近年來發(fā)展起來的腦機接口技術(shù)可以幫助像物理學(xué)家霍金一樣的神經(jīng)漸凍癥病人,、或者是脊髓損傷導(dǎo)致高位截癱的殘疾人,，與外界進(jìn)行溝通交流。腦機接口技術(shù)借助計算機解讀人腦的信號,，讓這類病人能夠自主操縱家電或者假肢,，實驗室研究已經(jīng)展示出可行性和應(yīng)用前景，但其臨床應(yīng)用碰到了難題,。采用無創(chuàng)傷的頭皮腦電腦機接口技術(shù)信號質(zhì)量差,，無法長期穩(wěn)定工作；基于植入微電極的腦機接口手術(shù)創(chuàng)傷大,，長期植入后由于神經(jīng)膠質(zhì)細(xì)胞的包裹,，神經(jīng)信號會減弱，導(dǎo)致腦機交互失效,。
清華大學(xué)醫(yī)學(xué)院生物醫(yī)學(xué)工程系洪波課題組和清華大學(xué)玉泉醫(yī)院,、解放軍總醫(yī)院神經(jīng)外科合作,，利用癲癇病人植入顱內(nèi)電極定位病灶的手術(shù)間期，研究實現(xiàn)了一種基于大腦皮層表面神經(jīng)信號的新型微創(chuàng)腦機接口,。該方法與已有腦機接口技術(shù)相比,，手術(shù)創(chuàng)傷小，神經(jīng)信號長期穩(wěn)定,。這項工作5月1日發(fā)表于國際神經(jīng)影像學(xué)期刊《神經(jīng)影像》（NeuroImage）,。
研究人員在病人眼前呈現(xiàn)一個隱藏著運動條紋的虛擬鍵盤，病人通過自己的視覺注意來選擇想要輸入的字符,，被注意的字符會引起更強的神經(jīng)活動,。該項研究發(fā)現(xiàn)這種增強的神經(jīng)活動主要表現(xiàn)為60赫茲以上的高頻振蕩，空間上集中于中顳葉一個很小的腦區(qū),，檢測這一區(qū)域高頻神經(jīng)信號的能量變化就可以確定病人要輸入的字符,。功能磁共振掃描發(fā)現(xiàn)，該區(qū)域與處理視覺運動的腦區(qū)非常吻合,。因為實驗采用了巧妙的視覺運動設(shè)計,，使得神經(jīng)響應(yīng)高度集中，可以通過功能磁共振精確定位,。
結(jié)合功能磁共振定位信息,，該項研究只獲取大腦皮層表面一個電極的神經(jīng)信號，實現(xiàn)了思維打字的功能,。這項研究首次實現(xiàn)了通過神經(jīng)影像精確定位的微創(chuàng)腦機接口技術(shù),，在國際上引起關(guān)注。
這項研究還展示了利用腦內(nèi)大腦皮層表面的高頻神經(jīng)信號研究腦功能網(wǎng)絡(luò)的獨特優(yōu)勢：直接而精準(zhǔn)地觀測毫秒級的快速神經(jīng)活動,，與功能磁共振技術(shù)結(jié)合,，可以為大腦皮層功能研究提供高時間分辨率和空間解析度的動態(tài)圖像，是研究語言,、注意,、記憶等高級認(rèn)知活動的有力工具。(生物谷Bioon.com)
DOI: 10.1016/j.neuroimage.2012.12.069
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Toward a minimally invasive brain–computer interface using a single subdural channel: A visual speller study
Dan Zhang, Huaying Song, Rui Xu, Wenjing Zhou, Zhipei Ling, Bo Hong
Electrocorticography (ECoG) has attracted increasing interest for implementing advanced brain–computer interfaces (BCIs) in the past decade. However, real-life application of ECoG BCI demands mitigation of its invasive nature by minimizing both the size of the involved brain regions and the number of implanted electrodes. In this study, we employed a recently proposed BCI paradigm that utilizes the attentional modulation of visual motion response. With ECoG data collected from five epilepsy patients, power increase of the high gamma (60–140 Hz) frequency range was found to be associated with the overtly attended moving visual stimuli in the parietal-temporal-occipital junction and the occipital cortex. Event-related potentials (ERPs) were elicited as well but with broader cortical distribution. We achieved significantly higher BCI classification accuracy by employing both high gamma and ERP responses from a single ECoG electrode than by using ERP responses only (84.22 ± 5.54% vs. 75.48 ± 4.18%, p < 0.005, paired t-test, 3-trial averaging, binary results of attended vs. unattended). More importantly, the high gamma responses were located within brain regions specialized in visual motion processing as mapped by fMRI, suggesting the spatial location for electrode implantation can be determined prior to surgery using non-invasive imaging. Our findings demonstrate the feasibility of implementing a minimally invasive ECoG BCI.
