Neuroscience
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Previous research has mapped out the brain regions that respond to semantic stimuli presented visually and auditorily, but there is debate about whether semantic representation is modality-specific (only written or only spoken) or modality-invariant (both written and spoken). The mechanism of semantic representation underlying native (L1) and second language (L2) comprehension in different modalities as well as how this mechanism is influenced by L2 proficiency, remains unclear. We used functional magnetic resonance imaging (fMRI) data from the OpenNEURO database to calculate neural pattern similarity across native and second languages (Spanish and English) for different input modalities (written and spoken) and learning sessions (before and after training). ⋯ Cross-language pattern similarity between L1 and L2 written words was observed in the right anterior temporal lobe. Brain-behavior correlations indicated that increased cross-language pattern similarity between L1 and L2 written words in the right anterior temporal lobe was associated with L2 written word comprehension. This study identified an effective neurofunctional predictor related to L2 written word comprehension.
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Recent researches have noted many changes of short-term dynamic modalities in mild cognitive impairment (MCI) patients' brain functional networks. In this study, the dynamic functional brain networks of 82 MCI patients and 85 individuals in the normal control (NC) group were constructed using the sliding window method and Pearson correlation. The window size was determined using single-scale time-dependent (SSTD) method. ⋯ R. This study on DFC states explores changes in the brain functional networks of patients with MCI from the perspective of alterations in the community structures of DFC states. The findings could provide new insights into the pathological changes in the brains of MCI patients.
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Our recent study revealed that fluorescent lamp light can penetrate deep into the brain of mice and rats leading to the development of typical histological characteristics associated with Parkinson's disease such as the loss of dopamine neurons in the substantia nigra. Monochromatic LED lights were thus used in this work to deepen our knowledge on the effects of the major wavelength peaks of fluorescent light on mouse and human dopaminergic cells. In particular, we exposed immortalized dopaminergic MN9D neuronal cells, primary cultures of mouse mesencephalic dopaminergic cells and human dopaminergic neurons differentiated from induced pluripotent stem cells (hiPSC) to different LED light wavelengths. ⋯ Notably, differentiated MN9D dopaminergic cells, which closely resemble mature dopamine neuronal phenotype, acutely exposed for 3 h at 610 nm, showed a clear increase in ROS production and cytotoxicity compared to controls undifferentiated MN9D cells. These increases were even more pronounced by the co-treatment with the oxidative agent H2O2. Collectively, these findings suggest that specific wavelengths, particularly those capable of penetrating deep into the brain, could potentially pose an environmental hazard in relation to Parkinson's disease.
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Short-chain fatty acids (SCFAs) are bioactive lipids that are released into the colon as a metabolite of bacterial fermentation of dietary fibers. Beyond their function in the gastrointestinal tract, SCFAs can also have effects inthe brain, as a part of the gut-brain axis. Recent investigations into potential therapeutic interventions via the manipulation of the gut microbiome-and thus their SCFA metabolites-has been emerging as a new branch of personalized medicine,especially for mental health conditions. ⋯ We found high colocalization of SCFA receptors in both microglia and serotonergic neurons and discovered that SCFA receptor expression in the dorsal raphe is driven by fiber solubility, while SCFA receptor expression in the hippocampus is driven by fiber amount. Higher dietary fiber was associated with decreased tyrosine hydroxylase expression. Thus, our results indicate that the amount and solubility of dietary fiber can change gene expression in the brain's microglia and serotonin neurons, potentially via sensitivity to circulating levels of SCFAs produced in the gut.
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Whether patients with myasthenia gravis (MG) exhibit cognitive impairment is controversial. Also the underlying mechanisms are unknown. ⋯ The results suggest that MG is accompanied by cognitive decline, as indicated by global cognitive function, visual-spatial function, language, memory, abnormalities in regional brain functional activity, and neurometabolite alterations (including GABA, NAA, and Cho) in the medial prefrontal cortex (MPFC) and left thalamus. Cognitive impairment in patients with MG may be related to abnormal regional brain functional activity and changes in neurometabolites, and regional brain functional activity may be modulated by specific neurometabolites.