生物谷综合：据美国生活科学网报道，一项针对一名中风患者的个案研究显示，和儿童一样，成年大脑可能也有“可塑性”，具有创造新神经通路的能力。
过去的研究认定：儿童的大脑具有创造新信号通道，改变或适应缺陷的非凡能力，这种现象被科学家称为大脑的可塑性。但成年大脑是否同样具有这种能力一直备受争议。在线版《神经科学杂志》（The Journal of Neuroscience）9月5日发表了这项最新研究成果。它显示，至少有一名中风患者的大脑视觉中枢的神经系统能自行重组，以修复遭损坏的神经通路，最后的结果是视觉感知能力发生变化(可能有所改善)。
美国麻省理工学院麦戈文大脑研究所博士后丹尼尔·迪尔克斯和同事们研究了一名中风患者的大脑，他们把患者简称为“B.L.”。丹尼尔·迪尔克斯是约翰·霍普金斯大学攻读研究生时完成这项研究的。B.L.中风损害了把信息从眼睛传送到初级视觉皮层的神经纤维。初级视觉皮层是大脑后面灰质中的一个区域，依然完好无损。这种损害中断了左上视区和初级视觉皮层通讯区之间的信息交流，在左上视觉区中造成一个盲区。这项针对BL的研究显示，在盲区下面的东西看起来有些变形。
研究人员猜测，这种变形是由初级视觉皮层的改组造成的。这些神经科学家对他们的想法进行了研究。当正方形等物体的图像出现在视区中的不同区域时，他们让BL把注意力放在一个中心盲区上。正方形突然出现在这个盲区时，迪莱科斯什么也没看到。当正方形出现在这个盲区下面时，他看到它变成长方形向上伸进这个盲区。与此同时，这名患者还看到“像铅笔一样”的三角形和“像雪茄一样”的圆形等。
磁共振成像对大脑扫描显示，初级视觉皮层(左上视区)对来自较低左视区的信息做出反应，这种情况在“正常”成人大脑中不会出现。研究负责人说，改变视觉信号的能力是可塑性特点之一，可以合理解释视觉变形的原因。丹尼尔表示：“我们发现了新的功能特性。当初级视觉皮层重新改组时，BL看到了不同图像。”
这一新发现为其他针对成人大脑可塑性能力的研究提供了有力证据。（援引新浪科技）
原始出处:
The Journal of Neuroscience, September 5, 2007, 27(36):9585-9594; doi:10.1523/JNEUROSCI.2650-07.2007
Behavioral/Systems/Cognitive
Human Adult Cortical Reorganization and Consequent Visual Distortion
Daniel D. Dilks,1,3 John T. Serences,2,4 Benjamin J. Rosenau,2 Steven Yantis,2 and Michael McCloskey1
Departments of 1Cognitive Science and 2Psychological and Brain Sciences, Johns Hopkins University, Baltimore, Maryland 21218, 3McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and 4Department of Cognitive Sciences, University of California, Irvine, California 92697
Correspondence should be addressed to Daniel D. Dilks, McGovern Institute for Brain Research, Massachusetts Institute of Technology, 46-4141G, Cambridge, MA 02144. Email: dilks@mit.edu
Neural and behavioral evidence for cortical reorganization in the adult somatosensory system after loss of sensory input (e.g., amputation) has been well documented. In contrast, evidence for reorganization in the adult visual system is far less clear: neural evidence is the subject of controversy, behavioral evidence is sparse, and studies combining neural and behavioral evidence have not previously been reported. Here, we report converging behavioral and neuroimaging evidence from a stroke patient (B.L.) in support of cortical reorganization in the adult human visual system. B.L.'s stroke spared the primary visual cortex (V1), but destroyed fibers that normally provide input to V1 from the upper left visual field (LVF). As a consequence, B.L. is blind in the upper LVF, and exhibits distorted perception in the lower LVF: stimuli appear vertically elongated, toward and into the blind upper LVF. For example, a square presented in the lower LVF is perceived as a rectangle extending upward. We hypothesized that the perceptual distortion was a consequence of cortical reorganization in V1. Extensive behavioral testing supported our hypothesis, and functional magnetic resonance imaging (fMRI) confirmed V1 reorganization. Together, the behavioral and fMRI data show that loss of input to V1 after a stroke leads to cortical reorganization in the adult human visual system, and provide the first evidence that reorganization of the adult visual system affects visual perception. These findings contribute to our understanding of the human adult brain's capacity to change and has implications for topics ranging from learning to recovery from brain damage.
Key words: cortical reorganization; cortical plasticity; primary visual cortex; perceptual distortion; adult human visual system; visual perception
Received Jan. 13, 2006; revised July 17, 2007; accepted July 19, 2007.
Correspondence should be addressed to Daniel D. Dilks, McGovern Institute for Brain Research, Massachusetts Institute of Technology, 46-4141G, Cambridge, MA 02144. Email: dilks@mit.edu
