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第59屆美國神經學會裡有篇研究指出，調節腦內多巴胺的相關藥物大大地影響人們對輸贏的反應。

研究者首開先例地多評估巴胺藥物能對紋狀體（striatum，腦內會受酬賞刺激的部份)造成多大的影響）。這份在倫敦偉康多斯特神經掃描中心（Wellcome Trust Centre for Neuroimaging in London）進行的研究，將募集到的39位介於18到39歲且身體健康的受試者份成為三組。一組給予賴復多巴（levodopa，服用後會增加多巴胺腦中濃度的藥），另一組則給予哈囉拍立得（haloperidol，一種多巴胺接受阻斷劑），第三組則給予安慰劑。多巴胺是種化學物質，會在神經細胞間傳遞信號時產生。

研究者對三組實驗參予者出示各種符號，而不同符號會將會帶來不同額度的獎金或虧損。為了獲取多一些獎金，研究參予者必須藉由嘗試錯誤中了解到各符號所對應的損益為何。

研究發現服用賴復多巴的受試者中有九成五的人比服用哈囉拍立得的人更傾向於選擇會帶來高獎金的符號。最後，賴復多巴組贏得了較多的的獎金，但輸的錢並沒有比較少。

目前任職於巴黎醫院的研究者佩西閣樓博士表示：「這結果顯示了，多巴胺會讓我們變得勇於追求所要的，卻不會讓我們去避開所不願見的結果。」

這樣的發現或許可以讓我們對多巴胺藥物的副作用、巴金森氏症以及精神分裂症有更多的了解。「研究結果也許能解釋為何降低多巴胺會導致巴金森氏症患者凡事缺乏動力，以及為何這群人在進行多巴胺替代療法後會出現諸如暴食和沉迷賭博等衝動行為。」

Dopamine-related Drugs Affect Reward-seeking Behavior

Science Daily — Drugs that adjust dopamine levels in the brain greatly affect how people react to success and failure, according to research presented at the American Academy of Neurology's 59th Annual Meeting in Boston.

In a first-of-its-kind study on humans, researchers measured how dopamine-related drugs affect the striatum, a part of the brain that is stimulated by rewards. The study, conducted at the Wellcome Trust Centre for Neuroimaging in London, involved 39 healthy people between the ages of 18 and 39. Participants were divided into three groups. One group was given levodopa, a drug that increases dopamine levels in the brain. Another took haloperidol, a dopamine receptor blocker. The third was given a placebo. Dopamine is a chemical naturally produced by the body that transmits signals between nerve cells.

Researchers showed each group symbols associated with winning or losing different amounts of money. To "win" more money, participants had to learn through trial and error which symbols resulted in which outcomes.

The study found people who took levodopa were 95 percent more likely to choose symbols associated with higher monetary gains than those who took haloperidol. As a result, the levodopa group won more money, but they did not lose less money.

"The results show dopamine drives us to get what we want, but not avoid what we fear," said study author Mathias Pessiglione, PhD, who now works at the Salpetriere Hospital in Paris, France.

The findings may provide a better understanding of the side effects of dopamine-related drugs and the disorders they are used to treat, such as Parkinson's disease and schizophrenia. "This study may explain why dopamine depletion leads to the lack of motivation often described in people with Parkinson's disease," said Pessiglione, "and how dopamine replacement therapy can cause compulsive behaviors, such as overeating and gambling addictions, in the same people."

Note: This story has been adapted from a news release issued by American Academy of Neurology.

引自：http://www.sciencedaily.com/releases/2007/04/070427072318.htm