譯自《經(jīng)濟(jì)學(xué)人》2018.1.4文章 Reading the brain from the outside--Can brain activity be deciphered withoutopening up the skull?
PATRICK KAIFOSH’S left hand lies flat on thetable in front of him. Occasionally his fingers twitch or his palm rises upslightly from the surface. There is nothing obvious to connect these movementswith what is happening on the tablet in front of him, where a game of asteroidsis being played. Yet he is controlling the spaceship on the screen as it spins,thrusts and fires.
Patrick Kaifosh的左手平放在他身前的桌上，他的手指偶爾抽動(dòng)下揖赴，手掌偶爾輕輕從桌面抬起。你很難把這些動(dòng)作和他面前顯示屏上的行星游戲聯(lián)系起來抑胎，然而實(shí)際上他正通過這些動(dòng)作控制著屏幕上飛船的旋轉(zhuǎn)燥滑、推進(jìn)和開火。
What enables him to do so is a sweatbandstudded with small gold bars that sits halfway up his left forearm. Each barcontains a handful of electrodes designed to pick up the signals of motor units(the combination of a motor neuron, a cell that projects from the spinal cord,and the muscle fibres it controls). These data are processed bymachine-learning algorithms and translated into the actions in the game. DrKaifosh, a co-founder of CTRL-Labs, the startup behind the device, has learnedto exercise impressive control over these signals with hardly any obviousmovement.
之所以能這樣做是因?yàn)樵谒笄氨壑胁坑幸粔K特殊的防汗帶阿逃，上面鑲有很小的黃金條铭拧，每個(gè)黃金條上都有一些用來捕捉人體運(yùn)動(dòng)單元信號的電子元件（運(yùn)動(dòng)單元是運(yùn)動(dòng)神經(jīng)的組合：一個(gè)從脊髓伸出的神經(jīng)細(xì)胞和由它控制的肌纖維），這些數(shù)據(jù)再通過機(jī)器學(xué)習(xí)算法處理轉(zhuǎn)換成游戲里面的動(dòng)作恃锉。CTRL-Labs的創(chuàng)始人之一Kaifosh博士搀菩，同樣也是這個(gè)設(shè)備的創(chuàng)始者，已經(jīng)學(xué)會(huì)用難以察覺的細(xì)微動(dòng)作來熟練控制這些信號了破托。
Some say that the claims of Dr Kaifosh andThomas Reardon, his co-founder, that CTRL-Labs has created a brain-machineinterface are nonsense. The sweatband is nowhere near the brain, and thesignals it is picking up are generated not just by the firing of a motor neuronbut by the electrical activity of muscles. “If this is a BCI, then the movementof my fingers when I type on a keyboard is also a brain output,” sniffs oneresearcher.Krishna Shenoy, who directs the neural prostheticssystems lab at Stanford University and acts as an adviser to the firm, thinksit is on the right side of the divide. “Measuring the movement of the hand ismotion capture. They are picking up neural activity amplified by the muscles.”
一些人認(rèn)為Kaifosh博士和他的合伙人Thomas Reardon宣稱他們的CTRL實(shí)驗(yàn)室已經(jīng)研發(fā)出腦機(jī)接口技術(shù)（BCI）的言論是荒謬的易桃。他們的綁帶并沒有靠近大腦造寝，收集的信號不光是運(yùn)動(dòng)神經(jīng)的活動(dòng)签赃，還有肌肉的電反應(yīng)尺上。“如果這是腦機(jī)接口技術(shù)河绽，那我敲擊鍵盤時(shí)手指的活動(dòng)也可以認(rèn)為是腦活動(dòng)。”一位研究人員嘲弄著說鉴未。斯坦福大學(xué)神經(jīng)修復(fù)系統(tǒng)實(shí)驗(yàn)室的主導(dǎo)人同時(shí)也是CTRL-LAB的咨詢師Krishna Shenoy則認(rèn)為這個(gè)設(shè)備是個(gè)分水嶺连茧，“衡量手的運(yùn)動(dòng)是一種動(dòng)作捕捉技術(shù)虐唠，它收集那些被肌肉放大的神經(jīng)活動(dòng)。”
It is not reasonableto expect consumers to undergo brain surgery
Whatever the?semantics, it isinstructive to hear the logic behind the firm’s decision to record the activityof the peripheral nervous system, rather than looking directly inside the head.The startup wants to create a consumer product (its potential uses includebeing an interface for interactions in virtual reality and augmented reality).It is not reasonable to expect consumers to undergo brain surgery, say thefounders, and current non-invasive options for reading the brain provide noisy,hard-to-read signals. “For machine-learning folk, there is no question whichdata set—cortical neurons or motor neurons—you would prefer,” says Dr Reardon.
