Changes in connectivity after visual cortical brain damage underlie altered visual function
Changes in connectivity after visual cortical brain damage underlie altered visual function
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DOI：
10.1093/brain/awn063
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发表时间：
2008-06-01
期刊：
影响因子：
14.5
通讯作者：
Cowey, Alan
中科院分区：
文献类型：
--
作者：
Bridge, Holly;Thomas, Owen;Cowey, Alan
大脑对损伤或改变的经验进行补偿的能力的全面程度还有待确定。对于评估和理解脑损伤后的康复来说，一个特别重要的问题是，恢复是否涉及新的和异常的神经连接，或者功能的任何变化是由于现有通路的功能招募，或者两者兼而有之。失明是视觉功能改变的一个很好的例子，在这种情况下，部分纹状皮质(V1)完全被破坏的受试者在临床盲区内保留了广泛的视觉能力。由于通向视皮层的主要通路被破坏，备用或恢复的视觉能力必须来自现有的替代通路，或形成新的通路。利用弥散加权MRI，我们发现左侧V1受损的对照组和盲视受试者GY在LGN(外侧膝状体核)和人类运动区MT+/V5之间显示同侧通路(绕过V1)。然而，GY还显示出两个在对照组中缺失的主要特征：(1)右侧LGN至左侧MT+/V5的对侧通路；(2)双侧MT+/V5之间的皮质-皮质联系。这两个观察结果都与GY先前的功能磁共振数据一致，显示MT+/V5的同侧激活增强。也有证据表明GY存在从左侧LGN到右侧MT+/V5的通路，尽管病变使其难以量化。这表明，在儿童大脑皮质受损后，使用不同的大脑区域来处理信息，可能会加强或建立特定的联系。
The full extent of the brain's ability to compensate for damage or changed experience is yet to be established. One question particularly important for evaluating and understanding rehabilitation following brain damage is whether recovery involves new and aberrant neural connections or whether any change in function is due to the functional recruitment of existing pathways, or both. Blindsight, a condition in which subjects with complete destruction of part of striate cortex (V1) retain extensive visual capacities within the clinically blind field, is an excellent example of altered visual function. Since the main pathway to the visual cortex is destroyed, the spared or recovered visual ability must arise from either an existing alternative pathway, or the formation of a new pathway. Using diffusion-weighted MRI, we show that both controls and blindsight subject GY, whose left V1 is destroyed, show an ipsilateral pathway between LGN (lateral geniculate nucleus) and human motion area MT+/V5 (bypassing V1). However, in addition, GY shows two major features absent in controls: (i) a contralateral pathway from right LGN to left MT+/V5, (ii) a substantial cortico-cortical connection between MT+/V5 bilaterally. Both observations are consistent with previous functional MRI data from GYshowing enhanced ipsilateral activation in MT+/V5. There is also evidence for a pathway in GY from left LGN to right MT+/V5, although the lesion makes its quantification difficult. This suggests that employing alternative brain regions for processing of information following cortical damage in childhood may strengthen or establish specific connections.