Callosal patches in primary visual cortex of Long Evans rats, normally associated with ocular dominance columns, emerge by postnatal day 10 (P10), but they do not form in rats monocularly enucleated a few days before P10. We investigated whether we could replicate the results of monocular enucleation by using tetrodotoxin (TTX) to block neural activity in one eye, or in primary visual cortex. Animals received daily intravitreal (P6–P9) or intracortical (P7–P9) injections of TTX, and our physiological evaluation of the efficacy of these injections indicated that the blockade induced by a single injection lasted at least 24 h. Four weeks later, the patterns of callosal connections in one hemisphere were revealed after multiple injections of horseradish peroxidase in the other hemisphere. We found that in rats receiving either intravitreal or cortical injections of TTX, the patterns of callosal patches analyzed in tangential sections from the flattened cortex were not significantly different from the pattern in normal rats. Our findings, therefore, suggest that the effects of monocular enucleation on the distribution of callosal connections are not due to the resulting imbalance of afferent ganglion cell activity, and that factors other than neural activity are likely involved.

中文翻译：

---

视网膜或皮质活动的阻断不会阻止通常与初级视觉皮层中的眼优势柱相关的胼胝体斑块的发展

Long Evans 大鼠初级视觉皮层中的胼胝体斑块，通常与眼优势柱相关，在出生后第 10 天 (P10) 出现，但它们不会在 P10 前几天单眼去核的大鼠中形成。我们研究了是否可以通过使用河豚毒素 (TTX) 来阻止一只眼睛或初级视觉皮层的神经活动来复制单眼摘除的结果。动物每天接受 TTX 玻璃体内 (P6-P9) 或皮质内 (P7-P9) 注射，我们对这些注射功效的生理评估表明，单次注射诱导的阻断持续至少 24 小时。四周后，在另一半球多次注射辣根过氧化物酶后，一个半球的胼胝体连接模式被揭示。我们发现，在接受玻璃体内或皮质注射 TTX 的大鼠中，在扁平皮质的切线切片中分析的胼胝体斑块的模式与正常大鼠的模式没有显着差异。因此，我们的研究结果表明，单眼去核对胼胝体连接分布的影响不是由于传入神经节细胞活动的失衡，而是可能涉及神经活动以外的因素。