“期待消費(fèi)者忍受腦外科手術(shù)太不合理」淘椋”
無論這句話意義如何扮叨，這個(gè)公司所做決定背后的邏輯都具有指導(dǎo)意義：記錄外圍神經(jīng)系統(tǒng)的活動(dòng)尘喝，而非直接進(jìn)入大腦內(nèi)部缔赠。發(fā)起者希望創(chuàng)造一個(gè)消費(fèi)者直接使用的產(chǎn)品（它的潛在應(yīng)用包括用于虛擬現(xiàn)實(shí)和增強(qiáng)現(xiàn)實(shí)的交互界面）戈抄。讓消費(fèi)者忍受大腦手術(shù)太不合理呛凶，創(chuàng)辦人說啰脚，而現(xiàn)有非侵入式解讀大腦方式提供的信號又太嘈雜、不易解讀∮缮樱“對于熟悉機(jī)器學(xué)習(xí)的人來說饿凛，更傾向于使用哪種數(shù)據(jù)集顯而易見——皮層神經(jīng)元數(shù)據(jù)或運(yùn)動(dòng)神經(jīng)元數(shù)據(jù)狞玛。”Reardon博士說涧窒。
This trade-offbetween the degree of invasiveness and the fidelity of brain signals is a bigproblem in the search for improved BCIs. But plenty of people are trying tofind a better way to read neural code from outside the skull.
在侵入度和信號保真度之間做權(quán)衡是BCI（腦機(jī)接口技術(shù)）研發(fā)中的主要問題心肪，但是更多人嘗試尋找從頭骨外部解讀大腦信號的更好方法。
The simplest wayto read electrical activity from outside is to conduct an electroencephalogram(EEG). And it is not all that simple. Conventionally, it has involved wearing acap containing lots of electrodes that are pressed against the surface of the scalp.To improve the signal quality, a conductive gel is often applied. That requiresa hairwash afterwards. Sometimes the skin of the scalp is roughened up to get abetter connection. As a consumer experience it beats going to the dentist, butnot by much.
從外部讀取腦電活動(dòng)最簡單的方法就是進(jìn)行腦電波掃描（EEG）纠吴。然而這并不簡單硬鞍，依照慣例，需要帶上包含很多電極的帽子戴已，這些電極壓在頭皮表面固该。為了增強(qiáng)信號質(zhì)量，還需要涂抹導(dǎo)電膏糖儡，因此用后還需洗發(fā)伐坏。有時(shí)還要把頭皮弄得更粗糙些以便更好連接。這種消費(fèi)體驗(yàn)比看牙醫(yī)好不到哪去握联。
Once on, eachelectrode picks up currents generated by the firing of thousands of neurons,but only in the area covered by that electrode. Neurons that fire deep in thebrain are not detected either. The signal is distorted by the layers of skin,bone and membrane that separate the brain from the electrode. And muscleactivity (of the sort that CTRL-Labs looks for) from eye and neck movements orclenched jaws can overwhelm the neural data.
