人脑眶额皮质表征奖赏信息的进展

文章围绕人脑眶额皮质在表征奖赏信息上的核心作用展开，分别从人脑眶额皮质表征奖赏信息的共同神经表征和特异性神经表征特点，奖赏加工和该脑区局部形态特征之间的关系以及眶额皮质表征奖赏信息的时间动态性等角度对最近的重要研究进展进行了一定的梳理和概括。最后，文章讨论了未来研究需要解决的由奖赏类型多样性和脑区间奖赏信息整合复杂性带来的系列问题。

Reward Processing in the Human Orbitofrontal Cortex: An Updated Review

The orbitofrontal cortex (OFC) is an important brain region in the human prefrontal cortex. Based on findings from electrophysiological studies in nonhuman primates and brain imaging studies in humans, this region has been demonstrated to play a critical role in representing key parameters of reward information, including reward magnitudes, reward types and expected/experienced reward value. Accumulating evidence has revealed two important features of such representation in this brain region: 1) neural representation of different kinds of reward on a common currency scale; 2) the existence of sub-regions that are specific to a particular type of reward. In addition, there is a growing interest in the potential relationship between local morphology in this brain region and its functional role in representing reward information. It has been found that the localizations of distinct experienced value signals (primary/secondary rewards) can be predicted from the organization of the human orbitofrontal sulci. More specifically, the experienced value signal induced by monetary reward outcome was systematically located in the rostral portion of the medial orbital sulcus. In contrast, the experienced value signal that was related to erotic reward outcome was located more posteriorly, that is, at the intersection between the caudal portion of the medial orbital sulcus and transverse orbital sulcus. Moreover, another line of research also found that reward dysfunction was related to the local morphology in this brain region in patients with mental and neurological disorders, including substance use disorder and schizophrenia. Despite such evidence, little is still known about the temporal dynamics of coding reward-related signals in the human OFC. Recent studies have provided important insights into it. Specifically, the expected value signal starts to rise around 400ms after cue presentation in the OFC. This latency is later than that of 170ms in the visual cortex, implying the OFC should not be an early part of the brain circuit representing expected value. Furthermore, regardless of reward or non-reward delivery, robust risk signals were observed, which started around 350ms after the outcome appeared. The latency of risk signals is shorter than that in the hippocampus, indicating the OFC should be a late part of the brain circuit responsible for processing risk information. The experienced value signal combined with subjective pleasure in the OFC started immediately at the time of reward/non-reward delivery. In this review, we summarized the rapid development in fields of reward processing in the human OFC on the basis of three lines of research, ranging from key features of the functional role of this brain region in computing and representing reward value, the potential link between structural properties and its functions in processing reward to the neural dynamics of reward value and risk coding in this brain region. Moreover, we take a further step toward discussing the possible implications for future research. We are hoping that this review would help researchers get an important picture of important findings that have been revealed over the past few years and therefore contributes to their own work in this field.