Distinct neural mechanisms for heading retrieval and context recognition in the hippocampus during spatial reorientation.

Reorientation, the process of regaining one's bearings after becoming lost, requires identification of a spatial context (context recognition) and recovery of heading direction within that context (heading retrieval). We previously showed that these processes rely on the use of features and geometry, respectively. Here, we examine reorientation behavior in a task that creates contextual ambiguity over a long timescale to demonstrate that mice learn to combine both featural and geometric cues to recover heading with experience. At the neural level, most CA1 neurons persistently align to geometry, and this alignment predicts heading behavior. However, a small subset of cells shows feature-sensitive place field remapping, which serves to predict context. Efficient heading retrieval and context recognition require integration of featural and geometric information in the active network through rate changes. These data illustrate how context recognition and heading retrieval are coded in CA1 and how these processes change with experience.

Navigable Space and Traversable Edges Differentially Influence Reorientation in Sighted and Blind Mice.

Reorientation enables navigators to regain their bearings after becoming lost. Disoriented individuals primarily reorient themselves using the geometry of a layout, even when other informative cues, such as landmarks, are present. Yet the specific strategies that animals use to determine geometry are unclear. Moreover, because vision allows subjects to rapidly form precise representations of objects and background, it is unknown whether it has a deterministic role in the use of geometry. In this study, we tested sighted and congenitally blind mice (Ns = 8-11) in various settings in which global shape parameters were manipulated. Results indicated that the navigational affordances of the context-the traversable space-promote sampling of boundaries, which determines the effective use of geometric strategies in both sighted and blind mice. However, blind animals can also effectively reorient themselves using 3D edges by extensively patrolling the borders, even when the traversable space is not limited by these boundaries.

Differential effect of sleep deprivation on place cell representations, sleep architecture, and memory in young and old mice.

Poor sleep quality is associated with age-related cognitive decline, and whether reversal of these alterations is possible is unknown. In this study, we report how sleep deprivation (SD) affects hippocampal representations, sleep patterns, and memory in young and old mice. After training in a hippocampus-dependent object-place recognition (OPR) task, control animals sleep ad libitum, although experimental animals undergo 5 h of SD, followed by recovery sleep. Young controls and old SD mice exhibit successful OPR memory, whereas young SD and old control mice are impaired. Successful performance is associated with two cellular phenotypes: (1) "context" cells, which remain stable throughout training and testing, and (2) "object configuration" cells, which remap when objects are introduced to the context and during testing. Additionally, effective memory correlates with spindle counts during non-rapid eye movement (NREM)/rapid eye movement (REM) sigma transitions. These results suggest SD may serve to ameliorate age-related memory deficits and allow hippocampal representations to adapt to changing environments.

Socioemotional Resources Account for Academic Adjustment in Moroccan Adolescents.

This study aimed to analyze the relationship of both positive socioemotional resources [emotional intelligence (EI) and social support] and negative states (test anxiety and depression) with academic adjustment, as measured by academic performance and self-concept, among Moroccan adolescents. The participants were 845 students from Morocco (372 boys, 473 girls; mean age 15.58 years; SD = 1.69; range = 13-18) who were attending secondary education (79.8%) or high school. The participants completed a questionnaire that included scales to measure the variables of interest, adapted for and validated in Moroccan adolescents. A multiple mediation serial model with four mediator variables confirmed that academic self-concept was positively and directly predicted by EI, academic performance, and social support, whereas test anxiety and depression had a negative effect. Second, EI predicted self-concept through its indirect effects on test anxiety and academic performance, social support, and depression. EI was the most protective factor. This model has good performance in explaining the variation in test anxiety (1.6%), depression (14.2%), social support (9.5%), academic performance (6.8%), and self-concept (35.7%). This study helps clarify the relationship of positive and negative socioemotional states with the academic performance of adolescents in Morocco. This study contributes to the literature by enhancing knowledge of adolescents in societies that, like Morocco, have a less elaborated tradition at these levels of education and that are considering education in their agenda as a way of enhancing national development and promoting EI to allow youth development in a healthier society.

Prior extinction increases acquisition context specificity in human predictive learning.

One experiment evaluated the effect of extinction on the context dependence of non-extinguished information in a situation in which physical (images), rather than predominantly verbal, contexts were used in human predictive learning. Participants received training in which different foods (Cues) were associated with the presence or the absence of gastric illness (outcome) in customers of different restaurants (contexts). One cue was associated with the gastric illness while a different cue was either extinguished or not between groups. A change in the context at test led to a general decrease in both predictive judgments and the speed of responding to the non-extinguished cue. However, these decreases were greater when training was conducted during extinction of the different cue demonstrating the extinction makes acquisition context-specific (EMACS) effect. Results are contrasted with failures to find the effect in other reports and discussed in terms of extinction leading to an allocation of attentional resources to the context, facilitating the context dependence of information.

