[跃动的神经] 跃动

　　So natural is our capacity for rhythm that most of us take it for granted: when we hear music, we tap our feet to the 2)beat or rock and sway, often unaware that we are even moving. But this instinct is, 3)for all intents and purposes, an evolutionary 4)novelty among humans. Nothing comparable occurs in other mammals nor probably elsewhere in the animal kingdom. Our talent for unconscious 5)entrainment lies at the core of dance, a 6)confluence of movement, rhythm and gestural representation. By far the most synchronized group practice, dance demands a type of interpersonal coordination in space and time that is almost nonexistent in other social contexts.
　　Even though dance is a fundamental form of human expression, neuroscientists have given it relatively little consideration. Recently, however, researchers have conducted the first brain-imaging studies of both amateur and professional dancers. These investigations address such questions as, How do dancers navigate through space? How do they 7)pace their steps? How do people learn complex series of 8)patterned movements?
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　　Perhaps the most fascinating question for neuroscientists to explore is why people dance in the first place. Certainly music and dance are closely related; in many instances, dance generates sound. 9)Aztec 10)danzantes in 11)Mexico City wear 12)leggings containing seeds from the 13)ayoyotl tree, called 14)chachayotes, which make a sound with every step. In many other cultures, people put noise-making objects―from 15)taps to 16)castanets to beads―on their bodies or clothes while they dance. In addition, dancers frequently clap, snap and stomp. As a result, we have 17)postulated a “body 18)percussion” hypothesis that dance evolved initially as a sounding phenomenon and that dance and music, especially percussion, evolved together as complementary ways of generating rhythm. The first percussion instruments may well have been components of dancing 19)regalia, not unlike Aztec chachayotes.
　　Unlike music, however, dance has a strong capacity for representation and imitation, which suggests that dance may have further served as an early form of language. Indeed, dance is the 20)quintessential gesture language. It is interesting to note that during all the movement tasks in our study, we saw activation in a region of the right 21)hemisphere corresponding to what is known as 22)Broca’s area in the left hemisphere. Broca’s area is a part of the 23)frontal lobe classically associated with speech production. In the past decade research has revealed that Broca’s area also contains a representation of the hands.
　　 This finding 24)bolsters the so-called gestural theory of language evolution, whose proponents argue that language evolved initially as a gesture system before becoming vocal. Our study is among the first to show that leg movement activates the right-hemisphere 25)homologue to Broca’s area, which offers more support for the idea that dance began as a form of representational communication.
本文为全文原貌 未安装PDF浏览器用户请先下载安装 原版全文 　　We view dance as a marriage of the representational capacity of language and the rhythmicity of music. This interaction allows people not only to tell stories using their bodies but to do so while synchronizing their movements with others’ in a way that fosters social 26)cohesion.
　　
　　我们自然地拥有节奏感，大多数人认为那是理所当然的：听到音乐时我们会随着节拍轻轻踏脚，或者摇摆身子，但常常根本没有意识到自己在动。但实际上，这种本能是人类在进化过程中获得的新奇禀赋。其他哺乳类动物也好，动物王国的其他领域也好，都没有可以与之媲美的。人类这种无意识协动的天赋正是舞蹈的神髓所在。一连串的动作、节拍和姿态表现融合成舞蹈。到目前为止，舞蹈可谓是同步程度最高的团体活动，几乎没有哪种社会性活动像它一样需要人们在时间和空间上达到如此精确的协调一致。
　　虽然舞蹈是人类的一种基本的表达方式，但它一直较少引起神经科学家的关注。而最近，研究人员首次对业余舞者和职业舞者分别进行了脑成像研究。研究针对解答的是这么一些问题：舞者是怎样驾驭空间的？他们是怎样调整舞步的？人们是怎么学会一连串复杂的花式动作的？
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　　也许最令神经科学家们着迷要探究的首要问题就是：人类为什么跳舞？当然，音乐和舞蹈是紧密相连的，很多时候，舞蹈会产生声响。墨西哥城的阿兹特克舞者，其绑腿（又称“开心
　　果”）挂饰里有哈由优特树的种子，他们每挪动一步，这些种子都会相碰发出声响。在其他的许多文化里，人们跳舞时都会在身上或衣服上加上诸如金属片、响板、珠子等等能够发出声音的物件。另外，舞者们还会一边跳舞一边频频拍手，打响指和跺脚。因此，我们提出了一个“躯体打击乐”的假设，这个假设认为舞蹈最初是从一些发声现象演化而来，并且舞蹈和音乐特别是打击乐，相互补充演化发展进而产生了节拍。第一件打击乐器很有可能就是来源于舞蹈服饰上的某些物件，类似于阿兹特克人佩戴的开心果。
　　然而跟音乐不同的是，舞蹈具有很强的表现力和模仿性，这就显示舞蹈也许曾经是一种早期的语言形式。舞蹈的确是典型的肢体语言。我们还发现了一个有趣的现象，研究中，受试者在完成所有动作测试任务时，其右侧大脑半球中对应于左侧大脑半球白洛嘉脑回的位置会被激活，而白洛嘉脑回是左侧大脑额叶里跟语言表达能力直接相关的区域。过去十多年的研究发现，白洛嘉脑回也控制着手语表达。
　　这个发现支持了语言进化研究里面所谓的手势理论。理论的拥护者指出，语言在成为一种发声的表达方式之前是由手势表达系统演化而来的。我们的研究率先发现了腿部运动会激活右侧大脑半球中对应于白洛嘉脑回的部位，这就进一步证明了舞蹈起初是一种表意沟通方式。
　　我们把舞蹈看作是语言表达能力和音乐节奏感的密切结合。这种结合不但使人们可以用身体来表达思想，而且在大家共同起舞的时候，人们之间的凝聚力也加强了。
　　
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