一旦戴上這種帽子桦沉，每個(gè)電極將收集上千個(gè)神經(jīng)元釋放出的電流，但只限于被電極覆蓋的區(qū)域金闽。且大腦深層神經(jīng)元釋放的信號不會(huì)被探測到纯露，信號被大腦和電極間層層的皮膚、骨頭代芜、筋膜干擾扭曲埠褪。眼部頸部的肌肉活動(dòng)（CTRL實(shí)驗(yàn)室尋找的那種）或者口部的咬合也會(huì)淹沒神經(jīng)數(shù)據(jù)。
Even so, someEEG signals are strong enough to be picked up pretty reliably. An“event-related potential”, for example, is an electrical signal that the brainreliably gives off in response to an external stimulus of some sort. One such,called an error-related potential (Errp), occurs when a user spots a mistake. Researchersat MIT have connected a human observer wearing an EEG cap to an industrialrobot called Baxter as it carried out a sorting task. If Baxter made a mistake,an Errp signal in the observer’s brain alerted the robot to its error;helpfully, if Baxter still did not react, the human brain generated an evenstronger Errp signal.
盡管如此，一些信號還是強(qiáng)到可以被可靠地收集组橄。例如“事件相關(guān)電信號”荞膘，它是大腦對特定外部刺激發(fā)出的一種可靠電信號。其中一種叫“錯(cuò)誤相關(guān)電信號”（ERRP）玉工，當(dāng)用戶犯錯(cuò)時(shí)會(huì)產(chǎn)生羽资。麻省理工學(xué)院的研究員將一臺(tái)名為Baxter的正在做分類工作的工業(yè)機(jī)器人連接到一名戴著腦部掃描頭盔（EEG）的人類觀察者身上。Baxter一旦犯錯(cuò)遵班，觀察者大腦發(fā)出的“錯(cuò)誤相關(guān)電信號（ERRP）”將警告機(jī)器人犯錯(cuò)屠升；有幫助的是，如果Baxter沒有任何反應(yīng)狭郑，人類大腦將發(fā)出更強(qiáng)的錯(cuò)誤相關(guān)電信號（ERRP）腹暖。
If the cap fits
Neurable, a consumer startup, hasdeveloped an EEG headset with just seven dry electrodes which uses a signalcalled the P300 to enable users to play a virtual-reality (VR) escape game.This signal is a marker of surprise or recognition. Think of the word “brain” andthen watch a series of letters flash up randomly on a screen; when the letter“b” comes up, you will almost certainly be giving off a P300 signal. InNeurable’s game, all you have to do is concentrate on an object (a ball, say)for it to come towards you or be hurled at an object.Ramses Alcaide,Neurable’s boss, sees the potential for entertainment companies like Disney(owner of the Star Wars and Marvel franchises) to license the software in themeparks and arcade games.
如果帽子合適
Neurable是一個(gè)由用戶發(fā)起的公司，他們開發(fā)了一種頭戴式腦部掃描設(shè)備（EEG）翰萨，它包含7個(gè)使用P300信號的電極脏答，依靠它用戶可以玩逃亡虛擬現(xiàn)實(shí)游戲。這種信號可以反映出大腦的驚奇反應(yīng)或識別反應(yīng)亩鬼。想著一個(gè)詞“brain”殖告，然后看到一串字母在屏幕上隨機(jī)顯現(xiàn)，當(dāng)字母‘b’出現(xiàn)時(shí)雳锋，你的大腦就會(huì)發(fā)出一個(gè)P300信號黄绩。在Neurable的游戲中，你需要做的就是集中注意力于某件物體上（比如一個(gè)球）玷过，然后它就會(huì)到自動(dòng)你手中或是被擲向其他物體爽丹。Neurable的老板Ramses Alcaide認(rèn)為一些娛樂公司，比如迪士尼辛蚊，可能在它們的主題公園或游樂場應(yīng)用該軟件粤蝎。
Thorsten Zander?of theTechnische Universit?t in Berlin thinks that “passive” EEG signals (those thatare not evoked by an external stimulus) can be put to good use too. Researchhas shown that brainwave activity changes depending on how alert, drowsy or focuseda person is. If an EEG can reliably pick this up, perhaps surgeons, pilots ortruck drivers who are becoming dangerously tired can be identified. Studieshave shown strong correlations between people’s mental states as shown by anEEG and their ability to spot weapons in X-rays of luggage.