Social Support and Emotional Intelligence as Protective Resources for Well-Being in Moroccan Adolescents.

This study aimed to test a structural model to examine the protective role of psychosocial variables, such as social support, emotional intelligence and their interaction, on the cognitive dimension of subjective positive well-being (life satisfaction) and negative well-being (depression) in Moroccan adolescents. The participants consisted of 1277 students (571 men, 694 women and 12 missing values) with a mean age of 16.15 years (SD = 2.22; range = 9 to 23) who attended 26 public schools in different territories of Morocco. These students were in secondary education (n = 893) and high school (n = 378) (6 missing values). The scales for measuring the variables of interest had to be adapted and validated as a previous step for the further proposal of a model of relations. Statistical analyses were conducted using structural equation modeling (SEM) to test the proposed model. The model that optimally adjusted the data confirmed the protective role of social support in the well-being of Moroccan adolescents. Consistent with previous studies, social support was directly related to well-being. However, it also modulated levels of satisfaction with life. Likewise, the inclusion of emotional intelligence as an additional protective factor contributed to the explanation of the well-being mechanisms in adolescents. In addition to direct associations with the levels of social support, satisfaction with life and depression (negative in the latter case), emotional intelligence participated in a complex chain affecting life satisfaction and life satisfaction affecting depression. Moreover, the interaction of emotional intelligence with social support was confirmed to determine levels of life satisfaction in adolescents. Specifically, social support multiplied the effects of the relationship between satisfaction with life and emotional intelligence in cases of moderate and high levels in Moroccan adolescents. This study fills a gap in the literature by adapting and further analyzing several scales with Moroccan samples of adolescents and by proposing and verifying a relational model that can help researchers and teachers to more precisely clarify these relations according to their context. The enhancement of protective factors, such as social support and emotional intelligence, will promote healthy youth development, thus creating healthier societies in the future.

Testing a cue outside the training context increases attention to the contexts and impairs performance in human predictive learning.

One experiment in human predictive learning explored the impact of a context change on attention to contexts and predictive ratings controlled by the cue. In Context A: cue X was paired with an outcome four times, while cue Y was presented without an outcome four times in Context B:. In both contexts filler cues were presented without the outcome. During the test, target cues X and Y were presented either in the context where they were trained, or in the alternative context. With the context change expectation of the outcome X, expressed as predictive ratings, decreased in the presence of X and increased in the presence of Y. Looking at the contexts, expressed as a percentage of the overall gaze dwell time on a trial, was high across the four training trials, and increased with the context change. Results suggest that the presentation of unexpected information leads to increases in attention to contextual cues. Implications for contextual control of behavior are discussed.

Attentional perspectives on context-dependence of information retrieval

Attention has been traditionally understood as an important factor on acquiring new information. A review of the literature suggests that attention, specifically attention to the contexts, also plays a relevant role on information retrieval. It also shows that attention to the contexts is modulated by the ambiguity of the situation, and the informative value contexts have. The virtues and limitations of different attentional theories of learning applied to the explanation of the effects of context change on retrieval of the information are discussed. This analysis uncovers the weaknesses of current research on context processing that should be corrected by future research: The need of independent measures of attention to the contexts, the evaluation of the mechanisms of contextual control, and the possibility of taking an evolutionary perspective on the effects of context change (AU)

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Melatonin influences NO/NOS pathway and reduces oxidative and nitrosative stress in a model of hypoxic-ischemic brain damage.

In this work, using a rat model combining ischemia and hypobaric hypoxia (IH), we evaluate the relationships between the antioxidant melatonin and the cerebral nitric oxide/nitric oxide synthase (NO/NOS) system seeking to ascertain whether melatonin exerts its antioxidant protective action by balancing this key pathway, which is highly involved in the cerebral oxidative and nitrosative damage underlying these pathologies. The application of the IH model increases the expression of the three nitric oxide synthase (NOS) isoforms, as well as nitrogen oxide (NOx) levels and nitrotyrosine (n-Tyr) impacts on the cerebral cortex. However, melatonin administration before IH makes nNOS expression response earlier and stronger, but diminishes iNOS and n-Tyr expression, while both eNOS and NOx remain unchanged. These results were corroborated by nicotine adenine dinucleotide phosphate diaphorase (NADPH-d) staining, as indicative of in situ NOS activity. In addition, the rats previously treated with melatonin exhibited a reduction in the oxidative impact evaluated by thiobarbituric acid reactive substances (TBARS). Finally, IH also intensified glial fibrillary acidic protein (GFAP) expression, reduced hypoxia-inducible factor-1alpha (HIF-1α), but did not change nuclear factor kappa B (NF-κB); meanwhile, melatonin did not significantly affect any of these patterns after the application of the IH model. The antioxidant melatonin acts on the NO/NOS system after IH injury balancing the release of NO, reducing peroxynitrite formation and protecting from nitrosative/oxidative damage. In addition, this paper raises questions concerning the classical role of some controversial molecules such as NO, which are of great consequence in the final fate of hypoxic neurons. We conclude that melatonin protects the brain from hypoxic/ischemic-derived damage in the first steps of the ischemic cascade, influencing the NO/NOS pathway and reducing oxidative and nitrosative stress.

