Clinical Memory Research Unit, Department of Clinical Sciences Malmö, Lund University, Lund, Sweden.
German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany.
Hippocampus. 2024 May;34(5):241-260. doi: 10.1002/hipo.23602. Epub 2024 Feb 28.
The medial temporal lobe (MTL) cortex, located adjacent to the hippocampus, is crucial for memory and prone to the accumulation of certain neuropathologies such as Alzheimer's disease neurofibrillary tau tangles. The MTL cortex is composed of several subregions which differ in their functional and cytoarchitectonic features. As neuroanatomical schools rely on different cytoarchitectonic definitions of these subregions, it is unclear to what extent their delineations of MTL cortex subregions overlap. Here, we provide an overview of cytoarchitectonic definitions of the entorhinal and parahippocampal cortices as well as Brodmann areas (BA) 35 and 36, as provided by four neuroanatomists from different laboratories, aiming to identify the rationale for overlapping and diverging delineations. Nissl-stained series were acquired from the temporal lobes of three human specimens (two right and one left hemisphere). Slices (50 μm thick) were prepared perpendicular to the long axis of the hippocampus spanning the entire longitudinal extent of the MTL cortex. Four neuroanatomists annotated MTL cortex subregions on digitized slices spaced 5 mm apart (pixel size 0.4 μm at 20× magnification). Parcellations, terminology, and border placement were compared among neuroanatomists. Cytoarchitectonic features of each subregion are described in detail. Qualitative analysis of the annotations showed higher agreement in the definitions of the entorhinal cortex and BA35, while the definitions of BA36 and the parahippocampal cortex exhibited less overlap among neuroanatomists. The degree of overlap of cytoarchitectonic definitions was partially reflected in the neuroanatomists' agreement on the respective delineations. Lower agreement in annotations was observed in transitional zones between structures where seminal cytoarchitectonic features are expressed less saliently. The results highlight that definitions and parcellations of the MTL cortex differ among neuroanatomical schools and thereby increase understanding of why these differences may arise. This work sets a crucial foundation to further advance anatomically-informed neuroimaging research on the human MTL cortex.
内侧颞叶（MTL）皮层位于海马体附近，对于记忆至关重要，并且容易积累某些神经病理学，如阿尔茨海默病神经纤维缠结。MTL 皮层由几个亚区组成，这些亚区在功能和细胞构筑特征上有所不同。由于神经解剖学学派依赖于这些亚区的不同细胞构筑定义，因此尚不清楚它们对 MTL 皮层亚区的划分在多大程度上重叠。在这里，我们提供了来自四个不同实验室的四位神经解剖学家提供的内嗅皮层和旁海马皮层以及 Brodmann 区（BA）35 和 36 的细胞构筑定义概述，旨在确定重叠和分歧划分的基本原理。从三个人类标本（两个右侧和一个左侧半球）的颞叶中获取尼氏染色系列。切片（50μm 厚）垂直于海马体的长轴制备，跨越 MTL 皮层的整个纵向范围。四位神经解剖学家在数字化切片上对 MTL 皮层亚区进行注释，切片之间间隔 5mm（20×放大倍数时像素大小为 0.4μm）。比较了神经解剖学家之间的分区、术语和边界放置。详细描述了每个亚区的细胞构筑特征。注释的定性分析表明，内嗅皮层和 BA35 的定义一致性更高，而 BA36 和旁海马皮层的定义则表现出神经解剖学家之间的重叠较少。细胞构筑定义的重叠程度部分反映在神经解剖学家对各自划分的一致性上。在结构之间的过渡区域观察到注释的一致性较低，在这些区域中，重要的细胞构筑特征表达不那么明显。研究结果强调了 MTL 皮层的定义和分区在神经解剖学学派之间存在差异，从而加深了对这些差异产生的原因的理解。这项工作为进一步推进基于解剖学的人类 MTL 皮层神经影像学研究奠定了重要基础。
