Orbitofrontal cortex as a cognitive map of task states

项目概述：眶额皮层作为任务状态的认知地图 眶额皮层（OFC）一直是前额叶皮层中最神秘的区域之一， 从抑制优势行为到经济决策中的价值评估。眶额肌功能障碍是 与一系列与决策有关的障碍有关，其中最主要的是强迫性障碍，如成瘾和强迫症。 最近，我们假设OFC代表任务空间的“认知地图”中任务的当前状态， 向大脑中其他地方的决策和学习区域提供任务相关信息的概要（Wilson等人， 2014，Neuron）。特别是，理论上的考虑和以前的经验数据表明，OFC尤其是 对于表示“部分可观察”的任务状态--包括不直接 环境中可用的信息，例如来自工作记忆的内部信息。 这一假设为解释各种现有的发现提供了一个统一的理论框架， 在该领域获得了相当大的吸引力（例如，该论文被引用超过50次，并在超过一半的 在最近一次关于OFC的会议上的讲话）。然而，该理论尚未得到直接验证，因为以前的数据也可以 用不同的解释来解释。在这里，我们建议测试OFC代表任务状态的假设，并 对比和区分这一功能从占主导地位的竞争假说，根据该OFC代表 奖励期望 在Aim 1中，我们将测试OFC是否对需要编码的年龄判断任务的状态进行编码。 不可观察的信息作为任务状态的关键部分，并且不涉及奖励。我们将使用功能性磁共振成像 测量人类的OFC活动，并利用多变量分析方法来测试任务状态是否可以被解码， OFC，以及这种状态表示是否与任务绩效相关并预测任务绩效。在目标2中，我们将区分 OFC的状态编码和值编码功能，通过向年龄判断任务添加奖励并测试是否 当奖励对任务绩效是工具性的还是附带性的时，OFC中的奖励是可解码的。我们 理论预测，只有在任务状态需要奖励时，奖励才会在OFC中表现出来。在整个过程中， 还分析了相关脑区的表征，如背外侧前额叶皮层、海马体和 高级视觉皮层，以确定OFC的独特功能，并建立任务状态之间的关系 任务相关信息在大脑的其他地方编码。 我们的发现将影响目前对眶额皮层在正常和异常学习和决策中作用的理解。 这将有助于解释为什么OFC对某些任务很重要，而对其他任务却不重要。此外，我们的工作将建立 从非侵入性脑成像数据解码内部任务状态以预测行为和分析个体的效用 任务表征的差异。这对于理解决策的确切性质尤其重要 例如药物滥用和其他强迫性疾病，这些疾病与眶额皮层密切相关。

Project summary: The orbitofrontal cortex as a cognitive map of task states The orbitofrontal cortex (OFC) has remained one of the most mysterious areas in the prefrontal cortex, with suggested functions ranging from inhibition of prepotent actions to valuation in economic decision making. OFC dysfunction is implicated in a wide range of decision-related disorders, chief among them compulsive disorders such as addiction and OCD. Recently, we hypothesized that the OFC represents the current state of the task within a “cognitive map” of task space, providing a summary of task-relevant information to decision-making and learning areas elsewhere in the brain (Wilson et al., 2014, Neuron). In particular, theoretical considerations and previous empirical data suggest that the OFC is especially important for representing task states that are “partially observable”—states that include information that is not directly available in the environment, such as internal information from working memory. This hypothesis offers a unifying theoretical framework for interpreting a wide variety of existing findings, and has already gained considerable traction in the field (e.g., the paper has been cited over 50 times and was mentioned in over half the talks in a recent conference on the OFC). However, the theory has not yet been tested directly, as previous data can also be explained by alternative interpretations. Here we propose to test the hypothesis that the OFC represents task states, and to contrast and differentiate this function from the dominant competing hypothesis according to which the OFC represents reward expectancies. In Aim1, we will test whether the OFC codes the states of an age-judgment task that requires encoding of unobservable information as a critical part of the task state, and that does not involve rewards. We will use fMRI to measure OFC activity in humans, and utilize multivariate analysis methods to test whether the task states can be decoded in OFC, and whether this state representation correlates with and predicts task performance. In Aim 2, we will differentiate the state coding and value coding functions of the OFC by adding rewards to the age-judgment task and testing whether rewards are decodable in OFC when they are instrumental to task performance versus incidental to task performance. Our theory predicts that rewards will be represented in OFC only if they are required as part of the task state. Throughout, we will also analyze representations in related brain areas such as the dorsolateral prefrontal cortex, the hippocampus and high-level visual cortices, to determine the unique function of the OFC, and to establish the relationship between task states in the OFC and task-relevant information encoded elsewhere in the brain. Our findings will impact on the current understanding of the role of OFC in both normal and aberrant learning and decision making, and will help explain why the OFC is important for some tasks but not others. Moreover, our work will establish the utility of decoding internal task states from non-invasive brain imaging data for predicting behavior and for analyzing individual differences in task representations. This is especially relevant to understanding the precise nature of decision-making deficiencies in disorders such as substance abuse and other compulsive disorders where the OFC is strongly implicated.