The role of different cues in the brain mechanism on visual spatial attention

The visual spatial attention mechanism in the brain was studied in 16 young subjects through the visual search paradigm of precue-target by the event-related potential (ERP) technique, with the attentive ranges cued by different scales of Chinese character and region cues. The results showed that the response time for Chinese character cues was much longer than that for region cues especially for small region cues. With the exterior interferences, the target stimuli recognition under region cues was much quicker than that under Chinese character cues. Compared with that under region cues, targets under Chinese character cues could lead to increase of the posterior P1, decrease of the N1 and increase of the P2. It should also be noted that the differences between region cues and Chinese character cues were affected by the interference types. Under exterior interferences, no significant difference was found between region cues and Chinese character cues; however, it was not the case under the interior interferences. Considering the difference between the exterior interferences and the interior interferences, we could conclude that with the increase of difficulty in target recognition there was obvious difference in the consumption of anterior frontal resources by target stimuli under the two kinds of cues.     

Brain dynamic mechanisms on the visual attention scale with Chinese characters cues

The temporal dynamics in brain evoked by the scale of visual attention with the cues of Chinese characters were studied by recording event-related potentials (ERPs). With the fixed orientation of visual attention, 14 healthy young participants performed a search task in which the search array was preceded by Chinese characters cues, “大, 中, 小” (large, medium, small). 128 channels scalp ERPs were recorded to study the role of visual attention scale played in the visual spatial attention. The results showed that there was no significant difference in the ERP components evoked by the three Chinese characters cues except the inferoposterior N2 latency. The targets evoked P2, N2 amplitudes and latency have significant differences with the different cues of large, middle and small, while P1 and N1 components had no significant difference. The results suggested that the processing of scale of visual attention was mainly concerned with P2, N2 components, while the P1, N1 components were mainly related with the processing of visual orientation information.     

Early ERP effects on the scaling of spatial attention in visual search

This article describes the examination of the spatial‘scaling＇ effect of visual attention with the technique of event-related potential （ERP）. Eighteen participants were involved in a visual search task in which the cue-target paradigm was used. The search array was three concentric circles consisting of randomly selected English letters that were equally distributed in each circle. The behavioral and ERP data were recorded, respectively. The behavioral results showed that the response time increased and the response accuracy decreased with the increase of precue size. The ERPs amplitude of PI and NI components evoked by search array increased with the reduction of precue size. However, the latencies of these ERP components did not show significant differences between conditions. The hierarchical data of both behavioral assessment and ERPs provided evidence for the spatial ＇scaling＇ effect of visual attention. The amplitudes of PI and N 1 components may be used as indices to examine the effect of spatial ＇scaling＇. In different tasks, the display-set size of stimuli and the task complexity may be important factors that affect the attention allocation.     

Neural suppression of distractors surrounding the spotlight: Evidence from steady-state visual evoked potentials

The present study investigated the allocation of spatial attention using steady-state visual evoked potentials(SSVEPs).The SSVEP is elicited in visual cortical areas by a repetitive flicker having the same fundamental frequency as the driving stimulus.Two flickers were applied with the letter stream presented in the center of the monitor and the distractor presented on either the left or right side of the target.Participants were instructed to detect the target letter in the letter stream.The distance of the two flickers was manipulated.The results show that the amplitudes of the SSVEPs elicited by the distractor were enhanced when it was in the closest position and suppressed when it was at a farther distance.But the amplitudes rebounded at the farthest distance.Meanwhile,the SSVEP elicited by the target flicker remained stable independent of the distance of the distractor.Thus,the present study indicates that focused attention involves neural suppression surrounding the classic spotlight,and the SSVEP paradigms open new avenues for studying the attentional suppression mechanism.     

An ERP study for the degrees of the difficulty in visual search

The present study mainly probed the relationships between ERP components and the degrees of difficulty in visual search. Three experimental and one controlled conditions were randomly selected. Results showed that the P1, N1, and P2 amplitudes and latencies had no significant differences among the three experimental and one controlled conditions, and the ERP waveforms of low perceptual load of visual search were different from that of high perceptual load. These results might indicate that the latencies and amplitudes of initial P1, N1 and P2 in high and low perceptual load conditions were almost the same. The ERP waveforms of parallel search were very different from that of serial search, and the ERP waveforms of serial search were very similar. The P3 amplitudes increased as the degrees of the difficulty in visual search decreased.     

