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 facing 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 male mice learn to combine both featural and geometric cues to recover heading. At the neural level, most CA1 neurons persistently align to geometry, and this alignment predicts heading behavior. However, a small subset of cells remaps coherently in a context-sensitive manner, which serves to predict context. Efficient heading retrieval and context recognition correlate with rate changes reflecting integration of featural and geometric information in the active ensemble. These data illustrate how context recognition and heading retrieval are coded in CA1 and how these processes change with experience.

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.

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.

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.