Basolateral amygdala inactivation impairs learned (but not innate) fear response in rats

Numerous studies have suggested that the amygdala is involved in the formation of aversive memories, but the possibility that this structure is merely related to any kind of fear sensation or response could not be ruled out in previous studies. The present study investigated the effects of bilateral inactivation of the amygdaloid complex in rats tested in the plus-maze discriminative avoidance task. This task concomitantly evaluates aversive memory (by discrimination of the two enclosed arms) and innate fear (by open-arm exploration). Wistar rats (3-5 months-old) were implanted with bilateral guide cannulae into basolateral amygdala. After surgery, all subjects were given 1 week to recover before behavioral experiments. Afterwards, in experiment 1, 15 min prior to training, 0.5 μl of saline or muscimol (1 mg/ml) was infused in each side via microinjection needles. In experiment 2 the animals received injections immediately after the training session and in experiment 3 rats were injected prior to testing session (24 h after training). The main results showed that (1) pre-training muscimol prevented memory retention (evaluated by aversive arm exploration in the test session), but did not alter innate fear (evaluated by percent time in open arms); (2) post-training muscimol impaired consolidation, inducing increased percent in aversive arm exploration in the test session and (3) pre-testing muscimol did not affect retrieval (evaluated by aversive enclosed arm exploration in the test session). The results suggest that amygdala inactivation specifically modulated the learning of the aversive task, excluding a possible secondary effect of amygdala inactivation on general fear responses. Additionally, our data corroborate the hypothesis that basolateral amygdala is not the specific site of storage of aversive memories, since retention of the previously learned task was not affected by pre-testing inactivation.     

阅读障碍的巨细胞系统缺陷理论之争

近几年诸多研究者认为阅读障碍是由于视觉系统巨细胞功能缺陷引起的。他们从对比度敏感性研究、巨细胞抑制功能研究与视觉运动知觉功能的研究结果中得到了支持证据。就这个问题的研究进行综述,表明不论是巨细胞功能缺陷理论的支持者还是反对者,都从巨细胞的对比度敏感性、视觉运动知觉与巨细胞抑制功能上得到了一些研究结果的支持。巨细胞功能缺陷理论的支持者还从阅读障碍的神经生理学研究和阅读的脑功能研究中得到了一些支持性的证据。新的研究结果揭示了巨细胞系统缺陷理论与阅读之间的关系以及巨细胞系统缺陷理论的应用价值。在巨细胞系统缺陷理论的进一步研究中,还需要统一实验方法与实验标准以获得更多的证据,同时需要有新的方法来有效区分小细胞系统与巨细胞系统     

The understanding of die as an object that has numerical functions. A longitudinal study using two children from the ages of 24 to 36 months interacting with an adult / La comprensión del dado como objeto con funciones numéricas. Un estudio longitudinal con dos niños desde los 24 a los 36 meses en interacción con un adulto

Abstract

We investigated the process through which children understand the conventional use of numbers in interaction with an adult. We analysed previous semiotic systems that support, transform and adjust to this new semiotic system — the numerical — and we investigated the communicative-educative basis that makes it possible. We conducted an exploratory and longitudinal study with one boy and one girl at 24, 27, 30, 33 and 36 months of age in a triadic interaction (adult-child-object) with their mothers at home. We adopt the pragmatic-semiotic perspective of the object, which considers that triadic interactions are the unit of analysis of early development. Our results show a great variety of semiotic mediators used by children and adults and both children’s progressive comprehension of the meaning and use of the die as a numerical object.     

Symbolic representation of the number three: a study with three-year-old children from contrasting socioeconomic environments

The goal of the present study was to compare a range of aspects in children’s symbolic knowledge about the number three among two groups of three-year-olds from contrasting socioeconomic backgrounds. Every child was presented with five tasks that focused on the number three and that had cognitive demands of different complexity: expressing their age, reciting the conventional number series up to three, quantifying a collection of three, and two tasks requiring the use of visually presented quantitative information.The results showed the same order of difficulty of the tasks in both socioeconomic groups and a clear performance difference depending on socioeconomic background. These findings show that symbolic knowledge about the number three does not come in an all or none fashion. Rather, different aspects of this symbolic competence become apparent in response to different tasks, and seem to depend largely on the socioeconomic environment in which children develop.     

Effects of mercury chloride (HgCl2) on Betta splendens aggressive display

Mercury chloride (HgCl2) is a toxic mercury salt and a major pollutant, that can be found in soil, water and air, with influences on behavior, physiology and adaptation to the environment. In this study two experiments were designed to examine interactions and effects of HgCl2 on some behavioral patterns of Siamese fighting fish (Betta splendens). In the first experiment we tested the effect of a progressive dose (five 0.04 mg) on aggressive display with exposure to a mirror, whereas in the second experiment we tested the effect of an acute dose (0.2 mg) on the aggressive display with exposure to a mirror. The experiments were performed on 5 consecutive sessions at intervals of 18 hours between sessions. Differences of performance were shown by subjects in the acute and progressive treatments when compared with a control treatment in the majority of behaviors evaluated, namely Floating, Slow Swimming, Wavy Swimming, Emerging, Bend, Square Move and Motor Display Components. Acute treatment was different from control only on Show Body, while the progressive group differed on Resting, Horizontal Display and Appropriate Display Components. Differences between Correlate Display Components and Total were also shown. Both the acute and progressive contamination with HgCl2 decrease the motor activity in the aggressive display, mirror-image test of Betta splendens, mainly on the progressive dose. This implies an impairment on feeding behavior, predator avoidance, reproductive behavior, mate choice and territoriality. These results suggest that in this fish species, the progressive dose has a greater effect on behavior in general and that both the acute and progressive contamination with mercury chloride affect many other aspects of behavior.