Brain-derived neurotrophic factor signaling in the HVC is required for testosterone-induced song of female canaries

Testosterone-induced singing in songbirds is thought to involve testosterone-dependent morphological changes that include angiogenesis and neuronal recruitment into the HVC, a central part of the song control circuit. Previous work showed that testosterone induces the production of vascular endothelial growth factor (VEGF) and its receptor (VEGFR2 tyrosine kinase), which in turn leads to an upregulation of brain-derived neurotrophic factor (BDNF) production in HVC endothelial cells. Here we report for the first time that systemic inhibition of the VEGFR2 tyrosine kinase is sufficient to block testosterone-induced song in adult female canaries, despite sustained androgen exposure and the persistence of the effects of testosterone on HVC morphology. Expression of exogenous BDNF in HVC, induced locally by in situ transfection, reversed the VEGFR2 inhibition-mediated blockade of song development, thereby restoring the behavioral phenotype associated with androgen-induced song. The VEGFR2-inhibited, BDNF-treated females developed elaborate malelike song that included large syllable repertoires and high syllable repetition rates, features known to attract females. Importantly, although functionally competent new neurons were recruited to HVC after testosterone treatment, the time course of neuronal addition appeared to follow BDNF-induced song development. These findings indicate that testosterone-associated VEGFR2 activity is required for androgen-induced song in adult songbirds and that the behavioral effects of VEGFR2 inhibition can be rescued by BDNF within the adult HVC. Copyright © 2009 Society for Neuroscience

Multiple constituencies of trust: a study of the Oman military

This paper presents findings from a study of employees' multiple trust foci. Social exchange theory and the notions of conceptual and cognitive distance are used to generate hypotheses on the anticipated effects of specific trust relationships on employees' attitudinal and behavioural outcomes such as intention to quit, job satisfaction, organizational commitment and organizational citizenship behaviours. Data from Omani military personnel suggest that employees distinguish between trust in the organization, trust in their direct boss and trust in co-workers. Several important attitudinal and behavioural outcomes are predicted by these specific trust foci

Anyone for higher speed limits? – Self-interested and adaptive political preferences

Swedish survey-evidence indicates that variables reflecting self-interest are important in explaining people’s preferred speed limits, and that political preferences adapt to technological development. Drivers who believe they drive better than the average driver as well as drivers of cars that are newer (and hence safer), bigger, and with better highspeed characteristics, prefer higher speed limits. In contrast, elderly people prefer lower speed limits. Furthermore, people report that they themselves vote more sociotropically than they believe others vote on average, indicating that we may vote less sociotropically than we believe ourselves. One possible reason for such self-serving biases is that people desire to see themselves as socially responsible. Copyright Springer Science + Business Media, Inc. 2005