根據(jù)一項新的研究,，年輕人最喜歡欣喜地期待著打開禮物，該研究揭示出了我們對獎賞的反應隨著衰老而變得成熟的生物化學原因。Karen Faith Berman及其同事聯(lián)合使用了幾種大腦成像技術從而尋找當更年輕和更年長的成年人得到獎賞——或得到獎賞的承諾——的時候，大腦的哪些部分受到了刺激,。多巴胺被認為是大腦的獎賞處理回路的貨幣，而且盡管大腦的多巴胺系統(tǒng)作為正常衰老的一部分而自然衰退,，這種衰退的后果仍然令人難以捉摸,。
這組科學家利用功能磁共振成像（fMRI）掃描證明了，在視頻投幣游戲機上預料到或者獲得一個獎賞的時候,，平均年齡25歲的年輕受試者比平均年齡65歲的老年受試者的多巴胺觸發(fā)的大腦區(qū)域的激活更加顯著,。盡管正電子發(fā)射計算機斷層掃描（PET）顯示年輕和年長的受試者大腦多巴胺的生產沒有差異，這組作者發(fā)現(xiàn)了在人類的多巴胺合成（用PET測量）和獎賞相關的大腦活動（用fMRI測量）之間的聯(lián)系,，發(fā)現(xiàn)了大腦調節(jié)回路伴隨著正常衰老的一些變化。相關論文發(fā)表在美國《國家科學院院刊》（PNAS）上,。（生物谷Bioon.com）
生物谷推薦原始出處：
PNAS,，doi: 10.1073/pnas.0802127105，Jean-Claude Dreher,，Karen Faith Berman
Age-related changes in midbrain dopaminergic regulation of the human reward system
Jean-Claude Dreher, Andreas Meyer-Lindenberg, Philip Kohn, and Karen Faith Berman
The dopamine system, which plays a crucial role in reward processing, is particularly vulnerable to aging. Significant losses over a normal lifespan have been reported for dopamine receptors and transporters, but very little is known about the neurofunctional consequences of this age-related dopaminergic decline. In animals, a substantial body of data indicates that dopamine activity in the midbrain is tightly associated with reward processing. In humans, although indirect evidence from pharmacological and clinical studies also supports such an association, there has been no direct demonstration of a link between midbrain dopamine and reward-related neural response. Moreover, there are no in vivo data for alterations in this relationship in older humans. Here, by using 6-[18F]FluoroDOPA (FDOPA) positron emission tomography (PET) and event-related 3T functional magnetic resonance imaging (fMRI) in the same subjects, we directly demonstrate a link between midbrain dopamine synthesis and reward-related prefrontal activity in humans, show that healthy aging induces functional alterations in the reward system, and identify an age-related change in the direction of the relationship (from a positive to a negative correlation) between midbrain dopamine synthesis and prefrontal activity. These results indicate an age-dependent dopaminergic tuning mechanism for cortical reward processing and provide system-level information about alteration of a key neural circuit in healthy aging. Taken together, our findings provide an important characterization of the interactions between midbrain dopamine function and the reward system in healthy young humans and older subjects, and identify the changes in this regulatory circuit that accompany aging.
