Neural mechanisms of reward processing and emotion

奖励处理和情绪的神经机制

基本信息

批准号：
10929824
负责人：
ELISABETH A MURRAY
金额：
$ 61.95万
依托单位：
NATIONAL INSTITUTE OF MENTAL HEALTH
依托单位国家：
美国
项目类别：
财政年份：
资助国家：
美国
起止时间：
至
项目状态：
未结题

项目摘要

Neurons in both the orbitofrontal cortex (OFC) and medial frontal cortex (MFC) encode the sensory properties, magnitude and subjective value of expected and received rewarding outcomes. In addition, the activity of neurons in these regions reflects anticipatory arousal, as measured by pupil diameter. Decision-making and representations of arousal are intimately linked. How these processes interact at the level of single neurons as well as neural circuits are unknown. To understand how OFC and MFC influence arousal and decision making, we recorded neural activity from both regions while animals made reward-guided decisions. Heart rate (HR) was recorded as a proxy for arousal. In intact animals we found that higher HR facilitated reaction times (RTs). Concurrently, a set of neurons in OFC and MFC selectively encoded trial-by-trial variations in HR independent of reward magnitude. After amygdala lesions, HR generally increased and the relationship between HR and RTs was reversed. Concurrent with this change, there was an increase in the proportion of MFC neurons encoding HR. At the population level, the balance of encoding in MFC shifted towards signaling HR, suggesting a specific mechanism through which arousal influences decision-making. The amygdala, along with the orbitofrontal cortex (OFC), has been implicated in stimulus-reward learning, affect, and modulation of autonomic arousal. For example, as noted above, the amygdala contributes to the development of neural activity in OFC related to stimulus-reward processing, and removal of the amygdala causes a reduction in both expected and received reward-value coding by OFC neurons. In animals, amygdala lesions have been reported to disrupt autonomic responses to the sight of highly palatable foods but not autonomic responses that accompany consumption of that food. In a Pavlovian conditioning task, humans with amygdala damage were found deficient in their autonomic responses to visual stimuli that predicted aversive outcomes and after receipt of those outcomes. It is not known, however, how selective amygdala removal affects autonomic responses during comparable stimulus-reward learning in animals. To investigate this issue, we tested animals with bilateral excitotoxic lesions of the amygdala and unoperated controls on an appetitive Pavlovian task, using conditioned autonomic responses (pupil size change) as our measure of learning. We examined how many sessions the monkeys needed to show pupil responses that differed significantly between CS+ and CS-, and whether the conditioned pupil responses were maintained across 4 consecutive sessions. We found no group differences in either the development of conditioned pupil responses or the ability to maintain those responses across days. Our results indicate that the amygdala is not necessary for the generation of sympathetic autonomic arousal in anticipation of fluid reward, at least as determined by a change in pupil responses. These results argue against the idea that the amygdala is essential for generating anticipatory autonomic responses to guide decision making.

眶额皮质 (OFC) 和内侧额叶皮质 (MFC) 中的神经元对预期和收到的奖励结果的感觉特性、大小和主观价值进行编码。此外，这些区域神经元的活动反映了预期的唤醒，通过瞳孔直径来测量。决策和唤醒的表征密切相关。这些过程如何在单个神经元和神经回路水平上相互作用尚不清楚。为了了解 OFC 和 MFC 如何影响唤醒和决策，我们记录了动物做出奖励引导决策时这两个区域的神经活动。记录心率（HR）作为觉醒的指标。在完整的动物中，我们发现较高的心率有利于反应时间（RT）。同时，OFC 和 MFC 中的一组神经元选择性地编码 HR 的逐次试验变化，与奖励大小无关。杏仁核损伤后，HR普遍增加，HR与RT之间的关系发生逆转。与这一变化同时发生的是，编码 HR 的 MFC 神经元的比例有所增加。在群体水平上，MFC 中的编码平衡转向 HR 信号，这表明唤醒影响决策的特定机制。杏仁核与眶额皮质 (OFC) 一起参与刺激奖励学习、情感和自主神经唤醒的调节。例如，如上所述，杏仁核有助于 OFC 中与刺激奖励处理相关的神经活动的发展，而杏仁核的去除会导致 OFC 神经元预期和收到的奖励值编码的减少。据报道，在动物中，杏仁核损伤会扰乱对美味食物的自主反应，但不会扰乱伴随食用该食物的自主反应。在巴甫洛夫条件反射任务中，发现杏仁核受损的人类对预测厌恶结果以及收到这些结果后的视觉刺激的自主反应存在缺陷。然而，目前尚不清楚选择性杏仁核去除如何影响动物在类似的刺激奖励学习过程中的自主反应。为了研究这个问题，我们使用条件性自主反应（瞳孔大小变化）作为我们的学习衡量标准，测试了双侧杏仁核兴奋性毒性损伤的动物和未手术对照的食欲巴甫洛夫任务。我们检查了猴子需要多少次才能显示出 CS+ 和 CS- 之间显着不同的瞳孔反应，以及条件性瞳孔反应是否在连续 4 个疗程中保持不变。我们发现，无论是条件性瞳孔反应的发展还是在几天内维持这些反应的能力，都没有群体差异。我们的研究结果表明，杏仁核对于产生液体奖励的交感神经自主唤醒不是必需的，至少从瞳孔反应的变化来看是这样。这些结果反驳了杏仁核对于产生预期自主反应以指导决策至关重要的观点。

项目成果

期刊论文数量（5）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

A role for primate subgenual cingulate cortex in sustaining autonomic arousal.

灵长类膝下扣带皮层在维持自主神经唤醒中的作用。

DOI：
发表时间：
2014-04-08
期刊：
影响因子：
11.1
作者：
Rudebeck, Peter H;Putnam, Philip T;Daniels, Teresa E;Yang, Tianming;Mitz, Andrew R;Rhodes, Sarah E V;Murray, Elisabeth A
通讯作者：
Murray, Elisabeth A

Gustatory responses in macaque monkeys revealed with fMRI: Comments on taste, taste preference, and internal state.

通过功能磁共振成像揭示猕猴的味觉反应：对味觉、味觉偏好和内部状态的评论。