J. Neurosci.,：左撇子变右撇子 大脑活性会增强

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　J. Neurosci.,：左撇子变右撇子 大脑活性会增强 你是左撇子吗？你曾想过要改变吗？一份最新的研究指出，纠正左撇子，让他们强制使用右手会使大脑部分区域活性增强。相关论文发表在《神经学杂志》（JournalofNeuroscience）上。手的活动往往是由大脑的相反区域控制，如惯用右手者移动手指时，其大脑左半部与动作有关区域的活性就会增强。那么纠正左撇子又会怎样呢？伦敦大学学院的StefanKl鰌pel及同事就此做了实验。他们让惯

图片说明：纠正了的左撇子大脑某些区域的活性会增强。

  生物谷：你是左撇子吗？你曾想过要改变吗？一份最新的研究指出，纠正左撇子，让他们强制使用右手会使大脑部分区域活性增强。相关论文发表在《神经学杂志》（Journal of Neuroscience）上。
   手的活动往往是由大脑的相反区域控制，如惯用右手者移动手指时，其大脑左半部与动作有关区域的活性就会增强。那么纠正左撇子又会怎样呢？
  伦敦大学学院的Stefan Kl鰌pel及同事就此做了实验。他们让惯用右手者、左撇子以及左撇子纠正者完成一个简单的任务，即根据看到的不同符号用不同的手按下按钮。研究人员同时用核磁共振成像（MRI）扫描仪观测他们大脑的活动。
  结果发现，正如所料，左撇子的大脑右半球与动作有关的区域活性强，右手者（包括从左撇子纠正者）的大脑左半球这一区域的活性强。令人感兴趣的是，研究人员发现纠正者大脑左半球区域的活性更强，并且纠正得越彻底活性越强。
  但是研究人员同时还发现，大脑另一些与动作规划有关区域的活性并没有这种转变，纠正者大脑这些区域的活性仍然与未纠正者大脑相应区域的活性类似，不过在强度上纠正者的增加了。Stefan Kl鰌pel说：“他们看起来还是左撇子，而且是强化了的左撇子。”
  美国宾州州立大学心理学家Clare Porac认为，许多纠正者很擅长双手手工技巧，这很好地支持了纠正者大脑两个半区都具有活性的事实。她认为此次研究说明了纠正者脑部活动会增强，但是他们的大脑工作强度并不会增加。
  Stefan Kl鰌pel表示，此次的研究有助于解释大脑怎样影响用手习惯。他说：“最重要的是我们知道了训练可以影响大脑的某些区域，而对另一些区域则不起作用。这不仅仅是关乎用手习惯，更重要的意义在于可塑性方面。”（科学网 ）
原始出处:
The Journal of Neuroscience, July 18, 2007, 27(29):7847-7853; doi:10.1523/JNEUROSCI.1299-07.2007
Can Left-Handedness be Switched? Insights from an Early Switch of Handwriting
Stefan Kl鰌pel,1,2,4 Anna Vongerichten,1 Thilo van Eimeren,1,3 Richard S. J. Frackowiak,2,5,6 and Hartwig R. Siebner1,7
1NeuroImage-Nord, Hamburg-Lübeck-Kiel, Germany, 2Wellcome Trust Centre for Neuroimaging, University College London, London WC1N 3BG, United Kingdom, 3Department of Neurology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany, 4Department of Neurology, Neurozentrum, University Clinic Freiburg, 79106 Freiburg, Germany, 5Laboratory of Neuroimaging, IRCCS Santa Lucia, 00179 Rome, Italy, 6Departement d'Etudes Cognitives, Ecole Normale Superieure, 75005 Paris, France, and 7Department of Neurology, Christian-Albrechts-University, 24105 Kiel, Germany
Correspondence should be addressed to Dr. Stefan Kl鰌pel, Wellcome Trust Centre for Neuroimaging, 12 Queen Square, London WC1N 3BG, UK. Email: s.kloppel@fil.ion.ucl.ac.uk

\"Converted\" left-handers are innately left-handed individuals forced as children to write with the right nondominant hand. We asked how a left-to-right handwriting switch shapes cortical sensorimotor representations of finger movements. In 16 adult converted left-handers and age-matched groups of 16 consistent right-handers and 16 left-handers, we studied movement-related neuronal activity with functional magnetic resonance imaging while participants performed simple unimanual and bimanual movements with right and left index fingers. In converted left-handers, movement-related activity in the primary sensorimotor hand area (SM1) and caudal dorsal premotor cortex (PMd) of the nondominant left hemisphere correlated with the left-to-right shift in handedness. The more right-handed converted left-handers had become, the greater the sensorimotor activation in these areas. Between-group comparisons showed that the switch from left to right hand also reinforced movement representations in the dominant right hemisphere. In converted left-handers, the right inferior parietal cortex and lateral PMd were more active relative to consistent right or left-handers in all motor tasks. These results suggest two distinct neuronal correlates of handedness in human sensorimotor cortex. Although those in executive sensorimotor cortex (i.e., SM1 and adjacent PMd) depend on the hand used throughout life, those in higher-order sensorimotor areas (i.e., inferior parietal cortex and rostrolateral PMd) are invariant and thus cannot be switched to the nondominant hemisphere by educational training.
Key words: handedness; converted left-handers; fMRI; motor control; parietal; plasticity