Kv4 potassium channels modulate hippocampal EPSP-spike potentiation and spatial memory in rats

Kv4 channels regulate the backpropagation of action potentials (b-AP) and have been implicated in the modulation of long-term potentiation (LTP). Here we showed that blockade of Kv4 channels by the scorpion toxin AmmTX3 impaired reference memory in a radial maze task. In vivo, AmmTX3 intracerebroventricular (i.c.v.) infusion increased and stabilized the EPSP-spike (E-S) component of LTP in the dentate gyrus (DG), with no effect on basal transmission or short-term plasticity. This increase in E-S potentiation duration could result from the combination of an increase in excitability of DG granular cells with a reduction of GABAergic inhibition, leading to a strong reduction of input specificity. Radioactive in situ hybridization (ISH) was used to evaluate the amounts of Kv4.2 and Kv4.3 mRNA in brain structures at different stages of a spatial learning task in naive, pseudoconditioned, and conditioned rats. Significant differences in Kv4.2 and Kv4.3 mRNA levels were observed between conditioned and pseudoconditioned rats. Kv4.2 and Kv4.3 mRNA levels were transiently up-regulated in the striatum, nucleus accumbens, retrosplenial, and cingulate cortices during early stages of learning, suggesting an involvement in the switch from egocentric to allocentric strategies. Spatial learning performance was positively correlated with the levels of Kv4.2 and Kv4.3 mRNAs in several of these brain structures. Altogether our findings suggest that Kv4 channels could increase the signal-to-noise ratio during information acquisition, thereby allowing a better encoding of the memory trace.     

Predicting posttraumatic growth among Hurricane Katrina survivors living with HIV: the role of self-efficacy,social support,and PTSD symptoms

Abstract

The study tested the model of adaptation after trauma by Benight and Bandura (2004) indicating that posttraumatic recovery may be predicted directly by coping self-efficacy (CSE) and indirectly by social support. These relations were investigated in the context of posttraumatic growth (PTG) among Hurricane Katrina survivors living with HIV. Additionally, it was hypothesized that among individuals with more intensive Posttraumatic Stress Disorder (PTSD) symptoms, those with strong CSE would experience the strongest PTG. Cross-sectional data were collected among 90 patients with HIV who reinitiated care at the HIV outpatient clinic. Questionnaires were administered approximately 14 months after the hurricane. Higher CSE was related to higher PTG among the survivors who suffered from more intensive PTSD symptoms. Received social support was directly related to only one index of PTG, relating to others. Furthermore, although there was a significant relationship between social support and CSE, the indirect conditional effect of received social support on PTG was not confirmed. Similar results were obtained across the indices of PTG, controlling for the level of exposure to hurricane-related trauma. Cross-sectional design and convenience character of the sample warrants replications.     

Abnormal Neural Sensitivity to Monetary Gains Versus Losses Among Adolescents at Risk for Depression

Major depressive disorder aggregates within families, although the mechanisms of transfer across generations are not well understood. In light of converging biological and behavioral evidence that depressive symptoms are associated with impaired reward processing, we examined whether adolescent girls with a parental history of depression would also exhibit abnormal reward sensitivity. We performed a negative mood induction and then recorded the feedback negativity, a neural index of reward processing, while individuals completed a gambling task. High-risk adolescents reported greater sadness following the mood induction compared to low-risk adolescents. Among the high-risk group, sadness was strongly associated with a blunted feedback negativity, even after controlling for baseline mood and trait neuroticism. This suggests that high-risk adolescents are more reactive to negative stimuli, which significantly alter neural sensitivity to monetary gains and losses. The feedback negativity might be used to identify information processing abnormalities in high-risk populations prior to the onset of a major depressive episode.     

Self-regulation of priming effects on behavior

In three experiments, we tested whether people can protect their ongoing goal pursuits from antagonistic priming effects by using if-then plans (i.e., implementation intentions). In Experiment 1, concept priming did not influence lexical decision time for a critical stimulus when participants had formed if-then plans to make fast responses to that stimulus. In Experiment 2, participants who were primed with a prosocial goal allowed a confederate who asked for help to interrupt their work on a focal task for a longer time if they had merely formed goal intentions to perform well than if they had also formed implementation intentions for concentrating on the task. In Experiment 3, priming the goal of being fast increased driving speed and errors for participants who had formed mere goal intentions to drive only as fast as safety allowed or who had formed no goal intentions, whereas the driving of participants who had formed such goal intentions as well as implementation intentions showed no such priming effects. Our findings indicate that implementation intentions are an effective self-regulatory tool for shielding actions from disruptive concept- or goal-priming effects.     

