Separating value from choice: delay discounting activity in the lateral intraparietal area.
Separating value from choice: delay discounting activity in the lateral intraparietal area.
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DOI：
10.1523/jneurosci.5742-09.2010
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发表时间：
2010-04-21
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影响因子：
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通讯作者：
Glimcher PW
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文献类型：
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作者：
Louie K;Glimcher PW
用于研究控制选择行为的神经生理信号的数学公式属于两个主要理论框架之一：“选择概率”或“主观价值”。这两个公式代表了与决策过程密切相关的行为量，但尚不清楚这些变量中的一个或两个是否主导了介导选择的神经机制。价值和选择概率在实践中很难区分，因为在自由选择任务中，价值更高的选项被选择得更频繁。这种区别对于感觉运动区域尤其重要，例如顶叶皮层，在那里观察到了与选择相关的价值信息和运动信号。我们记录的神经元的活动，在外侧顶内区（LIP），而猴子进行了不同的奖励延迟到强化的跨时选择任务。在这里，我们表明，顶叶神经元的活动是完全相关的延迟奖励的个人特定的折扣值，峰值主观价值调制发生在任务试验的早期。相反，在决策过程的后期，这些相同的神经元转变为对所选择的动作进行编码。当直接比较时，决策早期的强延迟相关调制是由主观价值驱动的，而不是猴子的选择概率。这些发现表明，除了收益信息，顶叶皮层还将延迟信息整合到经济价值函数的精确生理相关性中，独立于选择的概率。
The mathematical formulations used to study the neurophysiological signals governing choice behavior fall under one of two major theoretical frameworks: “choice probability” or “subjective value”. These two formulations represent behavioral quantities closely tied to the decision process, but it is unknown whether one of these variables, or both, dominates the neural mechanisms that mediate choice. Value and choice probability are difficult to distinguish in practice, because higher-valued options are chosen more frequently in free choice tasks. This distinction is particularly relevant for sensorimotor areas such as parietal cortex, where both value information and motor signals related to choice have been observed. We recorded the activity of neurons in the lateral intraparietal area (LIP) while monkeys performed an intertemporal choice task for rewards differing in delay to reinforcement. Here we show that the activity of parietal neurons is precisely correlated with the individual-specific discounted value of delayed rewards, with peak subjective value modulation occurring early in task trials. In contrast, late in the decision process these same neurons transition to encode the selected action. When directly compared, the strong delay-related modulation early during decision-making is driven by subjective value rather than the monkey's probability of choice. These findings show that in addition to information about gains, parietal cortex also incorporates information about delay into a precise physiological correlate of economic value functions, independent of the probability of choice.