Opposite actions of dopamine on aversive and appetitive memories in the crab

The understanding of how the reinforcement is represented in the central nervous system during memory formation is a current issue in neurobiology. Several studies in insects provide evidence of the instructive role of biogenic amines during the learning and memory process. In insects it was widely accepted that dopamine (DA) mediates aversive reinforcements. However, the idea of DA being exclusively involved in aversive memory has been challenged in recent studies. Here, we study the involvement of DA during aversive and appetitive memories in the crab Chasmagnathus. We found that DA-receptor antagonists impair aversive memory consolidation, in agreement with previous reports in insects, while administration of DA facilitates memory formation after a weak training protocol. In contrast, DA treatment during appetitive training was found to impair formation of long-term appetitive memory. In addition, as a first step in elucidating the neuroanatomical correlates of DA action on memory, we mapped dopaminergic neurons in the central nervous system of the crab. Results of the current study, together with those obtained in a previous work about the role of octopamine (OA), suggest that both amines (DA and OA) play a dual action in memory processes. On the one hand, DA and OA mediate the aversive and the appetitive signals, respectively, throughout training, while on the other hand, they interfere with the formation of memory of the opposite sign (DA in appetitive and OA in aversive). Our results support a new understanding about the way appetitive and aversive stimuli are processed during memory formation to ensure adaptive behavior.     

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.     

Psicobiología del síndrome de Down

Resumen

En este artículo revisamos los conocimientos que existen en la actualidad sobre el síndrome de Down, atendiendo a todos aquellos aspectos que, por su relevancia, facilitan una mejor comprensión de esta cromosomopatía. Después de una breve reseña histórica, y tras definir lo que se entiende por síndrome de Down, pasamos a ocuparnos de la alteración genética que lo determina, así como de los factores que parecen estar relacionados con su origen. A continuación estudiamos las alteraciones específicas que acompañan a este síndrome, considerando principalmente los aspectos morfológicos externos, el problema de la hipotonía muscular y otros trastornos biomédicos, el retraso mental y las diversas anomalías neuroanatómicas y neurofisiológicas que presentan los sujetos afectados. Por último, indicamos las nuevas perspectivas que se abren en el estudio de esta alteración genética.     

Efectos diferenciales de la frecuencia silábica: dependencia del tipo de prueba y características de los estímulos

Resumen

La frecuencia silábica posicional es una variable de reciente utilización en nuestro idioma. Por su carácter fonológico ha sido utilizada en este trabajo tanto para estudiar su papel en la lectura como para obtener algunas pistas sobre diferencias interlingüísticas entre nuestro idioma y otros que como el inglÉs son más opacos a la hora de traducir a sonidos su ortografía. Se utilizaron dos tipos de pruebas: decisión lÉxica y lectura que presumiblemente implican diferentes demandas cognitivas. Los resultados de la tarea de decisión lÉxica (Experimentos 1 y 3) muestran, en general, que la frecuencia silábica enlentece la respuesta del sujeto tanto en las palabras como en las pseudopalabras, confirmando algunos estudios previos (De Vega et al., 1990). Por el contrario, en la tarea de lectura (Experimentos 2 y 4) la frecuencia silábica tiende a acelerar la respuesta en la mayoría de los estímulos. Este comportamiento diferencial de los sujetos en función de la tÉcnica utilizada sugiere que mientras la decisión lÉxica exige el ascenso hasta el nivel de palabra, la lectura puede realizarse con Éxito desde un nivel prelÉxico silábico.     

Differential effects of the different Short Self-Applied Relaxation Therapy (SART) components on anxiety,activation and stress / Efectos diferenciales de los distintos componentes de la Relajación Breve Sugestiva Auto aplicada (RBSA) sobre la ansiedad,la activación y el estrés

Abstract

Relaxation techniques have evidence-based support in the research community. However, not all relaxation techniques have the same effectiveness or generate the same states of relaxation. For this reason, indications should be established for each of them. Studies into Self-Applied Relaxation Therapy (SART) show that they can decrease anxiety, stress, blood pressure and craving. This study explores to what extent each SART component is responsible for the results found, which is the most appropriate depending on the target variable to be controlled and whether any of the components are dispensable. Ninety-three university volunteer students participated in the study, aged between 18 and 45; 81.70% were female. Results showed that each of the components had similar efficacy and paradoxical effects on certain participants (8% to 26%). From a clinical perspective, this study concludes that SART can be adapted to the user, and a specific combination of components should be designed for each patient.     

Recuperación dependiente de estados afectivos en una tarea de reconocimiento

Resumen

Estudiamos los efectos de los estados afectivos de adquisición y recuperación en una tarea de reconocimiento. Los estados afectivos se indujeron por sugestiones posthipnóticas y los estímulos fueron fotografías de caras en blanco y negro. Empleamos un diseño factorial 2 (estado de adquisición) x 2 (estado de recuperación) con medidas repetidas. El intervalo entre las fases de adquisición y recuperación fue de 24 horas. El análisis de datos, basado en el modelo no-paramétrico de la teoría de detección de señales, confirma el efecto de dependencia de estados afectivos en una prueba de reconocimiento. Los resultados se discuten en relación a trabajos anteriores que no habían encontrado este efecto en pruebas similares.     

Peasants' Social Representation of Politicians in a Clientelist Rural Context

In Latin America, political clientelism is one of the main obstacles to the process of sustaining truly democratic practices. Thus, this article proposes to study peasants from the Province of Formosa, Argentina's social representation of politicians, in hopes of shedding light on the relationship between said representations and clientelist practices, with the objective of making a contribution to the development of alternative means towards democratization in the area. The results of this case study show that, at the center of the peasants' social representation of politicians, there lies a tendency to place their expectations for receiving assistance within a context of a personalized and hierarchical relationship framework. Nevertheless, the majority of these farmers consider the assistance received to be insufficient and inadequate, stating that politicians actually look to satisfy their own interests and not those of the general public. In conclusion, the peasants' social representation of politicians favors clientelist practices, even though these small farmers do not identify, via their culture or their expectations, with these practices. Copyright © 2012 John Wiley & Sons, Ltd.