啄木鳥如何在反復(fù)的高強度沖擊中存活而不造成腦損傷?

啄木鳥如何在反復(fù)的高強度沖擊中存活而不造成腦損傷?

Slamming a beak against the trunk of a tree would seem like an activity that would cause headaches, jaw aches and serious neck and brain injuries. Yet woodpeckers can do this 20 times per second and suffer no ill effects.

用喙撞擊樹干似乎會導(dǎo)致頭痛、下巴疼痛以及嚴(yán)重的頸部和腦部損傷。然而，啄木鳥可以做到20次/每秒，并且沒有任何不良影響。

Woodpeckers are found in forested areas worldwide, except in Australia. These birds have the unusual ability to use their beaks to hammer into the trunks of trees to make holes to extract insects and sap. Even more impressive they do this without hurting themselves.

啄木鳥在世界各地的森林地區(qū)都有發(fā)現(xiàn)，除了澳大利亞。這些鳥有一種不尋常的能力，用它們的喙敲進(jìn)樹干，鉆出洞來吸取昆蟲和汁液。更令人印象深刻的是，它們這樣做的時候并沒有傷害到自己。

We are materials scientists who study biological substances like bones, skins, feathers and shells found in nature. We are interested in the skull and tongue bone structure of woodpeckers, because we think their unusual anatomy could yield insights that could help researchers develop better protective head gear for humans.

我們是研究自然界中發(fā)現(xiàn)的骨骼、皮膚、羽毛和貝殼等生物物質(zhì)的材料科學(xué)家。我們對啄木鳥的頭骨和舌骨結(jié)構(gòu)很感興趣，因為我們認(rèn)為它們不同尋常的解剖結(jié)構(gòu)可以幫助研究人員開發(fā)出更好的保護人類頭部的裝備。

Concussions in people

腦震蕩的人

Woodpeckers endure many high impact shocks to their heads as they peck.

啄木鳥在啄食時，頭部會受到許多強烈的撞擊。

They have strong tail feathers and claws that help them keep their balance as their head moves toward the tree trunk at 7 meters (23 feet) per second. Then, when their beak strikes, their heads slow down at about 1,200 times the force of gravity (g).

它們有強壯的尾羽和爪子，當(dāng)它們的頭以每秒7米(23英尺)的速度向樹干移動時，這些羽毛和爪子可以幫助它們保持平衡。然后，當(dāng)它們的喙撞擊時，它們的頭部會以1200倍重力(g)的速度減速。

All of this occurs without the woodpecker sustaining concussions or brain damage.

所有這些都發(fā)生在啄木鳥沒有持續(xù)腦震蕩或腦損傷的情況下。

A concussion is a form of traumatic brain injury caused by repeated blows to the head. It is a common occurrence and happens frequently during contact sports like football or hockey.

腦震蕩是一種由反復(fù)擊打頭部造成的創(chuàng)傷性腦損傷。這是一種常見的現(xiàn)象，經(jīng)常發(fā)生在接觸性運動中，如足球或曲棍球。

Repeated traumatic brain injury eventually causes a progressive brain disorder, chronic traumatic encephalopathy (CTE), which is irreversible and results in symptoms such as memory loss, depression, impulsivity, aggressiveness and suicidal behavior.

反復(fù)的創(chuàng)傷性腦損傷最終會導(dǎo)致進(jìn)行性腦功能障礙，即慢性創(chuàng)傷性腦病(CTE)，這是不可逆轉(zhuǎn)的，會導(dǎo)致記憶喪失、抑郁、沖動、攻擊性和自殺行為等癥狀。

The National Football League says concussions in football players occur at 80 g. So how do woodpeckers survive repeated 1,200 g impacts without harming their brain?

美國國家橄欖球聯(lián)盟稱橄欖球運動員的腦震蕩發(fā)生在80克。那么，啄木鳥是如何在不傷害大腦的情況下，承受1200克的反復(fù)撞擊的呢?

We have looked for the key secrets of the woodpecker's ability to tolerate the high impact during the hammering. We studied the micro-structures of bones and then did a biomechanical analysis on the head.

我們已經(jīng)找到了啄木鳥在錘擊過程中承受高沖擊能力的關(guān)鍵秘密。我們研究了骨骼的微觀結(jié)構(gòu)，然后對頭部進(jìn)行了生物力學(xué)分析。

Unusual skull bone and tongue bone structures

不尋常的頭骨和舌骨結(jié)構(gòu)

By comparing the skulls of woodpeckers and chickens, we discovered that woodpeckers have impact-absorbing adaptations that other birds do not have. This includes specialized skull bones, neck muscles, beaks and tongue bones.