Attention to irrelevant contexts decreases as training increases: Evidence from eye-fixations in a human predictive learning task.

Participants were trained in a human predictive learning task in which they had to predict whether the ingestion of a given food (cue) by the imaginary customer of an imaginary restaurant (context) was followed by gastric malaise (outcome). One food was always followed by gastric malaise in one of the contexts, while other foods were not followed by gastric malaise in the same, or in an alternative context. Predictive responses and eye-fixations were recorded throughout the 48 training trials with each cue involved in the task. In agreement with the predictions of the Attentional Theory of Context Processing, attention to the contexts measured through eye-fixations decreased while attention to the cues increased as training progressed. The results of this study give support to the idea that contexts are actively processed at the beginning of acquisition, and that this processing decreases as training increases.

Extinction of Learned Fear Induces Hippocampal Place Cell Remapping.

The extinction of learned fear is a hippocampus-dependent process thought to embody new learning rather than erasure of the original fear memory, although it is unknown how these competing contextual memories are represented in the hippocampus. We previously demonstrated that contextual fear conditioning results in hippocampal place cell remapping and long-term stabilization of novel representations. Here we report that extinction learning also induces place cell remapping in C57BL/6 mice. Specifically, we observed cells that preferentially remapped during different stages of learning. While some cells remapped in both fear conditioning and extinction, others responded predominantly during extinction, which may serve to modify previous representations as well as encode new safe associations. Additionally, we found cells that remapped primarily during fear conditioning, which could facilitate reacquisition of the original fear association. Moreover, we also observed cells that were stable throughout learning, which may serve to encode the static aspects of the environment. The short-term remapping observed during extinction was not found in animals that did not undergo fear conditioning, or when extinction was conducted outside of the conditioning context. Finally, conditioning and extinction produced an increase in spike phase locking to the theta and gamma frequencies. However, the degree of remapping seen during conditioning and extinction only correlated with gamma synchronization. Our results suggest that the extinction learning is a complex process that involves both modification of pre-existing memories and formation of new ones, and these traces coexist within the same hippocampal representation.

Long-term stabilization of place cell remapping produced by a fearful experience.

Fear is an emotional response to danger that is highly conserved throughout evolution because it is critical for survival. Accordingly, episodic memory for fearful locations is widely studied using contextual fear conditioning, a hippocampus-dependent task (Kim and Fanselow, 1992; Phillips and LeDoux, 1992). The hippocampus has been implicated in episodic emotional memory and is thought to integrate emotional stimuli within a spatial framework. Physiological evidence supporting the role of the hippocampus in contextual fear indicates that pyramidal cells in this region, which fire in specific locations as an animal moves through an environment, shift their preferred firing locations shortly after the presentation of an aversive stimulus (Moita et al., 2004). However, the long-term physiological mechanisms through which emotional memories are encoded by the hippocampus are unknown. Here we show that during and directly after a fearful experience, new hippocampal representations are established and persist in the long term. We recorded from the same place cells in mouse hippocampal area CA1 over several days during predator odor contextual fear conditioning and found that a subset of cells changed their preferred firing locations in response to the fearful stimulus. Furthermore, the newly formed representations of the fearful context stabilized in the long term. Our results demonstrate that place cells respond to the presence of an aversive stimulus, modify their firing patterns during emotional learning, and stabilize a long-term spatial representation in response to a fearful encounter. The persistent nature of these representations may contribute to the enduring quality of emotional memories.

