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  • Your mortal enemy has captured you and hooked you up to a bizarre experiment.

    你的死敵抓住了你,並把你掛到了一個奇怪的實驗上。

  • He's extended your nervous system with one very long neuron

    他用一個非常長的神經元擴展了你的神經系統。

  • to a target about 70 meters away.

    到大約70米外的目標。

  • At some point, he's going to fire an arrow.

    在某些時候,他要射箭。

  • If you can then think a thought to the target before the arrow hits it,

    如果可以的話,那麼在箭矢射中目標之前,你就對著目標想一想。

  • he'll let you go.

    他會讓你走的

  • So who wins that race?

    那麼誰會贏得這場比賽呢?

  • In order to answer, we have to examine the hardware of thought: neurons.

    為了回答,我們必須研究思維的硬件:神經元。

  • The human brain has about 86 billion of these cells.

    人腦中大約有860億個這樣的細胞。

  • They transmit signals down their axons by way of electrical impulses,

    它們通過電脈衝的方式將信號傳遞到軸突上。

  • or action potentials.

    或動作電位。

  • One neuron can then pass that signal to the next at a synapse

    一個神經元可以在突觸處將該信號傳遞給下一個神經元。

  • by way of chemical neurotransmitters.

    通過化學神經遞質的方式。

  • The signal is received by the next neuron's dendrites,

    信號由下一個神經元的樹突接收。

  • propagated down its axon, and passed further along.

    傳播到其軸突上,並進一步沿。

  • So, the key factors that determine how quickly you think

    所以,決定你思維速度的關鍵因素是什麼?

  • include how long it takes to generate an initial action potential;

    包括產生初始行動潛力所需的時間;

  • propagate it down the length of the axon; and transport it through the synapse.

    沿著軸突的長度傳播;並通過突觸運輸。

  • We must also factor in the number of neurons involved

    我們還必須考慮到參與的神經元數量

  • and the distance the signal has to travel.

    以及信號要走的距離。

  • Let's see what this looks like in a simple pathwayyour knee-jerk reflex.

    讓我們來看看這看起來像一個簡單的途徑--你的膝跳反射。

  • A strike to your patellar tendon triggers an electrical impulse

    髕骨肌腱受到撞擊會引發電脈衝

  • that travels up a sensory neuron to your spine.

    傳送到你的脊柱的感覺神經元。

  • There the signal branches, and for the sake of simplicity,

    有信號分支,為了簡單。

  • we'll consider the segment that jumps into a motor neuron

    我們將考慮到跳入運動神經元的部分

  • to journey back down your leg.

    沿著你的腿往回走。

  • The total length of the neurons in that pathway

    該路徑中神經元的總長度。

  • is about 1 meter in someone who is 5 foot 5 inches,

    在一個身高5英尺5英寸的人身上,大約是1米。

  • and on average it takes 15 to 30 milliseconds from strike to kick.

    而從出手到踢出,平均需要15到30毫秒。

  • Speed is distance divided by time,

    速度是距離除以時間。

  • so this signal travels somewhere between 120 to 240 kilometers per hour.

    所以這個信號的時速在120到240公里之間。

  • The initial action potential accounts for 1 to 5 milliseconds

    最初的動作電位佔1至5毫秒。

  • and synaptic transmissions only take .1 to .5 milliseconds,

    而突觸傳輸只需要0.1到0.5毫秒。

  • so the bulk of that time is spent within the axons.

    所以大部分時間是在軸突內度過的。

  • This is consistent with research findings

    這與研究結果一致

  • that the average individual neuron sends signals at around 180 kilometers per hour.

    平均單個神經元以每小時180公里左右的速度發送信號。

  • But speeds can be boosted with myelination and increased axon diameter.

    但速度可以通過髓鞘化和增加軸突直徑來提升。

  • Myelin is a fatty sheath that insulates an axon,

    髓鞘是一種隔絕軸突的脂肪鞘。

  • preventing electrical currents from leaking out.

    防止電流外洩。

  • Meanwhile, axons with larger diameters offer less internal resistance.

