生物谷：人類大腦存在一種由馬達神經(jīng)細胞構(gòu)成的鏡像神經(jīng)系統(tǒng)（mirror neuron system）,，它能激活一種馬達路徑（motor pathways），從而使人類具有了模仿所見動作的能力,。那么如果身體無法模仿所見動作又會怎樣,？發(fā)表于7月12日《現(xiàn)代生物學》上的一篇論文稱,，在這種情況下，人類大腦會激活一種替代路徑以期達到模仿目的,。這表明大腦馬達系統(tǒng)的運作不僅僅是“復制”所見動作,，更主要的是為了達到某個目的。
該項研究由來自荷蘭,、意大利,、法國的科學家聯(lián)合小組完成。他們向16個正常測試者和2個身體有障礙（無手臂）的測試者放映一般需要用手完成的簡單動作（比如抓取杯子）的錄像,，同時應(yīng)用核磁共振成像技術(shù)（MRI）觀測他們的腦部活動,。
研究人員發(fā)現(xiàn)，在觀看錄像的時候,，所有正常的測試者大腦均激活了能讓他們抓取杯子的馬達路徑,，而無手臂者大腦則激活了能讓他們移動腳的馬達路徑。論文高級作者,、荷蘭格羅寧根大學的神經(jīng)科學家Christian Keysers教授認為,，這一結(jié)果強調(diào)了鏡像神經(jīng)系統(tǒng)的運作并不是簡單的模仿，而是有著特定的目的,。無手臂者認為他們能夠用腳抓起杯子,，所以他們的大腦就有了反應(yīng)。
美國加州大學洛杉磯分校的神經(jīng)學家Marco Iacoboni認為,，這一研究向我們清楚地展示了鏡像神經(jīng)元的作用在于模仿人而不僅僅是動作。但是他同時強調(diào),，兩組測試者腦部活動的水平和區(qū)域存在很大的差異，今后還需要花大力氣深入研究,。（科學網(wǎng)）
原始出處:
Current Biology, Vol , Issue ,
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Aplasics Born without Hands Mirror the Goal of Hand Actions with Their Feet
Valeria Gazzola,1 Henk van der Worp,2 Theo Mulder,2,3 Bruno Wicker,4 Giacomo Rizzolatti,5 and Christian Keysers1,
1 BCN Neuroimaging Center, University Medical Center Groningen, University of Groningen, A. Deusinglaan 2, 9713AW Groningen, The Netherlands
2 Center for Human Movement Sciences, University Medical Center, University of Groningen, 9700 AD Groningen, The Netherlands
3 Royal Netherlands Academy of Arts and Sciences, Kloveniersburgwal 29, 1011 JV Amsterdam, The Netherlands
4 Institut de Neurosciences Cognitives de la Méditerranée, Centre National de la Recherche Scientifique 31, Chemin Joseph Aiguier, 13009 Marseille, France
5 Dipartimento di Neuroscienze, Universita di Parma, Via Volturno, 43100 Parma, Italy
Corresponding author
Christian Keysers
[email protected]
The premotor and parietal mirror neuron system (MNS) is thought to contribute to the understanding of observed actions by mapping them onto “corresponding” motor programs of the observer [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24], but how would the MNS respond to the observation of hand actions if the observer never had hands? Would it not show changes of blood-oxygen-level dependent (BOLD) signal, because the observer lacks motor programs that can resonate [12, 25, 26], or would it show significant changes because the observer has motor programs for the foot or mouth with corresponding goals [15, 17, 19, 27, 28]? We scanned two aplasic subjects, born without arms or hands, while they watched hand actions and compared their brain activity with that of 16 control subjects. All subjects additionally executed actions with different effectors (feet, mouth, and, for controls, hands). The BOLD signal of aplasic individuals within the putative MNS was augmented when they watched hand actions, demonstrating the brain's capacity to mirror actions that deviate from the embodiment of the observer by recruiting voxels involved in the execution of actions that achieve corresponding goals by different effectors. This sheds light on the functional organization of the MNS and predominance of goals in imitation.
