Thompson A M, Thompson G C
Department of Otorhinolaryngology, University of Oklahoma Health Sciences Center, Oklahoma City 73190.
J Comp Neurol. 1993 Sep 15;335(3):402-12. doi: 10.1002/cne.903350309.
With the objective of defining the relationship of descending inferior colliculus projections to the olivocochlear system in the guinea pig, inferior colliculus neurons were anterogradely labeled with Phaseolus vulgaris-leucoagglutinin and olivocochlear neurons were retrogradely labeled with horseradish peroxidase in the same brain sections. Inferior colliculus neurons were found to project to many nuclei and regions of the hindbrain where olivocochlear neurons reside. The most substantial of these descending projections was to the ipsilateral medioventral periolivary region. Fewer descending projections terminated in the ipsilateral ventral nucleus of the lateral lemniscus, superior paraolivary nucleus, and rostral periolivary region; and even fewer ipsilateral projections terminated in the area surrounding the lateral superior olive, caudal periolivary region, and the lateroventral periolivary region. Descending neurons of the inferior colliculus also project to the contralateral hindbrain first via the lateral lemniscus and then the trapezoid body, to terminate in the contralateral medioventral periolivary region, superior paraolivary nucleus, rostral periolivary region, and the ventral nucleus of the lateral lemniscus. In addition to the projections into these regions that contain olivocochlear neurons, there are varicosities of inferior colliculus neurons that appear to contact the olivocochlear neurons themselves, both ipsilaterally and contralaterally, especially, but not only, in the ipsilateral medioventral periolivary region. We therefore conclude that descending inferior colliculus neurons do provide input to olivocochlear neurons and that the input is not limited to olivocochlear neurons of the ipsilateral medioventral periolivary region. However, given the robust nature of the projection to the ipsilateral medioventral periolivary region and the paucity of contacts observed in that region, we also conclude that the olivocochlear neuron is not the major target of descending inferior colliculus projections.
为了确定豚鼠中脑下丘下行投射与橄榄耳蜗系统之间的关系，在同一脑切片中，用菜豆白细胞凝集素对中脑下丘神经元进行顺行标记，并用辣根过氧化物酶对橄榄耳蜗神经元进行逆行标记。发现中脑下丘神经元投射到许多后脑的核团和区域，而橄榄耳蜗神经元就位于这些区域。这些下行投射中最主要的是到同侧的内侧腹侧橄榄周区域。较少的下行投射终止于同侧外侧丘系腹侧核、上橄榄旁核和橄榄前区；甚至更少的同侧投射终止于外侧上橄榄周围区域、橄榄后区和外侧腹侧橄榄周区域。中脑下丘的下行神经元还首先通过外侧丘系，然后通过斜方体投射到对侧后脑，终止于对侧的内侧腹侧橄榄周区域、上橄榄旁核、橄榄前区和外侧丘系腹侧核。除了投射到这些含有橄榄耳蜗神经元的区域外，中脑下丘神经元的曲张体似乎与同侧和对侧的橄榄耳蜗神经元本身接触，特别是但不限于同侧的内侧腹侧橄榄周区域。因此，我们得出结论，中脑下丘下行神经元确实为橄榄耳蜗神经元提供输入，并且这种输入不限于同侧内侧腹侧橄榄周区域的橄榄耳蜗神经元。然而，鉴于投射到同侧内侧腹侧橄榄周区域的强大性质以及在该区域观察到的接触较少，我们还得出结论，橄榄耳蜗神经元不是中脑下丘下行投射的主要靶点。
