Neuroscience
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Using ERP adaptation paradigms, studies have shown that the N170 adaptation effect is a stable phenomenon for both faces and words. However, the N170 adaptation effect for repeated identity remains unclear, so we have addressed this with two experiments. In Experiment 1, we investigated the face-related N170 repeated adaptation effect in a short interstimulus interval (ISI) and found that the N170 response elicited by faces was smaller when preceded by a same face adaptor than by another face adaptor. ⋯ For the first time, the results indicated that the N170 response elicited by words was larger with a different word as an adaptor relative to the same word as an adaptor. Our results demonstrate that the face-related N170 response is sensitive to visual face features and extend the characteristics of N170 with the sensitivity to repeated items to other familiar objects of expertise (i.e. words). The results also suggest that there are some common characteristics between faces and words in the early perceptual processing.
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The amygdalar basolateral nuclear complex (BLC) is a cortex-like structure that receives inputs from many cortical areas. It has long been assumed that cortico-amygdalar projections, as well as inter-areal intracortical connections, arise from cortical pyramidal cells. However, recent studies have shown that GABAergic long-range nonpyramidal neurons (LRNP neurons) in the cortex also contribute to inter-areal connections. ⋯ About half of the SOM+ neurons in the lateral entorhinal area labeled by FG were GABA+. FG+ neurons containing parvalbumin were only seen in the basal forebrain, and no FG+ neurons containing vasoactive intestinal peptide were observed in any brain region. Since LRNP neurons involved in corticocortical connections are critical for synchronous oscillations that allow temporal coordination between distant cortical regions, the LRNP neurons identified in this study may play a role in the synchronous oscillations of the BLC and hippocampal region that are involved in the retrieval of fear memories.
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Local circuits within the striatum of the basal ganglia include a small number of γ-aminobutyric acid (GABA)-ergic fast-spiking interneurons (FSI). The number of these cells is reduced in disorders of behavioral control, but it is unknown whether this is accompanied by altered electrophysiological properties. The genetically hypertensive (GH) rat strain exhibits impulsiveness and hyperactivity. ⋯ Putative FSI (pFSI) were encountered less often in GH rats compared to the Wistar control strain. pFSI in GH rats also exhibited a higher mean firing rate, higher intraburst firing rate, lower interburst interval, and shorter bursts compared to controls. AMPH increased the mean overall firing rate of Wistar rat pFSI but did not significantly alter the firing properties of this subtype in GH rats. These differences in the resting-state electrophysiological activity of pFSI in GH rats point to them as a cell type of particular interest in understanding striatal functioning across different strains.
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Icariin (ICA), a flavonoid extracted from the traditional Chinese herb Herba Epimedii that can freely cross the blood-brain barrier, inhibits neuroinflammation and attenuates oxidative stress damage. Our previous studies demonstrated that icariin exerts an antidepressant-like activity in a social defeat mouse model. However, it is unknown whether icariin is beneficial for the treatment of depression via its modulation of oxidative stress and neuroinflammation. ⋯ Interestingly, icariin negatively regulated the activation of the nod-like receptor protein 3 (NLRP3) inflammasome/caspase-1/IL-1β axis in the hippocampus of CMS rats. These results confirm that icariin exerts antidepressant-like effects, which may be mediated, at least in part, by enhanced antioxidant status and anti-inflammatory effects on the brain tissue via the inhibition of NF-κB signaling activation and the NLRP3-inflammasome/caspase-1/IL-1β axis. Our findings provide new information to understand the antidepressant action of icariin, which is targeted to the NLRP3-inflammasom in brain.
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Alzheimer's disease (AD), the most common cause of dementia in aging people, is found to have a critical link with the deposition of β-amyloid (Aβ) in the brain. The inhibition of β-site amyloid precursor protein-cleaving enzyme 1 (BACE1), a key enzyme for Aβ production, is a promising target for AD therapy. In pursuit to find a potent inhibitor of BACE1, we identified galangin, a natural flavonoid, had a significant lowering effect on Aβ levels. ⋯ We further investigated whether epigenetic mechanisms, such as histone acetylation and DNA methylation, were involved in galangin-induced transcriptional regulation of BACE1. Our data show that galangin induces a decrease of acetylated H3 in the BACE1 promoter regions through the up-regulation of endogenous HDAC1-mediated deacetylation, which is independent of DNA methylation status. The above findings suggest a novel mechanism for polyphenols' neuroprotective effect in neurodegeneration and galangin as a potential drug candidate for AD therapy.