Histamine reverses a memory deficit induced in rats by early postnatal maternal deprivation

Early partial maternal deprivation causes long-lasting neurochemical, behavioral and brain structural effects. In rats, it causes a deficit in memory consolidation visible in adult life. Some of these deficits can be reversed by donepezil and galantamine, which suggests that they may result from an impairment of brain cholinergic transmission. One such deficit, representative of all others, is an impairment of memory consolidation, clearly observable in a one-trial inhibitory avoidance task. Recent data suggest a role of brain histaminergic systems in the regulation of behavior, particularly inhibitory avoidance learning. Here we investigate whether histamine itself, its analog SKF-91844, or various receptor-selective histamine agonists and antagonists given into the CA1 region of the hippocampus immediately post-training can affect retention of one-trial inhibitory avoidance in rats submitted to early postnatal maternal deprivation. We found that histamine, SKF-91844 and the H2 receptor agonist, dimaprit enhance consolidation on their own and reverse the consolidation deficit induced by maternal deprivation. The enhancing effect of histamine was blocked by the H2 receptor antagonist, ranitidine, but not by the H1 receptor antagonist pyrilamine or by the H3 antagonist thioperamide given into CA1 at doses known to have other behavioral actions, without altering locomotor and exploratory activity or the anxiety state of the animals. The present results suggest that the memory deficit induced by early postnatal maternal deprivation in rats may in part be due to an impairment of histamine mediated mechanisms in the CA1 region of the rat hippocampus.     

Res Computans: The Living Subject from Yeast to Human

Since modernity, the concept of subject supposes both an anthropocentric and a dualistic view of life and reality. In this study, we carry out an analytic interpretation of the Descartes’ notion of subject, in order to build a different dimension of the concept of subject. We discuss the activity of computing, as the manner by which the living subject relates with and in-forms the world. We further examine computing in the aging yeast as an example of living subject and we try to comprehend the maturity of the subjectivity in Descartes’ res cogitans and in our proposed res computans.     

Mechanisms of contextual control when contexts are informative to solve the task

An experiment was conducted using a human instrumental learning task with the goal of evaluating the mechanisms underlying the deleterious effect of context-switching on responding to an unambiguous stimulus when contexts are informative to solve the task. Participants were trained in a context-based reversal discrimination in which two discriminative stimuli (X and Y) interchange their meaning across contexts A and B. In context A, discriminative stimulus Z consistently announced that the relationship between a specific instrumental response (RI) and a specific outcome (O1) was in effect. Performance in the presence of stimulus Z was equally deteriorated when the test was conducted outside the training context, regardless of whether the test context was familiar (context B) or new (context C). This result is consistent with the idea that participants code all the information presented in an informative context as context-specific with the context playing a role akin to an occasion setter.     

Shifts in color discrimination during early pregnancy

The present study explores two hypotheses: a) women during early pregnancy should experience increased color discrimination ability, and b) women during early pregnancy should experience shifts in subjective preference away from images of foods that appear either unripe or spoiled. Both of these hypotheses derive from an adaptive view of pregnancy sickness that proposes the function of pregnancy sickness is to decrease the likelihood of ingestion of foods with toxins or teratogens. Changes to color discrimination could be part of a network of perceptual and physiological defenses (e.g., changes to olfaction, nausea, vomiting) that support such a function. Participants included 13 pregnant women and 18 non-pregnant women. Pregnant women scored significantly higher than non-pregnant controls on the Farnsworth-Munsell (FM) 100 Hue Test, an objective test of color discrimination, although no difference was found between groups in preferences for food images at different stages of ripeness or spoilage. These results are the first indication that changes to color discrimination may occur during early pregnancy, and is consistent with the view that pregnancy sickness may function as an adaptive defense mechanism.     

