Comparison of corticosterone responses to acute stressors: Chronic jugular vein versus trunk blood samples in mice

A commonly used method for obtaining blood samples from mice is decapitation. However, there is an obvious need for repeated blood sampling in mice under stress-free conditions. Here, we describe a simple technique to repeatedly collect blood samples from conscious, freely moving mice through a chronically implanted jugular vein catheter. Furthermore, we compare plasma corticosterone (CORT) concentrations in samples obtained through the catheter 1 day after surgery with samples taken from trunk blood obtained under basal or acute stress conditions. CORT concentrations in repeated 100-μl venous blood samples were found to be similar to trunk blood samples both under basal conditions and after stressor exposure collected at identical time points (at 5, 15, and 60?min). Using both techniques, we demonstrate a progressive increase in CORT levels until 15?min after termination of stressor exposure and a decrease towards baseline values 60?min later. Anxiety-related behavior, as assessed on the elevated plus maze 3-4 days after surgery, did not differ between catheterized and non-catheterized mice. Our results provide evidence for application of jugular vein catheterization as a technique for repeated blood sampling in conscious laboratory mice. Use of this technique will greatly reduce the number of animals required for experiments involving endocrine endpoints.     

Can active navigation be as good as driving? A comparison of spatial memory in drivers and backseat drivers

When driving a vehicle, either the driver or a passenger (henceforth: backseat driver) may be responsible for navigation. Research on active navigation, primarily addressed in virtual environments, suggests that controlling navigation is more central for spatial learning than controlling movement. To test this assumption in a real-world scenario, we manipulated movement control through seating participants in the front or the back position of a tandem bike, and navigation control by presenting differently detailed maps to participants unfamiliar (Experiment 1) or familiar (Experiment 2) with an environment. Landmark knowledge was tested with recognition tasks. For participants unfamiliar with the environment (Experiment 1), passive navigation enabled better landmark recognition than active navigation, but there was no effect of movement control. For participants more familiar with the environment (Experiment 2), there was no effect of navigation control, but drivers showed better landmark recognition than backseat drivers. These findings are discussed in relation to action memory research. Measures of route and survey knowledge demonstrated that good performance resulted from active navigation (Experiment 1-2). Moreover, with regard to these measures, driving compensated for passive navigation if the environment was familiar (Experiment 2). An additional experiment in a lab setting (Experiment 3) validated the manipulation of navigation control and the used tasks and demonstrated the importance of real environment exposure. As our findings suggest, driving may be more relevant for remembering landmarks, but actively controlling navigation (even as a backseat driver) is more relevant for remembering a route than maneuvering a vehicle.     

Being Deluded After Being Excluded? How Emotion Regulation Deficits in Paranoia-Prone Individuals Affect State Paranoia During Experimentally Induced Social Stress

Emotion regulation (ER) has become a relevant construct to understanding paranoia. While the ER strategy called expressive suppression (e.g., poker face) may foster state paranoia by increasing arousal, another strategy called reappraisal (e.g., changing the perspective on situations) may reduce negative emotions and state paranoia when adaptively used. However, if reappraisal fails, this could increase paranoia. The aim of this study was to test the proposed effects of the ER strategies on state paranoia in the socially stressful situation of being excluded in paranoia-prone individuals. We conducted an experimental online study with N=116 participants who were randomized to a social inclusion or an exclusion condition using a virtual Cyberball ball-tossing game. They completed questionnaires on paranoia proneness and habitual ER strategies. Before and after the Cyberball task, participants rated their level of state paranoia. The impact of habitual ER strategies, paranoia proneness, and social stress on changes in state paranoia was investigated using linear regression analysis. The three-way interaction of social stress, paranoia proneness, and habitual reappraisal use significantly predicted state paranoia, t(114)=2.62, p=0.010. The decomposition of the interaction term revealed that in the social stress condition, the impact of reappraisal on state paranoia was moderated by the level paranoia proneness. Specifically, in high paranoia-prone individuals the use of reappraisal predicted higher state paranoia. The findings regarding habitual use of suppression were not significant. Although reappraisal is generally considered a functional strategy, its use in distressing social situations seems to be impaired in persons with higher paranoia proneness. A working model of emotion dysregulation in delusions is presented and possible implications for cognitive therapy of psychosis are discussed.     

Extended practice of reciprocal wrist and arm movements of varying difficulties

An experiment was designed to determine the degree to which reciprocal aiming movements of the wrist and arm with various accuracy requirements (Fitts' tasks) are enhanced by extended practice. The vast majority of research on motor learning shows performance improvement over practice. However, literature examining the effect of practice on Fitts' task performance is limited and inconclusive. Participants were asked to flex/extend their limb/lever in the horizontal plane at the wrist (arm stabilized) or elbow joint (wrist stabilized) in an attempt to move back and forth between two targets as quickly and accurately as possible. The targets and current position of the limb were projected on the screen in front of the participant. Target width was manipulated with amplitude constant (16°) in order to create indexes of difficulty (ID) of 1.5, 3, 4.5, and 6. Contrary to the earlier reports, after 20 days of practice, we found minimal changes in movement time or the movement time-ID relationships for the arm and wrist over practice. However, the variability in the movement endpoints decreased over practice and wrist movements at ID=6 were characterized by shorter movement times and longer dwell times relative to arm movements with dwell time for the wrist increasing over practice. These data are consistent with the notion that Fitts' tasks provide a stable measure of perceptual-motor capabilities.     