A Categorical Approach to Probability Theory

First, we discuss basic probability notions from the viewpoint of category theory. Our approach is based on the following four “sine quibus non” conditions: 1. (elementary) category theory is efficient (and suffices); 2. random variables, observables, probability measures, and states are morphisms; 3. classical probability theory and fuzzy probability theory in the sense of S. Gudder and S. Bugajski are special cases of a more general model; 4. a good model allows natural modifications. Second, we show that the category ID of D-posets of fuzzy sets and sequentially continuous D-homomorphisms allows to characterize the passage from classical to fuzzy events as the minimal generalization having nontrivial quantum character: a degenerated state can be transported to a nondegenerated one. Third, we describe a general model of probability theory based on the category ID so that the classical and fuzzy probability theories become special cases and the model allows natural modifications. Finally, we present a modification in which the closed unit interval [0,1] as the domain of traditional states is replaced by a suitable simplex.     

The God‐Shaped Hole: Addictive Disorders and the Search for Perfection

Clients with addictive disorders who have an internalized need for perfection benefit from an integration of spirituality into counseling treatment. This article provides a review of the literature, offers a spiritual approach for working with clients who struggle with addiction and perfectionism, and provides a case study to demonstrate the effectiveness of the integration of spirituality and counseling.     

Trait anxiety and dynamic adjustments in conflict processing

Recently, it has been assumed that high- and low-trait-anxious subjects differ in the way they use fundamental cognitive control mechanisms. The present study was designed to further elucidate this topic by focusing on trial-to-trial adjustments in neuronal correlates of conflict processing. An electroencephalogram was recorded while subjects (N=71) performed a gender discrimination version of the Stroop task. The conflict-related N400 of the ERP was influenced by an interaction between trait anxiety and previous trial context: An additional negative-going deflection in the N400 range was observed when the target—distractor pairing of the directly preceding trial was incongruent, but only in highly anxious subjects. Thus, highly anxious subjects appear to more strongly engage neuronal modules involved in conflict monitoring when previously exposed to a high stimulus-response conflict. These results indicate that trait anxiety is crucially linked to the way the cognitive system dynamically adapts to recent demands.     

The ontogeny of intentional communication in chimpanzees in the wild

The onset of intentional communication in children's first year of life represents a major milestone in human cognitive development. Similarly, it is well established that our closest living relatives, the great apes, communicate with signals characterized by at least first‐order intentionality. Despite the well‐documented influence of developmental experiences on socio‐cognitive abilities in apes, the developmental trajectory of intentional signal use as well as effects of social exposure remain poorly understood under naturalistic conditions. Here, we addressed these issues by studying the ontogeny of intentional communication in chimpanzee infants of two subspecies (Pan troglodytes schweinfurthii/verus) and communities living in their natural environments. Overall, we found that gestures and bimodal signal combinations were most commonly accompanied by markers of intentional communication: audience checking, persistence to the goal, and sensitivity to recipient’s attentional state. Within individuals, the proportion of communicative behaviours associated with goal persistence and sensitivity to attention increased with age. Cross‐sectional comparisons between infants revealed an age effect on the use of audience checking. Context, interaction partner and site affiliation affected the production of specific markers irrespective of infants' age. The present study provided hitherto undocumented evidence for the development of three important markers of intentional communication in great apes. Moreover, our results suggest that social exposure impacts early intentional signal use.     

Identity affirmation and social movement support

It is argued that the power of collective identification to mobilize people for collective action such as social movement support derives at least partly from processes of identity affirmation. The hypothesized identity‐affirming function of social movement support is tested in two laboratory experiments which revolve around collective identity as a supporter of the peace movement. In Experiment 1, we predicted and found that people who strongly identified with the peace movement showed more movement support (i.e. made more monetary donations to the peace movement) under conditions of uncertain as opposed to certain possession of identity as a movement supporter. In Experiment 2, we replicated this finding, but also found, in accordance with the notion of substitution, that the mobilizing effect of uncertain collective‐identity possession was undermined when an identity symbol was available that could function as a surrogate for more costly identity‐affirming behaviour. Further conceptual and social implications of the identity‐affirming function of social movement support are discussed. Copyright © 2007 John Wiley & Sons, Ltd.     

Complete recovery of olfactory associative learning by activation of 5-HT4 receptors after dentate granule cell damage in rats

Bilateral intradentate injections of 3.0 μg of colchicine induced a substantial loss of granule cells and damage to the overlying pyramidal cell layer in region CA1 in adult male Long-Evans rats. All rats with such lesions showed a significant associative learning deficit in an olfactory discrimination task, while being unimpaired in the procedural component of this task. Injection of a partial selective 5-HT₄ agonist (SL65.0155; 0.01 mg/kg, i.p., vs. saline) before the third of six training sessions enabled complete recovery of associative learning performance in the lesioned rats. Activation of 5-HT₄ receptors by a selective agonist such as SL65.0155 might therefore provide an opportunity to reduce learning and memory deficits associated with temporal lobe damage, and could be useful for the symptomatic treatment of memory dysfunctions related to pathological aging such as Alzheimer’s disease.