Overgeneralization of fear, but not avoidance, following acute stress

Research has demonstrated the spreading of fear from threat-related stimuli to perceptually similar, but innocuous, stimuli. Less is known, however, about the generalization of avoidance behavior. Given that stress is known to affect learning and memory, we were interested in the effect of acute stress on (over)generalization of fear and avoidance responses. On the first day, one geometrical shape was paired with a mild electrical stimulus (CS+), whereas another shape was not (CS-). One day later, after participants had been exposed to the Maastricht Acute Stress Test or a control task, generalization of avoidance responses and fear (shock expectancy and skin conductance responses) was tested to a range of perceptual generalization stimuli. Generalization gradients were observed across different outcome measures. Stress enhanced generalization of shock expectancy to the stimulus most similar to the CS+. Our findings confirm that stress can affect the generalization of fear, but further studies are warranted

After the honeymoon: The Obama effect on political attitudes and participation

My dissertation takes a mixed-methods approach to investigating the possibility of a lasting Obama Effect on the political attitudes and behaviors of Obama supporters from 2008. Defining the Obama Effect as the extraordinary enthusiasm surrounding Barack Obama’s 2008 campaign, I argue that a short term Obama Effect was clearly present in 2008 based on Obama’s electoral success, fundraising prowess, and ability to inspire volunteerism, as well as on the historic nature of his candidacy. But I ask, was it a lasting effect? My quantitative analyses—built upon panel survey data from the American National Election Studies—suggest little evidence of a lasting campaign effect that was positive and/or unique to Obama supporters. With regard to attitudes and behaviors such as political interest, political efficacy, or attendance of political events, Obama supporters often showed relative declines or stagnation over time when compared to nonsupporters or supporters of previous presidents. My qualitative analysis—based upon interviews with 30 former volunteers from the 2008 Obama campaign—does, however, indicated that the Obama Effect had a deep and lasting impact on his most enthusiastic support base, those who volunteered for his campaign. Many former Obama volunteers remained highly interested, civically engaged, and continually inspired as a result of their activism for the 2008 Obama campaign. In sum, I conclude that while that campaign may not have had its desired transformational effect on the broader American electorate, it did produce a positive and indeed a lasting impact on its most enthusiastic supporters

Modulation of Type 5 Metabotropic Glutamate Receptor-Mediated Intracellular Calcium Mobilization by Regulator of G Protein Signaling 4 (RGS4) in Cultured Astrocytes

Acting as GTPase activating proteins promoting the silencing of activated G-proteins, regulators of G protein signaling (RGSs) are generally considered negative modulators of cell signaling. In the CNS, the expression of RGS4 is altered in diverse pathologies and its upregulation was reported in astrocytes exposed to an inflammatory environment. In a model of cultured cortical astrocytes, we herein investigate the influence of RGS4 on intracellular calcium signaling mediated by type 5 metabotropic glutamate receptor (mGluR5), which is known to support the bidirectional communication between neurons and glial cells. RGS4 activity was manipulated by exposure to the inhibitor CCG 63802 or by infecting the cells with lentiviruses designed to achieve the silencing or overexpression of RGS4. The pharmacological inhibition or silencing of RGS4 resulted in a decrease in the percentage of cells responding to the mGluR5 agonist DHPG and in the proportion of cells showing typical calcium oscillations. Conversely, RGS4-lentivirus infection increased the percentage of cells showing calcium oscillations. While the physiological implication of cytosolic calcium oscillations in astrocytes is still under investigation, the fine-tuning of calcium signaling likely determines the coding of diverse biological events. Indirect signaling modulators such as RGS4 inhibitors, used in combination with receptor ligands, could pave the way for new therapeutic approaches for diverse neurological disorders with improved efficacy and selectivity

Multiple Endocrine Neoplasia Type 1 in Clinical Practice

peer reviewe

Nouveautés dans le diagnostic et la prise en charge des complications en lien avec l'acromégalie

peer reviewe

Modulation of Type 5 Metabotropic Glutamate Receptor-Mediated Intracellular Calcium Mobilization by Regulator of G Protein Signaling 4 (RGS4) in Cultured Astrocytes

