Influence of chronic corticosterone and glucocorticoid receptor antagonism in the amygdala on fear conditioning

Glucocorticoid receptor activation within the basolateral amygdala (BLA) during fear conditioning may mediate enhancement in rats chronically exposed to stress levels of corticosterone. Male Sprague-Dawley rats received corticosterone (400 microg/ml) in their drinking water (days 1-21), a manipulation that was previously shown to cause hippocampal CA3 dendritic retraction. Subsequently, rats were adapted to the fear conditioning chamber (day 22), then trained (day 23), and tested for conditioned fear to context and tone (day 25). Training consisted of two tone (20s) and footshock (500 ms, 0.25 mA) pairings. In Experiment 1, muscimol (4.4 nmol/0.5 microl/side), a GABAergic agonist, was microinfused to temporarily inactivate the BLA during training. Rats given chronic corticosterone showed enhanced freezing to context, but not tone, compared to vehicle-supplemented rats. Moreover, BLA inactivation impaired contextual and tone conditioning, regardless of corticosterone treatment. In Experiment 2, RU486 (0, 0.3, and 3.0 ng/0.2 microl/side) was infused on training day to antagonize glucocorticoid receptors in the BLA. Corticosterone treatment enhanced fear conditioning to context and tone when analyzed together, but not separately. Moreover, RU486 (3.0 ng/side) selectively exacerbated freezing to context in chronic corticosterone-exposed rats only, but failed to alter tone conditioning. Serum corticosterone levels were negatively correlated with contextual, not tone, conditioning. Altogether, these suggest that chronic corticosterone influences fear conditioning differently than chronic stress as shown previously. Moreover, chronic exposure to corticosteroids alters BLA functioning in a non-linear fashion and that contextual conditioning is influenced more than tone conditioning by chronic corticosterone and BLA glucocorticoid receptor stimulation.     

Correlational cuing as a function of target complexity and target-flanker similarity

It is generally assumed that the correlational cuing effect (CE) between targets and correlated flankers is due to learning association between the flankers and their correlated responses. The present study challenges this view. Experiment 1 shows that the CE for targets composed of color is eliminated as soon as the correlation is removed. Experiment 2 shows that the CE during training is not due to association of the flankers with responses. Experiment 3 shows that at least some of the CE during training with the correlation is due to repetition priming of the display. Experiment 4 replicates the results of Experiment 1 for orientation targets. In Experiments 5-7, more typical tasks with letter targets are examined, and it is demonstrated that preexperimental similarity between targets and correlated flankers is crucial. The CE for correlated but dissimilar target-flanker pairs, similar to that for color and orientation targets, is confined to on-line processes that occur during training. The CE is transferred, however, for correlated and similar target-flanker pairs. We propose that, at least for the simple stimulus to response mapping used in our study, the CE is not due to learning at all. Instead it is due to (1) on-line processes, such as repetition priming, that occur during training with the correlation and (2) a regular flanker effect (see, e.g., B. A. Eriksen & C. W. Eriksen, 1974) that occurs for similar target-flanker pairs.     

Causal Models of Physical Exercise Participation: Testing the Predictive Power of the Construct "Pressure to Change"

This study examines 2 different causal models to predict physical exercise motivation and behavior under a longitudinal perspective. The first model includes 5 latent variables that were hypothesized to have an impact on exercise intention and behavior: behavior-specific social support, exercise self-efficacy, perceived health benefits, perceived barriers, and subjective vulnerability to cardiovascular disease. The second model was based on all variables of the first model, but additionally included the new variable "pressure to change." Pressure to change was defined as the extent to which a person feels the necessity that specific personal life circumstances (e.g., health status, social relations) may not remain as they are and ought to be changed. It was hypothesized that the inclusion of health-related pressure to change would result in a better prediction of exercise intention. The proposed causal models were tested separately at the stages of exercise adoption and maintenance. Covariance structure analyses (LISREL) confirmed that pressure to change may be an important factor in the motivational process that leads to the adoption of regular physical exercise. Adding this latent variable to the basic model improved the amount of explained variance in exercise intention by 6%. Furthermore, the results did not support the assumption that cognitive control is critical especially during the acquisition of exercise behaviors, but may be less influential once the behavioral routines have been established. Our data rather indicate that regular physical exercise, even if performed on a regular basis for years, always remains a behavior that requires a high level of cognitive guidance.     

On the role of item similarity in retrieval-induced forgetting

We report on two experiments designed to examine how the similarity of retrieval-practised and not-retrieval-practised items influences the amount of retrieval-induced forgetting. Participants studied categorised item lists with each category consisting of exemplars from two different semantic subcategories. Using both the retrieval practice paradigm (Experiment 1) and the output interference paradigm (Experiment 2) we found that the retrieval of a subset of the studied items impaired the subsequent recall of the nonpractised items if the two types of items were fairly dissimilar to each other (same category but different subcategory) but did not induce impairment if the two types of items were highly similar (same category and subcategory). These results indicate that a high degree of similarity of practised and nonpractised items can eliminate retrieval-induced forgetting. They also suggest that forgetting in the retrieval practice paradigm and forgetting in the output interference paradigm are mediated by the same mechanisms. The relation of the present results to other very recent findings about the role of item similarity in retrieval-induced forgetting in discussed.     