Context-outcome associations underlie context-switch effects after partial reinforcement in human predictive learning

El valor predictivo que se asigna a claves reforzadas de forma continua se ve afectado por el cambio de contexto cuando éstas se entrenan en un contexto en el que otra clave diferente recibe reforzamiento parcial. Se llevó a cabo un experimento con el objetivo de explorar el mecanismo que subyace a este efecto de cambio de contexto. Se entrenó a participantes humanos en una situación de aprendizaje predictivo en la que una clave recibía reforzamiento parcial mientras que una clave objetivo (C1) recibía reforzamiento continuo en el contexto A y una segunda clave objetivo (U2) no era reforzada en el contexto B. Los participantes del grupo Parcial-Uno no recibieron reforzamiento parcial en B, mientras que los participantes del grupo Parcial-Ambos recibieron el mismo entrenamiento que en el contexto A, pero con claves distintas. Cuando las claves objetivo se probaron en el grupo Parcial-Uno, se observó mayor respuesta en el contexto A que en el contexto B, aunque las diferencias fueron menores ante la clave U2 que ante C1. No se encontraron diferencias entre contextos en el grupo Parcial-Ambos. Estos resultados están en consonancia con la hipótesis de que el cambio de contexto tras el reforzamiento parcial se debe principalmente a la formación de asociaciones contexto-consecuencia, aunque la diferencia entre el tamaño del efecto sobre la clave reforzada y no reforzada sugiere que también podría estar implicado un mecanismo modulador en estos efectos de cambios de contexto(AU)

Predictive value for continuously reinforced cues is affected by context changes when they are trained within a context in which a different cue undergoes partial reinforcement. An experiment was conducted with the goal of exploring the mechanisms underlying this context-switch effect. Human participants were trained in a predictive learning situation in which a cue received partial reinforcement while a target cue received continuous reinforcement in context A (C1) and another target cue was presented unreinforced in context B (U2). Participants in group Partial-One did not receive partial reinforcement in context B, while participants in group Partial-Both received the same training they received in context A, but with different cues. When target cues were tested in group Partial-One, greater responding in context A than in context B was found. Differences were smaller in cue U2 than in cue C1. No differences across contexts were found in group Partial-Both. These results are in agreement with the hypothesis that context-switch effects after partial reinforcement are mainly due to the formation of direct context-outcome associations, though the difference on the effect size on the reinforced and unreinforced cues suggests that a modulator mechanism may be also responsible for these context-switch effects(AU)

Partial reinforcement and context switch effects in human predictive learning.

Human participants were trained in a trial-by-trial contingency judgements task in which they had to predict the probability of an outcome (diarrhoea) following different cues (food names) in different contexts (restaurants). Cue P was paired with the outcome on half of the trials (partial reinforcement), while cue C was paired with the outcome on all the trials (continuous reinforcement), both cues in Context A. Test was conducted in both Context A and a different but equally familiar context (B). Context change decreased judgements to C, but not to P (Experiment 1). This effect was found only in the cue trained in the context where a different cue was partially reinforced (Experiment 2). Context switch effects disappeared when different cues received partial reinforcement in both contexts of training (Experiment 3). The implications of these results for an explanation of context switch effects in terms of ambiguity in the meaning of the cues prompting attention to the context (e.g., Bouton, 1997) are discussed.

Revisión de la teoría de la recuperación de la información: ¿qué convierte a la información en dependiente del contexto? / Revision of Retrieval Theory of forgetting: what does make information context-specific?

Este artículo explora el papel del contexto en la recuperación de la información, centrándose en los efectos diferenciales que el cambio de contexto tiene sobre la adquisición y la información interferente. Proponemos una modificación de la teoría de la recuperación de la información basada en resultados recientes de nuestro laboratorio que sugieren que la dependencia contextual de la información no depende de sus características específicas, sino de las características concretas de la situación que llevan a los participantes a prestar atención al contexto. Una vez aparece algo en la situación que lleva a los participantes a prestar atención al contexto, toda la información aprendida parece convertirse en específica del contexto, independientemente de si es el primer o segundo significado de la clave. Se proponen las bases de esta teoría atencional del procesamiento contextual

The role of context in retrieval of the information is explored, focusing in the differentiae effects of context change on acquisition and interfering information. Retrieval theory has proposed that context changes affect a specific type of information, either inhibitory or second-learned, interfering information. We propose a modification of retrieval theory based on recent results in our laboratory that suggests that context-specificity does not depend on specific features of the information, but on specific features of the situation that lead participants to pay attention to the context. Once there is something in the situation that leads participants to pay attention to the context, all the information learned seems to become context specific, regardless of whether it is the first or the second meaning of the cue. The outlines of this attentional theory of context processing are proposed

El resumen de los resultados en los artículos de investigación de Ciencias Comportamentales / Summary of results in research papers of behavioural sciences

