Search results for "Condition"
showing 10 items of 2530 documents
The Role of the Amygdala in the Extinction of Conditioned Fear
2006
The amygdala has long been known to play a central role in the acquisition and expression of fear. More recently, convergent evidence has implicated the amygdala in the extinction of fear as well. In rodents, some of this evidence comes from the infusion of drugs directly into the amygdala and, in particular, into the basolateral complex of the amygdala, during or after extinction learning. In vivo electrophysiology has identified cellular correlates of extinction learning and memory in the lateral nucleus of that structure. Human imaging experiments also indicate that amygdaloid activity correlates with extinction training. In addition, some studies have directly identified changes in mole…
Neuroinflammatory and behavioral susceptibility profile of mice exposed to social stress towards cocaine effects.
2021
Using the social defeat (SD) model, numerous studies have shown that stressed mice display an enhanced response to the motivational effects of cocaine in the self-administration (SA) and conditioned-place preference (CPP) paradigms. However, not all subjects exposed to stress express its harmful effects. Some are particularly susceptible to the deleterious effects of repeated SD, while resilient mice successfully cope with stressful experiences and display adjusted psychological functioning after stress. Vulnerability to develop stress-related disorders, such as depression, has been linked to coping strategies and more recently to individual differences in the immune system. However, no stu…
Cannabidiol Treatment Might Promote Resilience to Cocaine and Methamphetamine Use Disorders: A Review of Possible Mechanisms
2019
Currently, there are no approved pharmacotherapies for addiction to cocaine and other psychostimulant drugs. Several studies have proposed that cannabidiol (CBD) could be a promising treatment for substance use disorders. In the present work, the authors describe the scarce preclinical and human research about the actions of CBD on the effects of stimulant drugs, mainly cocaine and methamphetamine (METH). Additionally, the possible mechanisms underlying the therapeutic potential of CBD on stimulant use disorders are reviewed. CBD has reversed toxicity and seizures induced by cocaine, behavioural sensitization induced by amphetamines, motivation to self-administer cocaine and METH, context- …
Hippocampal theta phase-contingent memory retrieval in delay and trace eyeblink conditioning
2017
Hippocampal theta oscillations (3–12 Hz) play a prominent role in learning. It has been suggested that encoding and retrieval of memories are supported by different phases of the theta cycle. Our previous study on trace eyeblink conditioning in rabbits suggests that the timing of the conditioned stimulus (CS) in relation to theta phase affects encoding but not retrieval of the memory trace. Here, we directly tested the effects of hippocampal theta phase on memory retrieval in two experiments conducted on adult female New Zealand White rabbits. In Experiment 1, animals were trained in trace eyeblink conditioning followed by extinction, and memory retrieval was tested by presenting the CS at …
Learning to learn: Theta oscillations predict new learning, which enhances related learning and neurogenesis
2012
Animals in the natural world continuously encounter learning experiences of varying degrees of novelty. New neurons in the hippocampus are especially responsive to learning associations between novel events and more cells survive if a novel and challenging task is learned. One might wonder whether new neurons would be rescued from death upon each new learning experience or whether there is an internal control system that limits the number of cells that are retained as a function of learning. In this experiment, it was hypothesized that learning a task that was similar in content to one already learned previously would not increase cell survival. We further hypothesized that in situations in…
CD40 activity on mesenchymal cells negatively regulates OX40L to maintain bone marrow immune homeostasis under stress conditions
2021
BackgroundWithin the bone marrow (BM), mature T cells are maintained under homeostatic conditions to facilitate proper hematopoietic development. This homeostasis depends upon a peculiar elevated frequency of regulatory T cells (Tregs) and immune regulatory activities from BM-mesenchymal stem cells (BM-MSCs). In response to BM transplantation (BMT), the conditioning regimen exposes the BM to a dramatic induction of inflammatory cytokines and causes an unbalanced T-effector (Teff) and Treg ratio. This imbalance negatively impacts hematopoiesis, particularly in regard to B-cell lymphopoiesis that requires an intact cross-talk between BM-MSCs and Tregs. The mechanisms underlying the ability of…
Survie et/ou réactivation de microorganismes du sol sous hautes pressions gazeuses
2012
National audience; Le sol constitue une réserve considérable de microorganismes représentatifs de nombreuses communautés cellulaires. Les recherches reposent sur l’hypothèse qu’il existe, dans les échantillons de sol, des communautés microbiennes adaptées à des conditions physiques (pression, température) très différentes de celles rencontrées dans nos laboratoires : soit parce que les conditions de milieu ont changé (sol), soit parce que les conditions de prélèvement sont très différentes des conditions de culture (grands fonds marins). Dans cette optique, l’utilisation des hautes pressions gazeuses (200-1000 bars dans un premier temps) est envisagée afin d’essayer de réactiver des microor…
Nodular cast iron fatigue lifetime in cyclic plane bending
2012
The fatigue behavior of a component is strongly dependent on the material and its surface condition. Therefore, the manner in which the surface is prepared during component manufacturing (surface roughness, residual stresses etc.) has a decisive role in dictating the initiation time for fatigue cracks. The fatigue behavior of the same material, a nodular cast iron, with three different surface conditions (fine ground, sand blast and as-cast) has been investigated under cyclic plane bending. The results show differences in fatigue strength, which are associated with the surface conditions. The characteristics of the surface layers of the different test specimens were examined by metallograph…
Social support at work and job satisfaction among midwives: The mediating role of positive affect and work engagement.
2022
Aims: This study examined whether social support at work from superiors and colleagues is associated with positive affect at work, and whether work engagement creates a positive relationship with job satisfaction among midwives. We also investigated whether a positive affect and work engagement mediate the relationship between social support at work and job satisfaction. Design: This was a quantitative cross-sectional study. Methods: Data were collected from 163 midwives working in the Polish public healthcare system between June 2019 and December 2019. Results: There was a direct relationship between support from superiors and colleagues, positive affect at work, work engagement and job sa…
« Les militantes Unitaires des années 1930 : l'expérience française d'un syndicalisme communiste féminin au miroir de la situation européenne, 1929-1…
2019
International audience; Alors qu’au moment de la scission, la CGTU avait maintenu une Commission centrale féminine (CCF), à l’inverse de la CGT qui se contenta d’une déléguée nationale à la propagande féminine, la structure se voit rapidement déstabilisée par la valse - volontaire ou non - de ses responsables (Marie Guillot, Lucie Colliard, Alice Brisset). De plus, avec la bolchévisation (1924) puis l’affirmation de la ligne « classe contre classe » en 1929, la seconde moitié des années 20 s’accompagne de l’éviction des représentantes féminines à la Commission exécutive (Yvonne Clavel, Marie Orlianges, Lucie Colliard, Alice Brisset, Marie Bréant). Elimination des « passagères » , sectarisme…