柏林科技大學(xué)的Thorsten Zander認(rèn)為一些被動(dòng)腦電波信號（那些不是被外界刺激引發(fā)的信號）也能被很好地利用。研究顯示腦波活動(dòng)的變化取決于人大腦的警覺度嚼隘、昏沉度或注意力集中程度诽里。如果腦電波掃描技術(shù)（EEG）能可靠地收集這些信號，那些處于危險(xiǎn)疲憊狀態(tài)的外科醫(yī)生飞蛹、飛行員、卡車司機(jī)就能被識別出來了灸眼。研究表明卧檐，EEG技術(shù)反映出的人腦狀態(tài)跟人識別安檢機(jī)中武器的能力有很強(qiáng)的相關(guān)性。
Yet the uses ofEEGs remain limited. In a real-world environment like a cockpit, a car or anairport, muscle activity and ambient electricity are likely to confound anyneural signals. As for Neurable’s game, it relies not solely on brain activitybut also deploys eye-tracking technology to see where a player is looking. DrAlcaide says the system can work with brain signals alone, but it is hard for auser to disentangle the two.
然而EEG技術(shù)的應(yīng)用還是很有限的焰宣，在類似駕駛艙霉囚、汽車或機(jī)場的真實(shí)環(huán)境中，肌肉活動(dòng)和外界的電流很容易和神經(jīng)信號相混淆匕积。至于Neurable的游戲盈罐，它不單單依賴大腦活動(dòng)榜跌，還需應(yīng)用人眼追蹤技術(shù)追蹤玩家視線。Alcaide博士說系統(tǒng)可以只需要大腦信號盅粪，但對玩家來說要把視覺信號和腦信號相分離很難钓葫。
Othernon-invasive options also have flaws. Magnetoencephalography measures magneticfields generated by electrical activity in the brain, but it requires a specialroom to shield the machinery from Earth’s magnetic field. Functional magneticresonance imaging (fMRI) can spot changes in blood oxygenation, a proxy forneural activity, and can zero in on a small area of the brain. But it involvesa large, expensive machine, and there is a lag between neural activity andblood flow.
其他非侵入式方法也有瑕疵。
腦磁圖描技術(shù)可以測量腦電活動(dòng)產(chǎn)生的磁場票顾，但它需要一個(gè)特殊空間來隔離地球磁場础浮。功能性磁場共振成像技術(shù)可以探測到血氧變化，它可作為神經(jīng)活動(dòng)的替代指征奠骄，也能精確測量大腦中的一小塊區(qū)域豆同。但這需要大型而昂貴的機(jī)器，且血氧變化相對神經(jīng)活動(dòng)有滯后性含鳞。
If any area islikely to yield a big breakthrough in non-invasive recording of the brain, itis a variation on fNIRS, the infrared technique used in the experiment to allowlocked-in patients to communicate. In essence, light sent through the skull iseither absorbed or reflected back to detectors, providing a picture of what isgoing on in the brain. This technique does not require bulky equipment, andunlike EEG it does not measure electrical activity, so it is not confused bymuscle activity. Both Facebook and Openwater are focusing their efforts on thisarea.