Gender-specific contribution of a visual cognition network to reading abilities

Based on the assumption that boys are more likely to tackle reading based on the visual modality, we assessed reading skills, visual short-term memory (VSTM), visual long-term memory for details (VLTM-D), and general non-verbal cognitive ability in primary school children. Reading was within the normal range in both accuracy and understanding. There was no reading performance gap in favour of girls, on the contrary, in this sample boys read better. An entire array of visual, non-verbal processes was associated directly or indirectly with reading in boys, whereas this pattern was not observed for the girls.     

Social relationships and intraindividual variability in interpersonal behavior: correlates of interpersonal spin

Personality constructs are typically conceptualized as central tendencies of the individual. We explore whether dynamic personality constructs that quantify the within-individual variability of behavior across situations and over time predict the closeness of social relationships. We focused on interpersonal spin, defined as the degree of dispersion in a person's interpersonal behaviors around the interpersonal circumplex across situations and over time. We predicted that individuals with high spin would have social relationships that are less close than individuals with low spin. In 3 studies with different measures of relationship closeness, we found that (a) higher spinners reported that a larger proportion of their contacts in their workplace social networks were distant (Study 1); (b) co-workers were less satisfied and less often engaged in pleasant activities with higher spinners (Study 2); and (c) co-workers avoided higher spinners with whom they were well acquainted (Study 3). Moderated mediation analyses in Study 3 revealed that co-workers avoided well-acquainted higher spinners because they felt more negative affect when interacting with these individuals. The findings suggest the potential of dynamic personality constructs for improving our understanding of the characteristics of individuals' social relationships.     

Buddhists’ Religious and Health Practices

A web survey of Buddhists’ religious practices and beliefs, and health history and practices was conducted with 886 Buddhist respondents. Eighty-two percent were residents of the USA. Ninety-nine percent practiced Buddhist meditation and 70% had attended a formal retreat for intensive meditation practice. Eighty-six percent were converts to Buddhism and had been a Buddhist for a median of 9 years. Sixty-eight percent of respondents rated their health as very good or excellent. A one-point increase on a Buddhist Devoutness Index was associated with a 15% increase in the odds of being a non-smoker and an 11% increase in the odds of being in good to excellent health.     

Further investigation of the validity and reliability of the photographic figure rating scale for body image assessment

Previous studies have not fully investigated the psychometric properties of the Photographic Figure Rating Scale (PFRS). In 2 studies, we report on the test-retest reliability and convergent validity of ratings derived from the PFRS. In Study 1, 322 female university students in Britain provided self-ratings on the PFRS and objectively measured body mass index (BMI); a subsample of 132 women also completed the task after 5 weeks. In Study 2, 243 women from the community in Austria completed the PFRS along with a battery of other body image scales. Results of Study 1 showed that ratings on the PFRS had good test-retest reliability (all rs > .87) and good convergent validity in relation to BMI. Results of Study 2 showed that PFRS-derived body dissatisfaction scores were significantly correlated with a range of body image variables. These results provide evidence for the convergent validity and good test-retest reliability of the PFRS.     

Bias in self-motion perceived speed can enhance episodic memory

Prior experiences of a stimulus facilitate reprocessing of that stimulus on a subsequent occasion. This relative ease and speed with which information is processed is defined as fluency and can constitute a basis for memory judgment. Fluency can also be manipulated on line by perceptual bias (e.g., levels of noise), leading to an increase in recognition for items processed more fluently (e.g., items with less noise). Previous experiments using Remember–Know paradigm have shown an impact of perceptual fluency only on familiarity and not on recollection. Recent episodic memory models have postulated a strong link between episodic memory and spatial processes, especially with egocentric updating (Gomez et al. in Acta Psychol 132(3):221–227, 2009). The present experiment was conducted to determine whether self-motion fluency affects recognition performance and particularly has an impact on “Remember” responses. Thirty participants learned a 4-min path movie and then had to recognize among short paths if they were part of the learned path, followed by a Remember–Know procedure for recognized items. Self-motion fluency was manipulated with the presence of nimble acceleration applied on a small part of the recognition paths. Results show that the presence of a self-motion fluency increases significantly the proportion of remember responses solely on learned paths. This study spotlights for the first time a specific fluency effect on recollection and indicates an implication of egocentric-updating processing in episodic memory retrieval.