Simulation,simplicity, and selection: an evolutionary perspective on high-level mindreading

In this paper, I argue that a natural selection-based perspective gives reasons for thinking that the core of the ability to mindread cognitively complex mental states is subserved by a simulationist process—that is, that it relies on non-specialised mechanisms in the attributer’s cognitive architecture whose primary function is the generation of her own decisions and inferences. In more detail, I try to establish three conclusions. First, I try to make clearer what the dispute between simulationist and non-simulationist theories of mindreading fundamentally is about. Second, I try to make more precise an argument that is sometimes hinted at in support of the former: this ‘argument from simplicity’ suggests that, since natural selection disfavours building extra cognitive systems where this can be avoided, simulationist theories of mindreading are more in line with natural selection than their competitors. As stated, though, this argument overlooks the fact that building extra cognitive systems can also yield benefits: in particular, it can allow for the parallel processing of multiple problems and it makes for the existence of backups for important elements of the organism’s mind. I therefore try to make this argument more precise by investigating whether these benefits also apply to the present case—and conclude negatively. My third aim in this paper is to use this discussion of mindreading as a means for exploring the promises and difficulties of evolutionary arguments in philosophy and psychology more generally.     

Das prädiskursive Einverständnis. Wissenschaftlicher Wahrheitsbegriff und prozedurale Rechtfertigung

The pre-discoursive agreement. Theory of scientific truth and procedural justification. — On basis of the constructive philosophy of science, the attention is focussed to the pre-discoursive elements of discoursive theories of truth. By using a pragmatic approach it is shown that foundation of those pre-discoursive elements, like discourse rules or the basic terminology, is possible though the discourse rules are not available at this level. Propositions which can be shown in the presented theory to be true, always describe a know-how instead of a knowledge about the world. As a result, the relevance of the presented analysis for prototheories of scientific disciplines is investigated. This revised version was published online in August 2006 with corrections to the Cover Date.     

Reduction in rat phosphatidylethanolamine binding protein-1 (PEBP1) after chronic corticosterone treatment may be paralleled by cognitive impairment: a first study

Chronic stress is associated with hippocampal atrophy and cognitive dysfunction. This study investigates how long-lasting administration of corticosterone as a mimic of experimentally induced stress affects psychometric performance and the expression of the phosphatidylethanolamine binding protein (PEBP1) in the adult hippocampus of one-year-old male rats. Psychometric investigations were conducted in rats before and after corticosterone treatment using a holeboard test system. Rats were randomly attributed to 2 groups (n = 7) for daily subcutaneous injection of either 26.8 mg/kg body weight corticosterone or sesame oil (vehicle control). Treatment was continued for 60 days, followed by cognitive retesting in the holeboard system. For protein analysis, the hippocampal proteome was separated by 2D electrophoresis (2DE) followed by image processing, statistical analysis, protein identification via peptide mass fingerprinting and gel matching and subsequent functional network mapping and molecular pathway analysis. Differential expression of PEBP1 was additionally quantified by Western blot analysis. Results show that chronic corticosterone significantly decreased rat hippocampal PEBP1 expression and induced a working and reference memory dysfunction. From this, we derive the preliminary hypothesis that PEBP1 may be a novel molecular mediator influencing cognitive integrity during chronic corticosterone exposure in rat hippocampus.     

When cognitive scientists become religious, science is in trouble: On neurotheology from a philosophy of science perspective

Since the 1990s medical technology has afforded exciting possibilities for studying the brain. Together with knowledge accrued through psychology and psychiatry, it has set the stage for pioneering research and stimulated disciplines such as Social Neuroscience, the Cognitive Science of Religion, Cognitive Anthropology, and Cognitive Archaeology. Another discipline has arisen, Neurotheology, which is interested in the brain and religious experience. Early proponents such as d'Aquili and Newberg had a religious agenda in their work. Others, such as members of Transcendental Meditation, have used experimental and brain studies to legitimate religious agendas. Experiential shamanists have embarked on a similar legitimation process. The differences between science and therapy and spirituality have been blurred or denied. Neurotheological attempts to discover areas of the brain responsible for religious experiences have led to untenable results. The fact that such research has passed the peer review process of leading psychological, psychiatric, and neurological journals is perhaps more indicative of the pervasiveness of religiosity throughout American society than of objective brain science. This essay argues that neurotheology is an example of the struggle between confessional and critical approaches to the study of religion. The main difference is that the battlefield of this struggle is the brain.