Purpose Advances in neuroimaging have provided an understanding of the precuneus’(PCu) involvement in functions such as visuospatial processing and cognition. While the PCu has been previously determined to be apart of a higher-order default mode network (DMN), recent studies suggest the presence of possible dissociations from this model in order to explain the diverse functions the PCu facilitates, such as in episodic memory. An improved structural model of the white-matter anatomy of the PCu can demonstrate its unique cerebral connections with adjacent regions which can provide additional clarity on its role in integrating information across higher-order cerebral networks like the DMN. Furthermore, this information can provide clinically actionable anatomic information that can support clinical decision making to improve neurologic outcomes such as during cerebral surgery. Here, we sought to derive the relationship between the precuneus and underlying major white-mater bundles by characterizing its macroscopic connectivity. Methods Structural tractography was performed on twenty healthy adult controls from the Human Connectome Project (HCP) utilizing previously demonstrated methodology. All precuneus connections were mapped in both cerebral hemispheres and inter-hemispheric differences in resultant tract volumes were compared with an unpaired, corrected Mann–Whitney U test and a laterality index (LI) was completed. Ten postmortem dissections were then performed to serve as ground truth by using a modified Klingler technique with careful preservation of relevant white matter bundles. Results The precuneus is a heterogenous cortical region with five major types of connections that were present bilaterally. (1) Short association fibers connect the gyri of the precuneus and connect the precuneus to the superior parietal lobule and the occipital cortex. (2) Four distinct parts of the cingulum bundle connect the precuneus to the frontal lobe and the temporal lobe. (3) The middle longitudinal fasciculus from the precuneus connects to the superior temporal gyrus and the dorsolateral temporal pole. (4) Parietopontine fibers travel as part of the corticopontine fibers to connect the precuneus to pontine regions. (5) An extensive commissural bundle connects the precuneus bilaterally. Conclusion We present a summary of the anatomic connections of the precuneus as part of an effort to understand the function of the precuneus and highlight key white-matter pathways to inform surgical decision-making. Our findings support recent models suggesting unique fiber connections integrating at the precuneus which may suggest finer subsystems of the DMN or unique networks, but further study is necessary to refine our model in greater quantitative detail.

目的神经影像学的进步提供了对楔前叶 (PCu) 参与视觉空间处理和认知等功能的理解。虽然 PCu 先前已被确定为高阶默认模式网络 (DMN) 的一部分，但最近的研究表明可能存在与该模型的分离，以解释 PCu 促进的各种功能，例如在情景记忆中。PCu 的白质解剖结构的改进结构模型可以证明其与相邻区域的独特大脑连接，这可以进一步阐明其在跨高阶大脑网络（如 DMN）整合信息中的作用。此外，该信息可以提供临床上可操作的解剖信息，这些信息可以支持临床决策以改善神经系统结果，例如在脑手术期间。在这里，我们试图通过描述其宏观连通性来推导楔前叶和潜在的主要白质束之间的关系。方法利用先前证明的方法，对来自人类连接组计划 (HCP) 的 20 名健康成人对照进行结构性纤维束成像。所有楔前叶连接都在两个大脑半球进行了映射，并将所得束体积的半球间差异与未配对的、校正的 Mann-Whitney U 检验进行比较，并完成了偏侧指数 (LI)。然后，通过使用改进的 Klingler 技术并仔细保存相关的白质束，进行了十次尸检以作为基本事实。结果楔前叶是一个异质的皮层区域，有五种主要类型的连接存在于双侧。(1)短联合纤维连接楔前叶回，将楔前叶与顶上小叶和枕叶皮质相连。(2) 扣带束的四个不同部分将楔前叶连接到额叶和颞叶。(3)楔前叶的中纵束连接颞上回和颞背外侧极。(4) 桥脑顶纤维作为皮质脑桥纤维的一部分行进，以连接楔前叶和脑桥区域。(5) 一个广泛的连合束连接双侧楔前叶。结论我们总结了楔前叶的解剖连接，作为了解楔前叶功能的一部分，并强调关键的白质通路，为手术决策提供信息。我们的研究结果支持最近的模型，表明独特的纤维连接在楔前叶整合，这可能表明 DMN 或独特网络的子系统更精细，但需要进一步研究以更详细地改进我们的模型。