感覺(jué)系統(tǒng)的基本功能是準(zhǔn)確地把瞬息萬(wàn)變的環(huán)境信息提供給大腦，而大腦的一個(gè)基本功能是在不斷變化的內(nèi)環(huán)境下，準(zhǔn)確地感知外部世界。這樣的正常功能，對(duì)于日常生活、生存以及腦功能如在適當(dāng)?shù)那樾蜗伦龀稣_的判斷、計(jì)劃以及zui終決定等至關(guān)重要。然而，感覺(jué)系統(tǒng)如何在不同的生理狀態(tài)下完成高保真的輸入，我們的了解卻十分有限。

中科院武漢物理與數(shù)學(xué)研究所徐富強(qiáng)研究員和李安安博士等人以嗅覺(jué)系統(tǒng)的*中樞嗅球作為研究對(duì)象，通過(guò)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)（高基線和低基線兩種狀態(tài)），利用電生理記錄的方法研究動(dòng)物在這兩種情況下嗅球如何編碼同一氣味刺激的信息。研究表明，動(dòng)物在處于這兩種運(yùn)行狀態(tài)下，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。這種對(duì)同一刺激獨(dú)立于大腦狀態(tài)的神經(jīng)表達(dá)現(xiàn)象并不受所使用的麻醉劑類型、氣味結(jié)構(gòu)和濃度、嗅球的不同功能層、同一功能層內(nèi)不同的位點(diǎn)以及電信號(hào)類型（不同頻段的局部場(chǎng)電位和多單位放電）的影響。因此，嗅球?qū)ν粴馕洞碳さ木幋a是通過(guò)相對(duì)穩(wěn)定的神經(jīng)元組合，以反應(yīng)強(qiáng)度而不是相對(duì)反應(yīng)強(qiáng)度來(lái)實(shí)現(xiàn)，同時(shí)提示嗅球中存在目前還不清楚的神經(jīng)機(jī)制來(lái)確保在不同大腦狀態(tài)下對(duì)氣味準(zhǔn)確編碼，從而將外界氣味信息可靠地傳遞到更的嗅覺(jué)中樞，形成相應(yīng)的嗅覺(jué)感知。

研究結(jié)果Brain-state–independent neural representation ofperipheral stimulation in rat olfactory bulb發(fā)表在美國(guó)《國(guó)家*院刊》（PNAS）上.

該研究得到國(guó)家自然科學(xué)基金委杰出青年基金、國(guó)家創(chuàng)新研究群體和中科院“百人計(jì)劃”項(xiàng)目的支持。（轉(zhuǎn)生物谷Bioon.com）

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 accuray 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.