Cognitive Control in Aging

这个项目的总体目标是实现一个更好的理解的过程，意图转化为行动，在正常老化的成年人：所谓的“执行控制”的过程。以前的行为研究表明，老年人的执行能力显着和渐进的下降。本项目的具体目的是研究从一个任务切换到另一个使用高密度电生理记录（事件相关电位（ERP））作为我们的依赖措施涉及的执行过程。这使我们能够直接评估控制过程所涉及的区域网络中的潜在大脑动力学。我们的初步数据表明，任务转换的赤字与年龄可能实际上是由于前额叶皮质功能障碍，一个普遍持有的假设，而是，可能会导致从顶叶皮质过程的激活不足。这使我们假设，衰老的核心缺陷实际上可能是无法维持注意力--这一过程与以下因素有关： 顶叶激活我们将使用的实验范式如下，是一个完善的任务转换范式的修改，允许直接比较以前的心理物理数据的财富。在每次试验中，将呈现由字母和数字组成的刺激。在连续的三次试验中，受试者将判断字母是元音还是辅音;在接下来的三次试验中，他们将判断数字是偶数还是奇数; 然后重复该顺序。因此，受试者将被要求在字母分类任务和数字分类任务之间切换。将记录他们的ERP以及他们的行为表现（反应时间[RT]和错误率）。这将使我们能够比较受试者在三种类型的试验中的ERP和行为表现：1）受试者从一项任务转换到另一项任务后的第一次试验（“转换后”试验）; 2）第二次试验。 任务转换后（“嵌套”试验）; 3）任务转换前的试验（“转换前”试验）。因此，转换所需的执行过程将在“转换后”试验之前和/或期间活跃。因此，与这些过程相关的ERP将被发现a）在“转换前”试验的后期阶段，和/或B）在“转换后”试验的非常早期阶段。“嵌套”试验提供了一个基线，用于比较“转换前”和“转换后”试验。这些比较的结果将揭示年轻人和正常老年人任务转换中涉及的执行过程的神经机制。高密度ERP记录和地形图将使我们能够评估额叶，顶叶和早期感觉区对这些过程的相对贡献。

The overall goal of this project is to achieve a better understanding of the processes whereby intentions are translated into actions in normally aging adults: so-called 'executive control' processes. Previous behavioral research has suggested significant and progressive reductions in executive abilities in aging adults. The specific aim of this project is to study the executive processes involved in switching from one task to another using high-density electrophysiological recordings (event-related potentials (ERPs)) as our dependent measures. This allows us to directly assess the underlying brain dynamics across the network of areas involved in control processes. Our preliminary data suggest that the deficits in task-switching seen with aging may not in fact be due to prefrontal cortical dysfunction, a commonly held hypothesis, but rather, may result from deficient activation of parietal cortical processes. This has led us to hypothesize that a core deficit in aging may in fact be an inability to sustain attention- a process associated with parietal activations. The experimental paradigm we will use is as follows, and is a modification of a well-established task-switching paradigm, allowing for direct comparisons to the wealth of previous psychophysical data. On every trial, a stimulus comprised of a letter and a number will be presented. For three successive trials, subjects will judge whether the letter is a vowel or a consonant; for the next three trials, they will judge whether the number is even or odd; this sequence will then be repeated. Thus, subjects will be required to switch between a letter-categorization task and a number-categorization task. Their ERPs, as well as their behavioral performance (reaction times [RTs] and error rates), will be recorded. This will allow us to compare subjects' ERPs and behavioral performance on three types of trial: 1) the first trial after subjects have switched from one task to the other ('post-switch' trials); 2) the second trial after a task-switch ('nested' trials); 3) the trial immediately preceding a switch of task ('pre-switch' trials). Thus, the executive processes required to switch will be active before and/or during the 'post-switch' trial. The ERPs associated with these processes will therefore be found a) in the late stages of the 'pre-switch' trials, and/or b) in the very early stages of the 'post-switch' trials. The 'nested' trials provide a baseline against which to compare both the 'pre-switch' and the 'post-switch' trials. The results of these comparisons will shed light on the neural mechanisms underlying the executive processes involved in task switching in both young and normally aging adults. High-density ERP recordings and topographic mapping will permit us to assess the relative contributions of frontal, parietal and earlier sensory areas to these processes.