Neurobiological Bases of Economic Choice Behavior

描述(由申请者提供)：经济选择是指当个人完全基于主观偏好做出选择时所观察到的行为--例如，在餐厅菜单之外。选择行为是经济学和心理学的传统研究热点。然而，从医学的角度来看，经济选择也是至关重要的，因为选择不足经常出现在额叶神经障碍和成瘾患者中。在行为上，证据表明，经济选择需要为可用选项赋值--例如，为菜单上的不同项目赋值。然而，潜在的神经生物学机制仍然知之甚少。来自病变、功能成像和电生理学的证据表明，眶前皮质(OFC)可能在经济选择中发挥重要作用。此应用程序的首要目标是详细检查这一皮质区域的贡献。这将通过记录清醒猴子在从事经济选择任务时单个神经元的活动来实现。在我们的实验中，猴子在提供不同量的不同饮料之间进行选择。他们的选择为这两种果汁的相对价值提供了一种行为衡量标准。我们的初步研究表明，OFC中的神经元编码猴子分配给所提供和选择的果汁的价值，这表明选择是基于这种神经元群体的活动。这一观察提出了几个关键问题，这些问题将在这里提出的实验中得到解决。首先，价值的神经元表征是否会随着行为背景的变化而变化？例如，神经元评估系统可能会适应背景值范围，以利用最大的辨别能力，就像视觉系统如何适应周围光线一样。其次，OFC神经元编码的是经济效用还是纯粹的价值？选择往往是在涉及风险和成本的选择之间做出的，这两者都反映在预期效用中。如果选择是基于OFC的活动，我们预计这一领域的神经元将编码经济效用，而不是纯粹的价值。最后，尽管有大量关于额叶解剖的文献，但哪些区域接受价值编码神经元的解剖投射仍然不清楚。为了解决这个问题，我们将结合解剖痕迹和神经生理记录。这项研究还将为PI提供一个学习组织学和解剖学技术的机会，这将补充他的专业知识组合。

DESCRIPTION (provided by applicant): Economic choice is the behavior observed when individuals make choices solely based on subjective preferences-for example out of a restaurant menu. Choice behavior is a traditional focus in economics and psychology. However, economic choice is also critically important from a medical perspective, as choice deficits are often observed in patients with neurological disorders of the frontal lobe and in addiction. Behaviorally, evidence indicates that economic choice entails assigning values to the available options-for example, to different items on the menu. The underlying neurobiological mechanisms remain, however, poorly understood. Evidence from lesions, functional imaging and electrophysiology suggest that the orbitofrontal cortex (OFC) may play an important role in economic choice. The overarching goal of this application is to examine the contribution of this cortical area in detail. This will be achieved by recording the activity of individual neurons in awake monkeys while they engage in economic choice tasks. In our experiments, monkeys choose between different beverages offered in variable amounts. Their choices provide a behavioral measure for the relative value of the two juices. Our preliminary studies indicate that neurons in OFC encode the value monkeys assign to offered and chosen juices, suggesting that choices are based upon the activity of this neuronal population. This observation raises several critical questions that will be addressed in the experiments proposed here. First, does the neuronal representation of value vary depending on the behavioral context? For example, the neuronal valuation system might adapt to the contextual value range to exploit maximal discriminatory power, in a way similar to how the visual system adapts to ambient light. Second, do OFC neurons encode economic utility or pure value? Choices are often made between options that involve risks and costs, both reflected in the expected utility. If choices are based on the activity of OFC, we expect neurons in this area to encode economic utility, as distinguished from pure value. Finally, in spite of a substantial literature on the anatomy of the frontal lobe, what areas receive anatomical projections from value-encoding neurons remains unclear. To address this issue, we will combine anatomical tracings with neurophysiological recordings. This study will also provide the PI an opportunity to learn histological and anatomical techniques that will complement his portfolio of expertise.