?美國加州大學(xué)Irvine分校的研究人員發(fā)現(xiàn)，腦部釋放的神經(jīng)傳遞素——乙酰膽堿的多少決定了記憶的細節(jié)程度,。
??在老鼠身上進行的實驗中,，神經(jīng)生物和行為學(xué)教授Norman Weinberger以及他的同事證明，高水平的乙酰膽堿能幫助大腦記憶更多細節(jié),。這一結(jié)果第一次將乙酰膽堿濃度和細節(jié)記憶結(jié)合起來,，并將對記憶類疾病的治療帶來影響。
??以上結(jié)果將發(fā)表在11月的刊物《Neurobiology of Learning and Memory》上,。
??Weinberger表示：“我們第一次證明了刺激腦部的某個特定區(qū)域能控制細節(jié)記憶量,。大腦有很多機制用于記憶存儲，而乙酰膽堿水平是這一過程的關(guān)鍵因素,。”
??在他們的實驗中,，研究人員將老鼠放置于充斥了各種頻率聲音的空間中。他們同時刺激老鼠腦部的下橄欖核,，一個通過控制乙酰膽堿影響聽覺皮層的區(qū)域,。在一些實驗中，這種刺激較強,，而另一些時候較弱,。第二天當(dāng)聲音重新奏響時，科學(xué)家可以通過測量呼吸頻率了解老鼠的記憶情況,。
??結(jié)果表明,，對下橄欖核刺激較弱時，釋放的乙酰膽堿量較少,，所以老鼠只能記住音調(diào)而記不住頻率細節(jié),。但是當(dāng)刺激強烈時，它們也記住了頻率,。
??Weinberger說：“我們知道乙酰膽堿在學(xué)習(xí)和記憶過程中起著重要作用,，例如目前對于Alzheimer癥的治療方法就是在腦部釋放更多的乙酰膽堿。找到控制這種信息傳遞素濃度的方法對于治療記憶相關(guān)的疾病至關(guān)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.
