On Quantifying Surprise: The Variation of Event-Related Potentials With Subjective Probability

Two factors are known to determine the waveform of event-related potentials (ERP) elicited by task-relevant stimuli: the a priori probability of the stimuli and the sequence of immediately preceding stimuli. The relative contribution of these factors to the ERP waveform was assessed at nine levels of a priori probability (from .10 to .90). Random sequences of high (1500 Hz) and low (1000 Hz) tones were presented to 10 male subjects at each level of probability, both when the events were task-relevant and when the subjects were performing an alternate task to which the tones were irrelevant. The EEG was recorded from five midline electrode sites referred to linked mastoids. The amplitude of the P300 and Slow Wave components was inversely proportional to the a priori probability of task-relevant events. At every level of a priori probability, the magnitude of the P300 complex (N200-P300-Slow Wave) was diminished when the eliciting tone repeated the preceding tone, and was enhanced when it was preceded by the other tone. Thus, a priori probability and sequential structure appear to be independent determinants of the P300 complex.     

An event-related brain potential study of cross-modal links in spatial attention between vision and touch

Event-related potential (ERP) evidence for the existence of cross-modal links in endogenous spatial attention between vision and touch was obtained in an experiment where participants had to detect tactile or visual targets on the attended side and to ignore the irrelevant modality and stimuli on the unattended side. For visual ERPs, attentional modulations of occipital P1 and N1 components were present when attention was directed both within vision and within touch, indicating that links in spatial attention from touch to vision can affect early stages of visual processing. For somatosensory ERPs, attentional negativities starting around 140 ms poststimulus were present at midline and lateral central electrodes when touch was relevant. No attentional somatosensory ERP modulations were present when vision was relevant and tactile stimuli could be entirely ignored. However, in another task condition where responses were also required to infrequent tactile targets regardless of their location, visual-spatial attention modulated somatosensory ERPs. Unlike vision, touch apparently can be decoupled from attentional orienting within another modality unless it is potentially relevant.     

Effects of small dose of brotizolam on P300

Nine healthy men (mean age, 22.2 years) participated in two experimental sessions cross-overed randomly in a double blind manner; one with a placebo and the other with 0.125 mg of brotizolam (BTZ) administered in the morning. Resting electroencephalogram and event-related potential under oddball paradigm was recorded before and 1, 2, 4, 6 and 8 h after the administration. Mean 30-msec bin amplitude from 240 msec to 450 msec after the stimulus was compared between placebo and drug sessions in order to observe P300. Brotizolam reduced the amplitude of P300 at 6 h after administration. It was noted that the effects of BTZ were most marked at Fz.     

两种对精神分裂症患者检查方法对比分析

目的：探讨精神分裂症患者探究性眼球轨迹运动与事件相关电位P300的相关性及其差异性。方法：对50例精神分裂症患者分别使用眼球轨迹运动检查仪和事件相关电位检查仪进行测试。结果：50例精神分裂症患者D分值为正分;而P300潜伏期延长则与症状相关。结论：眼球轨迹运动和事件相关电位作为对精神分裂症患者的检测,前者有助于临床辅助诊断,后者则有助于精神分裂症患者病理心理研究和疗效的判断。     

嗅觉味觉功能的临床检测

目的:探讨嗅觉障碍患者嗅觉和味觉功能的改变。方法:284例受试者中,健康人92例,嗅觉功能减退92例,嗅觉功能丧失100例,分别采用T&T、嗅觉事件相关电位(OERPs)及三滴法进行嗅觉和味觉功能检测。结果:T&T结果,嗅觉功能减退和丧失患者跟健康人比较差异有统计学意义(P<0.05)。OERPs结果显示,嗅觉功能障碍患者跟健康人比较N1、P2波潜伏期延长且振幅降低,差异有统计学意义(P<0.05)。三滴法结果显示,嗅觉功能障碍患者跟健康人比较味觉功能有明显减退,差异有统计学意义(P<0.05)。各组之间男女比较差异无统计学意义。结论:嗅觉功能障碍患者同时伴有味觉功能的减退,嗅觉和味觉功能的减退与性别关联不大。嗅觉味觉的联合检查可以全面系统反映受试者的化学感觉功能,为临床诊断和治疗提供科学依据。     