Acting as GTPase activating proteins promoting the silencing of activated G-proteins, regulators of G protein signaling (RGSs) are generally considered negative modulators of cell signaling. In the CNS, the expression of RGS4 is altered in diverse pathologies and its upregulation was reported in astrocytes exposed to an inflammatory environment. In a model of cultured cortical astrocytes, we herein investigate the influence of RGS4 on intracellular calcium signaling mediated by type 5 metabotropic glutamate receptor (mGluR5), which is known to support the bidirectional communication between neurons and glial cells. RGS4 activity was manipulated by exposure to the inhibitor CCG 63802 or by infecting the cells with lentiviruses designed to achieve the silencing or overexpression of RGS4. The pharmacological inhibition or silencing of RGS4 resulted in a decrease in the percentage of cells responding to the mGluR5 agonist DHPG and in the proportion of cells showing typical calcium oscillations. Conversely, RGS4-lentivirus infection increased the percentage of cells showing calcium oscillations. While the physiological implication of cytosolic calcium oscillations in astrocytes is still under investigation, the fine-tuning of calcium signaling likely determines the coding of diverse biological events. Indirect signaling modulators such as RGS4 inhibitors, used in combination with receptor ligands, could pave the way for new therapeutic approaches for diverse neurological disorders with improved efficacy and selectivity

Avoiding at all costs? An exploration of avoidance costs in a novel Virtual Reality procedure

Approach-avoidance behaviours play a major role in the development and maintenance of anxiety disorders as repeated avoidance behaviours are assumed to prevent fear extinction. Approach-avoidance decisions (Conditioned Stimulus (CS)-avoidance and Unconditioned Stimulus (US)-avoidance) and their effect on fear extinction and renewal were investigated using a Virtual Reality fear conditioning procedure with ecologically relevant avoidance costs (temporal delay and physical effort). Participants had to choose between a safe (low approach incentive, no US) and a risky stimulus (high approach incentive, US in 75%). After differential fear acquisition and avoidance learning, participants were randomized to an Avoidance condition or No Avoidance condition during fear extinction. Fear extinction took place in either the original contingency learning context or in a new context and was followed up by a renewal test. Furthermore, the influence of trait anxiety, distress tolerance, and intolerance of uncertainty on approach-avoidance decisions was investigated. Exploratively, a second experiment with varying avoidance costs was conducted. Results were not indicative of renewal and no robust associations with the individual difference measures were found. However, results showed high (Study 1), but not low (Study 2), avoidance costs resulted in less avoidance behaviour. Even though there were no between-group differences, exploratory comparisons of avoiders and non-avoiders in both studies demonstrated that avoidance behaviours protected from extinction learning, resulting in the maintenance of retrospective US expectancies and a sustained preference for the safe stimulus. These findings provide insight in how avoidance behaviours maintain fear and how treatment might be improved by focusing on avoidance costs

Avoiding at all costs?: An exploration of avoidance costs in a novel Virtual Reality procedure

Approach-avoidance behaviours play a major role in the development and maintenance of anxiety disorders as repeated avoidance behaviours are assumed to prevent fear extinction. Approach avoidance decisions (Conditioned Stimulus (CS)-avoidance and Unconditioned Stimulus (US) avoidance) and their effect on fear extinction and renewal were investigated using a novel Virtual Reality fear conditioning procedure that included avoidance costs that are relevant in real-life settings (i.e., temporal delay and physical effort). Participants had to choose between a safe (low approach incentive, no US) and risky stimulus (high approach incentive, US in 75 %). After differential fear acquisition and avoidance learning, participants were randomized to an Avoidance condition or No Avoidance condition during fear extinction. Fear extinction took place in either the original contingency learning context or in a new context and was followed by a renewal test. Furthermore, the influence of trait anxiety, distress tolerance, and intolerance of uncertainty on approach-avoidance decisions was investigated. Exploratively, a second experiment with varying avoidance costs was conducted. Results showed that high (Study 1), but not low (Study 2), avoidance costs resulted in less avoidance behaviour. Even though there were no between-group differences, exploratory comparisons of avoiders and non-avoiders in both studies demonstrated that avoidance behaviours protected from extinction learning, resulting in the maintenance of retrospective US expectancies and a sustained preference for the safe stimulus. Finally, no renewal effect and no robust associations with the individual difference measures were found. Collectively, these findings provide insight in how avoidance behaviours maintain fear and how treatment might be improved by focusing on avoidance costs