Effects of event probability and sequence on children with attention-deficit/hyperactivity, reading, and math disorder.

BACKGROUND: We investigated the impact of stimulus probability and sequence on performance and event-related potentials of 310 children classified into 12 combinations of attention-deficit/hyperactivity disorder (Not-attention-deficit/hyperactivity disorder, Inattentive and Combined subtypes) with presence/absence of reading disorder and math disorder. METHODS: Subjects pressed buttons to displays of the letters O and X, which were presented with probabilities of either .17/.83 or .50/.50. Greater response selection was required in the .17/.83 condition. RESULTS: Stimulus probability had comparable effects on all diagnostic groups. The extent of mismatch between a stimulus and preceding events elicited less systematic increases in errors, P3b latency, and P3b amplitude among both attention-deficit/hyperactivity disorder subtypes than controls. Mismatch with preceding trials more greatly reduced math disorder and reading disorder + math disorder children's speed in the Rare task and accuracy in both conditions. Math disorder and reading disorder + math disorder subjects also registered less the effects of alternations of the infrequent O on N2 amplitude and on P3b latency. CONCLUSIONS: Math disorder and reading disorder + math disorder youngsters' lower sensitivity to sequence irregularity in their event-related potentials along with greater disruption of performance suggest working memory deficits that adversely affected response selection. Comorbidity of attention-deficit/hyperactivity disorder and reading disorder did not affect the results.     

Evaluation of embryonic alcoholism from auditory event-related potential in fetal rats

Auditory event-related potential (AERP) is a kind of electroencephalography that measures the responses of perception, memory and judgement to special acoustic stimulation in the auditory cortex. AERP can be recorded with not only active but also passive mode. The active and passive recording modes of AERP have been shown a possible application in animals. Alcohol is a substance that can markedly affect the conscious reaction     

Dysfunctional attentional networks in children with attention deficit/hyperactivity disorder: evidence from an event-related functional magnetic resonance imaging study.

BACKGROUND: Although there is evidence for attentional dysfunction in children with attention deficit/hyperactivity disorder (ADHD), the neural basis of these deficits remains poorly understood. METHODS: We used event-related functional magnetic resonance imaging (fMRI) to investigate brain activations related to three particular aspects of attention: alerting, reorienting, and executive control. Sixteen medication-naive boys with ADHD and 16 healthy boys, aged 8 to 12 years, were studied. RESULTS: Behaviorally, children with ADHD showed a significant impairment only in their executive control system compared to healthy subjects. Neurally, children with ADHD (relative to controls) recruited deviant brain regions for all three attentional networks: less right-sided activation in the anterior cingulate gyrus during alerting, more fronto-striatal-insular activation during reorienting, and less fronto-striatal activation for executive control. ADHD symptom severity was associated with dysregulation of the blood oxygen level dependent (BOLD) signal within the putamen during reorienting and executive control. CONCLUSIONS: Our results demonstrated altered brain mechanism in ADHD associated with all three attentional networks investigated. For alerting and executive attention, our data indicate a deviant mechanism of cortical control, while ADHD children may have adopted altered strategies for reorienting of attention. Our results also stress the etiological role of functional abnormalities in the putamen in medication-naive ADHD.     

How specific are deficits in mismatch negativity generation to schizophrenia?

BACKGROUND: Mismatch negativity (MMN) is an auditory event-related potential that provides an index of auditory sensory memory. Deficits in MMN generation have been repeatedly demonstrated in chronic schizophrenia. Their specificity to schizophrenia has not been established. METHODS: Mismatch negativity to both duration and frequency deviants was investigated in gender- and age-matched patients with schizophrenia or schizoaffective disorder (n = 26), bipolar disorder (n = 16), or major depression (n = 22) and healthy control subjects (n = 25). RESULTS: Only patients with schizophrenia demonstrated significantly smaller mean MMN than did healthy control subjects. Detailed analyses showed significantly smaller MMN to both duration and frequency deviants in patients with schizophrenia than in healthy control subjects; however, the reduction of frequency MMN in patients with schizophrenia was not significant in the comparison across all groups. Mismatch negativity topography did not differ among groups. No consistent correlations with clinical, psychopathologic, or treatment variables were observed. CONCLUSIONS: Mismatch negativity deficits, and by extension deficits in early cortical auditory information processing, appear to be specific to schizophrenia. Animal and human studies implicate dysfunctional N-methyl-D-aspartate receptor functioning in MMN deficits. Thus MMN deficits may become a useful endophenotype to investigate the genetic underpinnings of schizophrenia, particularly with regard to the N-methyl-D-aspartate receptor.     

鸡40Hz听觉相关电位记录方法及反应阈正常值

为能在同一系统内同时探讨多项测试条件和参数对鸡４０Ｈｚ听觉相关电位记录结果的影响，采用正交试验法为实验模型，对短音的升／降时间，平台时间，滤波下降和，滤波上限等四个因素进行筛选，以获得最佳的测试条件。结果发现，短音的升／降时间与平台时间为２－１－２周期，滤波范围为２０－７０Ｈｚ时测试结果最佳。     

