EEG gamma-band activity in rapid serial visual presentation

Evidence is available that oscillatory activity in the gamma frequency range (>30 Hz) might be related to the attentional selection of target items. Rapid serial visual presentation (RSVP) paradigms are instrumental in addressing cognitive functions such as visual attention, and they are increasingly combined with the measurement of electrical brain activity. In the present study, gamma-band responses for target and standard stimuli were investigated in an RSVP oddball paradigm. In a first study, stimuli were presented at a frequency of 10 Hz, the stimulus sequence consisted of rare colored letters (targets) and frequent black letters (standards). In addition, stimulus size was varied across experimental blocks. Significant target modulations were observed for the P3 ERP and induced (i.e., not phase-locked) gamma-band responses. Besides this late activation, no further gamma-band responses were observed. A second study aimed at replicating these findings by employing a reduced stimulus presentation rate of 7.1 Hz. Again, besides the P3 ERP a late increase in induced gamma-band activity was observed. However, as compared to Study 1, this induced response was less pronounced. The induced gamma-band response observed in the present studies might reflect utilization of information derived from previous processing steps for behavioral performance or memory storage as suggested in the ‘match-and-utilization-model’ of gamma activity.     

Electrophysiological evidence of facial inversion with rapid serial visual presentation

Using measurements of event-related potentials (ERPs) during a facial recognition task, we aimed to investigate the facial inversion effect and the role of time-based attention in processing upright and inverted faces. We presented upright and inverted faces at the T2 (target 2) position using a rapid serial visual presentation paradigm. Our results indicate that the N170 component shows the usual face inversion effect (FIE), in which inverted faces elicit larger N170 amplitudes and a longer elicit N170 latency. We also found that upright faces elicit larger P1 amplitudes than inverted faces over the left hemisphere. This study indicates that the N170 and P3, but not the P1, components are modulated by time-based attention. In addition, we found that the N170 amplitude was modulated by an attentional blink (AB) based on behavioral data. These results suggest that the disruption of facial configuration processing caused by inverted faces is relatively independent of attentional resources.     

针对快速序列视觉呈现脑电信号的时空混合特征提取方法

快速序列视觉呈现脑机接口（RSVP-BCI）是目前基于人脑对目标进行早期发现任务中最为常用的技术,该技术能够获取人脑对环境的快速感知。脑电信号（EEG）具有非平稳和信噪比较低的特点,因此在单次试验中准确解码大脑活动较为困难。为解决RSVP-BCI技术中单次试验分类准确率不高的问题,本文提出一种基于时空域混合特征提取的新方法。该方法充分考虑大脑活动的时空模式,分别在时域和空域采用主成分分析（PCA）和共空间模式（CSP）对EEG信号进行特征提取,构成时空混合CSP-PCA(STHCP)方法,通过时域、空域两次特征提取最大化目标类与非目标类之间的判别距离,有效地降低特征维数。STHCP的单试次解码曲线下面积（AUC）较三种基准算法[空间加权费希尔（Fisher）线性判决-PCA(SWFP)、CSP及PCA算法]分别提高了17.9%、22.2%及29.2%,为利用RSVP-BCI技术进行快速高效的目标检测提供了新方法。     

Attentional biases among body-dissatisfied young women: An ERP study with rapid serial visual presentation

In the current study, rapid serial visual presentation (RSVP) task combined with event related potentials (ERP) was used to investigate attention biases toward body-related words in a nonclinical sample of body dissatisfied females. Consistent with the hypotheses, the amplitudes of N100, N170 and P3 are sensitive to different body-related words in the RSVP paradigm only among body weight dissatisfied women (WD group), while control group did not show this difference. The early anterior N100 and bi-lateral parietal and occipital N170 amplitudes elicited by fatness-related words were larger than those elicited by thinness-related and neutral words among WD group, a finding which is consistent with the presence of a ‘negativity bias’. Also, WD group women showed significantly different amplitudes in response to three categories of stimuli with thin words eliciting the largest P3 amplitudes, followed by fat words and the least neutral words. The current findings indicated that attention biases toward body weight related words were evident during both sensory and cognitive stages of information processing. Findings are also consistent with hypotheses of cognitive-behavioral accounts of body weight dissatisfaction which propose, in part, that individual differences on cognitive tasks reveal underlying psychopathology; attentional biases reflect disordered body schema, not disordered eating, and can therefore be seen in non-clinical samples.     

中医中的医学信息检测与处理的锐器

中医诊断客观化、数字化的进展并不令人乐观.究其原因,一方面研究思路与手段存在诸多问题,另一方面人们对中医自身的认识还很片面、模糊甚至错误.笔者试图从测量学与现代信息检测和处理角度,对中医中的临床医学信息检测与处理思路和手段含英咀华.拨云见日,中医中的临床医学信息检测与处理的思路和手段不仅与现代一些信息检测、处理的思路和手段相暗合,也有对现有手段和方法完善的地方,还有具备极高借鉴价值的东西.这些思路与手段不仅为医学信息检测与处理,也可为其他领域的信息检测与处理提供很有价值的借鉴.     