通過比較啄木鳥和雞的頭骨，我們發(fā)現(xiàn)啄木鳥有其他鳥類沒有的吸收沖擊力的適應(yīng)性。這包括特殊的頭骨、頸部肌肉、喙和舌骨。

The skull bones have a different chemical composition and density. For example, one structural adaptation is achieved through increasing the accumulation of minerals in the bones to make them stiffer and stronger compared to other birds.

頭骨有不同的化學(xué)成分和密度。例如，一種結(jié)構(gòu)上的適應(yīng)是通過增加骨骼中礦物質(zhì)的積累來實現(xiàn)的，從而使它們比其他鳥類更堅硬、更強壯。

Surprisingly, the skull bone is very thin and there is less fluid that separates the brain from the skull bone than in other birds and animals. That would suggest that the skull is adapted to be harder and tougher at the same time.

令人驚訝的是，與其他鳥類和動物相比，啄木鳥的頭骨非常薄，大腦和頭骨之間的液體更少。這表明，同樣情況下啄木鳥的頭骨能適應(yīng)更硬的材質(zhì)。

Typically in the real-world materials science, there is a general trade-off between hardness and toughness. However, having both hard and tough materials on the head lessens the amount of impact transferred to the brain.

通常在真實世界的材料科學(xué)中，在硬度和韌性之間有一個普遍的平衡。然而，在頭部放置硬的和硬的材料會減少傳遞到大腦的沖擊力。

A second different is that woodpeckers have less internal fluid surrounding the brain than other big animals. This helps to limit the motion of the brain during the pecking. The reduced amount of fluid has an effect that is analogous to the yolk of a hard-boiled egg, which won't get damaged by shaking, compared to the yolk of a raw, uncooked egg.

另一個不同之處在于，啄木鳥大腦周圍的內(nèi)部液體比其他大型動物要少。這有助于限制啄食時大腦的運動。減少的液體量產(chǎn)生的效果類似于煮熟的雞蛋的蛋黃，與生的、未煮熟的雞蛋的蛋黃相比，它不會因為搖晃而受損。

Woodpeckers also have a bone embedded in their tongue that helps to extract insects from the trees. The unusual tongue wraps around the back of the skull and anchors at the front between the eyes. This configuration lets the tongue and its bone act as a spring, dampening the physical force and related vibrations.

啄木鳥的舌頭上還嵌有一根骨頭，可以幫助它們從樹上捕食昆蟲。這種不尋常的舌頭包裹著頭骨的后部，位于兩眼之間的前部。這種結(jié)構(gòu)讓舌頭和它的骨頭充當(dāng)彈簧，減弱物理力和相關(guān)的振動。

Different types of bone

不同類型的骨骼

The stiffness and strength of a typical skeletal bone is due to a dense sheath of compact bone that encapsulated a porous, spongy bone. But the woodpecker's tongue bone has the opposite structure: a flexible sheath and a harder core bone. This inside-out configuration provides better flexibility and can absorb higher impacts and vibrations.

典型的骨骼的硬度和強度是由于致密的骨鞘包裹著多孔的海綿狀骨。但啄木鳥的舌骨卻有相反的結(jié)構(gòu):一個靈活的鞘和一個堅硬的核心骨。這種由內(nèi)而外的結(jié)構(gòu)提供了更好的靈活性，可以吸收更高的沖擊和振動。

Our work suggests that the woodpecker's unusual skull and tongue bones are an example of impact-resistant structures essential for protecting the woodpecker's brain during pecking behavior.

我們的研究表明，啄木鳥不同尋常的頭骨和舌骨，是在啄木鳥啄木行為時保護其大腦所必需的抗撞擊結(jié)構(gòu)的一個因素。

Currently, biologists and neuroscientists are actively working on studying the woodpecker's brain to see if there is any pathological evidence of brain injuries – like CTE in humans.

目前，生物學(xué)家和神經(jīng)科學(xué)家正在積極研究啄木鳥的大腦，以確定是否存在腦損傷的病理證據(jù)——比如人類的CTE。

We hope this research reveals whether there are other protective or healing mechanisms at play at the level of tissues or cells in woodpecker brains which will, we hope, reveal how to protect and heal human brain injuries.

我們希望這項研究能揭示啄木鳥大腦組織或細(xì)胞層面是否存在其他保護或愈合機制，從而揭示如何保護和治愈人類大腦損傷。