來(lái)自北京師范大學(xué)認(rèn)知神經(jīng)科學(xué)與學(xué)習(xí)重點(diǎn)實(shí)驗(yàn)室,，美國(guó)NIH藥物濫用研究所的兩個(gè)研究組合作，完成了題為“Coupling of functional connectivity and regional cerebral blood flow reveals a physiological basis for network hubs of the human brain”的文章,，指出無(wú)論是靜息休息狀態(tài),，還是任務(wù)應(yīng)答調(diào)控狀態(tài)下，在血流供應(yīng)和大腦功能拓?fù)浣Y(jié)構(gòu)之間都存在緊密聯(lián)系,，這也許有助于揭示人類(lèi)大腦功能互作組的生理基礎(chǔ)機(jī)制,。相關(guān)成果公布在1月PNAS雜志在線版上。
文章的通訊作者是北京師范大學(xué)賀永研究員,，以及美國(guó)NIH藥物濫用研究所楊一鴻研究員,，其中賀永研究員主要從事計(jì)算神經(jīng)影像與人腦連接組學(xué)研究，即采用多個(gè)模態(tài)的神經(jīng)影像技術(shù)（結(jié)構(gòu),、擴(kuò)散和功能磁共振成像）,，結(jié)合數(shù)學(xué)圖論的計(jì)算方法，研究活體人腦結(jié)構(gòu)和功能網(wǎng)絡(luò)的連接模式,。
人類(lèi)大腦功能網(wǎng)絡(luò)包含了一些密集的連接樞紐,，這些連接點(diǎn)在休息和工作狀態(tài)下，擔(dān)負(fù)著不同區(qū)域信息傳遞的關(guān)鍵職責(zé),，然而迄今為止,，科學(xué)家們對(duì)于這些功能性連接點(diǎn)，與大腦生理學(xué)反應(yīng)之間的關(guān)聯(lián),，比如局部腦血流量（rCBF）,，知之甚少。
在這篇文章中,，研究人員利用血氧合度依賴(lài)對(duì)比（Blood Oxygenation Level Dependent Contrast,，BOLD Contrast），以及動(dòng)脈自旋標(biāo)記灌注對(duì)比（arterial-spin–labeling perfusion contrasts）的功能磁共振成像數(shù)據(jù),，分析了休息狀態(tài)和 N-back工作記憶任務(wù)狀態(tài)下,，大腦功能連接強(qiáng)度（functional connectivity strength，F(xiàn)CS）和局部腦血流量rCBF,。
在休息狀態(tài)下,，研究人員發(fā)現(xiàn)了高FCS的功能大腦連接點(diǎn)，主要出現(xiàn)在默認(rèn)模式(default mode),，insula和視覺(jué)區(qū)域中,，F(xiàn)CS顯示出與rCBF明顯的空間相關(guān)性，并且比較于視覺(jué)和感覺(jué)網(wǎng)絡(luò),，在默認(rèn)模式網(wǎng)絡(luò)（DMN,，包括內(nèi)側(cè)額葉-頂葉皮層）和執(zhí)行管控神經(jīng)網(wǎng)絡(luò)(ECN，包括側(cè)額葉-頂葉皮質(zhì))中關(guān)聯(lián)性更強(qiáng),。
而且這種關(guān)聯(lián)性取決于連接的距離,，也就是說(shuō)，rCBF與長(zhǎng)距離連接點(diǎn),，比與短距離連接點(diǎn)的關(guān)聯(lián)更強(qiáng),。值得注意的是,，幾個(gè)DMN和ECN區(qū)域表現(xiàn)出了每單元連接強(qiáng)度，更高的rCBF（rCBF/FCS ratio）,，而這一指標(biāo)在后視覺(jué)區(qū)域較低。
在工作記憶的實(shí)驗(yàn)中,，研究人員發(fā)現(xiàn)FCS-rCBF耦合和 rCBF/FCS ratio受到ECN和/或DMN區(qū)域負(fù)載任務(wù)的調(diào)控,。此外，任務(wù)誘導(dǎo)的側(cè)頂葉中FCS和rCBFA的改變與行為表現(xiàn)正相關(guān),。
這些研究結(jié)果表明,，無(wú)論是靜息休息狀態(tài)，還是任務(wù)應(yīng)答調(diào)控狀態(tài)下,，在血流供應(yīng)和大腦功能拓?fù)浣Y(jié)構(gòu)之間都存在緊密聯(lián)系,，這也許有助于揭示人類(lèi)大腦功能互作組的生理基礎(chǔ)機(jī)制。
賀永研究組曾建立了世界上第一個(gè)活體人腦結(jié)構(gòu)連接網(wǎng)絡(luò)草圖,，發(fā)現(xiàn)了人腦不同區(qū)域之間的灰質(zhì)厚度具有“小世界”組織方式,，并由此建立了阿爾茨海默氏病和白質(zhì)多發(fā)硬化病的腦結(jié)構(gòu)網(wǎng)絡(luò)失連接模型。
doi: 10.1073/pnas.1214900110
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Coupling of functional connectivity and regional cerebral blood flow reveals a physiological basis for network hubs of the human brain
Xia Liang, Qihong Zou, Yong He, and Yihong Yang
Human brain functional networks contain a few densely connected hubs that play a vital role in transferring information across regions during resting and task states. However, the relationship of these functional hubs to measures of brain physiology, such as regional cerebral blood flow (rCBF), remains incompletely understood. Here, we used functional MRI data of blood-oxygenation-level–dependent and arterial-spin–labeling perfusion contrasts to investigate the relationship between functional connectivity strength (FCS) and rCBF during resting and an N-back working-memory task. During resting state, functional brain hubs with higher FCS were identified, primarily in the default-mode, insula, and visual regions. The FCS showed a striking spatial correlation with rCBF, and the correlation was stronger in the default-mode network (DMN; including medial frontal-parietal cortices) and executive control network (ECN; including lateral frontal-parietal cortices) compared with visual and sensorimotor networks. Moreover, the relationship was connection–distance dependent; i.e., rCBF correlated stronger with long-range hubs than short-range ones. It is notable that several DMN and ECN regions exhibited higher rCBF per unit connectivity strength (rCBF/FCS ratio); whereas, this index was lower in posterior visual areas. During the working-memory experiment, both FCS–rCBF coupling and rCBF/FCS ratio were modulated by task load in the ECN and/or DMN regions. Finally, task-induced changes of FCS and rCBF in the lateral-parietal lobe positively correlated with behavioral performance. Together, our results indicate a tight coupling between blood supply and brain functional topology during rest and its modulation in response to task demands, which may shed light on the physiological basis of human brain functional connectome
