據(jù)美國(guó)物理學(xué)家組織網(wǎng)10月18日（北京時(shí)間）報(bào)道,，哈佛大學(xué)神經(jīng)生物學(xué)家培養(yǎng)出一種能“聞”出光線的小鼠，為研究人員更好地理解嗅覺(jué)功能的神經(jīng)機(jī)制提供了一種新工具,。本周的Nature Neuroscience雜志詳述了這項(xiàng)研究,，這為未來(lái)研究氣味和感受之間的關(guān)系以及其他感知系統(tǒng)的神經(jīng)機(jī)制開(kāi)辟了新方向。
要分析大腦的嗅覺(jué)感知是如何辨別氣味的,，最好的方法是研究大腦的活動(dòng)方式,。但氣味種類繁多，化學(xué)成分非常復(fù)雜,，變化微細(xì)讓人難以捉摸,，因此追尋這些由嗅覺(jué)刺激形成的大腦模式非常困難。
如果讓鼻子作為視網(wǎng)膜那會(huì)怎么樣呢,？哈佛大學(xué)分子與細(xì)胞生物學(xué)教授溫卡泰斯·默西和冷泉港實(shí)驗(yàn)室的同事利用遺傳光學(xué)技術(shù),，把一種光敏蛋白質(zhì)跟小鼠的嗅覺(jué)輸入系統(tǒng)結(jié)合，培育了一批轉(zhuǎn)基因小鼠,，它們的所有嗅覺(jué)感受神經(jīng)元都能表達(dá)視網(wǎng)膜素轉(zhuǎn)導(dǎo)通道2（channelrhodopsin-2）蛋白質(zhì),，這些轉(zhuǎn)基因小鼠的嗅覺(jué)路徑因此變成由光來(lái)激活，代替氣味來(lái)研究大腦神經(jīng)細(xì)胞如何區(qū)別不同氣味,。
嗅覺(jué)信息會(huì)在大腦中形成不同的三維空間組織形態(tài),，由于光輸入很容易被控制，研究人員因此能設(shè)計(jì)一系列試驗(yàn),，利用光選擇性地刺激鼻子里的特定感覺(jué)神經(jīng),，研究大腦中嗅球的激活模式。
默西說(shuō),，因?yàn)橛猛鈦?lái)光照代替氣味在大腦中形成的空間組織只是一種臨時(shí)性結(jié)構(gòu),，新研究也存在一定的局限，并不能完全解釋氣味感受能力。研究還顯示,，在氣味被感受的過(guò)程中,，“嗅聞”的時(shí)機(jī)起著很大作用。（生物谷Bioon.com）
生物谷推薦英文摘要：
Nature Neuroscience doi:10.1038/nn.2673
Non-redundant odor coding by sister mitral cells revealed by light addressable glomeruli in the mouse
Ashesh K Dhawale, Akari Hagiwara, Upinder S Bhalla, Venkatesh N Murthy & Dinu F Albeanu
Sensory inputs frequently converge on the brain in a spatially organized manner, often with overlapping inputs to multiple target neurons. Whether the responses of target neurons with common inputs become decorrelated depends on the contribution of local circuit interactions. We addressed this issue in the olfactory system using newly generated transgenic mice that express channelrhodopsin-2 in all of the olfactory sensory neurons. By selectively stimulating individual glomeruli with light, we identified mitral/tufted cells that receive common input (sister cells). Sister cells had highly correlated responses to odors, as measured by average spike rates, but their spike timing in relation to respiration was differentially altered. In contrast, non-sister cells correlated poorly on both of these measures. We suggest that sister mitral/tufted cells carry two different channels of information: average activity representing shared glomerular input and phase-specific information that refines odor representations and is substantially independent for sister cells.
