Individual, age-dependent differences in ACC-mediated adaptive decision making

描述（由申请人提供）：我们从经验中学习，做出更有效的决定，经常调整我们的期望，以匹配我们过去所经历的结果。在一个动态的世界中，这种调整过程本身必须具有适应性，因为有时发生的变化会使过去的结果与未来的预期无关。例如，一个采花者必须认识到，一棵垂死的树将不再像健康时那样结出那么多的果实。这项研究的目的是验证一个新的假设，即决策中的某些个体差异，包括一些系统地依赖于年龄的个体差异，是由观察到的世界变化如何影响使用过去经验来为未来决策提供信息的差异造成的。我们认为，个体在如何认识和应对两种不同形式的不确定性方面存在很大差异。不确定性的一种形式被称为噪声，它代表了一个稳定过程中的随机波动。另一种形式的不确定性被称为波动性，它代表了过程本身的根本变化。个体的适应性决策包括在面对嘈杂或不稳定的新数据时总是调整预期的倾向，以及形成相对不受新数据影响的稳定预期的倾向。我们已经确定了控制这种适应性信念更新的计算原理，其中包括对当前环境中不稳定变化发生率的先前预期的重要性。我们还提出，重要的潜在计算是由前扣带皮层（ACC）神经元的活动编码的。为了验证这些假设，我们使用了两个互补的目标，提供了不同年龄的个体受试者执行任务时的ACC活动的多种测量方法，这些任务旨在直接测量大脑活动

DESCRIPTION (provided by applicant): We learn from experience to make more effective decisions, often adjusting our expectations to match outcomes that we have experienced in the past. In a dynamic world, this adjustment process must itself be adaptive, because sometimes changes occur that render past outcomes irrelevant to future expectations. For example, a forager must recognize that a dying tree will no longer yield as much fruit as when it was healthy. The goal of the proposed research is to test the novel hypothesis that certain individual differences in decision- making, including some that depend systematically on age, result from differences in how observed changes in the world affect the use of past experiences to inform future decisions. We propose that individuals differ substantially in how they recognize and respond to two different forms of uncertainty. One form of uncertainty, called noise, represents random fluctuations in an otherwise stable process. The other form of uncertainty, called volatility, represents fundamental changes in the process itself. Individual, adaptive decision-making ranges from a tendency to always adjust expectations in the face of either noisy or volatile new data, to a tendency to form stable expectations that are relatively unaffected by new data. We have identified computational principles that govern this kind of adaptive belief updating, which include the importance of prior expectations about the rate of occurrence of volatile changes in the current environment. We also propose that the important underlying computations are encoded by the activity of neurons in the anterior cingulate cortex (ACC). To test these hypotheses, we use two complementary Aims that provide multiple measures of ACC activity in individual subjects of different ages performing tasks designed to measure directly the amount of influence each new piece of information has on existing beliefs about a dynamic environment. The first Aim uses combined behavior and neurophysiological recordings in younger and older monkeys, providing measurements of the relevant neural computations with high spatial and temporal resolution. The second Aim uses combined behavior and fMRI- and EEG-based measurements of brain activity in human subjects, which can be compared directly to the higher-resolution monkey data. The human studies also include several versions of the task, including one designed to manipulate and measure prior expectations about the rate of environmental changes directly, that provide a broader view of the individual and age-related differences that occur with these kinds of decisions. The proposed research represents a novel field of study that is likely to provide far-reaching insights into how individuals make effective decisions in a dynamic world.