Advanced Neuroimaging Center, National Institutes for Quantum Science and Technology, Chiba, 263-8555, Japan.
Sci Rep. 2024 Aug 23;14(1):19619. doi: 10.1038/s41598-024-70414-6.
Temporal discounting, in which the recipient of a reward perceives the value of that reward to decrease with delay in its receipt, is associated with impulsivity and psychiatric disorders such as depression. Here, we investigate the role of the serotonin 5-HT receptor (5-HTR) in modulating temporal discounting in the macaque dorsal caudate nucleus (dCDh), the neurons of which have been shown to represent temporally discounted value. We first mapped the 5-HTR distribution in macaque brains using positron emission tomography (PET) imaging and confirmed dense expression of 5-HTR in the dCDh. We then examined the effects of a specific 5-HTR antagonist infused into the dCDh. Blockade of 5-HTR significantly increased error rates in a goal-directed delayed reward task, indicating an increase in the rate of temporal discounting. This increase was specific to the 5-HTR blockade because saline controls showed no such effect. The results demonstrate that 5-HTRs in the dCDh are involved in reward-evaluation processes, particularly in the context of delay discounting, and suggest that serotonergic transmission via 5-HTR may be a key component in the neural mechanisms underlying impulsive decisions, potentially contributing to depressive symptoms.
时间折扣，即奖励接受者感知到奖励的价值随着奖励收到时间的延迟而降低，与冲动和抑郁等精神障碍有关。在这里，我们研究了 5-羟色胺 5-HT 受体（5-HTR）在调节猕猴背侧尾状核（dCDh）中时间折扣中的作用，该核中的神经元被证明代表了时间折扣的价值。我们首先使用正电子发射断层扫描（PET）成像绘制了猕猴大脑中的 5-HTR 分布图，并确认 5-HTR 在 dCDh 中表达密集。然后，我们检查了将特定的 5-HTR 拮抗剂注入 dCDh 中的效果。5-HTR 阻断显著增加了目标导向延迟奖励任务中的错误率，表明时间折扣率增加。这种增加是 5-HTR 阻断的特异性，因为生理盐水对照没有显示出这种效果。结果表明，dCDh 中的 5-HTR 参与了奖励评估过程，特别是在延迟折扣的情况下，并且表明通过 5-HTR 的血清素传递可能是冲动决策的神经机制中的关键组成部分，可能导致抑郁症状。
