Eugenol as an anti-stress agent: modulation of hypothalamic-pituitary-adrenal axis and brain monoaminergic systems in a rat model of stress

Stress is the leading psychopathological cause for several mental disorders. Physiological and psychological responses to stress are mediated by the hypothalamic?pituitary?adrenal (HPA), sympathoadrenal system (SAS), and brain monoaminergic systems (BMS). Eugenol is reported to substantially modulate brain functions by regulating voltage-gated cation channels and release of neurotransmitters. This study was designed to evaluate the anti-stress effect of eugenol in the 4-h restraint model using rats. Ulcer index was measured as a parameter of the stress response. HPA axis and the SAS were monitored by estimating plasma corticosterone and norepinephrine (NE), respectively. Analysis of NE, serotonin (5-HT), dopamine, and their metabolites in discrete brain regions was performed to understand the role of BMS in the anti-stress effect of eugenol. Stress exposure increased the ulcer index as well as plasma corticosterone and NE levels. Eugenol pretreatment for 7 days decreased the stress-induced increase in ulcer index and plasma corticosterone but not NE levels, indicating a preferential effect on the HPA axis. Furthermore, eugenol showed a ?U?-shaped dose?response curve in decreasing ulcer index and plasma corticosterone levels. Eugenol also reversed the stress-induced changes in 5-HT levels in all brain regions, whereas NE levels were reversed in all brain regions except hippocampus. These results suggest that eugenol possesses significant anti-stress activity in the 4-h restraint model and the effect is due to modulation of HPA and BMS.     

Chess & Schizophrenia: Murphy v Mr Endon, Beckett v Bion

This paper reconvenes Samuel Beckett's psychotherapy with Wilfred Bion during 1934-1936 during which time Beckett's conceived and began writing this second novel, Murphy. Based on Beckett's visits to the Bethlem & Maudsley Hospital and his observation of the male nurses, the climax of Murphy is a chess match between Mr Endon (a male schizophrenic patient) and Murphy (a male psychiatric nurse). The precise notation of the Endon v Murphy chess match tells us that the Beckett intended it to be an exemplar of an anti-match, perhaps a metaphor for the tragedy of being locked into madness. It is also argued that the match offers us insight into Beckett's experience of the process of psychotherapy with Bion. Based on new information from Beckett's nephew and Bion's widow, hypotheses about the long term impact of the Bion-Beckett analysis are advanced as a mutual experience which shaped the lives and later literary output of both men, producing conjoined career writings which continue to offer us stark and sublime condensations of depression, psychosis, and the challenges of therapy and recovery.     

Experience of agency and sense of responsibility

The experience of agency refers to the feeling that we control our own actions, and through them the outside world. In many contexts, sense of agency has strong implications for moral responsibility. For example, a sense of agency may allow people to choose between right and wrong actions, either immediately, or on subsequent occasions through learning about the moral consequences of their actions. In this study we investigate the relation between the experience of operant action, and responsibility for action outcomes using the intentional binding effect (Haggard, Clark, & Kalogeras, 2002) as an implicit, quantitative measure related to sense of agency. We studied the time at which people perceived simple manual actions and their effects, when these actions were embedded in scenarios where their actions had unpredictable consequences that could be either moral or merely economic. We found an enhanced binding of effects back towards the actions that caused them, implying an enhanced sense of agency, in moral compared to non-moral contexts. We also found stronger binding for effects with severely negative, compared to moderately negative, values. A tight temporal association between action and effect may be a low-level phenomenal marker of the sense of responsibility.     

Virtual reality goes to war: a brief review of the future of military behavioral healthcare

Numerous reports indicate that the incidence of posttraumatic stress disorder (PTSD) in returning OEF/OIF military personnel is creating a significant healthcare challenge. These findings have served to motivate research on how to better develop and disseminate evidence-based treatments for PTSD. Virtual Reality delivered exposure therapy for PTSD has been previously used with reports of positive outcomes. This article details how virtual reality applications are being designed and implemented across various points in the military deployment cycle to prevent, identify and treat combat-related PTSD in OIF/OEF Service Members and Veterans. The summarized projects in these areas have been developed at the University of Southern California Institute for Creative Technologies, a U.S. Army University Affiliated Research Center, and this paper will detail efforts to use virtual reality to deliver exposure therapy, assess PTSD and cognitive function and provide stress resilience training prior to deployment.     