Expatriates and Trade

Using unique cross-sectional data on international bilateral migration stocks, I evaluate the contribution to bilateral trade of expatriates from the OECD countries living in less developed economies, and of immigrants from less developed economies located within the OECD. The expatriates' role in trade differs both quantitatively and qualitatively from the role of immigrants. A 10% increase in the size of expatriate community leads to a 0.6% average increase in its OECD country-of-origin imports, as compared to a notably stronger 2.5% impact of immigrants into the OECD countries. Furthermore, unlike in the case of immigrants located within the OECD, the estimates on expatriates' role in exports are not statistically different from zero. The imports-facilitating role of expatriates' networks is centered in host countries with low institutional quality. In economies lying within the lowest third of the institutional quality distribution, a 10% increase in expatriate stock would lead to a 1.7% increase in imports into their country of origin. The study further addresses the hypothesis that bilateral immigrant-driven trade gains might be offset by lower trade volumes with other trade partners. The estimates suggest that despite the consistency with offsetting immigrant-driven shifts in trade flows, the overall net effect of immigrant networks on aggregate trade is still non-negative.     

Pure versus guided mirror exposure to reduce body dissatisfaction: a preliminary study with university women

While effectiveness of mirror exposure to reduce body dissatisfaction has been demonstrated, the exposure was almost always combined with other interventions. The aim of the study was to evaluate the effectiveness of a pure mirror exposure intervention compared with a guided mirror exposure (participants are guided to describe their body shape in a non-evaluative manner) and an imagery exposure intervention (participants are guided to describe their body through mental representation). Thirty-one women with high body dissatisfaction received five sessions of treatment under one of the three conditions. All interventions reduced body dissatisfaction, but only the mirror exposures successfully reduced the frequency of negative thoughts and feelings of ugliness. Pure mirror exposure was more effective than guided exposure for reducing body discomfort within and between sessions. Pure mirror exposure, based on the traditional extinction paradigm, led to strong emotional activation followed by a fast decrease in emotional reactivity.     

Spatial interference between gaze direction and gaze location: a study on the eye contact effect

Perceived gaze in faces is an important social cue that influences spatial orienting of attention. In three experiments, we examined whether the social relevance of gaze direction modulated spatial interference in response selection, using three different stimuli: faces, isolated eyes, and symbolic eyes (Experiments 1, 2, and 3, respectively). Each experiment employed a variant of the spatial Stroop paradigm in which face location and gaze direction were put into conflict. Results showed a reverse congruency effect between face location to the right or left of fixation and gaze direction only for stimuli with a social meaning to participants (Experiments 1 and 2). The opposite was observed for the nonsocial stimuli used in Experiment 3. Results are explained as facilitation in response to eye contact.     

Validation of a Spanish version of the Muscle Appearance Satisfaction Scale: Escala de Satisfacción Muscular

The psychometric properties of a Spanish version of the Muscle Appearance Satisfaction Scale (MASS; Mayville, Williamson, White, Netemeyer, & Drab, 2002) were examined using a sample of five hundred and sixty-one male weightlifters. Exploratory and confirmatory factor analyses suggested that the 19-item Spanish version of the MASS called the Escala de Satisfacción Muscular (ESM), was represented by five subscales similar to the original MASS. Internal consistency of the measure was good (α=.86-.95), and various measures of construct validity indicated that the ESM may be a useful measure of Muscle Dysmorphia symptoms among Spanish speaking populations.     

Is 26 + 26 smaller than 24 + 28? Estimating the approximate magnitude of repeated versus different numbers

It has recently been suggested that regardless of the dimension at hand (i.e., numerosity, length, time), similar operational mechanisms are involved in the comparison process based on approximate magnitude representation. One piece of evidence for this hypothesis lies in the presence of similar behavioral effects for any comparison (i.e., the distance effect). In the case of length comparison, the comparison process can be biased by summation toward either an underestimation or an overestimation: The sum of equal-size stimuli is underestimated, whereas the sum of different-size stimuli is overestimated. Relying on the hypothesis that similar operational mechanisms underlie the comparison process of any magnitude, we aim at extending these findings to another magnitude dimension. A number comparison task with digit numbers was used in the two experiments reported presently. The objective was to investigate whether summation also biases magnitude representation of numerical and symbolic information. The results provided evidence that the summation bias can also apply to numerical magnitude comparison, since the sum of repeated numbers (26 + 26) was underestimated whereas the sum of different numbers (24 + 28) was overestimated. We propose that these effects could be accounted for by a heuristic linking cognitive effort and magnitude estimation.