Robinson Jennifer L, Zhou Xinyu, Bird Ryan T, Leavitt Mackenzie J, Nichols Steven J, Blaine Sara K, Deshpande Gopikrishna
Department of Psychological Sciences, Auburn University, Auburn, AL, United States.
Department of Electrical and Computer Engineering, Auburn University Magnetic Resonance Imaging Research Center, Auburn University, Auburn, AL, United States.
Front Hum Neurosci. 2021 Nov 1;15:729836. doi: 10.3389/fnhum.2021.729836. eCollection 2021.
The hippocampus is one of the most phylogenetically preserved structures in the mammalian brain. Engaged in a host of diverse cognitive processes, there has been increasing interest in understanding how the hippocampus dynamically supports these functions. One of the lingering questions is how to reconcile the seemingly disparate cytoarchitectonic organization, which favors a dorsal-ventral layering, with the neurofunctional topography, which has strong support for longitudinal axis (anterior-posterior) and medial-lateral orientation. More recently, meta-analytically driven (e.g., big data) approaches have been employed, however, the question remains whether they are sensitive to important task-specific features such as context, cognitive processes recruited, or the type of stimulus being presented. Here, we used hierarchical clustering on functional magnetic resonance imaging (fMRI) data acquired from healthy individuals at 7T using a battery of tasks that engage the hippocampus to determine whether stimulus or task features influence cluster profiles in the left and right hippocampus. Our data suggest that resting state clustering appears to favor the cytoarchitectonic organization, while task-based clustering favors the neurofunctional clustering. Furthermore, encoding tasks were more sensitive to stimulus type than were recognition tasks. Interestingly, a face-name paired associate task had nearly identical clustering profiles for both the encoding and recognition conditions of the task, which were qualitatively morphometrically different than simple encoding of words or faces. Finally, corroborating previous research, the left hippocampus had more stable cluster profiles compared to the right hippocampus. Together, our data suggest that task-based and resting state cluster profiles are different and may account for the disparity or inconsistency in results across studies.
海马体是哺乳动物大脑中系统发育上保存最完好的结构之一。由于它参与了众多不同的认知过程，人们对了解海马体如何动态支持这些功能的兴趣与日俱增。一个长期存在的问题是，如何协调看似不同的细胞结构组织（其有利于背腹分层）与神经功能地形图（其强烈支持纵轴（前后）和内外侧方向）。最近，已经采用了元分析驱动（例如大数据）的方法，然而，问题仍然是它们是否对重要的任务特定特征敏感，例如情境、所招募的认知过程或所呈现刺激的类型。在这里，我们对从健康个体在7T下使用一系列涉及海马体的任务获取的功能磁共振成像（fMRI）数据进行分层聚类，以确定刺激或任务特征是否会影响左右海马体中的聚类概况。我们的数据表明，静息状态聚类似乎有利于细胞结构组织，而基于任务的聚类则有利于神经功能聚类。此外，编码任务比识别任务对刺激类型更敏感。有趣的是，一个面孔-名字配对联想任务在任务的编码和识别条件下具有几乎相同的聚类概况，这在定性形态测量上与单词或面孔的简单编码不同。最后，与先前的研究一致，与右侧海马体相比，左侧海马体具有更稳定的聚类概况。总之，我们的数据表明，基于任务的聚类概况和静息状态聚类概况是不同的，并且可能解释了不同研究结果中的差异或不一致。
