Harrison J M, Irving R
Science. 1966 Nov 11;154(3750):738-43. doi: 10.1126/science.154.3750.738.
Examination of the structural organization of the auditory system of the brain stem shows that the system is composed of a number of separate ascending pathways. This suggests that there may be at least two auditory systems, analogous to the rod and cone pathways in vision. We examined this possibility by investigating the variation in relative size of the medial and lateral superior olivary nuclei in a number of different mammalian species. The lateral superior olive is present in the hedgehog (an insectivore), cat (acarnivore), and squirrel monkey a(primate), but the medial superior olive is absent in the hedgehog. In a group of animals of the same taxonomic order (rodents) the lateral superior olive was present in all species examined, but the medial superior olive was almost wholly absent in the mouse and very prominent in the chinchilla and guinea pig. The absence of the medial superior olive in some animals is surprising because recent anatomical and physiological work has implicated the nucleus in auditory localization. Because of this implication, the medial and lateral olivary nuclei were examined in three species of bat and one dolphin, all echolocating animals. The medial superior olive was absent in these animals, and the lateral superior olive was prominent. These observations support the idea that the medial and lateral superior olives are nuclei on two different ascending auditory systems. It was also noted that the medial superior olive was always well developed in animals with well-developed eyes, and this suggested that the nucleus is in some way related to the visual system. We examined this idea by studying the relation between the numbers of cells in the medial superior olive and in the nucleus of the 6th cranial nerve (one of the motor nuclei concerned with eye movement) in a number of mammalian species. An approximately linear function was found between the sizes of the 6th nucleus and of the medial superior olive in three primates with cone-cell retinas (squirrel monkey, man, and macaque) and four rodents with rod-cell retinas (mouse, rat, guinea pig, and chinchilla). The cell numbers for the ground squirrel (a rodent with cone-cell retina) fitted an extension of the primate curve, and the cell numbers for the cat (in whose retina rods predominate) fitted an extension of the rodent curve. Thus, it is clear that the medial superior olive is related to the visual system, and that it is present in animals with cone-cell fovea and retina (diurnalanimals) and animals with rod-cell retina (that is, nocturnal animals) having good vision. In nonvisual nocturnal animals the nucleus is small or absent. The medial superior olive is probably not concerned with auditory localization in the psychophysical sense but is probably concerned with the movement of head and eyes in the direction of a sound in space. Localization in the psychophysical sense and fine auditory discrimination probably depend upon the ascending pathway which includes the lateral superior olive.
对脑干听觉系统结构组织的检查表明，该系统由若干独立的上行通路组成。这表明可能至少存在两个听觉系统，类似于视觉中的视杆和视锥通路。我们通过研究多种不同哺乳动物物种中内侧和外侧上橄榄核相对大小的变化来检验这种可能性。外侧上橄榄核存在于刺猬（食虫动物）、猫（食肉动物）和松鼠猴（灵长类动物）中，但刺猬中没有内侧上橄榄核。在同一分类目（啮齿动物）的一组动物中，所有被检查的物种都有外侧上橄榄核，但内侧上橄榄核在小鼠中几乎完全不存在，而在毛丝鼠和豚鼠中非常显著。某些动物中没有内侧上橄榄核这一情况令人惊讶，因为最近的解剖学和生理学研究表明该核与听觉定位有关。基于这一关联，我们对三种蝙蝠和一只海豚（均为回声定位动物）的内侧和外侧橄榄核进行了检查。这些动物中没有内侧上橄榄核，外侧上橄榄核则很显著。这些观察结果支持了内侧和外侧上橄榄核是两个不同上行听觉系统中的核的观点。还注意到，在眼睛发育良好的动物中，内侧上橄榄核总是发育良好，这表明该核在某种程度上与视觉系统有关。我们通过研究多种哺乳动物物种中内侧上橄榄核和第六脑神经核（与眼球运动有关的运动核之一）中的细胞数量之间的关系来检验这一观点。在三种具有视锥细胞视网膜的灵长类动物（松鼠猴、人类和猕猴）以及四种具有视杆细胞视网膜的啮齿动物（小鼠、大鼠、豚鼠和毛丝鼠）中，发现第六脑神经核和内侧上橄榄核的大小之间存在近似线性的函数关系。地松鼠（一种具有视锥细胞视网膜的啮齿动物）的细胞数量符合灵长类动物曲线的延伸，而猫（其视网膜中视杆细胞占主导）的细胞数量符合啮齿动物曲线的延伸。因此，很明显内侧上橄榄核与视觉系统有关，并且它存在于具有视锥细胞中央凹和视网膜的动物（昼行性动物）以及具有视杆细胞视网膜且视力良好的动物（即夜行性动物）中。在非视觉夜行性动物中，该核很小或不存在。内侧上橄榄核可能在心理物理学意义上与听觉定位无关，但可能与头部和眼睛向空间中声音方向的运动有关。心理物理学意义上的定位和精细听觉辨别可能取决于包括外侧上橄榄核的上行通路。
