McMullen N T, de Venecia R K
Department of Anatomy, University of Arizona College of Medicine, Tucson 85724.
Brain Res. 1993 Aug 27;620(2):317-22. doi: 10.1016/0006-8993(93)90173-k.
Thalamocortical afferents to the primary auditory cortex of the rabbit were labeled by the iontophoretic injection of the anterograde tracers PHA-L or biocytin into the ventral division of the medial geniculate body (vMGB). Single injections of either tracer into the vMGB labeled multiple "patches" of afferent axons in lamina III/IV of the ipsilateral auditory cortex. Serial section analysis revealed that single patches were elongated in the rostral-caudal axis forming bands of approximately 2 mm in length. The orientation of the bands was similar to the isofrequency contours of the tonotopic maps derived from prior electrophysiological experiments. Within the coronal plane, the topography of the patches is remarkably similar to the intermittent distribution of binaural interaction subclasses described in physiological studies. Our results are consistent with a model of vMGB organization containing functionally distinct, parallel anatomical pathways to AI.
通过将顺行示踪剂PHA-L或生物胞素离子导入注射到内侧膝状体腹侧部（vMGB），对家兔初级听觉皮层的丘脑皮质传入纤维进行标记。将两种示踪剂中的任何一种单次注射到vMGB中，均可标记同侧听觉皮层III/IV层中多个传入轴突“斑块”。连续切片分析显示，单个斑块在头-尾轴上呈细长形，形成长度约为2毫米的带。这些带的方向与先前电生理实验得出的音频拓扑图的等频率轮廓相似。在冠状平面内，斑块的拓扑结构与生理学研究中描述的双耳相互作用亚类的间歇性分布非常相似。我们的结果与一个包含功能上不同的、通向初级听觉皮层（AI）的平行解剖通路的vMGB组织模型一致。