Impaired semantic processing during task‐set switching: Evidence from the N400 in rapid serial visual presentation

The cognitive system is able to reconfigure mental resources flexibly to adapt to new a task. While task‐set switching is known to be detrimental to behavioral performance, less is known about the precise loci of these effects on stimulus processing. We measured event‐related potentials to explore the neural consequences of task‐set switching on semantic processing. We examined the context‐sensitive N400 component evoked by the second of two target words embedded in a rapid serial visual presentation under conditions that involved either a task‐set switch or no switching. Whereas the N400 was unaffected by the lag separating the targets in the absence of switching, it was delayed and attenuated in the switch condition when the targets were adjacent in the sequence. These findings indicate that task‐set reconfiguration temporarily prevents semantic activation and provide evidence for the nonautomaticity of semantic processing of words.     

Necessity of the target discrimination in the P300-based complex trial protocol test for concealed information

The two most common types of ERP-based protocols to detect concealed information are the 3-stimulus protocol (3SP) and Complex Trial Protocol (CTP). Both protocols traditionally include presentation of a target (a stimulus with assigned significance requiring a unique behavioral response). The intention of the target presentation is forcing subjects to pay attention to all stimuli, especially to guilty knowledge stimuli, called probes. It was unclear though, how the presence of a targets influences probe recognition, and thus, the concealed information test (CIT) effect—the difference in P300 response to the probe and Irrelevant (crime-unrelated) stimuli. The question of target necessity was first raised in relation to the 3SP, and it was found that although omitting target stimuli reduced P300 amplitudes for all probe and irrelevant stimuli, the CIT effect was not reduced. The current study investigated how the presence or absence of the target/nontarget discrimination in the CTP affects the CIT effect, by comparing two CTP groups both with (T) and without (NT) the target/nontarget discrimination. The results demonstrated that this discrimination significantly increases the P300 effect. We found a greater P300 CIT effect in the T group than in the NT group, suggesting that for field use, it is better to retain the target discrimination in the CTP. CIT effects were also seen with P300 latency, but not reaction time.     

P300-based detection of concealed autobiographical versus incidentally acquired information in target and non-target paradigms

The basic rationale of P300-based tests of concealed information compares responses to critical (‘probe’) and non-critical (‘irrelevant’) items. Accuracy, both in the laboratory and the field, is the degree to which responding to probes exceeds that to irrelevants. The present laboratory study assessed the influence of two factors on accuracy. The first, varied between subjects, was whether the paradigm included probes, irrelevants, and target items (as is the case in most P300 preparations), or whether the paradigm included only probe and irrelevant items. The second, orthogonally varied, within-subject factor was whether the probe was an autobiographical item (the subject's name), or incidentally acquired (as in common field applications). Accuracy was greater with the subject's name as probe, perhaps because of the greater potency of autobiographical items than incidentally acquired ones, even when these are learned to a 100% accuracy. On the other hand, contrary to expectations from a work-load interpretation, the removal of the target did not affect accuracy, but rather decreased P300 magnitude to both probes and irrelevants in the non-target group.     

Selective cholinergic lesions in the rat nucleus basalis magnocellularis with limited damage in the medial septum specifically alter attention performance in the five-choice serial reaction time task

Selective immunotoxic cholinergic lesions in the nucleus basalis magnocellularis (NBM) impair visuospatial attention performance in a 5-choice serial reaction time task (5-CSRT task). The features of the reported deficits, however, do not perfectly match among studies, in which some lesions may have been too weak while others largely encroached onto the septal region. Using the 5-CSRT task, we therefore re-assessed the effects of NBM lesions that produced minimal septal damage. Long-Evans adult male rats were trained to stable 5-CSRT task performance (stimulus duration: 0.5 s) and subsequently subjected to intra-NBM injections of 192 IgG-saporin (200 ng/side). The lesions induced more than 90% loss of choline acetyltransferase-positive neurons in the NBM vs. only 28% in the medial septum. The decrease of the optical density of acetylcholinesterase reaction products was significant in the cortex (-91%), not in the hippocampus. In the 5-CSRT task, the lesions resulted in increased omissions (from 10% to 30%) and decreased correct responses (from 80% to 60%), with negligible or no effects on all other usually collected variables. This deficit disappeared with lengthened stimulus duration (i.e. 0.5-1 and then 5 s). Furthermore, overall performance levels decreased when the stimulus duration was shortened (i.e. 0.5-0.2 s) or its intensity attenuated, and rats with cholinergic lesions remained consistently impaired vs. controls. These results show that disruption of sustained visual attention functions by damage to the NBM cholinergic neurons can be evidenced despite weak or no effects on variables accounting for motivational, locomotion- or impulsivity-related biases. Discrepancies with previously reported results are discussed in terms of differences in lesion extent/specificity and training levels.     

