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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Functional organization of human occipital-callosal fiber tracts
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Functional organization of human occipital-callosal fiber tracts

机译：人枕-call纤维束的功能组织

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Diffusion tensor imaging (DTI) and fiber tracking (FT) were used to measure the occipital lobe fiber tracts connecting the two hemispheres in individual human subjects. These tracts are important for normal vision. Also, damage to portions of these tracts is associated with alexia. To assess the reliability of the DTI-FT measurements, occipital-callosal projections were estimated from each subject's left and right hemispheres independently. The left and right estimates converged onto the same positions within the splenium. We further characterized the properties of the estimated occipital-callosal fiber tracts by combining them with functional MRI. We used functional MRI to identify visual field maps in cortex and labeled fibers by the cortical functional response at the fiber endpoint. This labeling reveals a regular organization of the fibers within the splenium. The dorsal visual maps (dorsal V3, V3A, V3B, V7) send projections through a large band in the middle of the splenium, whereas ventral visual maps (ventral V3, V4) send projections through the inferior-anterior corner of the splenium. The agreement between the independent left/right estimates, further supported by previous descriptions of homologous tracts in macaque, validates the DTI-FT methods. However, a principal limitation of these methods is low sensitivity: a large number of fiber tracts that connect homotopic regions of ventral and lateral visual cortex were undetected. We conclude that most of the estimated tracts are real and can be localized with a precision of 1-2 mm, but many tracts are missed because of data and algorithm limitations.
机译：扩散张量成像（DTI）和纤维追踪（FT）用于测量连接在个体人类受试者中两个半球的枕叶纤维束。这些道对于正常视力很重要。而且，这些道的部分受损与缺氧有关。为了评估DTI-FT测量的可靠性，分别从每个受试者的左半球和右半球估计枕骨call的投影。左右估计收敛到脾内的相同位置。我们通过结合功能性MRI进一步表征了估计的枕-纤维束的特性。我们使用功能性MRI通过纤维末端的皮质功能响应来识别皮层和标记纤维中的视野图。该标签显示了脾内纤维的规则组织。背侧视觉图（背侧V3，V3A，V3B，V7）通过脾中部的大条带发送投影，而腹侧视觉图（腹侧V3，V4）通过脾部的下前角发送投影。独立的左/右估计之间的一致性，再加上先前对猕猴中同源线的描述，进一步证实了DTI-FT方法的有效性。但是，这些方法的主要局限性是灵敏度低：未检测到连接腹侧和外侧视觉皮层同位区域的大量纤维束。我们得出的结论是，大多数估计的区域都是真实的，并且可以以1-2 mm的精度进行定位，但是由于数据和算法的限制，许多区域被遗漏了。

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