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

为了分析基底节的纤维连接和输出路径的组织，需要将微量注射吸管精确地穿透到脑深部结构中。为此，我们在本研究中开始使用三维超声设备。三维超声成像是基于超声图像的自动体积采集和计算机辅助图像重建的新技术。三维重建的多平面分析和表面渲染有助于观察脑深部微注射吸管的情况。利用这一技术，我们可以将逆行荧光示踪剂荧光金局部注射到黑质网状部的靶核--上丘的深层。因此，我们可以在基底节的输出核--黑质网状部观察到逆行标记的神经元。结果表明，猴脑三维超声是一种比常规二维超声更有力的实验工具，可用于基底节输出组织的顺行或逆行追踪研究。

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.