Wilber Aaron A, Clark Benjamin J, Demecha Alexis J, Mesina Lilia, Vos Jessica M, McNaughton Bruce L
Canadian Centre for Behavioural Neuroscience, The University of Lethbridge Lethbridge, AB, Canada ; Department of Neurobiology and Behavior, University of California Irvine, CA, USA.
Canadian Centre for Behavioural Neuroscience, The University of Lethbridge Lethbridge, AB, Canada ; Department of Psychology, The University of New Mexico Albuquerque, NM, USA.
Front Neural Circuits. 2015 Jan 5;8:146. doi: 10.3389/fncir.2014.00146. eCollection 2014.
A central feature of theories of spatial navigation involves the representation of spatial relationships between objects in complex environments. The parietal cortex has long been linked to the processing of spatial visual information and recent evidence from single unit recording in rodents suggests a role for this region in encoding egocentric and world-centered frames. The rat parietal cortex can be subdivided into four distinct rostral-caudal and medial-lateral regions, which includes a zone previously characterized as secondary visual cortex. At present, very little is known regarding the relative connectivity of these parietal subdivisions. Thus, we set out to map the connectivity of the entire anterior-posterior and medial-lateral span of this region. To do this we used anterograde and retrograde tracers in conjunction with open source neuronal segmentation and tracer detection tools to generate whole brain connectivity maps of parietal inputs and outputs. Our present results show that inputs to the parietal cortex varied significantly along the medial-lateral, but not the rostral-caudal axis. Specifically, retrosplenial connectivity is greater medially, but connectivity with visual cortex, though generally sparse, is more significant laterally. Finally, based on connection density, the connectivity between parietal cortex and hippocampus is indirect and likely achieved largely via dysgranular retrosplenial cortex. Thus, similar to primates, the parietal cortex of rats exhibits a difference in connectivity along the medial-lateral axis, which may represent functionally distinct areas.
空间导航理论的一个核心特征涉及复杂环境中物体之间空间关系的表征。顶叶皮质长期以来一直与空间视觉信息的处理相关联，最近来自啮齿动物单单元记录的证据表明该区域在编码自我中心和以世界为中心的框架中发挥作用。大鼠顶叶皮质可细分为四个不同的前后和内外区域，其中包括一个先前被表征为次级视觉皮质的区域。目前，关于这些顶叶细分区域的相对连接性知之甚少。因此，我们着手绘制该区域整个前后和内外跨度的连接图谱。为此，我们使用顺行和逆行示踪剂，并结合开源神经元分割和示踪剂检测工具，以生成顶叶输入和输出的全脑连接图谱。我们目前的结果表明，顶叶皮质的输入沿内外轴有显著变化，但沿前后轴没有变化。具体而言，压后皮质的连接在内侧更强，但与视觉皮质的连接虽然通常稀疏，但在外侧更显著。最后，基于连接密度，顶叶皮质与海马体之间的连接是间接的，并且可能主要通过颗粒下的压后皮质实现。因此，与灵长类动物类似，大鼠的顶叶皮质在内外轴上的连接存在差异，这可能代表功能上不同的区域。
