RSK2 signaling in brain habenula contributes to place aversion learning

RSK2 is a Ser/Thr kinase acting in the Ras/MAPK pathway. Rsk2 gene deficiency leads to the Coffin-Lowry Syndrome, notably characterized by cognitive deficits. We found that mrsk2 knockout mice are unable to associate an aversive stimulus with context in a lithium-induced conditioned place aversion task requiring both high-order cognition and emotional processing. Virally mediated shRNA-RSK2 knockdown in the habenula, whose involvement in cognition is receiving increasing attention, also ablated contextual conditioning. RSK2 signaling in the habenula, therefore, is essential for this task. Our study reveals a novel role for RSK2 in cognitive processes and uncovers the critical implication of an intriguing brain structure in place aversion learning.     

A contribution to the study of the metric and Euclidean structures of dissimilarities

This paper is concerned with the geometric properties of dissimilarity coefficients defined on finite sets and especially with their Euclidean nature. We present several particular transformations which preserve Euclideanarity and we complete, through the study of a one-parameter family, the current knowledge of the metric and Euclidean structure of coefficients based on binary data. These results are directly deduced from two theorems which prove the positive semi-definite status of some quadratic forms which play a large role in some definitions of dissimilarity commonly used.The authors wish to thank B. Fichet for his helpful suggestions, the associate Editor and an anonymous reviewer for comments and highly constructive criticisms on earlier drafts of the paper.     

When stereotypes hurt: Three studies of penalties for sex-role reversals

Three studies that demonstrate penalties for sex-role reversals are reported. In each study, subjects evaluated men and women who behaved either in line with sex-role stereotypes or counter to them. The results show that popularity ratings and perceived psychological adjustment of both passive-dependent men and aggressive-assertive women were adversely affected. The findings are discussed in terms of their contribution to recent theories about women's achievement motivation.     

Forced compliance: Commitment to compliance and commitment to activity

It is argued that the standard manipulation of free choice in a forced compliance situation has fostered confusion between the two different types of choices offered to subjects, namely commitment or non-commitment to compliance with the experimenter and choice of counter-attitudinal activity per se. From a theoretical viewpoint, the two choices have very different implications. The former is a prerequisite to dissonance arousal; the latter may bring about consonant cognitions which reduce the dissonance ratio. Two experiments which separated these two choices confirmed the above predictions, derived from a radical conception of the dissonance theory (Beauvois and Joule, 1981, 1994). The results are inconsistent with the reinterpretation of dissonance effects in self-perception terms.