在非侵入式記錄大腦活動(dòng)的方法中可能有突破的是改進(jìn)的FNIRS技術(shù)影锈，實(shí)驗(yàn)中用這種紅外技術(shù)可以讓鎖住的病人正常交流。大體原理是蝉绷，透過頭骨的光線被吸收或是被反射回探測器形成大腦活動(dòng)圖片精居。這項(xiàng)技術(shù)不需要龐大的機(jī)器，它不像EEG技術(shù)測量大腦電活動(dòng)潜必，所以也不會(huì)受肌肉活動(dòng)影響靴姿。Facebook和Openwater公司都著重在該領(lǐng)域進(jìn)行研究。
The obstacles toa breakthrough are formidable, however. Current infrared techniques measure anepiphenomenon,blood oxygenation(the degree ofwhich affects the absorption of light), rather than the actual firing ofneurons. The light usually penetrates only a few millimetres into the cortex.And because light scatters in tissue (think of how your whole fingertip glowsred when you press a pen-torch against it), the precise source of reflectedsignals is hard to identify.
然而距離突破性的進(jìn)展還有很多的困難磁滚，目前的紅外技術(shù)可以測量附帶現(xiàn)象和血氧含量（反映了紅外光的吸收量）佛吓，而不是真正的神經(jīng)發(fā)射。紅外光只能穿透頭皮幾毫米垂攘，由于光在組織中會(huì)發(fā)生散射（想想當(dāng)你按壓紅外筆時(shí)整個(gè)指尖都紅了）维雇，反射信號也很難被精確識別。
Facebook is notsaying much about what it is doing. Its efforts are being led by MarkChevillet, who joined the social-media giant’s Building 8 consumer-hardwareteam fromJohns HopkinsUniversity. To cope with the problem oflight scattering as it passes through the brain, the team hopes to be able topick up on bothballistic photons, which passthrough tissue in a straight line, and what it terms “quasi-ballistic photons”,which deviate slightly but can still be traced to a specific source. The clockis ticking. Dr Chevillet has about a year of a two-year programme left todemonstrate that the firm’s goal of brain-controlled typing at 100 words aminute is achievable using current invasive cell-recording techniques, and toproduce a road map for replicating that level of performance non-invasively.
Facebook沒有透漏太多進(jìn)展晒他。他們的研究由加入了約翰霍普金斯大學(xué)社會(huì)傳媒巨頭 “8幢用戶-硬件團(tuán)隊(duì)”的Mark Chevillet領(lǐng)導(dǎo)吱型。為了處理光透過大腦后的散射問題，該團(tuán)隊(duì)希望能同時(shí)收集在組織中沿直線傳播的彈道光子陨仅，該光子稱為“準(zhǔn)彈道光子”津滞，雖然有略微偏差但仍可被準(zhǔn)確追溯至源頭。時(shí)間很緊迫灼伤，Chevillet博士還剩1年時(shí)間去實(shí)現(xiàn)公司一個(gè)2年項(xiàng)目的目標(biāo)触徐，該目標(biāo)是利用現(xiàn)有非侵入式細(xì)胞記錄技術(shù)達(dá)到大腦控制打字每分鐘100字，并繪制出那個(gè)水平的腦圖譜狐赡。
Openwater ismuch less tight-lipped. Ms Jepsen says that her San Francisco-based startupuses holography to reconstruct how light scatters in the body, so it canneutralise this effect. Openwater, she suggests, has already created technologythat has a billion times the resolution of an fMRI machine, can penetrate thecortex to a depth of 10cm, and can sample data in milliseconds.
Openwater公司則沒有那么守口如瓶了撞鹉，Jepsen女士說他們在弗朗西斯科的項(xiàng)目使用全息攝影術(shù)修正光線在體內(nèi)的散射，這可以中和散射影響。她也透露Openwater公司已開發(fā)出效果比FMRI好十億倍的技術(shù)鸟雏，可以滲透到皮層下方深達(dá)10厘米享郊，也可以以毫秒的速度取樣。
Openwater hasyet to demonstrate its technology, so these claims are impossible to verify.Most BCI experts are sceptical. But Ms Jepsen has an impressive background inconsumer electronics and display technologies, and breakthroughs by theirnature upend conventional wisdom. Developer kits are due out in 2018.