流感病毒快速检测方法在儿童流感样病例病原诊断中的应用

目的对一种流感病毒快速检测方法在儿童流感样病例病原诊断中的应用效果进行评估。方法 2010年12月至2011年4月采集流感样病例患儿咽拭子标本350例,使用甲型及乙型流感病毒抗原检测试剂盒（QuickNaviTM-Flu,胶乳免疫层析法）进行抗原检测,并与病毒分离法进行比较。对于抗原检测和病毒分离法结果不相符的标本采用RT-PCR验证。结果 QuickNaviTM-Flu抗原快速检测流感病毒的结果与病毒分离法的一致性好,其检测甲型流感病毒的敏感度为89.9%,特异度为94.4%。经RT-PCR验证,14例抗原检测与病毒分离法结果不相符样本中13例结果为阳性（与抗原检测一致）,使得该抗原检测方法的敏感度和特异度升至91.0%和99.6%。抗原检测乙型流感病毒经RT-PCR验证前后的结果一致,敏感度和特异度分别为87.5%和100%。该方法检测出的阳性标本中包括了甲3型、乙型（Victoria和Yamagata系）流感病毒和新发的2009甲型H1N1,并与常见的呼吸道病毒之间无交叉反应。结论 QuickNaviTM-Flu作为流感病毒抗原检测的试剂盒,可一次同时检测出甲型和乙型流感病毒,耗时短,操作简便,具有良好的敏感度和特异度,适用于流感样病例病原的快速诊断。     

Formation of cognitive structures in conditioned-reflex behavior in monkeys: Relationship with type of visual information

The characteristics of learning processes and long-term memory (LTM) were studied in rhesus macaques discriminating visual stimuli (geometrical figures of different shapes, sizes, and orientations, and with different spatial relationships between image components). Trained monkeys were tested for the ability to perform invariant recognition after stimulus transformation, i.e., changes in size, shape, number of objects, and spatial relationships. Analysis of behavioral characteristics (correct solutions, refusals to decide, motor response times) revealed differences associated with the type of visual information. When monkeys discriminated between black and white geometrical figures of different shapes and orientations, as well as black-and-white figures with different shapes or orientations, the learning time was short and transformation of the stimuli had no effect on correct solutions: there was complete transfer of learning. When monkeys discriminated figures of different sizes or complex images with different spatial relationships, the learning time was significantly greater. Changes in the size and shape of figures led to significant reductions in correct solutions and significant increases in refusals to solve the task and in motor reaction times. Invariance of discrimination in this case appeared after additional training. The results obtained here showed that in conditioned reflex learning, the sensory processing of stimuli has the result that discriminatory features are formed in LTM, i.e., cognitive structures (functional neurophysiological mechanisms), these supporting the classification of visual images. The temporal conditioned link of the executive reaction is established with these. Their formation is determined by the type of sensory information and the existence in LTM of separate subsystems for spatial and non-spatial information. Translated from Rossiiskii Fiziologicheskii Zhurnal imeni I. M. Sechenova, Vol. 94, No. 1, pp. 81–94, January, 2008.     

A novel countermeasure against the reaction time index of countermeasure use in the P300-based complex trial protocol for detection of concealed information

A P300 deception detection protocol was tested using simultaneous versus serial countermeasures and stimulus acknowledgment responses. Previously, P300 showed recognition and elevated reaction time identified countermeasure use. Probe-irrelevant P300 differences were significant in both countermeasure groups and control group. Detection rates were 11/12 for controls, 10/12 for serial countermeasure users, and 11/13 for simultaneous countermeasure users. Reaction time detected countermeasure use in serial responders, but not simultaneous responders. The simultaneous response reaction times were indistinguishable from controls.     

Self-testing for the detection of SARS-CoV-2 infection with rapid antigen tests for people with suspected COVID-19 in the community

ObjectivesTo evaluate the performance of nasal mid-turbinate self-testing using rapid antigen detection tests (RDT) for persons with suspected coronavirus disease 2019 (COVID-19) in the community. Self-testing for COVID-19 infection with lateral flow assay severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RDT, provides rapid results and could enable frequent and extensive testing in the community, thereby improving the control of SARS-CoV-2.MethodsParticipants visiting a municipal SARS-CoV-2 testing centre, received self-testing kits containing either the BD Veritor System (BD-RDT) or Roche SARS-CoV-2 antigen detection test (Roche-RDT). Oro-nasopharyngeal swabs were collected from the participants for quantitative RT-PCR (qRT-PCR) testing. As a proxy for contagiousness, viral culture was performed on a selection of qRT-PCR positive samples to determine the Ct-value at which the chance of a positive culture dropped below 0.5 (Ct-value cut-off). Sensitivity and specificity of self-testing were compared to qRT-PCR with a Ct-value below the Ct value cut-off. Determinants independently associated with a false-negative self-test result were determined.ResultsA total of 3201 participants were included (BD-RDT n = 1595; Roche-RDT n = 1606). Sensitivity and specificity of self-testing compared with the qRT-PCR results with a Ct-value below the Ct-value cut-off were 78.4% (95% CI 73.2%–83.5%) and 99.4% (95% CI 99.1%–99.7%), respectively. A higher age was independently associated with a false-negative self-testing result with an odds ratio of 1.024 (95% CI 1.003–1.044).ConclusionsSelf-testing using currently available RDT has a high specificity and relatively high sensitivity to identify individuals with a high probability of contagiousness.