根據(jù)牛津大學科學家的研究結(jié)果,，大腦能在受傷后將一些組織特定功能轉(zhuǎn)移到新的健康組織。
研究結(jié)果發(fā)表在最近的刊物《神經(jīng)元》（Neuron）上,，它將幫助科學家們更好的了解中風之后大腦的恢復(fù)過程,。當中風病人大腦被損傷之后，其未受傷的健康大腦組織活躍性通常會提高,，這在恢復(fù)得較差的病人身上表現(xiàn)得更加明顯,。
但是之前科學家一直不清楚這究竟是恢復(fù)緩慢的表現(xiàn)還是幫助病人恢復(fù)的一種適應(yīng)過程——大腦在努力將功能轉(zhuǎn)移到健康組織。
實驗心理學系及MRI中心的Jacinta O’Shea博士和同事利用TMS技術(shù)在健康志愿者身上模擬了大腦損傷,，這一技術(shù)使得主管選擇運動的皮層活動暫時中斷,。然后志愿者被要求完成一些任務(wù)。
結(jié)果表明,，在一開始這些志愿者做出正確的反應(yīng)的速度確實較慢,，但是在4分鐘之后，他們的表現(xiàn)又恢復(fù)正常了,。O’Shea表示：“這意味著大腦或許在其它部分進行了重建,，以補償失去的功能。”
通過對志愿者大腦進行掃描,，科學家發(fā)現(xiàn)在恢復(fù)過程中未被影響的部分活躍性確實加強了,。接下來科學家又對新的活躍區(qū)域進行了干擾，結(jié)果志愿者的表現(xiàn)再次受到影響,。這確認了受到損傷的大腦組織功能轉(zhuǎn)移到了健康的部分,。
轉(zhuǎn)移僅僅發(fā)生在這些功能需要時，O’Shea說：“而且重建的速度非常驚人,，這只需要數(shù)分鐘時間,。我們的發(fā)現(xiàn)表明了大腦的靈活性。”
原文鏈接：http://www.physorg.com/news97504911.html
原始出處:
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
[email protected]
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.
