Tychsen L, Burkhalter A
Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
J Comp Neurol. 1997 Nov 10;388(1):32-46. doi: 10.1002/(sici)1096-9861(19971110)388:1<32::aid-cne3>3.0.co;2-p.
To quantify asymmetries of input from the two eyes into each cerebral hemisphere, we measured ocular dominance column (ODC) widths and areas in the striate visual cortex (area V1) of macaque monkeys. Ocular dominance stripes in layer 4C were labeled by using transneuronal transport of intraocularly injected wheat germ agglutinin-horseradish peroxidase (WGA-HRP) or cytochrome oxidase (CO) histochemistry, after deafferentation of one eye or even by leaving afferent input intact. In infant monkey aged 4 and 8 weeks, ocular dominance stripes labeled by WGA-HRP appeared adultlike with smooth, sharply defined borders. In normal infant and normal adult macaque, ocular dominance stripes driven by the nasal retina (i.e., contralateral eye) were consistently wider than stripes driven by the temporal retina (i.e., ipsilateral eye). Asymmetries in the percentage of area V1 driven by nasal vs. temporal ODCs showed a similar "nasal bias": in infant macaque, approximately 58% of ODCs in V1 were driven by nasal retina, and in adult macaque approximately 57%. The asymmetries tended to be slightly smaller in opercular V1 and greater in calcarine V1. "Spontaneous" ocular dominance stripes were revealed by CO staining of V1 in a naturally strabismic monkey and in a monkey made strabismic by early postnatal alternating monocular occlusion. In these animals, ocular dominance stripes and CO blobs corresponding to the nasal retina stained more intensely for CO in both the right and left V1. ODC spacing and the nasotemporal asymmetry in ODC width and area were similar in strabismic and normal monkeys. Our results in normal monkeys extend the observations of previous investigators and verify that nasotemporal inputs to opercular and calcarine V1 are unequal, with a consistent bias favoring inputs from the nasal retina. The CO results in strabismic macaque suggest that the nasal ODC bias promotes interocular suppression when activity in neighboring ODCs is decorrelated by abnormal binocular experience in infancy.
为了量化两只眼睛输入到每个大脑半球的不对称性，我们测量了猕猴纹状视觉皮层（V1区）中眼优势柱（ODC）的宽度和面积。在一只眼睛去传入神经后，甚至在传入输入保持完整的情况下，通过眼内注射小麦胚凝集素-辣根过氧化物酶（WGA-HRP）的跨神经元运输或细胞色素氧化酶（CO）组织化学对4C层中的眼优势条纹进行标记。在4周和8周龄的幼猴中，由WGA-HRP标记的眼优势条纹呈现出类似成年猴的特征，边界光滑且清晰。在正常幼猴和成年猕猴中，由鼻侧视网膜驱动的眼优势条纹（即对侧眼）始终比由颞侧视网膜驱动的条纹（即同侧眼）更宽。由鼻侧与颞侧ODC驱动的V1区面积百分比的不对称性表现出类似的“鼻侧偏向”：在幼猴中，V1区约58%的ODC由鼻侧视网膜驱动，在成年猕猴中约为57%。这种不对称性在枕叶V1区往往略小，而在距状V1区则更大。通过对一只自然斜视的猴子以及一只在出生后早期通过交替单眼遮挡而致斜视的猴子的V1区进行CO染色，揭示了“自发”的眼优势条纹。在这些动物中，对应于鼻侧视网膜的眼优势条纹和CO斑在左右V1区中CO染色都更强烈。斜视猴子和正常猴子的ODC间距以及ODC宽度和面积的鼻颞不对称性相似。我们在正常猴子中的研究结果扩展了先前研究者的观察结果，并证实了枕叶和距状V1区的鼻颞输入是不相等的，始终存在偏向鼻侧视网膜输入的倾向。斜视猕猴的CO结果表明，当相邻ODC中的活动因婴儿期异常的双眼经历而失去相关性时，鼻侧ODC偏向会促进眼间抑制。