An ERP study for the degrees of the difficulty in visual search

The present study mainly probed the relationships between ERP components and the degrees of difficulty in visual search. Three experimental and one controlled conditions were randomly selected. Results showed that the P1, N1, and P2 amplitudes and latencies had no significant differences among the three experimental and one controlled conditions, and the ERP waveforms of low perceptual load of visual search were different from that of high perceptual load. These results might indicate that the latencies and amplitudes of initial P1, N1 and P2 in high and low perceptual load conditions were almost the same. The ERP waveforms of parallel search were very different from that of serial search, and the ERP waveforms of serial search were very similar. The P3 amplitudes increased as the degrees of the difficulty in visual search decreased.     

The time course of visual categorization： Electrophysiological evidence from ERP

Categorization is the process to ascertain the identity of an object by a specific standard[1,2]. Categorization isa fundamental cognitive process; in fact, the raw per- ception would be of little use without the effective clas- sification of original inf…     

Detection of salient objects with focused attention based on spatial and temporal coherence

The understanding and analysis of video content are fundamentally important for numerous applications,including video summarization,retrieval,navigation,and editing.An important part of this process is to detect salient (which usually means important and interesting) objects in video segments.Unlike existing approaches,we propose a method that combines the saliency measurement with spatial and temporal coherence.The integration of spatial and temporal coherence is inspired by the focused attention in human vision.In the proposed method,the spatial coherence of low-level visual grouping cues (e.g.appearance and motion) helps per-frame object-background separation,while the temporal coherence of the object properties (e.g.shape and appearance) ensures consistent object localization over time,and thus the method is robust to unexpected environment changes and camera vibrations.Having developed an efficient optimization strategy based on coarse-to-fine multi-scale dynamic programming,we evaluate our method using a challenging dataset that is freely available together with this paper.We show the effectiveness and complementariness of the two types of coherence,and demonstrate that they can significantly improve the performance of salient object detection in videos.     

心算负载任务对事件相关电位信号特征影响的研究

事件相关电位是神经科学研究中重要的一种认知电位,也是脑机接口中常用的特征信号之一。心算任务引起的心理负载能够诱发事件相关电位。常用的信号特征主要为时域波形特征。无法全面分析评估特征特点。研究中设计了三种心算任务,时域上研究诱发的事件相关电位的波形特征,频域上利用格兰杰因果关系分析方法研究任务脑功能网络连接,探讨三种心算任务诱发事件相关电位特征信号的效果和特点。为构建基于ERP特征信号的脑机接口新范式提供理论依据和技术支持。     

基于视觉注意机制的眼底图像视盘快速定位与分割

视盘定位与分割对利用眼底图像进行眼科计算机辅助诊断十分重要。视觉注意机制模拟人类视觉系统从而能在复杂场景中快速定位目标。利用视盘在眼底图像中视觉显著度高这一特性,提出基于视觉注意模型实现视盘的快速定位并分割的算法。算法首先对不同眼底图像进行归一化,接着采用高斯金字塔提取图像不同尺度的颜色、亮度和方向特征图(feature map),进一步整合得到显著性图(saliency map),在显著性图中提取FOA(focus of attention)从而定位视盘。接着在视盘定位区域采用统计排序滤波器(rank-filter)抹除血管,在极坐标中采用亚像素提取图像边缘,实现视盘分割。采用国际Messidor数据库来验证算法的性能,定位精度为95%,运行时长为0.213 s,与其他算法相比,算法具有准确性高和实用性强等特点,具有良好的应用潜力。     

基于协同电子商务的ERP与CRM的整合

信息时代要求企业既具有快速柔性的生产模式,又具有个性化服务的营销模式。依托协同电子商务平台和信息集成技术将企业前端客户关系系统(CRM)和后端企业资源计划系统(ERP)整合起来,实现从客户到供应商的完全连通,企业内部流程与外部交易完全一体化,通过CRM实现与客户的互动营销,通过ERP实现整个供应链上数据流的畅通,从而形成企业的竞争优势。     

复配阻垢剂对碳酸钙阻垢效果及垢晶微观形貌影响

针对石南1631注水井结垢问题,以该注水井水样分析数据为基础,应用Scale-Chem结垢预测软件对该注水井的结垢类型进行了预测,得到该注水井的主要结垢类型为碳酸钙垢,并与现场垢样分析结果进行了对比。为了减缓结垢对注水的影响,选用五种阻垢剂对该注水井水样开展了阻垢效果研究。在阻垢剂单剂对注入水水样阻垢效果实验研究的基础上,将优选出的阻垢剂PESA与DTPMPA以2:1 复配,当阻垢剂浓度为80mg/L时,阻垢率达到90.26%。为明确复配阻垢剂的阻垢机理,对加入不同复配阻垢剂浓度前后形成的垢晶进行了扫描电镜分析与X-射线衍射分析,分析结果表明,复配阻垢剂对碳酸钙晶体的形貌与晶体粒径均有一定程度的影响,在实验所用复配阻垢剂浓度范围内,阻垢剂浓度越高,碳酸钙晶体的平均粒径越小;复配阻垢剂主要通过螯合增溶与晶格畸变,在碳酸钙垢的形成过程起到了抑制作用。     

