美国加州大学Irvine分校的研究人员发现，脑部释放的神经传递素——乙酰胆碱的多少决定了记忆的细节程度。
在老鼠身上进行的实验中，神经生物和行为学教授NormanWeinberger以及他的同事证明，高水平的乙酰胆碱能帮助大脑记忆更多细节。这一结果第一次将乙酰胆碱浓度和细节记忆结合起来，并将对记忆类疾病的治疗带来影响。
以上结果将发表在11月的刊物《NeurobiologyofLearningandMemory》上。
Weinberger表示：“我们第一次证明了刺激脑部的某个特定区域能控制细节记忆量。大脑有很多机制用于记忆存储，而乙酰胆碱水平是这一过程的关键因素。”
在他们的实验中，研究人员将老鼠放置于充斥了各种频率声音的空间中。他们同时刺激老鼠脑部的下橄榄核，一个通过控制乙酰胆碱影响听觉皮层的区域。在一些实验中，这种刺激较强，而另一些时候较弱。第二天当声音重新奏响时，科学家可以通过测量呼吸频率了解老鼠的记忆情况。
结果表明，对下橄榄核刺激较弱时，释放的乙酰胆碱量较少，所以老鼠只能记住音调而记不住频率细节。但是当刺激强烈时，它们也记住了频率。
Weinberger说：“我们知道乙酰胆碱在学习和记忆过程中起着重要作用，例如目前对于Alzheimer症的治疗方法就是在脑部释放更多的乙酰胆碱。找到控制这种信息传递素浓度的方法对于治疗记忆相关的疾病至关重要。”
英文原文：
UCI neurobiologists uncover evidence of a 'memory code'
By examining how sounds are registered during the process of learning, UC Irvine neurobiologists have discovered a neural coding mechanism that the brain relies upon to register the intensity of memories based on the importance of the experience.
While neurobiologists have long hypothesized this type of neural coding, the study presents the first evidence that a "memory code" of any kind may exist. The UCI researchers believe that this code, as well as similar codes that may be discovered, will not only broaden our understanding of normal learning and memory but also may shed light on learning disorders. It may also one day be possible to manipulate these codes to control what and how we remember – not only basic sounds, but complicated information and events.
"This memory code may help explain both good and poor memory," said Norman Weinberger, a professor of neurobiology and behavior in UCI’s Center for the Neurobiology of Learning and Memory. "People tend to remember important experiences better than routine ones."
Weinberger and his colleagues found that when the brain uses this coding method, information is stored in a greater number of brain cells, which should result in a stronger memory. However, the researchers believe that if the brain fails to use the code, the resulting memory – even if it is an important one – would be weaker because fewer neurons would be involved.
Weinberger and postdoctoral researcher Richard Rutkowski discovered this coding system through studying how the primary auditory cortex responds to various sounds.
In the study, the researchers trained rats to press a bar to receive water when they heard a certain tone. The tone was varied in its importance to different rats as shown by their different levels of correct performance.
After brain mapping these test rats, the researchers found that the greater the importance of the tone, the greater the area of the auditory cortex that became tuned to it. The results in rats that received the same tones but were trained to a visual stimulus did not differ from those in untrained rats, showing that the behavioral importance of the tone, not its mere presence, was the critical factor.
Study results appear on the Online Early Edition of the Proceedings of the National Academy of Sciences. The National Institute on Deafness and Other Communication Disorders supported the effort.
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