人类颜色和运动知觉的事件相关功能磁共振成像

目的 :利用新近发展起来的事件相关功能磁共振成像技术探测人类颜色和运动知觉区的特点。材料和方法 :用1.5T磁共振成像系统对 7名受试者行扫描。颜色刺激和运动刺激随机呈现。数据经预处理和统计分析获得脑激活图和局部血氧反应曲线。结果 :颜色刺激主要激活第四视觉区 (V4) ,但颞中回复合体 + (MT+ )也有轻度激活 ;运动刺激主要激活MT+ ,但V4也有一定激活。结论 :尽管V4主要参与颜色知觉 ,但在一定程度上也可参与运动知觉 ;类似地 ,尽管MT+ 的主要功能是运动知觉 ,但在一定程度上也参与颜色知觉的加工。事件相关方法可能比组块设计更为灵敏。     

Caffeine effects on ERPs and performance in an auditory Go/NoGo task

OBJECTIVE: Previous research has shown that caffeine produces a general increase in arousal. The present study examined caffeine-induced arousal effects on performance and auditory ERPs. We sought components showing amplitude changes without topography changes, as would be expected of a pure arousal amplification of source activity. METHODS: The effects of a single oral dose of caffeine (250 mg) were examined in a randomised double-blind placebo-controlled repeated-measures cross-over study. Subjects abstained from caffeine for 4h before the testing sessions, which were conducted, in the afternoon, one week apart. A simple auditory Go/NoGo task was used, with a random mix of 75 tones at 1000 Hz and 75 at 1500 Hz. All tones were 60 dB SPL, 50 ms duration (rise/fall time 5 ms), with SOA 1100 ms. RESULTS: There was a reduction in RT, but no effects on omission or commission errors. The major ERP effects of caffeine were focal rather than global increases in P1, P2 and P3b amplitudes to Go stimuli, with no changes in latency. There were no effects on N1 or N2 to Go stimuli, and no effects on any components in response to NoGo stimuli. CONCLUSIONS: The results suggest that caffeine differentially improves aspects of the processing related to response production and task performance, contrary to the widespread amplification of ERP component amplitudes, and latency reductions, expected of an increase in general arousal. SIGNIFICANCE: These results add auditory ERP data to the list of complex effects of caffeine on brain function and behaviour. They appear to rule out a simple arousal interpretation, and suggest directions for future research.     

基于2-back任务下ERP特征的脑力疲劳客观评价研究

利用事件相关电位(ERP)技术研究2-back任务下长时间的工作记忆所诱发的脑力疲劳的脑电特征变化,从而获取脑力疲劳评价的客观指标。32名健康男性受试者,年龄22～28岁,均分为两组:疲劳组和正常组。疲劳组通过连续执行100 min 2-back任务来诱发脑力疲劳,而正常组在前后分别执行10 min的2-back任务,中间80 min休息。采集实验过程中的主观疲劳评分值、行为绩效及脑电信号并进行分析。任务后疲劳组与正常组相比,思维清晰度和注意力明显减弱,困倦程度增加,综合疲劳感上升,且操作2-back的反应时明显延长,正确率下降,即从主观评价和行为绩效相结合的角度验证了所诱发的脑力疲劳模型的有效性。进一步比较疲劳组与正常组的ERP特征参数的变化情况,结果表明:相比正常组,随着脑力疲劳的加深,疲劳组的P300(F=2.539,P <0.05)和错误相关负波(ERN)(F=10.040,P <0.05)的波幅都明显下降,其他参数则未发生明显变化(均有P> 0.05)。因此,P300和ERN被证实可以作为评价长时间工作记忆任务下脑力疲劳模型的潜在指标,为后期研究脑力疲劳对抗措施提供依据。     

血管性认知功能损害的P300特点及其相关因素

目的研究血管性认知功能损害(vascularcognitiveimpairment,VCI)患者P300的变化特点,探讨P300在早期识别VCI中的应用价值。方法采用听觉Oddball程序,测定40例VCI和15例血管性痴呆(vasculardementia,VD)患者的P300,同时测定MMSE,并与影像学特点、相关危险因素综合分析评价。结果VCI和VD两组患者P300潜伏期显著延长,波幅明显降低(P<0.01,P<0.001),并与MMSE的评分降低显著相关(r=-0.599,P<0.05);以病灶位于额、颞叶者P300的异常更显著;患有糖尿病者P300的异常变化更明显。结论P300波能客观的反映患者的认知机能,且较MMSE敏感,能更早地反映细微的认知障碍或智能障碍;P300测定对于早期确定患者有无认知障碍及其程度以及对患者预后的预测有很重要的临床应有价值。     

Human movement-related potentials vs desynchronization of EEG alpha rhythm: a high-resolution EEG study

Movement-related potentials (MRPs) and event-related desynchronization (ERD) of alpha rhythm were investigated with an advanced high-resolution electroencephalographic technology (128 channels, surface Laplacian estimate, realistic head modeling). The working hypothesis was that MRPs and alpha ERD reflect different aspects of sensorimotor cortical processes. Both MRPs and alpha ERD modeled the responses of primary sensorimotor (M1-S1), supplementary motor (SMA), and posterior parietal (PP, area 5) areas during the preparation and execution of unilateral finger movements. Maximum responses were modeled in the contralateral M1-S1 during both preparation and execution of the movement. The SMA and PP responses were modeled mainly from the MRPs and alpha ERD, respectively. The modeled ipsilateral M1-S1 responses were larger and stronger in the alpha ERD than MRPs. These results may suggest that alpha ERD reflects changes in the background oscillatory activity in wide cortical sensorimotor areas, whereas MRPs represent mainly increased, task-specific responses of SMA and contralateral M1-S1.