Knudsen E I, Knudsen P F
J Comp Neurol. 1983 Aug 1;218(2):187-96. doi: 10.1002/cne.902180206.
The optic tectum of the owl contains a topographic representation of auditory space. We have investigated the source of this space-mapped auditory activity by using retrograde tracing with horseradish peroxidase. The major source of auditory input to the optic tectum is the ipsilateral external nucleus of the inferior colliculus (ICX), which is known to contain a map of auditory space also. Additional minor projections originate in the superficial nucleus of the inferior colliculus and the nucleus isthmi parvocellularis. There is no apparent projection to the optic tectum from the contralateral ICX or any other brainstem auditory nucleus. The projection from the ICX to the optic tectum is point-to-point: rostral ICX projects to rostral tectum, caudal ICX to caudal tectum, dorsal ICX to dorsomedial tectum, and ventral ICX to ventral tectum. Thus, the space-mapped organization that exists in the ICX is passed on by topographic projections to the optic tectum.
猫头鹰的视顶盖包含听觉空间的拓扑表征。我们通过使用辣根过氧化物酶逆行追踪法，研究了这种空间映射听觉活动的来源。视顶盖听觉输入的主要来源是同侧下丘的外侧核（ICX），已知该核也包含听觉空间图谱。其他次要投射起源于下丘的浅层核和峡核小细胞部。对侧ICX或任何其他脑干听觉核均未发现对视顶盖有明显投射。从ICX到视顶盖呈点对点投射：ICX的嘴侧投射到顶盖嘴侧，ICX的尾侧投射到顶盖尾侧，ICX的背侧投射到顶盖背内侧，ICX的腹侧投射到顶盖腹侧。因此，ICX中存在的空间映射组织通过拓扑投射传递到视顶盖。
