Neuroscience
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L2 processing is shaped by L1 experience; however, it is not completely understood whether L1 reading experience also influences how the brain learns L2 under different learning conditions. In this study, we compare brain mechanisms of Spanish word learning in Chinese and English speakers using two learning conditions: speech-based learning and handwriting-based learning. The behavioral data suggest an advantage for learning that uses handwriting over speech-based learning across all participants. ⋯ Thus, the handwriting-based learning engaged visuo-orthographic regions to a greater degree in highly skilled Chinese speakers. In summary, the current findings suggest that handwriting facilitates lexical learning by enhancing orthographic involvement in Chinese speakers, while the handwriting condition enhanced phonological involvement in English speakers. This difference between Chinese and English speakers might be due to different L1 learning experience.
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In the adult hippocampal dentate gyrus (DG), the majority of newly generated cells are eliminated by apoptotic mechanisms. The apoptosis repressor with caspase recruitment domain (ARC), encoded by the Nol3 gene, is a potent and multifunctional death repressor that inhibits both death receptor and mitochondrial apoptotic signaling. The aim of the present study was to parse the role of ARC in the development of new granule cell neurons. ⋯ ARC knockout is not associated with increased numbers of microglia or with microglia activation. However, hippocampal brain-derived neurotrophic factor (BDNF) protein content is significantly increased in ARC-/- mice, possibly representing a compensatory response. Collectively, our results suggest that ARC plays a critical cell-autonomous role in preventing cell death during adult granule cell neogenesis.
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Some models of motivation distinguish between intrinsic and extrinsic motivation. While past work has examined the neural and cognitive correlates of extrinsic motivation, research on intrinsic motivation has relied primarily on behavioral measures of performance and learning. In particular, no past work has examined the neural and cognitive correlates of social performance expectancy, which is linked to intrinsic motivation. ⋯ EEG was used to examine motor-action preparation as measured by suppression of beta band activity over the motor cortex and feedback processing as measured by the Reward Positivity (RewP). Results revealed expectancy of difficult (vs. easy) trials narrowed attentional scope, reduced beta activity over the motor cortex, and enhanced RewP amplitudes to win feedback. These findings suggest that enhancing intrinsic motivation through expectancies of positive social comparison engages similar neural and cognitive correlates as extrinsic motivators high in motivational intensity.
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Ionizing radiation (IR) is one of the major biological limiting factors of human deep-space missions. Despite the dominant paradigm about the negative effects of IR on the CNS, the anxiolytic, antidepressant, anti-aggressive, and pro-cognitive effects have recently been discovered. The mechanisms of these phenomena remain undisclosed. ⋯ Notably, the maturation of rats led not only to the rebalancing of the glutamate/GABA ratio by reducing the glutamate content, but also to leveling the differences in the expression levels of the analyzing biomolecules. Thus, the combined action of IR at moderate doses resulted in long-term changes in psycho-emotional status and, surprisingly, an increase in the efficiency of spatial learning performance. We suggest that IR (within the range of composition and doses used) can be relatively safe for the functions of the CNS.
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Reproductive experience in mammals produces significant neuroendocrine and behavioral changes that are necessary to ensure the survival of the mother and the young. Exposure to stress during postpartum may affect the proper development of maternal behaviors. The present study examined whether previous reproductive experience affects neurobehavioral responses in females exposed to mother-infant separation stress during the postpartum period (4.5 h/day for 3 weeks). ⋯ Multiparity increased cell proliferation and cell survival in female rats and these changes occurred independently of pup exposure. The expression of BDNF was higher in the CA1 area in MULT rats. Although multiparity protects the mother against some of the effects of maternal separation stress, promoting behaviors directed to the pups during the early postpartum, preventing anxiety-like behaviors and mitigating memory deterioration after weaning, the data showed that disrupting natural dam-pup interaction produced neurobiological consequences on the mother even with multiple reproductive experience.