Reaction time distribution analysis of spatial correspondence effects

Since 1994, group reaction time (RT) distribution analyses of spatial correspondence effects have been used to evaluate the dynamics of the spatial Simon effect, a benefit of correspondence of stimulus location information with response location for tasks in which stimulus location is irrelevant. We review the history and justification for analyzing group RT distributions and clarify which conditions result in the Simon effect decreasing across the distribution and which lead to flat or increasing functions. Although the standard left-right Simon effect typically yields a function for which the effect decreases as RT increases, in most other task variations, the Simon effect remains stable or increases across the RT distribution. Studies that have used other means of evaluating the temporal dynamics of the Simon effect provide converging evidence that the changes in the Simon effect across the distribution are due mainly to temporal activation properties, an issue that has been a matter of some dispute.     

A formal ideal-based account of typicality

Inspired by Barsalou’s (Journal of Experimental Psychology: Learning, Memory, and Cognition, 11, 629–654, 1985) proposal that categories can be represented by ideals, we develop and test a computational model, the ideal dimension model (IDM). The IDM is tested in its account of the typicality gradient for 11 superordinate natural language concepts and, using Bayesian model evaluation, contrasted with a standard exemplar model and a central prototype model. The IDM is found to capture typicality better than do the exemplar model and the central tendency prototype model, in terms of both goodness of fit and generalizability. The present findings challenge the dominant view that exemplar representations are most successful and present compelling evidence that superordinate natural language categories can be represented using an abstract summary, in the form of ideal representations. Supplemental appendices for this article can be downloaded from .     

Glucocorticoids are required for extinction of predator stress-induced hyperarousal

Background

The role of glucocorticoids in extinction of traumatic memories has not been fully characterized despite its potential as a therapeutic target for acquired posttraumatic stress disorder (PTSD). The predator stress paradigm allows us to determine whether glucocorticoids mediate the extinction of both context-dependent and context-independent fear memories.

Methods

Male C57BL/6J mice were exposed to a predator (cat) then repeatedly exposed to the predator stress context in the absence of the cat. Context-dependent (associative) fear memory was assessed as suppression of activity during re-exposure to the predator stress context without the cat (extinction trials). Context-independent fear (non-associative) was assessed seven days after extinction trials using measures of hyperarousal and anxiety-like behaviours in environments unlike the predator stress context. To assess the role of glucocorticoids, mice were injected with metyrapone (50 mg/kg) 90 min prior to extinction trials in predator stressed mice and context-dependent and context-independent fear memories were assessed. Finally, metyrapone-treated predator stressed mice were injected with corticosterone (5 or 10 mg/kg) immediately following extinction trials and context-dependent and context-independent fear memories were assessed.

Results

Repeated re-exposure to the predator stress context without the cat present extinguished context-dependent fear memory, and also reduced hyperarousal, a generalized, chronic PTSD-like symptom. We show that extinction of context-independent predator stress-induced hyperarousal is dependent on endogenous glucocorticoids during the extinction trials. Furthermore, the inhibition of extinction by metyrapone on startle amplitude was reduced by exogenous administration of corticosterone following extinction trials. Overall, these data implicate glucocorticoids in the extinction of hyperarousal, a core symptom of PTSD.     

Evidence for goal-independent attentional capture from validity effects with unexpected novel color cues—A response to Burnham (2007)

Can a stimulus capture attention independent of the observer’s goals and intentions? In a recent review, (Burnham, Psychonomic Bulletin &; Review, 14, 392–422, 2007) argued that there is no convincing evidence that attention capture is ever completely independent of the goals and intentions of the observer. By contrast, surprise capture studies have shown that a color singleton can capture attention on its unannounced first occurrence, if it is new and unexpected, and hence is not part of the intentional set. However, the evidence from surprise capture studies has been criticized on methodological grounds. Here, we tested surprise capture in a new paradigm that avoids previous methodological complications. The results refute the prior criticisms and reinstate surprise capture as prime evidence for goal-independent capture.     

Chronic stress, cognitive functioning and mental health

This review aims to discuss the evidence supporting the link between chronic stress, cognitive function and mental health. Over the years, the associations between these concepts have been investigated in different populations. This review summarizes the findings that have emerged from older populations as well as from populations suffering from pathological aging, namely Mild Cognitive Impairment and Alzheimer's Disease. Although older adults are an interesting population to study in terms of chronic stress, other stress-related diseases can occur throughout the lifespan. The second section covers some of these stress-related diseases that have recently received a great deal of attention, namely burnout, depression, and post-traumatic stress disorder. Given that chronic stress contributes to the development of certain pathologies by accelerating and/or exacerbating pre-existing vulnerabilities that vary from one individual to the other, the final section summarizes data obtained on potential variables contributing to the association between chronic stress and cognition.