Diameter, Length, Speed, and Conduction Delay of Callosal Axons in Macaque Monkeys and Humans: Comparing Data from Histology and Magnetic Resonance Imaging Diffusion Tractography
Diameter, Length, Speed, and Conduction Delay of Callosal Axons in Macaque Monkeys and Humans: Comparing Data from Histology and Magnetic Resonance Imaging Diffusion Tractography
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DOI：
10.1523/jneurosci.0761-13.2013
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发表时间：
2013-09-04
影响因子：
5.3
通讯作者：
Innocenti, Giorgio M.
中科院分区：
文献类型：
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作者：
Caminiti, Roberto;Carducci, Filippo;Innocenti, Giorgio M.
3只猕猴和13名健康志愿者接受了3特斯拉扫描仪的扩散张量MRI，用于不同区域的胼胝体束的扩散道追踪（DTT）重建。在6只猕猴和3名人类受试者中，从组织学数据中获得纤维束的长度，并结合轴突直径分布的信息，以估计来自不同区域的胼胝体传导延迟。结果表明，在猴子中，与DTT获得的束长度的频谱密切匹配，从组织学重建的轴突标记的顺行运输示踪剂估计。对于胼胝体的每个部分，我们得到了非常相似的传导延迟，无论是从纤维束成像或标记轴突的组织学分析获得的传导距离。这种直接验证的DTT测量的组织学方法在猴子的胼胝体传导距离和延迟在人类中的计算的先决条件，这是我们以前获得的胼胝体轴突的长度外推的猴子，成比例的两个物种的脑体积。对于这项分析，我们使用的轴突直径分布从胼胝体的四个不同部门。和猴子一样，人类的胼胝体传导延迟最短的是运动区、躯体感觉区和运动前区;最长的是颞叶区、顶叶区和视觉区。这些结果提供了第一个组织学验证的解剖数据的连接长度在灵长类动物大脑的基础上DTT成像。
Three macaque monkeys and 13 healthy human volunteers underwent diffusion tensor MRI with a 3 Tesla scanner for diffusion tract tracing (DTT) reconstruction of callosal bundles from different areas. In six macaque monkeys and three human subjects, the length of fiber tracts was obtained from histological data and combined with information on the distribution of axon diameter, so as to estimate callosal conduction delays from different areas. The results showed that in monkeys, the spectrum of tract lengths obtained with DTT closely matches that estimated from histological reconstruction of axons labeled with an anterogradely transported tracer. For each sector of the callosum, we obtained very similar conduction delays regardless of whether conduction distance was obtained from tractography or from histological analysis of labeled axons. This direct validation of DTT measurements by histological methods in monkeys was a prerequisite for the computation of the callosal conduction distances and delays in humans, which we had previously obtained by extrapolating the length of callosal axons from that of the monkey, proportionally to the brain volumes in the two species. For this analysis, we used the distribution of axon diameters from four different sectors of the corpus callosum. As in monkeys, in humans the shortest callosal conduction delays were those of motor, somatosensory, and premotor areas; the longer ones were those of temporal, parietal, and visual areas. These results provide the first histological validation of anatomical data about connection length in the primate brain based on DTT imaging.