气液搅拌反应器尺寸变化对多层桨功率消耗和混合特性的影响

运用流体力学的基本理论,对多层桨的液泛、再循环这两种重要现象作了描述,得到多层桨液泛点和再循环起始点的判据n_(F2)=2.8Q~(0.5)D~(0.2)/d~2;n_(F3)=2.6Q~(0.5)D~(0.2)/d~2;n_(Rm)=1.1Q~(0.2)D/d~2(m=2,3),以及适宜的操作范围n>n_R>n_F(式中,n、Q、D、d分别为转速、通气量、搅拌槽内径、叶轮直径;下角F、R分别为液泛点、再循环起始点),并在实验的基础上,提出多层桨功率数据的放大方法。     

农村普惠金融发展水平测度及其对农户经营性收入的空间效应研究

在构建农村普惠金融发展水平评价指标体系的基础上,计算了农村普惠金融发展水平指数,运用空间自相关分析方法和空间杜宾模型分别对农村普惠金融发展水平的时空差异和对农户经营性收入的空间效应进行了分析.结果表明：1) 2009年—2016年期间,我国农村普惠金融发展水平整体呈现出“V”字型的发展和变化趋势.2) 我国农村普惠金融发展存在显著的空间效应,区域农村普惠金融的发展存在溢出效应,且局部出现集聚性和集聚阴影效应.3) 农村普惠金融发展水平可以通过空间的交互作用产生出规模效应和溢出效应,进而有效提升农户经营性收入.4) 农村普惠金融发展对农村经营性收入影响上,不管是直接空间效应还是间接空间效应均显著为正,且间接影响更为强烈.即农村普惠金融发展的溢出效应能够促使相邻地区的农村普惠金融发展影响本地区农户的经营性收入.     

关于生物高分子元素活性中心分布规律的第四统计力学理论标度的研究(Ⅳ)——生物高分子活性中心的阴阳性与氧化电位的关系

各种生物体包括中药在内都有各自不同的元素分布 ,而且它们各自氧化电势也不同 ,通常氧化电势越高 ,离子所呈现的阳性越强 ;反之氧化电势越小 ,小到负值时离子的阴性越强。作者从大量中药元素的分析数据中发现 ,传统中药学里所说的药的阴阳性 ,在很大程度上与第四长周期里的元素的氧化电势分布有密切关系。在阳性药中 ,氧化电势高的元素占优势 ,而在阴性药中氧化电势低的元素占优势 ,可以用氧化电势来衡量中药阴阳性和药味。首次提出了从人体内元素含量比值的变化来衡量人体阴阳是否平衡的观点。     

大尺度上藓类植物嵌套分布格局及其保护策略——基于中国东部自然保护区和国家森林公园数据的分析

在大的空间尺度上,研究了我国苔藓植物多样性的地理分布格局,系统地收集了1 534种藓类植物在我国中东部地区80个自然保护区和国家森林公园分布的数据,分析了中国藓类植物主要类群在80个地理单元物种分布的嵌套水平和多样性保护的SLOSS（single large or several small）策略.研究发现,藓类、侧蒴藓类、顶蒴藓类、金发藓类-烟杆藓类、泥炭藓科（Spagnaceae）、丛藓科（Pottiaceae）、青藓科（Brachytheciaceae）、木灵藓科（Orthotrichaceae）、曲尾藓科（Dicranaceae）和真藓科（Bryaceae）存在明显的嵌套分布现象.不同地区之间的藓类植物,以贵州境内保护区的藓类植物嵌套分布程度最高,浙江和两广地区的为最低.无论从科还是从属和种的水平上,在面积相近的情况下,均倾向于建立一个大的自然保护区（SL）策略,特别是对于木灵藓科、金灰藓科（Pylaisiaceae）、曲尾藓科、泥炭藓科、提灯藓科.对生境专一性强的种类越多的藓类群,越倾向于SL策略.就不同的地理区域来讲,在浙江境内建立自然保护区,更倾向于建立多个小的保护区（SS）策略,在贵州境内更倾向于SL策略.