美國(guó)科學(xué)家近日首次發(fā)現(xiàn)了一種稱作“動(dòng)態(tài)連接”（dynamic connectivity）的神經(jīng)元工作機(jī)制,，它能幫助大腦更敏銳地感受到外界刺激,。這一發(fā)現(xiàn)使得科學(xué)家能更好地解釋為何大腦能快速地區(qū)分出刺激的種類,。相關(guān)論文12月16日在線發(fā)表于《自然—神經(jīng)學(xué)》（Nature Neuroscience）上,。
當(dāng)大腦接收刺激信號(hào)時(shí),，許多神經(jīng)細(xì)胞會(huì)同時(shí)開啟活性,，使得大腦無法對(duì)信號(hào)進(jìn)行準(zhǔn)確識(shí)別,。這時(shí)會(huì)產(chǎn)生一種稱為側(cè)抑制（lateral inhibition）的現(xiàn)象，即受到刺激的神經(jīng)細(xì)胞會(huì)向鄰近細(xì)胞發(fā)出“?；?rdquo;信號(hào)，減低了“噪音”,，使得刺激信號(hào)能更容易地被鑒別,。
在最新的研究中,，美國(guó)神經(jīng)認(rèn)知中心（CNBC）的Nathan Urban和同事仔細(xì)研究了大腦嗅球區(qū)的側(cè)抑制過程。迄今為止,，科學(xué)家認(rèn)為嗅球區(qū)的神經(jīng)連接是固定的,，只能進(jìn)行很緩慢的變化,。
然而，研究人員發(fā)現(xiàn),，這些連接并不是固定的,，它們能根據(jù)特定的刺激而發(fā)生快速的變化,。當(dāng)大量神經(jīng)細(xì)胞都對(duì)刺激作出反應(yīng)時(shí)，這種動(dòng)態(tài)連接使得側(cè)抑制的作用得到加強(qiáng),，過濾了來自其它神經(jīng)細(xì)胞的“噪音”，從而大腦能夠清楚地識(shí)別出這種刺激，并將其與相似刺激區(qū)別開來,。
Urban表示,，通過理解大腦的工作方式,，我們能夠?qū)⑦@一機(jī)制應(yīng)用于大腦面臨的其它問題上。另外,，研究人員還利用計(jì)算機(jī)將這一大腦機(jī)制轉(zhuǎn)化成了一個(gè)運(yùn)算法則——活性依賴側(cè)抑制（ADLI）電腦模型,，這使得研究人員能更容易地在大腦其它區(qū)域應(yīng)用這一機(jī)制,。比如,，在一張模糊圖片上運(yùn)用這一模型,，能夠得到對(duì)比強(qiáng)烈的清晰圖片（見圖片說明）,。（科學(xué)網(wǎng) 梅進(jìn)/編譯）
原始出處:
Nature Neuroscience
Published online: 16 December 2007 | doi:10.1038/nn2030
Activity-dependent gating of lateral inhibition in the mouse olfactory bulb
Armen C Arevian1,2, Vikrant Kapoor2,3 & Nathaniel N Urban1,2,3
Abstract
Lateral inhibition is a circuit motif found throughout the nervous system that often generates contrast enhancement and center-surround receptive fields. We investigated the functional properties of the circuits mediating lateral inhibition between olfactory bulb principal neurons (mitral cells) in vitro. We found that the lateral inhibition received by mitral cells is gated by postsynaptic firing, such that a minimum threshold of postsynaptic activity is required before effective lateral inhibition is recruited. This dynamic regulation allows the strength of lateral inhibition to be enhanced between cells with correlated activity. Simulations show that this regulation of lateral inhibition causes decorrelation of mitral cell activity that is evoked by similar stimuli, even when stimuli have no clear spatial structure. These results show that this previously unknown mechanism for specifying lateral inhibitory connections allows functional inhibitory connectivity to be dynamically remapped to relevant populations of neurons.
Center for Neuroscience, University of Pittsburgh, A210 Langley Hall, Pittsburgh, Pennsylvania 15260, USA.
Center for the Neural Basis of Cognition, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, USA.
Department of Biology, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, USA.
Correspondence to: Nathaniel N Urban1,2,3 e-mail: [email protected]