El objetivo principal será la aplicación de desarrollos metodológicos recientes de cara a la adecuada elaboración del apartado de resultados propio de los artículos de investigación, atendiendo especialmente al campo de la Psicología y disciplinas comportamentales afines. Para ello, se exponen las generalidades sobre el resumen de información, resaltando especialmente la explicación detallada sobre la elección de la medida de error. En una segunda parte se presentan aspectos más específicos, discutiendo con detenimiento la adaptación de la medida de variabilidad error en función de dos parámetros básicos: el tipo de diseño de investigación y el grado de generalidad de la hipótesis de investigación. El trabajo se cierra con un ejemplo de aplicación de los conceptos expuestos con unos breves apuntes sobre la forma de agregar barras de error a los gráficos a partir de un programa de Hoja de Cálculo, como Microsoft Excel©

The main aim of this paper is the application of recent methodological developments in order to write adequately the results section of research papers, particularly in the field of Psychology and other behavioural sciences. Thus, we illustrate some general issues about how the in-formation should be summarized, emphasizing the need to explain in detail the choice of the error measure. The second part of the paper introduces more specific issues, as the adaptation of the error variability with reference to two parameters: the research design and the degree of generalization of the research hypothesis. This paper concludes with an applied example of the above issues, including some brief remarks about the way to add error bars to figures and graphics using a spread sheet program (i.e. Microsoft Excel©)

Overlap of pathology in paralytic rabies and axonal Guillain-Barre syndrome.

We describe clinical and pathological features of a case of paralytic rabies with acute axonal neuropathy that closely resembled axonal Guillain-Barre syndrome. This case emphasizes that there is overlap of both clinical and pathological features in paralytic rabies and axonal Guillain-Barre syndrome. These findings raise the possibility that infectious and autoimmune etiologies can lead to similar morphological changes in the nerves.

Utilidad de la biopsia muscular en el diagnóstico del síndrome de Reye / Usefulness of muscular biopsy in the diagnosis of Reye's syndrome

Se estudiaron cinco niños con síndrome de Reye: de ellos cuatro lactantes, que cursaron con el padecimiento en su forma grave, con crisis convulsivas tempranas y evolución tórpida, diferente a la descrita para pacientes de mayor edad, lo que dificultó clasificarlos inicialmente en forma adecuada. El tratamiento estuvo dirigido básicamente a mantener las constantes vitales y disminuir el edema cerebral. Un paciente murió y tres quedaron con secuelas neurológicas graves. En todos los casos se efectuó biopsia muscular y hepática, a los cuales se les practicó tinción de rojo oleoso. Al microscopio de luz, se encontró infiltración grasa microvesicular dentro de las células musculares. Ya que los pacientes con sindrome de Reye presentan defectos de la coagulación y la biopsia hepática puede incrementar las complicaciones por sangrado, la biopsia muscular puede ser una alternativa útil para establecer el diagnóstico en pacientes con datos clínicos que sugieran esta entidad. Sin embargo la infiltración grasa del músculo estriado no está establecida como un procedimiento rutinario en el diagnóstico de esta enfermedad

El empleo de la vacuna Sabin, de virus poliomielítico vivo, en México: Resultados de un estudio en gran escala / The use of the salk vaccine, in the polio live virus, in Mexico: Study Results

Los resultados de los presentes estudios indican, en primer lugar, la inocuidad de la vacuna Sabin de virus poliomielítico vivo. No se observaron reacciones adversas, relacionadas con la ingestión de las diversas cepas, entre los niños vacunados de cuatro ciudades mexicanas, ni hubo prueba de que entre los casos ocurridos en niños no vacunados, hubiera alguna relación con los vacunados

Los resultados de las pruebas serológicas, en sueros pareados obtenidos de un grupo de niños seleccionados al azar, antes y después de la vacunación, indican que las cepas atenuadas de Sabin fueron altamente inmunizantes. Las tasas globales de conversión de anticuerpos fueron las siguientes: del tipo 1, 84 por ciento; del tipo 2, 81 por ciento, y del tipo 3, 73 por ciento

Los resultados obtenidos en México, D.F., y en Guadalajara señalan los problemas especiales creados por el fenómeno de interferencia por numerosos virus entéricos e indican que los futuros programas de vacunación debieran abarcar por lo menos al 80 por ciento de la población susceptible en el período más breve posible, de manera parecida a la realizada en Toluca y anteriormente descrita por el Dr. Sabin

La administración de la vacuna en las condiciones descritas, en México, y en Guadalajara, durante un período de varias semanas, y que abarcó sólo una fracción de la población susceptible (17 por ciento en México, D.F., y 30 por ciento en ...(AU)