执行37分钟听觉Odd-ball任务中事件相关电位变化与注意的关系

Relationship between changes in event-related potential and attention during 37 minutes' successive auditory Odd-ball task

背景:许多报道只是分别观察了执行Oddball任务完成过程中事件相关电位各成分的变化,没有结合实验任务模式全面分析各成分的变化及其可能存在的内在联系。目的:通过测定健康人在执行连续37min听觉辨别Odd-ball任务过程中的事件相关电位,分析事件相关电位各成分的变化特征与注意的关系。设计、时间及地点:经典的37min持续Oddball听觉辨别任务及盲法评估试验,于2003-04/2007-07在日本北九州产业医科大学康复科完成。对象:20名健康在读大学生,全部为右利手,试验前所有学生均签署知情同意书。方法:在执行任务过程中,学生观察以10%的概率出现的2kHz短音靶刺激,靶刺激是随机分布于以90%的概率出现的1kHz短音非靶刺激之间,全部实验过程为37min,包括1214个声音刺激。前4min为练习阶段,让学生熟悉任务,之后开始真正的实验过程,将其划分为阶段1,阶段2,阶段3,每阶段为10.9分。主要观察指标:在额叶、顶叶和额顶中点采集靶刺激和非靶刺激的事件相关电位,非靶刺激包括靶刺激之前第1个和之后第1个非靶刺激的事件相关电位。除了用传统的平均加权法进行研究外,同时进行了单次P3成分分析。实验结束后,所有学生填写问卷,要求填写在各个实验阶段中的主观感受包括他们的清醒度、注意程度和对实验的兴趣程度等。结果:①各反应电位在不同实验阶段的变化:靶刺激之前第1个非靶刺激的事件相关电位的N1波幅、靶刺激N2的波幅及靶刺激P3的波幅在实验的不同阶段发生显著变化。②不同反应电位之间的比较:靶刺激之前第1个非靶刺激的事件相关电位的N1波幅显著小于靶刺激之后第1个非靶刺激的事件相关电位和靶刺激的N1(实验阶段2、3的额叶、额顶中点和顶叶);靶刺激之前第1个非靶刺激的事件相关电位的P2潜伏期显著小于靶刺激之后第1个非靶刺激的事件相关电位的P2潜伏期(实验阶段2的额叶、额顶中点和顶叶位置上和实验阶段3的额叶);靶刺激之前第1个非靶刺激的事件相关电位的P2的波幅显著小于靶刺激之后第1个非靶刺激的事件相关电位的P2波幅(实验阶段2的额顶中点、在实验阶段3的额叶、额顶中点和顶叶);认知电位变化最敏感区在额叶。③总的平均加权的靶刺激之前第1个非靶刺激的事件相关电位波形。有正负(N1-P2)波峰复合波形,而且在刺激启动后300ms回到基线水平,而总平均加权的靶刺激之后第1个非靶刺激的事件相关电位波形的正负(N1-P2)复合波峰的连续负波在刺激启动后450ms之后回到基线水平(额叶和额顶中点)。④事件相关电位的单次分析显示类型2(非P3成分)出现的百分率在额叶位置上显著大于在顶叶位置(实验阶段1,2和3);类型2出现的百分率在实验阶段3的显著大于在实验阶段1(额叶和额顶中点)。⑤在各个实验阶段中,反应时间差异无显著性意义。⑥根据问卷调查,所有的被测试者均认为试验任务非常简单,测试早期处于紧张、全神贯注的状态,随着试验的进展感到轻松、单调和机械化的完成任务,注意力时有分散,但未在测试过程中入睡。结论:在执行37min听觉辨别任务过程中,事件相关电位各成分的变化是认知调整的结果,各成分的变化存在内在的联系,推测这种变化与被检者适应过程有关,并直接反映注意不同因素的影响。

BACKGROUND： Many studies observed changes in event-related potential （ERP） during Odd-ball task, but the possible internal relationship among them has not been analyzed through experimental task pattern. OBJECTIVE： To explore the relationship between changes in ERP and attentional factors through measurement of normal person＇s ERP in 37 minutes＇ successive auditory Odd-ball task. DESIGN, TIME AND SETTING： 37 minutes＇ successive auditory Odd-ball task and blinded evaluation. The experiment was performed at the Department of Rehabilitation Medicine, University of Occupational and Environmental Health between April 2003 and July 2007. PARTICIPANTS： A total of 20 healthy college students, right handed, were participated in the study. The written informed consent was obtained from all participants. METHODS： In the task, the students were asked to discriminate rare （10%） target tones （2 kHz） from frequent （90%） non-target tones （1 kHz） and to press button as quickly and accurately as possible after hearing the target tone in continuous 37 minutes （1 214 tone stimulations） which was divided into 4 minutes rehearsal and 3 sessions, 10.9 minutes for each session. MAIN OUTCOME MEASURES： EEG at forehead zone （Fz）, central zone（Cz）, and parietal zone （Pz） in response to target tone （target）, immediately preceding the target tone （non-target 1） and following the target tone （non-target 2） in each session were averaged separately to analyze changes in ERP components, Le. N1 and P2 of nomtarget 1 and non-target 2, N1, N2 and P3 of target in 3 sessions and topographic distribution. Single trial analysis of P3 was also performed. After performing the task, all students answered the questionnaire about the degree of their interest, awareness and attention during three sessions. RESULTS： （1）Amplitude of N1 of non-target 1, amplitude of N2 of the target and amplitude of P3 of the target at different sessions changed significantly. （2）Amplitude of N1 of non-target 1 was significantly smaller than that of non-target 2 and target in session 2 and session 3 on Fz, Cz and Pz, latency of P2 of non-target 1 was significantly smaller than that of non-target 2 in session 2 on Fz, Cz and Pz, and in session 3 on Fz. Amplitude of P2 of non-target 1 was significantly smaller than that of non-target 2 in session 2 on Cz and in session 3 on Fz, Cz and Pz. The most sensitive position in changes of ERP was on Fz. （3） The waveform of averaged ERP of non-target 1 had positive and negative components of N1 and P2 and returned to the baseline 300 ms after the stimulation and that of non-target 2 returned to the baseline 450 ms after the stimulation on Fz and Cz. （4）Single trial analysis of P3 showed that the incidence of type 2 （No P3 component） was significantly larger on Fz than on Pz in all 3 sessions; and incidence of type 2 significantly larger in the session 3 than in session 1 on Fz and Cz. （5）There was no significant difference in response time in three sessions. （6）AII Subjects answered the questionnaire, and they thought the task was quite easy. They were concentrated on the task at first but soon felt the task was too easy and boring, so they lost their attention sometimes and automatically performed the task, but no one fell in sleep during the test. CONCLUSION： During 37 minutes＇ successive auditory Odd-ball task, changes in ERP components result from cognitive adjustment and the relations between them might show the habituation of the subjects, and reflected the effect of different attentional factors.