大腦如何在瞬息萬(wàn)變的環(huán)境中準(zhǔn)確感知?dú)馕?？中科院武漢物理與數(shù)學(xué)研究所最近的研究結(jié)果發(fā)現(xiàn)，嗅覺系統(tǒng)的第一中樞——嗅球——在腦不同的運(yùn)行狀態(tài)下對(duì)氣味的響應(yīng)總強(qiáng)度大致相同,，說(shuō)明人或動(dòng)物對(duì)氣味的分別并不是在嗅球完成,，可能是在更高級(jí)的嗅覺中樞實(shí)現(xiàn)。
這一研究成果,，3月22日發(fā)表于美國(guó)科學(xué)院院刊,，并入選為封面文章之一。耶魯大學(xué)FahmeedHyder教授專門撰文評(píng)論該成果,。除中科院武漢物數(shù)所外,，武漢光電國(guó)家實(shí)驗(yàn)室和湖北第二師范學(xué)院也參與了該研究。
據(jù)論文作者之一李安安博士介紹,，該結(jié)果從另一方面來(lái)看,，嗅球能把不同腦狀態(tài)下獲取的嗅覺信息真實(shí)可靠地送到更高級(jí)中樞。
相對(duì)于科學(xué)界對(duì)視覺與聽覺的深入研究,，嗅覺研究相對(duì)較少,。嗅覺對(duì)于動(dòng)物早期生存，尋找食物和配偶,，認(rèn)知獵物和天敵,，都非常重要。嗅覺也明顯地影響人類的生理心理及社會(huì)行為,。中科院武漢物數(shù)所嗅覺神經(jīng)生物學(xué)課題組重點(diǎn)研究對(duì)象是嗅球——在嗅覺的信息編碼,、處理和傳送過程中占有重要地位的腦區(qū)。
課題組通過對(duì)麻醉深度的操控,，使動(dòng)物大腦處于不同的運(yùn)行狀態(tài),，并記錄兩種狀態(tài)下嗅球?qū)馕洞碳さ姆磻?yīng)。結(jié)果發(fā)現(xiàn),，嗅球中的神經(jīng)總活動(dòng)和神經(jīng)元放電頻率分布,，在氣味刺激后與各自基線相比均發(fā)生明顯改變，但氣味刺激后兩種狀態(tài)之間相比,，并無(wú)明顯差別,。進(jìn)一步的實(shí)驗(yàn)證實(shí)，大腦在不同狀態(tài)下,，一種尚待研究的神經(jīng)機(jī)制可確保對(duì)氣味準(zhǔn)確編碼,，將外界氣味信息可靠地傳遞到嗅球，形成相應(yīng)的嗅覺感知,。
此成果對(duì)于人們進(jìn)一步了解感覺系統(tǒng),，如何在不同條件下完成高保真的信息輸入，有積極作用,。（生物谷Bioon.com）
生物谷推薦原文出處：
PNAS doi: 10.1073/pnas.1013814108
Brain-state–independent neural representation of peripheral stimulation in rat olfactory bulb
Anan Lia,b, Ling Gonga, and Fuqiang Xua,c,1
Abstract
It is critical for normal brains to perceive the external world precisely and accurately under ever-changing operational conditions, yet the mechanisms underlying this fundamental brain function in the sensory systems are poorly understood. To address this issue in the olfactory system, we investigated the responses of olfactory bulbs to odor stimulations under different brain states manipulated by anesthesia levels. Our results revealed that in two brain states, where the spontaneous baseline activities differed about twofold based on the local field potential (LFP) signals, the levels of neural activities reached after the same odor stimulation had no significant difference. This phenomenon was independent of anesthetics (pentobarbital or chloral hydrate), stimulating odorants (ethyl propionate, ethyl butyrate, ethyl valerate, amyl acetate, n-heptanal, or 2-heptanone), odor concentrations, and recording sites (the mitral or granular cell layers) for LFPs in three frequency bands (12–32 Hz, 33–64 Hz, and 65–90 Hz) and for multiunit activities. Furthermore, the activity patterns of the same stimulation under these two brain states were highly similar at both LFP and multiunit levels. These converging results argue the existence of mechanisms in the olfactory bulbs that ensure the delivery of peripheral olfactory information to higher olfactory centers with high fidelity under different brain states.
