à l'Assemblée fédérale ont des préférences qui reflètent mieux les opinions des citoyens les plus riches. Cette sous-représentation des opinions des citoyens modestes et de ceux faisant partie du centre de la distribution des revenus peut en partie être attribuée à des différences dans les taux de participation et de connaissance politiques entre ces groupes de citoyens. La thèse met également en évidence le rôle joué par la représentation descriptive - autrement dit, la similitude en termes de statut économique entre les représentants et les représentés - dans la représentation des opinions et intérêts des citoyens. Par ailleurs, la structure du système partisan en Suisse ne reflétant pas la multidimensionnalité des préférences politiques des citoyens, les électeurs ne parviennent pas à traduire la complexité de leurs préférences politiques dans un choix de vote, ce qui, dans la configuration actuelle des forces politiques, tend à favoriser l'élection de représentants aux opinions proches de la droite sur les questions économiques. Enfin, une analyse de la représentation politique au niveau cantonal tend à soutenir la thèse selon laquelle le manque de régulation en matière de financement des partis en Suisse pourrait partiellement expliquer les inégalités dans la représentation des opinions politiques des citoyens aux revenus distincts. - Do economic inequalities translate into political inequalities through electoral representation? This is the central research question of this thesis, which also investigates the mechanisms that lead to potential economically based inequalities in the representation of citizens' policy preferences. Focusing on the case of Switzerland and making use of data provided by the post- electoral survey Selects 2007, this research demonstrates that regarding the rare policy domains in which the preferences of citizens are clearly linked to economic cleavages - redistribution and social security in particular - members of the Federal Assembly have policy preferences that best reflect the policy preferences of richer citizens. The under-representation of the opinions of relatively poor citizens and of those being the in the middle of the income distribution can be to some extent be explained by differences in political participation and political information across income groups. The thesis also puts forward the role played by descriptive representation - the similarity between representatives and represented in terms of their socioeconomic status - for the representation of citizens' preferences and interests. In addition, the structure of the party system in Switzerland does not reflect the multidimensionality of policy preferences among citizens who, as a result, have a hard time translating their complex preferences into a vote choice. Given the configuration of political actors, this tends to favour the election of representatives from the right who do not represent the preferences of their voters on economic issues. Finally, an analysis of representation at the cantonal level tends to confirm that the lack of party finance regulations in Switzerland may partially explain inequalities in the representation of citizens with different levels of income.

On the origins of electoral systems and political parties. The role of elections in multi-member districts

The old, understudied electoral system composed of multi-member districts, open ballot and plurality rule is presented as the most remote scene of the origin of both political parties and new electoral systems. A survey of the uses of this set of electoral rules in different parts of the world during remote and recent periods shows its wide spread. A model of voting by this electoral system demonstrates that, while it can produce varied and pluralistic representation, it also provides incentives to form factional or partisan candidacies. Famous negative reactions to the emergence of factions and political parties during the 18th and 19th centuries are reinterpreted in this context. Many electoral rules and procedures invented since the second half of the 19th century, including the Australian ballot, single-member districts, limited and cumulative ballots, and proportional representation rules, derived from the search to reduce the effects of the originating multi-member district system in favor of a single party sweep. The general relations between political parties and electoral systems are restated to account for the foundational stage here discussed.

Assesing the political viability of labour market reform: The case of employment protection

We analyze the political support for employment protection legislation.Unlike my previous work on the same topic, this paper pays a lot ofattention to the role of obsolescence in the growth process.In voting in favour of employment protection, incumbent employeestrade off lower living standards (because employment protectionmaintains workers in less productive activities) against longer jobduration. The support for employment protection will then depend onthe value of the latter relative to the cost of the former. Wehighlight two key deeterminants of this trade-off: first, the workers'bargaining power, second, the economy's growth rate-more preciselyits rate of creative destruction.

Relationship of aerobic fitness and motor skills with memory and attention in preschoolers (Ballabeina): A cross-sectional and longitudinal study.

Background: The debate about a possible relationship between aerobic fitness and motor skills with cognitive development in children has recently re-emerged, because of the decrease in children's aerobic fitness and the concomitant pressure of schools to enhance cognitive performance. As the literature in young children is scarce, we examined the cross-sectional and longitudinal relationship of aerobic fitness and motor skills with spatial working memory and attention in preschool children.Methods: Data from 245 ethnically diverse preschool children (mean age: 5.2 (0.6) years, girls: 49.4%) analyzed at baseline and 9 months later. Assessments included aerobic fitness (20 m shuttle run) and motor skills with agility (obstacle course) and dynamic balance (balance beam). Cognitive parameters included spatial working memory (IDS) and attention (KHV-VK). All analyses were adjusted for age, sex, BMI, migration status, parental education, native language and linguistic region. Longitudinal analyses were additionally adjusted for the respective baseline value.Results: In the cross-sectional analysis, aerobic fitness was associated with better attention (r = 0.16, p = 0.03). A shorter time in the agility test was independently associated with a better performance both in working memory (r = -0.17, p = 0.01) and in attention (r = -0.20, p = 0.01). In the longitudinal analyses, baseline aerobic fitness was independently related to improvements in attention (r = 0.16, p = 0.03), while baseline dynamic balance was associated with improvements in working memory (r = 0.15, p = 0.04).Conclusions: In young children, higher baseline aerobic fitness and motor skills were related to a better spatial working memory and/or attention at baseline, and to some extent also to their future improvements over the following 9 months.