PDF(Pubmed)
Abstract：
The existence of cortical columns, regarded as computational units underlying both lower and higher-order information processing, has long been associated with highly evolved brains, and previous studies suggested their absence in rodents. However, recent discoveries have unveiled the presence of ocular dominance columns (ODCs) in the primary visual cortex (V1) of Long-Evans rats. These domains exhibit continuity from layer 2 through layer 6, confirming their identity as genuine ODCs. Notably, ODCs are also observed in Brown Norway rats, a strain closely related to wild rats, suggesting the physiological relevance of ODCs in natural survival contexts, although they are lacking in albino rats. This discovery has enabled researchers to explore the development and plasticity of cortical columns using a multidisciplinary approach, leveraging studies involving hundreds of individuals-an endeavor challenging in carnivore and primate species. Notably, developmental trajectories differ depending on the aspect under examination: while the distribution of geniculo-cortical afferent terminals indicates matured ODCs even before eye-opening, consistent with prevailing theories in carnivore/primate studies, examination of cortical neuron spiking activities reveals immature ODCs until postnatal day 35, suggesting delayed maturation of functional synapses which is dependent on visual experience. This developmental gap might be recognized as \'critical period\' for ocular dominance plasticity in previous studies. In this article, I summarize cross-species differences in ODCs and geniculo-cortical network, followed by a discussion on the development, plasticity, and evolutionary significance of rat ODCs. I discuss classical and recent studies on critical period plasticity in the venue where critical period plasticity might be a component of experience-dependent development. Consequently, this series of studies prompts a paradigm shift in our understanding of species conservation of cortical columns and the nature of plasticity during the classical critical period.
摘要：
皮质柱的存在，被视为低阶和高阶信息处理的计算单元，长期以来一直与高度进化的大脑有关，以前的研究表明它们在啮齿动物中不存在。然而,最近的发现揭示了Long-Evans大鼠初级视觉皮层（V1）中存在眼优势柱（ODC）。这些域表现出从第2层到第6层的连续性,确认它们是真正的ODC。值得注意的是,在布朗挪威大鼠中也观察到ODC，一种与野鼠密切相关的品系，表明ODCs在自然生存环境中的生理相关性，尽管白化病大鼠缺乏它们。这一发现使研究人员能够使用多学科方法探索皮质柱的发育和可塑性，利用涉及数百个个体的研究，这是对食肉动物和灵长类动物物种的挑战。值得注意的是,发育轨迹根据所检查的方面而有所不同：而膝皮质传入末端的分布甚至在睁眼之前就表明成熟的ODC，与食肉动物/灵长类动物研究中的流行理论一致，皮层神经元尖峰活动的检查显示，直到出生后第35天，未成熟的ODC，这表明功能突触的成熟延迟，这取决于视觉体验。在先前的研究中，这种发育差距可能被认为是眼优势可塑性的“关键时期”。在这篇文章中,我总结了ODC和膝皮质网络的跨物种差异，接下来是关于发展的讨论，可塑性,和大鼠ODCs的进化意义。我在关键期可塑性可能是经验依赖发展的组成部分的场所讨论了有关关键期可塑性的经典和最新研究。因此,这一系列研究促使我们对皮质柱的物种保护和经典关键时期可塑性的理解发生了范式转变。
