The role of monoamines in reward processing in the prefrontal cortex

为了阐明奖励处理的神经元基质，我们记录了猴子在执行各种认知任务时背外侧前额叶皮层（DLPFC）的神经元活动。通过一种具有两种奖励条件（奖励/无奖励）的动眼肌延迟反应任务，我们发现DLPFC包含不同的神经元群，这些神经元群在差异空间反应后编码结果，这应该在不同反应与其结果的关联中发挥作用。这种编码对于根据规则灵活控制行为可能是至关重要的，这被认为是DLPFC的关键作用。为了解决这个问题，我们检查了猴子在执行动眼肌规则转移任务时的神经元活动，该任务要求它们根据反应-结果改变行为规则。DLPFC神经元的一个子集根据当前试验（回顾性代码）和下一个试验（前瞻性代码）中使用的规则显示出不同的活动。这些神经元的活性增加了，特别是当猴子不得不改变规则时。规则的回溯性编码和前瞻性编码可能是基于反应-结果的规则转移的关键神经元基质和基于被转移规则的保留。接下来，为了研究奖励预期如何影响感觉记忆和运动准备的神经元过程，我们记录了执行延迟反扫视任务的猴子DLPFC的神经元活动，该任务可以在奖励和无奖励条件下将感觉记忆的神经元活动与运动准备的神经元活动分离开来。我们发现，奖赏预期增强了DLPFC中感觉记忆的神经元过程，而不是运动准备的神经元过程。此外，为了在先前结果的基础上检查单胺类药物在改变行为中的作用，我们在猴子执行动眼肌规则转移任务时，向DLPFC注射了多巴胺能和去甲肾上腺素能拮抗剂。我们发现d1 -多巴胺拮抗剂诱导了一种以坚持错误增加为特征的缺陷。DLPFC中的d1 -多巴胺受体可能参与执行控制功能；即，基于结果和规则的交替行为。少

To clarify neuronal substrates for reward processing, we recorded neuronal activity in the dorsolateral prefrontal cortex (DLPFC) while the monkey performed various cognitive tasks. Using a variant of the oculomotor delayd-response task with two reward conditions (reward/non-reward), we found that the DLPFC contains distinct neuronal groups that code outcome following the differential spatial response, which should play a role in associating different response with its outcome. Such coding may be critical for flexible control of behavior according to a rule, which has been considered a critical role of the DLPFC. To address this issue, we examined neuronal activity while monkeys performed an oculomotor rule-shifting task that required them to shift behavioral rules based on response-outcome. A subset of DLPFC neurons showed differential activity by the rule that was used in the current trial (a retrospective code), and that would be used in the next trial (a prospective code). The acti … More vity of these neurons increased particularly when the monkey had to alter the rule. The retrospective and prospective coding of rules may be critical neuronal substrates for rule-shifting based on response-outcome and retention of the shifted rule, respectively. Next, to examine how the reward expectation affects neuronal processes of the sensory memory and that of motor preparation, we recorded neuronal activities from the DLPFC of monkeys that performed a variant of delayd anti-saccade task that can dissociate neuronal activity for sensory memory from that for motor preparation under reward and no-reward conditions. We found that the reward expectation enhances the neuronal process for sensory memory but not for motor preparation in the DLPFC. Further, to examine the involvement of monoamines in changing behavior based on the previous outcome, we injected dopaminergic and noradrenergic antagonists into the DLPFC, while the monkeys were performing an oculomotor rule-shifting task. It was found that D1-dopamine antagonist induced a deficit characterized by the increase in perseveration-errors. D1-dopamine receptors in the DLPFC are likely to be involved in a function of executive control ; i.e., alternating behavior based on outcome and rule. Less