Analysis of the output pathway from the basal ganglia by using tracer injection under ultrasonography

为了分析基底节区输出通路的纤维连接和组织，需要将显微注射管精确地插入脑深部结构。为此，我们在本研究中开始使用三维超声设备。三维超声成像是一种基于超声图像自动体积采集和计算机辅助图像重建的新技术。三维重建多平面分析和表面绘制有助于观察显微注射管在脑深部结构中的作用。利用这种技术，我们可以将氟金（一种逆行荧光示踪剂）局部注射到上丘的深层，即黑质网状部的靶核。因此，我们可以在基底神经节的输出核黑质网状部观察到逆行标记的神经元。本研究结果表明，在研究猴脑基底节区输出组织的正反行示迹研究中，三维超声成像是一种比传统二维超声成像更有效的活体实验工具。

Precise penetration of a microinjection pipette into the deep brain structure is necessary to analyze fiber connection and organization of the output pathway of the basal ganglia. For this purpose, we started to use a three-dimensional ultrasonographic equipment in this study. The three-dimensional ultrasonography is new technology based on automatic volume acquisition of ultrasonographic images, and computer-aided image reconstruction. Three-dimensional reconstruction for multiplanar analysis and surface rendering were useful to observe the microinjection pipette in the deep brain structure. Using this technique, we could obtain localized injection of Fluorogold, a retrograde fluorescent tracer, into the deep layers of the superior colliculus, that is a target nucleus of the substantia nigra pars reticulata. Thus, we could observe retrogradely labeled neurons in the substantia nigra pars reticulata, an output nucleus of the basal ganglia. The present results indicate that the three-dimensional ultrasonography for monkey brain is a more powerful tool for experiments in vivo than conventional two-dimensional ultrasonography in antero- or retrograde tracing studies on the output organization of the basal ganglia.