生物谷報道：Baylor醫(yī)學(xué)院的研究人員發(fā)表在2006年12月的《神經(jīng)學(xué)雜志》上的文章指出：對果蠅進(jìn)行特殊的訓(xùn)練其中也包括休息時期后，發(fā)現(xiàn)鈣離子流向覃型神經(jīng)元細(xì)胞促使了長時記憶的形成,。
   “我們有證據(jù)表明長時記憶的形成確實(shí)是分子方面的改變”,。Baylor醫(yī)學(xué)院的分子和細(xì)胞生物學(xué)教授Ronald Davis博士說“這看起來長時記憶的形成中記憶痕跡是存在的。
    Davis和他的同事們用間隔試驗(yàn)方法使果蠅能夠把某種氣味與輕微的電擊聯(lián)系起來,。這種方法給果蠅一種訓(xùn)練,，然后休息再進(jìn)行另一種訓(xùn)練,。這種休息是誘導(dǎo)產(chǎn)生數(shù)天以上的長時記憶的關(guān)鍵步驟,。在這項(xiàng)研究中，五次間隔的試驗(yàn)?zāi)軌虍a(chǎn)生持續(xù)超過一天的記憶,。他們接著用一種稱為成像功能的技術(shù)來看果蠅大腦何時形成記憶,。
    “在訓(xùn)練前，我們能看到當(dāng)果蠅處在某種氣味下覃型神經(jīng)元就有鈣離子流入”,，Davis說,。當(dāng)他們在間隔訓(xùn)練后把果蠅暴露在某種氣味下24小時，他們就會看到有大量的鈣離子流向覃神經(jīng)元細(xì)胞,，鈣離子的增加與果蠅長時記憶的形成是相平行的,。使用特殊的實(shí)驗(yàn)室技術(shù),，他和實(shí)驗(yàn)室其他同事表示他們能夠通過阻斷蛋白質(zhì)的功能而阻斷鈣離子的流向，這種蛋白質(zhì)是形成新的神經(jīng)突觸進(jìn)而產(chǎn)生長期記憶的關(guān)鍵,。

Figure 1. The α/β Mushroom Body Neurons Respond with Calcium Influx into Their α and β Axon Branches when Odors or Electric Shock Stimuli Are Delivered to Drosophila

(A) Cartoon illustrating the Drosophila α/β Mushroom Body (MB) neurons in isolation along with their processes and the locations from which functional images were obtained. The cell bodies of the MB neurons are clustered in the posterior and dorsal part of the brain. Each α/β MB neuron extends a single axon in a common nerve that extends toward the anterior face of the brain, where each axon splits into a vertically oriented branch (α branch) and a horizontally oriented branch (β branch). The branches of the α/β MB neurons remain clustered in brain neuropil regions known as the α lobe and the β lobe, which contain the α branches and the β branches of the neurons, respectively. For functional imaging, a small portion of cuticle was removed from the dorsal head and the fly was stably mounted under a confocal microscope. Functional images from living flies were collected from a dorsal and slightly frontal perspective of the fly at two depths: one to visualize calcium influx into the α branches of the α/β neurons, and one to visualize calcium influx into the β branches. The pinhole of the confocal was open during imaging so that fluorescence was collected from a thick optical section encompassing the structures of interest.

(B) Representative time course for the fluorescence response to the odor 3-octanol (Oct) in the α and β branches of MB neurons. The response was calculated as the percent increase in fluorescence over baseline (%ΔF/Fo) as a function of time. For subsequent bar graphs, the %ΔF/Fo was calculated as the percent difference between the maximum average intensity over five successive imaging frames during the 3 s odor application and the average intensity over five successive frames just prior to odor application.

(C) Images of the basal fluorescence of Uas-G-CaMP expressed with c739-Gal4 in the α and β branches of the axons of α/β MB neurons (1st and 3rd columns). The change in fluorescence (%ΔF/Fo), calculated as the percent change in fluorescence (ΔF) relative to baseline (Fo) that occurs following exposure to Oct or benzaldehyde (Ben), is illustrated as a false color image (2nd and 4th columns) to the right of each panel showing the basal fluorescence. Each pseudocolor image shown here and in other figures is a single frame snapshot of the response during stimulation. Since the spatial response pattern fluctuates between frames during the stimulation on a pixel-by-pixel basis, the group data (D) better represent the average peak response across the flies that were imaged.

(D) The amplitude of the response to odor from group data for both the α and β branches (n = 6 to 8) is shown. The ratio ΔF/Fo was typically close to 4% and proved to be statistically significant (t test) compared with zero for both odors. Error bars are the standard error of the mean.

(E) Images of the basal fluorescence of Uas-G-CaMP expressed with c739-Gal4 in the α and β branches of the axons of α/β MB neurons (1st and 3rd columns). The response (%ΔF/Fo) of the α and β branches to 90V electric shock pulses is illustrated as a false color image to the right of each panel showing the basal fluorescence.

(F) Calcium influx into the α and β branches of the axons of α/β MB neurons that occurs with 90V, 1.25 s electric shock pulses every 5 s. The traces represent the average %ΔF/Fo across the region of interest in both α and β branches. An obvious calcium response was observed, with each shock pulse riding on top of a decaying background due to bleaching over a 60 s scanning period. 

原文出處：

December 7, 2006: 52 (5)  845－856

Drosophila α/β Mushroom Body Neurons Form a Branch-Specific, Long-Term Cellular Memory Trace after Spaced Olfactory Conditioning
Dinghui Yu, David-Benjamin G. Akalal, and Ronald L. Davis
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