健康与遗传心理学研究室知识库

本工作在提高执行功能测量的信度和效度基础上，应用结构方程建模方法研究不同执行功能和加工速度在认知年老化过程中的作用，及其相互关系;并对记忆刷新及其年老化的ERP特点作初步的研究。主要结果如下:
第一，所设计的9项执行功能任务信度良好，结构效度理想;显示注意转换、抑制优势反应和记忆刷新为三种相对独立的执行功能。
第二，在认知年老化结构模型中，不同执行功能和不同加工速度任务的路径系数差异较大。其中，记忆刷新在认知年老化过程中的中介作用最大，这种作用甚至大于加工速度的作用;另一方面，当加工速度任务中含有较多的执行成分时，加工速度在认知年老化过程中的中介作用也将增大。
第三，ERP研究部分，发现随着系列位置的增加，在控制条件下，头皮后部P250波幅有增大趋势，头皮前部的P300变化不明显;而在刷新条件下从系列位置4开始后部P250波幅有减小的趋势，从系列位置3开始前部P300波幅显著增大。与青年组相比，老年组在刷新条件下额叶活动加强、偏侧化效应减弱，并伴随P300潜伏期的延长。
行为研究发现，执行功能(尤其是记忆刷新)在认知年老化过程中起重要的中介作用;加工速度在认知年老化过程中的中介作用部分受执行功能的影响。研究结果不仅为执行衰退假说提供了实验依据，而且对加工速度理论进行了有益的补充和修正，在一定程度上实现了认知年老化领域这两种理论的整合。事件相关电位研究提示，记忆刷新过程可能存在抑制和提取两种机制的作用，大脑前后部区域表现出明显的互动关系。与青年人相比，老年人在记忆刷新过程中额叶需要投入更多的认知资源，说明老年人的额叶功能存在特异性的衰退，为认知年老化的执行衰退假说提供了ERP方面的证据。

Executive function is higher-order, strategic cognitive activity which controls and integrates other cognitive actions. This thesis investigated the role of executive function in cognitive aging and included two parts: behavioral study and event-related potentials (ERP) study.
In the first part, the reliability of nine measures, and the construct validity of three underlying executive functions (i.e. task switching, inhibition of prepotent responses, and memory updating) was verified. Then, the role of different kinds of executive function in cognitive aging was explored using structural equation modeling (SEM) methods, and the relative contribution of executive function and mental speed to cognitive aging was compared. Based on the result of behavioral study, in the second part, the relevant ERP components according to memory updating, and age-related changes were explored subsequently.
The main findings of the behavioral part were that: First, the referring nine executive measures were highly reliable. Confirmatory factor analysis also implied that three underlying executive functions were clearly separable. Second, it is found that the roles of executive function and mental speed were variable in the model of cognitive aging, when different kinds of executive function and mental speed were chosen. Furthermore, the relations between mental speed and both age and other measures of cognition were enhanced, as measures of mental speed become more complex and comprising more executive components. These results indicated that the role of executive function (especially for memory updating) should be reconsidered in cognitive aging, as well as giving a beneficial supplement for processing speed theory.
The main findings of the ERP studies were that: First, in the condition of updating, an attenuated left posterior P250 and an enhanced anterior P300 effect were found when the serial position increased. Second, elderly participants had increased updating-related activity with an enhanced serial effect over frontal regions. In addition, the latency of P300 was prolonged in the elderly. Taken together, these results suggested that two mechanism (inhibitory and retrieval) were needed in memory updating processes, which consistent with interaction between prefrontal cortical areas of updating/retrieval processes and posterior cortical areas o.f stimulus temporal storage. Compare to younger participants, memory updating processes of older participants rely more on frontal resources.