據(jù)9月4日的《科學(xué)》雜志報(bào)道說(shuō)，一項(xiàng)獨(dú)特的實(shí)驗(yàn)對(duì)單一神經(jīng)元在進(jìn)行某一活動(dòng)時(shí)的放電情況以及在該活動(dòng)作為記憶而被主動(dòng)回憶時(shí)的放電情況進(jìn)行了比較,。比較結(jié)果顯示了腦子在自動(dòng)回憶時(shí)會(huì)呈現(xiàn)什么樣的情況,。
Hagar Gelbard-Sagiv 及其同僚向一小群癲癇病人（這些病人被治療性地植入了腦電極）播放了The Simpsons 和其它電視節(jié)目的剪輯,，并在這些剪輯播放時(shí)對(duì)其腦子的海馬區(qū)以及相關(guān)結(jié)構(gòu)中的單一神經(jīng)元的活動(dòng)進(jìn)行監(jiān)測(cè)。當(dāng)這些人在幾分鐘之后主動(dòng)回憶這些電視表演時(shí),，同樣這一批的神經(jīng)元再一次地增加了它們的放電率,。甚至在這些人告訴研究人員關(guān)于對(duì)這些表演的記憶已經(jīng)“進(jìn)入腦海”之前，這些神經(jīng)元就已經(jīng)躍升到活躍狀態(tài)，這表明在這一部分的腦中,，主動(dòng)回憶和神經(jīng)元“回放”之間存在著一個(gè)直接的聯(lián)系,。當(dāng)人們?cè)诨貞浥c初戀情人見面的的那一時(shí)刻時(shí)，人們腦中會(huì)出現(xiàn)不斷變化的神經(jīng)元群的放電,。
研究人員長(zhǎng)期以來(lái)就提出假設(shè)：每一種放電的模式可能都對(duì)某種獨(dú)特記憶具有特異性,，而且無(wú)論人們是在何地何時(shí)出現(xiàn)這一記憶，神經(jīng)元都應(yīng)該具有相同的放電模式,。對(duì)大鼠進(jìn)行的一項(xiàng)新的研究現(xiàn)在已經(jīng)證實(shí)了這一假設(shè),。就任何人所知，大鼠實(shí)際上并不會(huì)墜入情海,；但它們可以被訓(xùn)練在不同的迷宮分支中行走,。并從一個(gè)分支轉(zhuǎn)移到另外一個(gè)分支。它們還必須在每次通過(guò)迷宮的旅行之間在一個(gè)輪子中跑動(dòng),。在這一間期,，鼠籠中是黑暗且安靜的，所以此時(shí)沒有什么環(huán)境中的刺激需要大鼠來(lái)處理,。為了成功地完成這一作業(yè),，大鼠必須在輪中跑動(dòng)時(shí)記住它們剛剛所通過(guò)的是哪一個(gè)迷宮的分支，這樣它們可以決定下一次再進(jìn)入哪一個(gè)分支,。
Eva Pastalkova 及其同僚在大鼠完成這些練習(xí)時(shí)記錄了大鼠腦中的多種神經(jīng)元的活動(dòng),。研究人員觀察到，大鼠在迷宮中及在輪子中跑動(dòng)時(shí),，神經(jīng)元具有相同的活動(dòng)模式,，并且在相同的時(shí)間過(guò)程中完成。文章的作者說(shuō),，這些神經(jīng)元放電模式可能代表了大鼠對(duì)跑過(guò)迷宮的第一個(gè)分支的回憶,。（生物谷Bioon.com）
生物谷推薦原始出處：
Science 5 September 2008: Vol. 321. no. 5894, pp. 1322 - 1327 DOI: 10.1126/science.1159775
Internally Generated Cell Assembly Sequences in the Rat Hippocampus
Eva Pastalkova, Vladimir Itskov,* Asohan Amarasingham, Gy?rgy Buzsáki
A long-standing conjecture in neuroscience is that aspects of cognition depend on the brain's ability to self-generate sequential neuronal activity. We found that reliably and continually changing cell assemblies in the rat hippocampus appeared not only during spatial navigation but also in the absence of changing environmental or body-derived inputs. During the delay period of a memory task, each moment in time was characterized by the activity of a particular assembly of neurons. Identical initial conditions triggered a similar assembly sequence, whereas different conditionsgave rise to different sequences, thereby predicting behavioral choices, including errors. Such sequences were not formed in control (nonmemory) tasks. We hypothesize that neuronal representations, evolved for encoding distance in spatial navigation, also support episodic recall and the planning of action sequences.
Center for Molecular and Behavioral Neuroscience, Rutgers, The State University of New Jersey, 197 University Avenue, Newark, NJ 07102, USA.
