分类： 生物学 >> 生物物理学 >> 神经科学 提交时间： 2016-05-18
Chen, Juan
He, Yingchen
Zhu, Ziyun
Peng, Yujia
Zhang, Xilin
Fang, Fang
Chen, Juan
He, Yingchen
Zhu, Ziyun
Peng, Yujia
Zhang, Xilin
Fang, Fang
Fang, Fang
Fang, Fang
Zhou, Tiangang
摘要：Crowding, the identification difficulty for a target in the presence of nearby flankers, is ubiquitous in spatial vision and is considered a bottleneck of object recognition and visual awareness. Despite its significance, the neural mechanisms of crowding are still unclear. Here, we performed event-related potential and fMRI experiments to measure the cortical interaction between the target and flankers in human subjects. We found that the magnitude of the crowding effect was closely associated with an early suppressive cortical interaction. The cortical suppression was reflected in the earliest event-related potential component (C1), which originated in V1, and in the BOLD signal in V1, but not other higher cortical areas. Intriguingly, spatial attention played a critical role in the manifestation of the suppression. These findings provide direct and converging evidence that attention-dependent V1 suppression contributes to crowding at a very early stage of visual processing.
分类： 生物学 >> 生物物理学 >> 生物力学与生物流变学 提交时间： 2016-05-05
摘要：Recent deep sequencing surveys of mammalian genomes have unexpectedly revealed pervasive and complex transcription and identified tens of thousands of RNA transcripts that do not code for proteins. These non-coding RNAs (ncRNAs) highlight the central role of RNA in gene regulation. ncRNAs are arbitrarily divided into two main groups: The first includes small RNAs, such as miRNAs, piRNAs, and endogenous siRNAs, that usually range from 20 to 30 nt, while the second group includes long non-coding RNAs (lncRNAs), which are typically more than 200 nt in length. These ncRNAs were initially thought to merely regulate gene expression at the post-transcriptional level, but recent studies have indicated that ncRNAs, especially lncRNAs, are extensively associated with diverse chromatin remodeling complexes and target them to specific genomic loci to alter DNA methylation or histone status. These findings suggest an emerging theme of ncRNAs in epigenetic regulation. In this review, we discuss the wide spectrum of ncRNAs in the regulation of DNA methylation and chromatin state, as well as the key questions that needs to be investigated and acknowledging the elegant design of these intriguing macromolecules.
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