精神分裂症认知功能障碍与事件相关电位P300的相关性研究

目的 探讨首发精神分裂症患者认知障碍与事件相关电位P300之间的相关性。方法 应用丹麦丹迪公司KeyPointV2．12诱发电位仪（ERPs）,对60例精神分裂症患者、3例急性精神分裂样障碍患者及40例健康人（对照组）使用听觉Oddball范式检测P300成分,同时运用阳性和阴性症状量表（PANSS）对患者组进行精神症状评定,并用主成分分析方法分离出几个症状因子。结果 PANSS项目主成分分析显示认知障碍、阴性症状、抑郁症状、敌对／兴奋、妄想／幻觉5个因子;与健康对照组相比,P300波幅在F2、Cz、P2、T3、T45个记录区差异均有显著性（P〈0．05,P〈0．01）,P300潜伏期无显著差异（P〉0．05）,患者组认知障碍因子仅与Fz、T3处P300波幅呈负相关（r=-0．43,P〈0．01;r=-0．33,P〈0．05）。结论 额及颞区P300波幅降低反映精神分裂症患者一定程度的认知损害。     

精神分裂症患者事件相关电位MMN对照研究

目的探讨精神分裂症患者事件相关电位失匹配负波(mismatch negativity,MMN)的特征及发病次数对MMN的影响。方法对35例精神分裂症患者(病例组)和30名志愿者(对照组)行事件相关电位MMN的检测,并比较首发病患与复发病患MMN潜伏期、波幅的差异。结果①病例组和对照组Fz,Cz点均可见较明显MMN波形,精神分裂症组波形欠规则。②相对于对照组而言,病例组在Fz,Cz点潜伏期没有显著性变化,而波幅降低,差异具有统计学意义(P<0.05)。③首发病患和复发病患MMN的潜伏期和波幅差异均没有统计学意义。结论精神分裂症患者存在认知功能缺陷,MMN可以为其提供临床参考,且MMN是一个素质性指标,与发病次数没有显著性相关。     

正常人汉语句子事件相关电位N400的研究

目的研究汉语句子结尾词匹配与不匹配事件相关电位N400的变化,探讨正常人汉语句子N400的特征。方法对15名21~36岁右利手健康受试者,进行汉语正常句子结尾匹配词(匹配)与句子结尾歧义词(不匹配)N400的研究。结果受试者对句子结尾词匹配与不匹配的N400成分在潜伏期及波幅有显著性差异(P<0.05),句子不匹配结尾词的N400潜伏期较长,N400波幅高。N400广泛分布于脑部各区,左侧波幅偏高。结论汉语句子结尾字匹配与不匹配的N400与字词认知中的语义密切相关,可作为一个有临床价值的认知电位而用于临床多种伴有语言障碍疾病的评估。     

面孔表情识别事件相关电位的性别效应

目的考察面孔表情加工对应的事件相关电位（event-related potentials，ERP）时空模式的性别差异。方法采用正性、中性、负性三种面孔表情简笔画图片为刺激，31名受试者（男18例，女13例）执行隐含面孔表情识别任务，比较了不同性别的ERP差异波（正性和负性分别减去中性表情对应的ERP波形所得的“清绪波”）及N210（对应于文献中的N170）的异同。结果正性情绪波显著的差异在100-200ms的分布由左侧逐渐过渡到右侧、260-280ms分布于两侧但以左侧为主、360-380ms为前部；负性情绪波显著的差异在360-380ms分布在头皮右侧、500-520ms则在左侧并向后部扩布。女性面孔表情识别左半球的比右半球N210潜伏期明显延长。结论不同性别间对面孔表情的神经加工存在差异，女性N210左半球加工速度迟于右半球。     

An electrophysiological investigation of discourse coherence in healthy adults

This study used event-related potentials (ERPs) to investigate discourse-coherence processing. Because there are scant data on ERP indices of discourse coherence in typical adults, it is important to study a non-clinical population before examining clinical populations. Twelve adults listened to a story with sentences in a coherent versus incoherent order. Sequences of nonsense syllables served as a control. ERPs in the 200–400?ms time window, reflecting phonological and lexical processing, and in the 600–900?ms time window, reflecting later discourse processing for integration, were investigated. Results revealed a right anterior and posterior positivity that was greater for coherent than for incoherent discourse during the 600–900?ms time window. These findings point to an index of discourse coherence and further suggest that ERPs can be used as a clinical tool to study discourse-processing disorders in populations with brain damage, such as aphasia and traumatic brain injury.