Nishio Monami, Liu Xingyu, Mackey Allyson P, Arcaro Michael J
Department of Psychology, School of Arts and Sciences, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
PLoS Biol. 2025 Sep 18;23(9):e3003378. doi: 10.1371/journal.pbio.3003378. eCollection 2025 Sep.
Postnatal brain development in primates involves prolonged structural maturation of the cortex, laying the foundation for advanced perceptual and cognitive functions. In humans, cortical development is thought to progress along a hierarchical gradient from early-maturing sensorimotor regions to later-developing association areas. However, developmental changes across cortical depth, which contribute to both local computation and large-scale network integration, have been largely unexplored. It also remains unclear which features of these maturational trajectories are conserved across primates and how they may have been further extended or modified in humans. Using the T1-weighted/T2-weighted (T1w/T2w) MRI ratio as a noninvasive measure of cortical microarchitecture, we systematically compared depth-dependent and regional developmental trajectories in humans and macaques. We identified a conserved "inside-out" gradient of maturation, with deeper cortical depths exhibiting steeper increases in T1w/T2w ratio and earlier plateaus than superficial depths. This depth-dependent pattern was embedded within a broader hierarchical gradient of maturation across the cortical surface, extending from sensorimotor regions to association cortex. While the spatial structure of these gradients was shared across species, humans exhibited markedly prolonged development across the entire cortical hierarchy, including both sensory and association cortices, and across cortical depths. These findings suggest that conserved developmental gradients are elaborated in humans to support an extended window of postnatal plasticity, enabling the experience-dependent refinement of cortical circuits that underlie the complex, integrative functions central to human perception and cognition.
灵长类动物出生后的大脑发育涉及皮质的长期结构成熟，为高级感知和认知功能奠定基础。在人类中，皮质发育被认为是沿着从早期成熟的感觉运动区域到后期发育的联合区域的层次梯度进行的。然而，对皮质深度的发育变化在很大程度上尚未得到探索，而这些变化对局部计算和大规模网络整合都有贡献。目前也不清楚这些成熟轨迹的哪些特征在灵长类动物中是保守的，以及它们在人类中可能是如何进一步扩展或改变的。我们使用T1加权/T2加权（T1w/T2w）MRI比率作为皮质微结构的非侵入性测量方法，系统地比较了人类和猕猴中依赖深度和区域的发育轨迹。我们确定了一个保守的“由内向外”成熟梯度，皮质较深的深度比较浅的深度表现出T1w/T2w比率更陡峭的增加和更早的平稳期。这种依赖深度的模式嵌入在整个皮质表面更广泛的成熟层次梯度中，从感觉运动区域延伸到联合皮质。虽然这些梯度的空间结构在物种间是共享的，但人类在整个皮质层次中，包括感觉和联合皮质以及皮质深度，都表现出明显延长的发育过程。这些发现表明，保守的发育梯度在人类中得到了细化，以支持出生后可塑性的延长窗口，使依赖经验的皮质回路得以完善，这些回路是人类感知和认知核心的复杂整合功能的基础。
