认知与发展心理学研究室知识库

时间加工是人类最重要的认知能力之一，对人们的生活意义重大。其内在的神经机制也一直是研究热点之一。过去的几十年中，无数研究者使用多种研究手段和技术对时间加工的神经机制进行了探索，提出了多种可能与时间加工相关的神经结构，分布在包括额、顶、枕、颗叶的多个部位。但是基于技术本身的限制，这些研究在时间或者空间精确性上有所欠缺。如脑成像研究的结果因其时间敏感性并不高，记录到的激活脑区可能并非是与时间重要加工过程紧密相关的，而头皮脑电的方法虽然在时间精确度上非常高，但是其无法得到精确的脑区位置，定位出的神经结构可能并不精确。在动物身上进行的单细胞记录技术既有空间也有时间灵敏度，但是猴子等动物的大脑结构与人类的脑结构仍然存在差异，不能完全将动物实验的结果迁移到人类身上，基于此，借助癫痈病人的颅内电极置入方式记录病人颅内脑电的方法就体现出了优越性，空间结构上，可以通过fMRI等医学影像结果复原出精确的电极位置从而准确地判断出活动脑区的名称，时间结构上，其高频采样(2000赫兹)的方式能够将结果的精度推进到毫秒级别，可以说这些优点让皮层脑电图(iEEG)的方式成为探索时间加工神经机制的最合适的选择。
本研究即采用这种方式来研究时间加工的神经机制。研究一中采用经典的时间分辨任务，结果发现右侧额下回盖部部位出现了稳定激活，这种稳定体现在两个方面，其一，在四个病人同一脑区部位都出现了激活，即此结果是被试间稳定的;其二，从被试内角度来看，在实验范式的6种条件中都出现较为显著的激活即此结果是条件间稳定的。综上，这种激活可以肯定是非常稳定的结果，并非由变异值引起，结合前人文献也发现，在多种研究中都发现该脑区会在被试进行时间加工任务时出现激活，最新的一篇脑损伤病人的研究也发现，损伤了该部位会让病人的时间加工任务表现降低。因此，可以肯定该脑区部位与视觉时间的加工紧密相关。围绕这一结果，实验二通过改变标准刺激的时间长度侧面证明实验一的发现，实验三起则通过增加颜色比较任务来更好地分离出时间相关性的脑区，通过正常人的表现证明该任务难度适中能够在癫痈病人身上实施，同时也证明颜色与时间任务不存在交互效应。实验四就是利用实验三中的范式来收集癫痈病人的脑电数据，证明了右侧额下回盖部区的时间相关性。

Time processing is one of important cognitive functions which is significant fornormal lives. Internal neural mechanism of time processing is one of popular research topics. In past decades, many researchers use many research technologies to explore neural mechanisms of time processing and propose many potential neural substrates of time processing including frontal, parietal and temporal cortex. Due to technological limitations, these researches lack temporal or spatial resolutions. Fmri is lack of temporal sensitivity so the activated brain areas may not closely correlate with core time processing procedures. Similarly, ERP is sensitive to time but hard to identify accurate brain areas of cognitive functions. The results by using single neuron recording technology of animals can’t be extended to human beings due to different physiological structures between animals and human beings. In sum, the intracranial electroencephalography (iEEG) of epilepsy patients has advantages on time processing researches. The brain areas of each electrode can be accurately identified by CT, fMRI and the high sampling rate (2000Hz) can help researchers collect data at the millisecond level. All these advantages make iEEG the best choice in exploring neural mechanisms of time processing.
This study adopts iEEG to explore neural mechanisms of time processing. In experiment 1 by using the classical time discrimination paradigm, robust high gamma activations were found in right pars opercularis. Four patients show activations in the right pars opercularis. In all 6 conditions this brain areas showed high-gamma activities. In total the activities of right pars opercularis are robust across subjects and across conditions. In sum, the activities are quite convincing and not elicited by deviated trials. Previous studies also demonstrate this brain area can be activated in time processing. A recent study shows the patients with right pars opercularis damaged show decreased performance in time related tasks. So, this area is related with visual time processing. In experiment 2, we use the standard cue with variable durations and also prove the result of experiment 1. In experiment 3, the normal subjects show normal performance in dual task with color and time discrimination which have no mutual relationships and this paradigm can be applied on epilepsy patients. In experiment 4, we use the experimental paradigm in experiment 3 to demonstrate the right pars opercularis is time related.