    同時,直徑較大的軸突提供的內阻較小。

  • These compounded factors can raise the speed of an action potential

    這些複合因素可以提高動作電位的速度。

  • as high as 432 kilometers per hour.

    高達每小時432公里。

  • There's plenty of variation: some people think faster than others,

    有很多變化:有些人的思維比別人快。

  • and your own speed of thought changes throughout your lifetime.

    而自己的思維速度在一生中也會發生變化。

  • In particular, as you reach old age,

    尤其是到了老年。

  • the myelin sheath covering your axons wears down,

    覆蓋在你的軸突上的髓鞘磨損了。

  • and other neuronal structures degrade.

    和其他神經元結構退化。

  • Back to the dastardly experiment.

    回到卑鄙的實驗中去。

  • Arrows shot from recurve bows fly, on average,

    彎弓射出的箭平均會飛。

  • around 240 kilometers per hour.

    每小時240公里左右。

  • Which means that given a sufficiently long, myelinated or large-diameter neuron,

    也就是說,給定一個足夠長的、有髓的或大直徑的神經元。

  • your thoughts actually could win the race.

    你的想法其實可以贏得比賽。

  • Butthere's a wrinkle.

    但是... ... 有一個皺紋。

  • The arrow and thought don't leave the gate at the same time;

    箭頭和思想不要同時離開大門。

  • first the arrow fires, then once you perceive it,

    先是箭在弦上,然後一旦察覺。

  • your signal can start down its path.

    你的信號可以開始它的路徑。

  • Processing images or music, participating in inner speech,

    處理影像或音樂,參與內心的言語。

  • and recalling memories all require complicated neural pathways

    和回憶記憶都需要複雜的神經通路。

  • that are nowhere close to the linearity of the knee-jerk reflex.

    與膝跳反射的直線性相差甚遠。

  • The speed at which these thoughts occur is mostly consistent,

    這些念頭發生的速度大多一致。

  • with variations based on myelination and axon diameter.

    與基於髓鞘和軸突直徑的變化。

  • But the duration of a thought will vary significantly depending on its routes,

    但一個念頭的持續時間會因其路線不同而有很大的不同。

  • pitstops, and destination.

    停靠站和目的地。

  • In this case, when you perceive a threatening stimulus,

    在這種情況下,當你感知到一個威脅性的刺激時。

  • you'll invoke a fear startle response.

    你會引起恐懼的驚嚇反應。

  • Similar to the knee-jerk response,

    類似於膝蓋的反應。

  • a startle can be involuntary and quite fast.

    驚嚇可以是不自主的,而且相當快。

  • If the string twangs loud enough,

    如果琴絃顫動的聲音足夠大。

  • you might react in less than 65 milliseconds.

    你可能會在65毫秒內做出反應。

  • More likely though, your startle reaction will be based on sight.

    不過更有可能的是,你的驚嚇反應會基於視覺。

  • Our eyes can process an image as quickly as 13 milliseconds,

    我們的眼睛可以以13毫秒的速度處理影像。

  • but computation of what you're seeing and determining the danger it poses

    但計算你所看到的東西,並確定它所帶來的危險。

  • can take as long as 180 to 200 milliseconds.

    可能需要180到200毫秒之久。

  • In that time the arrow will have gained a head start of about 13 meters.

    屆時,箭頭將獲得13米左右的起點。

  • The target is far enough away

    目標足夠遠

  • that you've got just enough of a chance to catch up,

    你有足夠的機會趕上。

  • if you can quickly, and quite literally, think your way out.

    如果你能迅速地,相當字面上,想出你的辦法。

Your mortal enemy has captured you and hooked you up to a bizarre experiment.

你的死敵抓住了你,並把你掛到了一個奇怪的實驗上。

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B2 中高級 中文 神經元 軸突 信號 速度 直徑 突觸

思維的速度有多快?- 塞納-馬修 (How fast is the speed of thought? - Seena Mathew)

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    林宜悉 發佈於 2020 年 11 月 16 日
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