1秒以上时距判断的ERP研究

ERP Study on Duration Estimation of 1s

以视觉呈现时距信号,采用时间泛化范式要求被试判断5种探测时距(1～4秒)与标准时距(2秒)之间的长度关系,并记录11名大学生在时距判断过程中的事件相关电位(ERP),继而探讨不同探测时距条件下CNV波幅特征变化以及左、右侧额叶在时距判断中的功能。结果发现:1秒、1.42秒以及2秒条件下,CNV波幅峰出现在探测时距结束点,2.84秒、4秒条件下,CNV波幅峰出现在大约2秒处(标准时距);CNV负性翻转至基线位置在1秒、1.42秒、2秒条件下随探测时距的增长而延后,而在2.84秒、4秒两种条件下无显著差异;左、右侧额叶处诱发的CNV波幅峰潜时在2.84秒、4秒探测时距条件下无显著差异,且均在2秒附近。这说明在1秒以上视时距判断中CNV波幅峰反映了基于记忆中标准时距的时距判断的决策过程;CNV负性翻转至基线位置与时距判断的决策阶段存在共变关系,CNV负性翻转至基线位置相当于负荷解脱过程中的一个由负翻正的转折点;左、右侧额叶均参与了时距脉冲累加过程。

11 undergraduates（male,6;female,5;mean age,22.1）participated in the experiment.The durations of 1s,1.42s,2s,2.84s,and 4s were taken as visual probe duration signals to compare with the standard duration of 2s.There are 12 blocks in the process,and 30 trials in every block.After one block,participant was asked to rest for 30 seconds and then study the standard duration T1 for 5 times.The whole time is about 60 minutes.The results showed that in the condition of 1s,1.42s and 2s,CNV peak existed at the end point of the probe duration,while in the condition of 2.84s and 4s,it existed around 2s（standard duration）;in the condition of 1s,1.42s,and 2s,the Latency of zero crossing as the CNV return to baseline was delayed with the increase of probe duration,while in the condition of 2.84s and 4s,there was no significant difference;The evoked CNV peak latency by left and right frontal lobe had no significant difference in the probe condition of 2.84s and 4s.Besides,they were both around 2s.In the process of super-second visual duration judgment,CNV peak existed in the decision process of duration estimation based on the standard duration in the memory;there was covariation between the Latency of zero crossing as the CNV return to baseline and decision-making period of duration estimation,and the Latency of zero crossing as the CNV return to baseline was correspond to a turning point from the negative to the positive in the load extrication process;both the left and right frontal lobe participated in the process of duration impulse accumulation.