Openwater公司還需進(jìn)一步闡明他們的技術(shù)孝鹊，所以這些言論還無法證實(shí)炊琉，大多數(shù)腦機(jī)接口技術(shù)專家對此都持懷疑態(tài)度。但Jepsen女士在消費(fèi)電子顯示技術(shù)領(lǐng)域有很很強(qiáng)的背景惶室，而突破性進(jìn)展經(jīng)常會(huì)顛覆人們的傳統(tǒng)觀念温自。開發(fā)工具將于2018年待售。
In the meantime,other efforts to decipher the language of the brain are under way. Some involveheading downstream intothe peripheral nervous system.One example of that approach is CTRL-Labs; another is provided by Qi Wang, atColumbia University, who researches the role of thelocus coeruleus,a nucleus deep in the brain stem that plays a role in modulating anxiety andstress. Dr Wang is looking at ways of stimulating the vagus nerve, which runsfrom the brain into the abdomen, through the skin to see if he can affectthelocus coeruleus.
同時(shí)皇钞，其他破譯大腦語言的努力也在持續(xù)進(jìn)行中悼泌，其中一些最終跟外圍神經(jīng)系統(tǒng)技術(shù)合流。其中一個(gè)例子是CTRL實(shí)驗(yàn)室夹界，另外一個(gè)來自哥倫比亞大學(xué)的王奇馆里，他研究了位于腦干深處的原子核“藍(lán)斑核”調(diào)節(jié)焦慮和壓力的作用。王先生致力于透過皮膚刺激從腦部通向腹部的迷走神經(jīng)可柿，觀察這些刺激能否作用于藍(lán)斑核鸠踪。
Others arelooking at invasive approaches that do not involve drilling through the skull.One idea, from a firm called SmartStent, using technology partly developed withthe University of Melbourne, is to use a stent-like device called a “stentrode”that is studded with electrodes. It is inserted via a small incision in theneck and then guided up through blood vessels to overlie the brain. Once thedevice is in the right location, it expands from about the size of a matchstickto the size of the vessel and tissuegrows into its scaffolding,keeping it in place. Human trials of the stentrode are due to start next year.
另些人嘗試侵入式的方法，但不用鉆通顱骨复斥。其中一個(gè)來自于SmartStent公司的想法营密，部分利用墨爾本大學(xué)研發(fā)的技術(shù)，使用一個(gè)鍍有電極的支架狀設(shè)備stentrode目锭，通過頸部小切口植入體內(nèi)评汰，再通過血管流向大腦，一旦到達(dá)準(zhǔn)確位置痢虹，它就會(huì)從火柴桿大小展開到血管大小被去，周圍組織會(huì)把它包裹固定住。Stentrode技術(shù)的人體試驗(yàn)將在明年進(jìn)行奖唯。
Another approachis to put electrodes under the scalp but not under the skull. Maxime Baud, aneurologist attached to the Wyss Centre, wants to do just that in order tomonitor the long-term seizure patterns of epileptics. He hopes that once thesepatterns are revealed, they can be used to provide accurate forecasts of when aseizure is likely to occur.
另一種方法是把電極放在頭皮下面而不是頭骨下面惨缆。隸屬于懷斯中心的神經(jīng)學(xué)家Maxime Baud想通過這種方法跟蹤捕獲癲癇病的長期規(guī)律，他希望發(fā)現(xiàn)這些規(guī)律丰捷，并用來精確預(yù)測癲癇病的發(fā)病時(shí)間坯墨。
Yet others thinkthey need to go directly to the source of action potentials. And that meansheading inside the brain itself.
然而一些人認(rèn)為他們應(yīng)該直接進(jìn)入到產(chǎn)生行動(dòng)電勢的源頭，那意味著要進(jìn)入大腦內(nèi)部瓢阴。
