The hippocampus is necessary for binding and reconstituting information in relational memory. These essential memory functions are supported by the distinct cytoarchitecture of the hippocampal subfields. Magnetic resonance elastography is an emerging tool that provides sensitive estimates of microstructure vis-à-vis tissue mechanical properties. Here, we report the first in vivo study of human hippocampal subfield viscoelastic stiffness and damping ratio. Stiffness describes resistance of a viscoelastic tissue to a stress and is thought to reflect the relative composition of tissue at the microscale; damping ratio describes relative viscous-to-elastic behavior and is thought to generally reflect microstructural organization. Measures from the subiculum (combined with presubiculum and parasubiculum), cornu ammonis (CA) 1–2, and CA3-dentate gyrus (CA3-DG) were collected in a sample of healthy, cognitively normal men (n = 20, age = 18–33 years). In line with known cytoarchitecture, the subiculum demonstrated the lowest damping ratio, followed by CA3-DG and then combined CA1–CA2. Moreover, damping ratio of the CA3-DG—potentially reflective of number of cells and their connections—predicted relational memory accuracy and alone replicated most of the variance in performance that was explained by the whole hippocampus. Stiffness did not differentiate the hippocampal subfields and was unrelated to task performance in this sample. Viscoelasticity measured with magnetic resonance elastography appears to be sensitive to microstructural properties relevant to specific memory function, even in healthy younger adults, and is a promising tool for future studies of hippocampal structure in aging and related diseases.

海马体对于在关系记忆中绑定和重构信息是必要的。这些基本的记忆功能得到了海马亚区独特的细胞结构的支持。磁共振弹性成像是一种新兴工具，可提供微观结构相对于组织机械特性的敏感估计。在这里，我们报告了人类海马子场粘弹性刚度和阻尼比的首次体内研究。刚度描述了粘弹性组织对应力的抵抗力，被认为反映了组织在微观尺度上的相对组成；阻尼比描述了相对的粘弹性行为，并被认为通常反映了微观结构组织。来自 subiculum 的措施（结合 presubiculum 和 parasubiculum），cornu ammonis (CA) 1-2，n = 20，年龄 = 18-33 岁）。与已知的细胞结构一致，下托的阻尼比最低，其次是 CA3-DG，然后是 CA1-CA2。此外，CA3-DG 的阻尼比（可能反映细胞数量及其连接）预测了关系记忆的准确性，并且单独复制了由整个海马体解释的大部分性能差异。刚度不区分海马亚区，并且与该样本中的任务表现无关。用磁共振弹性成像测量的粘弹性似乎对与特定记忆功能相关的微观结构特性敏感，即使在健康的年轻人中也是如此，并且是未来研究衰老和相关疾病中海马结构的有前途的工具。