Neuron：大脑能迅速使受损组织重建
根据牛津大学科学家的研究结果，大脑能在受伤后将一些组织特定功能转移到新的健康组织。
研究结果发表在最近的刊物《神经元》（Neuron）上，它将帮助科学家们更好的了解中风之后大脑的恢复过程。当中风病人大脑被损伤之后，其未受伤的健康大脑组织活跃性通常会提高，这在恢复得较差的病人身上表现得更加明显。
但是之前科学家一直不清楚这究竟是恢复缓慢的表现还是帮助病人恢复的一种适应过程——大脑在努力将功能转移到健康组织。
实验心理学系及MRI中心的Jacinta O’Shea博士和同事利用TMS技术在健康志愿者身上模拟了大脑损伤，这一技术使得主管选择运动的皮层活动暂时中断。然后志愿者被要求完成一些任务。
结果表明，在一开始这些志愿者做出正确的反应的速度确实较慢，但是在4分钟之后，他们的表现又恢复正常了。O’Shea表示：“这意味着大脑或许在其它部分进行了重建，以补偿失去的功能。”
通过对志愿者大脑进行扫描，科学家发现在恢复过程中未被影响的部分活跃性确实加强了。接下来科学家又对新的活跃区域进行了干扰，结果志愿者的表现再次受到影响。这确认了受到损伤的大脑组织功能转移到了健康的部分。
转移仅仅发生在这些功能需要时，O’Shea说：“而且重建的速度非常惊人，这只需要数分钟时间。我们的发现表明了大脑的灵活性。”
原文链接：http://www.physorg.com/news97504911.html
原始出处:
Neuron, Vol 54, 479-490, 03 May 2007
Article
Functionally Specific Reorganization in Human Premotor Cortex
Jacinta O'Shea,1,
Heidi Johansen-Berg,2 Danielle Trief,1 Silke Göbel,1,3 and Matthew F.S. Rushworth1,2
1 Department of Experimental Psychology, University of Oxford, South Parks Road, Oxford OX1 3UD, United Kingdom
2 Centre for Functional MRI of the Brain, John Radcliffe Hospital, University of Oxford, South Parks Road, Oxford OX1 3UD, United Kingdom
Corresponding author
Jacinta O'Shea
jacinta.oshea@psy.ox.ac.uk
Summary
After unilateral stroke, the dorsal premotor cortex (PMd) in the intact hemisphere is often more active during movement of an affected limb. Whether this contributes to motor recovery is unclear. Functional magnetic resonance imaging (fMRI) was used to investigate short-term reorganization in right PMd after transcranial magnetic stimulation (TMS) disrupted the dominant left PMd, which is specialized for action selection. Even when 1 Hz left PMd TMS had no effect on behavior, there was a compensatory increase in activity in right PMd and connected medial premotor areas. This activity was specific to task periods of action selection as opposed to action execution. Compensatory activation changes were both functionally specific and anatomically specific: the same pattern was not seen after TMS of left sensorimotor cortex. Subsequent TMS of the reorganized right PMd did disrupt performance. Thus, this pattern of functional reorganization has a causal role in preserving behavior after neuronal challenge.
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