我该做，还是不该做？
如果你曾为放弃一份安逸工作而选另一份更有刺激性的工作而苦恼过，或者曾思虑过婚外的风流韵事，那你一定经历过冲突和焦虑——这是我们要在互为冲突的动机中不得不做出抉择时产生的神经过敏。现在，通过对老鼠的研究，研究人员认为，他们已发现大脑中负责这一精神痛苦的区域。这一发现可能有助于寻找更好地治疗焦虑和其它情绪失调的药物。
（图）呀! 研究者识别出鼠脑中冲突产生时引起焦虑的部分。
1980年代人们首次搞清了焦虑的神经基础，当时研究者就发现可用一种治疗焦虑的药物刺激受体，一种名叫复合胺（serotonin）的神经传递素。最近的研究也证实了这一点(ScienceNOW,27March2002)，但科学家对于复合胺所起的作用以及它在大脑何处起作用仍然知之甚少。
为进一步探讨这一作用，一支由哥伦比亚大学的神经生物学家金里奇（Jay Gingrich）带领的小组破解了老鼠的一个基因，此基因对一名为5HT2A的复合胺感受器（受体）进行编码，这是迄今为止识别出的这类感受器之一。（已识别出的超过十二个）。在大脑的几个区域富有5HT2A，它们与冲突性焦虑有关。……
这一发现也支持了最近其他研究者的大脑成像研究，表明大脑皮层是焦虑的主要调整器。
英国剑桥大学的Angela Roberts 认为，这项研究是有关复合胺介入行为的一个非常有趣的例子。她认为，由于治疗药物通常针对复合胺受体，所以这一发现显然对于各种神经心理失调的治疗具有重要的意义。
潘发勤编译自ScienceNow,Should I, Or Shouldn‘t I? By Michael Balter，ScienceNOW Daily News，27 July 2006,http://sciencenow.sciencemag.org/
Should I, Or Shouldn't I?
By Michael Balter
ScienceNOW Daily News
27 July 2006
If you‘ve ever worried about leaving the safety of one job for the excitement of another, or contemplated an extramarital affair, chances are you experienced conflict anxiety--the nervousness that occurs when we have to choose between competing impulses. Now, researchers working with mice believe they have identified the part of the brain responsible for this mental anguish. The discovery may aid the search for better drugs for anxiety and other emotional disorders.
The neural basis of anxiety first began to become clear in the 1980s, when researchers discovered that a drug used to treat anxiety stimulates receptors for a neurotransmitter called serotonin. More recent research has confirmed this connection (ScienceNOW, 27 March 2002), but scientists still know very little about the role that serotonin plays and where in the brain it acts.
To explore this role further, a team led by neurobiologist Jay Gingrich of Columbia University knocked out a gene in mice that encodes a serotonin receptor called 5HT2A, one of more than a dozen such receptors identified to date. 5HT2A is abundant in several areas of the brain and is thought to be involved in conflict anxiety. The researchers put the mice through a battery of tests designed to induce a conflict between safety and novelty-seeking behavior. In one experiment, the team recorded how much time the mice spent in dark versus brightly lit spaces. In another, the researchers placed the mice in an elevated maze, where some sections were completely open and others had walls. Compared to control mice, the knockout animals spent significantly more time engaged in novelty-seeking behavior. For example, they spent twice as much time in the brightly lit part of the cage, which mice usually avoid, Gingrich and his colleagues report in tomorrow‘s Science.
Next, the researchers gave the mice their serotonin receptors back, but only in the cerebral cortex. When the mice were put through the tests, they acted just as anxious as normal animals did. The finding bolsters recent brain imaging studies by other researchers suggesting that the cortex is the master regulator of anxiety.
The study is a "very interesting example" of serotonin‘s involvement in behavior, says Angela Roberts, a neuroscientist at Cambridge University in the United Kingdom. She adds that because serotonin receptors are frequent targets of therapeutic drugs, the findings "clearly have important implications for the treatment of a variety of neuropsychiatric disorders."